### 19 Environmental Impact Analysis (EIA)

Page 19-48 Petrobras America Inc. Development Operations Coordination Document Cascade / Chinook Development Project Table 19-17 Race and Ethnicity Characteristics of the State of Mississippi and Mississippi Counties Where Onshore Support Facilities may be Located

Category Jackson County State of Mississippi Total Population 139,668 2,967,297RaceandEthnicity White 72.1% 59.1%
Black or African American 21.5% 37.0%

American Indian and Alaska Native 0.4% 0.5%

Asian 2.2% 0.9%
Native Hawaiian or Pacific Islander - -

Two or More Races 1.9% 1.1% Hispanic or Latino (of any race) 4.6% 2.7%

Source: U.S. Census Bureau 2010 

### As of the 2010 U.S. Census, the median household income in Mississippi was $36,764, and 21.8% of families lived below poverty level. Some 26.0% of people are under 18 years and over age 65. Jackson County had a higher median household income ($48,187), a lower than state percentage of families living below poverty level (14.1%). Economic characteristics data from the 2010 U.S Census for the state of Mississippi and Jackson County are summarized below in Table 19-18.

Table 19-18 Economic Characteristics of the State of Mississippi and Mississippi

Counties Where Onshore Support Facilities may be Located

Category Jackson County State of Mississippi Population under 18 years old 25.8% 26.9% Population Over 65 years old 12.5% 12.8%
Median Household Income in 2009 (Dollars) 48,187 36,764

Total Families 48,332 1,085,836 Families Below Poverty Level Income 14.1% 21.8%

Source: U.S. Census Bureau 2010


### 19(b).13 Infrastructure Marine Support Vessels As of 2002, there were 376 supply vessels (platform supply vessels) and anchor handling tugs/supply vessels in the GoM (MMS 2002). Of the 376 supply vessels, 116 were built since 1996. The numbers of marine support and construction vessels are described in detail in Section 15.

### 19 Environmental Impact Analysis (EIA)

Petrobras America Inc. Page 19-49 Development Operations Coordination Document Cascade / Chinook Development Project Helicopters Helicopters are one of the primary modes of transporting personnel between service bases and offshore platforms, drilling rigs, and barges (MMS 2001). They would also be periodically utilized to transport certain types of equipment and supplies to the FPSO, drilling rigs, and construction vessels. The number of helicopters to be used is described in detail in Section 15. Helicopters are regulated by the Federal Aviation Administration (FAA) and can stop to refuel on several offshore platforms (MMS 2002). The FPSO and drilling rigs will be setup with fueling stations onboard.
19(b).14 Onshore Infrastructure

Port Fourchon Port Fourchon is a multiuse port located at the mouth of Bayou Lafourche, approximately 60 miles south of New Orleans. The port has several support bases supporting the offshore oil and gas industry in the GoM. The port can service deepwater supply vessels due to the channel depth, allowing these vessels to take on fuel, water, deck cargo, and other necessities efficiently at the same covered dock (Coastal Marine Institute [CMI]/MMS 2002). Port Fourchon also houses a large number of docks with crane service, loading/unloading equipment, warehouses, refrigerated warehouse, and numerous storage yards. The port is connected to the GoM via the inshore channel of Belle Pass and Bayou Lafourche, with a depth of 24 feet and a bottom width of 300 feet (MMS 2004).

Contractors or Vendors OCS development in the GoM is supported by an extensive onshore infrastructure. In turn, this industry is supported by thousands of contractors and businesses which can be found adjacent to port facilities. Offshore support businesses include the fabrication industry; which in the last 50 years has been termed the cornerstone of the offshore oil and gas industry, with a corridor extending from the Texas/Mexico border to Alabama (MMS 2002). Other support services include construction and repair, drilling, chemical, and transportation companies. Onshore support companies include pipe laying and burial, shipbuilding, maintenance, and repair. Warehouses are also required onshore for storage, as well as, quarters for crew. The proposed development would utilize existing infrastructure at support and service facilities located in Port Fourchon, as well as the onshore transport, refining, and processing capabilities at the ports and facilities located along the Gulf coast from Texas to Mississippi.

Land Use The oil and gas industry in the GoM has resulted in an extensive network of onshore and offshore support facilities, and onshore refining, separation, and processing facilities for crude oil and natural gas. No expansion of existing facilities or construction of new facilities would be necessary as part of the proposed action. No new dredging or land use changes to coastal areas would occur as a result of the Cascade / Chinook Development.

### 19 Environmental Impact Analysis (EIA)

Page 19-50 Petrobras America Inc. Development Operations Coordination Document Cascade / Chinook Development Project Recreational and Commercial Fishing Marine Fisheries, including recreational and commercial fishing, are previously addressed in Section 19(b).8 Marine Fisheries . Due to the significant water depth at the project site, recreational fishing activities are not expected to occur in or around the area. Some pelagic longline commercial fishing is likely to occur near or within the area of the Cascade / Chinook fields.
19(b).15 Archeological Resources [PROPRIETARY] Archeological resources are protected under the Archeological Resources Protection Act of 1979 (PL 96-95, 16 USC 470aa-mm). Archaeological resources are any material remains of human life or activities that are at least 50 years of age and are of archaeological interest. Shipwreck sites on the OCS are protected by MMS through NTL 2005-G07, Archaeological Resource Surveys and Reports . There are more than 2,100 historic shipwrecks in the Federal waters of the GoM (MMS 2005). In addition to identifying the reported or known locations of these shipwrecks, this study also assigned a location reliability rating to each of these sites. The report lists blocks currently requiring an archaeological survey and report; and modifications to the survey lane spacing for blocks already on the list. The shipwreck database identifies two types of high-probability areas. The first area is within 10 km from shore and the second is near to historic ports, barrier islands, and other similar areas (Pearson et al. 2003). Based on this and other studies, MMS has determined where the highest potential for historic resources exists in the GoM per NTL 2006-G07, Revisions to the List of OCS Lease Blocks Requiring Archaeological Resource Surveys and Report . Details about recent discoveries, and their potential eligibility for listing under the National Register of Historic Places, can be found in Enright et al . (2006) and MMS (2005). The Lease OCS-G 16965 block in the Cascade Field (Walker Ridge Area, Block 206) is not located in an area of high shipwreck potential. To identify shallow hazards and to ensure any historic sites are identified and avoided, a shallow hazards assessment of the seafloor was conducted. The location of the shipwreck will not impact the routing of the pipeline (i.e. there is adequate space in the geophysical survey corridor to avoid the shipwreck). The finding was reported to BOEM as required.

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Petrobras America Inc. Page 19-51 Development Operations Coordination Document Cascade / Chinook Development Project 19(b).16 Other Uses of the Marine Environment Nearshore and offshore uses of the marine environment include military use areas and commercial uses, which are described below. Military Activities The military has designated several areas within the GoM for training, operations, and testing which are known as Military Warning Areas (MWAs). The Central Planning Area has five designated MWAs used for military operations; four of these are located within 100 miles of the proposed project locations in Walker Ridge Blocks 425 and 469. These areas are designated W-92 (approximately 30 miles north of the site), W-59A (approximately 112 miles), W-59BC (approximately 150 miles), and W-147AB (approximately 112 miles). PAI would not conduct operations within these areas but the supply vessels, helicopters, and tankers would likely transit the MWAs on their way to onshore support facilities. Ordinance Disposal Areas There are two inactive disposal areas located in the Mississippi Canyon area but these are approximately 80 miles (128 km) from the proposed site and PAI is not proposing to conduct operations that could affect munitions that have been disposed in these areas. Other Mineral Exploitation To date, sand and gravel is not being mined offshore Texas in federal waters of the OCS; however, sources for future mining have been identified. In Louisiana, the Ship Shoal area has been identified as a potential source of sand for barrier island and inland marsh restoration projects. Any potential sand and gravel source sites are over 100 miles (161 km) away to not cause any effect to the proposed activities. Another potential resource for extraction is gas hydrates. There has been exploration into the location and distribution of gas hydrates along the continental slope of the GoM which could lead to commercial extraction within the next few years. Lightering Operations Lightering operations involve the offloading of crude oil from very large crude carriers (VLCCs) or ultra large crude carriers (ULCCs) to smaller shuttle tankers at sea. These small tankers then transport the crude to onshore terminals for offloading. For safety reasons the USCG has designated lightering areas in the GoM under 33 CFR 156.300 Subpart B; these are located more than 60 miles (96 km) from the baseline of the territorial sea (Mineral Management Service 2000). The entire area around the Cascade / Chinook development is within the Gulfmex No. 2 area, which has been designated until 2015 as a lightering zone for single-hulled tankers as shown in Figure 19-6. Walker Ridge Blocks 469 and 470 are on the zone’s southern boundary. Only three companies are currently conducting lightering operations in the Gulfmex No. 2 lightering zone (Clark 2006). These companies, along with the approximate percentage of lightering operations in the Gulfmex 2 zone, are: Skaugen

### 19 Environmental Impact Analysis (EIA)

Page 19-52 Petrobras America Inc. Development Operations Coordination Document Cascade / Chinook Development Project Petrotrans (40-45%), American Eagle Tankers (40-45%) and Heinrich Lightering Services (15-20%; Clark 2006). Because most of the lightering vessels are now double hulled and can lighter outside these areas, the Gulfmex No. 2 lightering zone is not highly utilized by industry and is only required for non-double hulled tankers; which will be phased out by 2015 (Clark 2006). The area that is used within Gulfmex No. 2 is also located closer to shore in the very northeast corner of lightering area, which is far from the Cascade / Chinook Development. Any lightering vessels and crude oil carriers using the Gulfmex No. 2 zone are unlikely to affect PAI’s operations.

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Petrobras America Inc. Page 19-53 Development Operations Coordination Document Cascade / Chinook Development Project

Figure 19-6 - Gulfmex No. 2 Lightering Area

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Page 19-54 Petrobras America Inc. Development Operations Coordination Document Cascade / Chinook Development Project 

### 19(c) Project Impacts
Table 19-19 and subsequent sections describe the potential impacts to marine and coastal resources that may occur from the impact producing factors that discussed in Section 19(a). If an effect was identified, it has been determined that it would likely result in a minor, temporary impact. The only impact producing factor which could have significant effects is a catastrophic oil spill, which would be an extremely unlikely event given the controls that PAI will have in place. See Section 1(f) to review the controls associated with well drilling and FPSO offloading, which is the operation which provides the most credible exposure to oil spills from an FPSO.

Table 19-19 - Potential Impacts to Marine and Coastal Resources

Environmental Resources Impact Producing Factors (IPFs)Emissions(air,noise,light,etc.)Effluents(muds,cuttings,otherdischargestothewatercolumnorseafloor)Physicaldisturbancestotheseafloor(rigoranchoremplacements,etc.)WastessenttoshorefortreatmentordisposalAccidents(e.g.oilspills)Neworunusualtechnology

Site Specific Resources
Chemosynthetic communities 

###       Water quality 

###       Fisheries 

###       Marine mammals 

###       Sea turtles 

###       Air quality 

###       Shipwreck sites (known or potential) 

###      
Resources in the Vicinity

Essential fish habitat 

###       Marine and pelagic birds 

###       Public health and safety 

###      

Coastal and Onshore Resources

Beaches 

###       Wetlands 

###       Shorebirds and coastal nesting birds 

###       Coastal wildlife refuges 

###       Wilderness areas 

###       Key:  = Denotes that there could be a potential impact. Refer to Section 19(c) for details of the analysis.

 = Denotes that no impact was identified.

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Petrobras America Inc. Page 19-55 Development Operations Coordination Document Cascade / Chinook Development Project 19(c).1 Air Emissions Emissions of air pollutants during the project would occur from the FPSO, shuttle vessels, drilling rigs, construction vessels, and marine support vessels and helicopters. This would primarily occur from the combustion of fuels related to the various engines, generators, and other pumps or motors. Refer to Section 8 and Appendix 3 for additional details. The initial evaluation compares the worst-case emissions to the BOEM exemption criteria. The proposed operations in the Cascade Field do not exceed the BOEM exemption level criteria and therefore would not be expected to have an impact on onshore areas. In some unusual situations during production operations (i.e. process upsets), gas could be flared for short durations. The FPSO would be equipped with two independent flare systems, one operating at high pressure and the other at low pressure, to collect and burn residual gases released from safety valves, pressure control valves, blowdown valves, pipelines, etc. It is possible that some emergency flaring could occur for short periods (i.e. several days per well) during well testing. This was addressed in the initial DOCD. Hydrogen sulfide (H 2 

### S) is not present in significant amounts (i.e. the amount present is less then 20 ppmv) in the Cascade reservoir. Overall, the emissions of pollutants from this project are not expected to impact offshore air quality. The project site is approximately 165 miles (265.5 km) from the Louisiana coast. As indicated in Section 19 (b)1, air quality to onshore is dependent upon meteorological conditions: wind speed and direction, atmospheric stability, and mixing height which govern dispersion and transport of potential pollutants; smaller meso-scale wind flowpatterns, such as the land/sea breeze phenomenon, periodic tropical cyclones, and midlatitude frontal systems. Emissions during well drilling and production would be rapidly dispersed by surface winds, with an annual average of 13.3 miles per hour (21.3 km per hr)(MMS 2001). The closest shoreline is to the north of the facility. Therefore, facility emissions traveling with the prevailing winds have to travel a greater distance before impacting the shoreline, and have a greater opportunity to be dispersed. In addition, the proposed development is located more than 200 miles (320 km) from the BNWA, with the prevailing winds blowing facility emissions away from BNWA. Near shore air emissions associated with Shuttle Vessels should not provide a significant impact as there are significantly less emissions from Shuttle Vessel unloading operations at terminals relative to Shuttle Vessel loading out in the Gulf. Not only will less air emissions be generated at the terminals due to a decreased need for power utilization (i.e. holding the Shuttle Vessel on station in offshore environmental conditions), the terminals will have vapor recovery units to minimize the VOCs that could be released during unloading operations at terminals. The project would not result in any changes to onshore infrastructure and the site is located at least 165 miles (265.5 km) offshore. Therefore, no effects to sensitive receptors, such as schools, residential areas, and hospitals, would occur. Air quality could

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Page 19-56 Petrobras America Inc. Development Operations Coordination Document Cascade / Chinook Development Project be affected in the event of an oil spill. The VOCs, which would escape to the atmosphere from a surface slick, accidental explosion, or clean up response in-situ burning, are precursors to photochemically produced ozone (MMS 2008). The likelihood of occurrence is remote and would be relatively short duration.
19(c).2 Noise Emissions Noise associated with this project will occur from the operation of the FPSO, Shuttle Vessels, drilling rig, construction vessels, marine support vessels, and helicopters, which can transmit noise through both air and water. The classification societies will verify that the major marine vessels (e.g. FPSO, Shuttle Vessels, and drilling rig) have acceptable noise levels prior to mobilization to the GoM in alignment with the classification society rules. PAI shall verify that noise limits are managed in accordance with regulatory requirements during the Phase 1 operations.
Given the amount of vessel traffic from all sources in the GoM, the level of noise from marine support vessels and Shuttle Vessels transiting to and from shore is expected to contribute an insignificant amount of the total ambient noise level. According to NOAA Fisheries in its assessment of oil and gas operations, it is believed that low frequency noise created by drilling activities may be detected by sperm whales, resulting in some harassment although no adverse effects would occur (NOAA 2002). Short-term, minor impacts could occur to marine mammals in the vicinity of the project area as a result of noise produced during construction, primarily from the use of thrusters on the DP marine vessels, which would be used to drill the two wells on Cascade Field. It is possible that underwater noise during FPSO production operations could also have the potential to affect marine mammals if they are feeding or transiting through the area, but this is expected to result in less noise than during construction because neither the FPSO nor the shuttle vessels would use DP thrusters for station keeping, however the FPSO was addressed in the initial DOCD. The dedicated field tug would assist the Shuttle Vessels during offloading operations to maintain a safe distance between the FPSO and the Shuttle Vessel. If marine mammals are in the vicinity, they are likely to move away from the noise sources and not be significantly affected. Noise from passing service vessels could also startle cetaceans and temporarily disrupt their movements. The project would likely have minimal effects on marine mammals or other sensitive noise receptors in the GoM.
19(c).3 Effluents and Discharges Operational wastes generated from this development would occur from the FPSO, Shuttle Vessels, drilling rig, construction vessels, and marine support vessels. These would include water based drilling fluids, cuttings from water based drilling fluids, cuttings from synthetic based drilling fluids, mud / cuttings / cement at the seabed, well test completion fluids, produced water, sanitary wastes, domestic wastes, uncontaminated seawater, uncontaminated bilge water, uncontaminated ballast water, desalination unit water, hydrostatic water, and deck drainage. All ocean discharges will be discharged overboard in compliance with the NPDES GP requirements. All other wastes would be

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Petrobras America Inc. Page 19-57 Development Operations Coordination Document Cascade / Chinook Development Project transported to shore for disposal in permitted or licensed commercial facilities or for recycling. Refer to Section 7 and Appendix 7 for details. Drilling fluids and cuttings would be either water based or synthetic based (SBF); oil based fluids will not be used. The discharge of SBF is limited to a specific retention on cuttings (ROC) value required by the NPDES GP. The ROC is a film of SBF that is left on the cuttings after the cuttings dryer process. Therefore, the majority of the SBF is separated from the drill cuttings and re-circulated. While the colder temperatures and greater depths of the fields would likely result in little degradation of the synthetic components adhering to the discharged drill cuttings, SBFs are not expected to affect water quality or the benthic community, even in the event of an accidental discharge (Boland et al. 2004). All drilling muds and cuttings generated would be discharged according to NPDES GP limitations. Treatment chemicals could be used, if needed, to stimulate well production, to assist product flow assurance, or to treat or prevent operational problems that may occur in the production process. Minor, localized impacts to marine water quality would occur from the proposed discharges and effluents during the life of the project. Effects are expected to be minimal based on compliance with the NPDES General Permit.
19(c).4 Physical Disturbances to the Seafloor Results of baseline monitoring of the Cascade Field project area show soft bottom seafloor conditions, in which burrowing infauna are most abundant. There is no known hard-bottom in project area of the proposed Cascade wells or their associated jumper connectors. No chemosynthetic communities were observed. Impact producing factors to the seafloor habitat would involve drilling activities and installing jumper connector with resuspension of the soft sediments likely. However, impacts from installation of the well and jumper connection will not likely to have significant impact due to short duration of construction activities and small aerial footprint. Proposed use of a DP capable drill ship to install the well further reduces the anticipated impact associated with the action. Rapid burial by sediment accumulation of greater than one foot (30 cm) in thickness would be lethal to those organisms that do inhabit the proposed project area (MMS2008). Accidental spill from a well blowout could rapidly smother infauna. Recolonization would be expected however. Dispersal from strong ocean currents could have an effect increasing an impact area should an inadvertent spill occur. The primary concern is habitat alteration during construction/drilling activities and inadvertent spills. Site-specific mitigation measures include:

 

### Conduct pre-drilling surveys;

 

### Monitor during and post-drilling; and

 

### No explosives or anchoring are part of this supplemental activity, therefore no significant impact would occur and no mitigation measure required.

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Page 19-58 Petrobras America Inc. Development Operations Coordination Document Cascade / Chinook Development Project Petrobras completed seafloor mapping of the project area in advance of project installation, ensuring appropriate siting to avoid and minimize potential impacts and hazards associated with the seafloor. As per NTL 2008-G06, PAI will be conducting Remotely Operated Vehicle surveys to assist with site-specific mitigation, as necessary. Monitoring results conducted following the successful installation of initial project activities showed no impacts to the seafloor. All facilities associated with this development, except for Shuttle Vessel and marine support vessel transit to and from shore, will be located in water depths beyond 8,000 feet (2,438 m). Benthic communities such as seagrass beds, corals and live bottom habitat (typically found in waters less than 100 feet (30.48 m)), pinnacle communities (typically located in water depths less than 1,300 feet (396 m)), or deepwater corals (typically located in water depths as deep as 3,280 feet (1,000 m)), would not be affected. A DP capable drill ship, semi-submersible drill rig would be used to drill and complete the well which would not cause any effects to the seafloor from mooring. The jumper connector would also be installed with a DP construction vessel, which would prevent any impacts to the seafloor. Any pipeline installation activities would primarily cause suspension of sediments as a pipe is laid across the seabed, which would cause a slight increase in turbidity of the water column. Suspended sediments would eventually settle within a relatively short timeframe. Based on the surveys conducted, geophysical signatures related to chemosynthetic communities or hard-ground substrates are not present in the project area. There is no evidence of hydrocarbon seepage to the seafloor in the geophysical data. The occurrence of periodic strong bottom currents in this area have scoured and eroded the seafloor. The multibeam data reveal an eroded seafloor exhibiting furrows, anti-dunes, and flukes. There was also no indication of chemosynthetic communities in the area of the well site and jumper connector (GEMS 2007; see Appendix 2). No impacts would occur to either hard bottom substrate or chemosynthetic communities in the project area. An ROV monitoring survey would be conducted in accordance with NTL 2008-G06, Remotely Operated Vehicle Surveys in Deepwater, to verify that no previously unknown, high-value benthic communities exist in the vicinity of proposed activities. Any potential to impact benthic resources would be further minimized by the requirement to avoid potential chemosynthetic communities by a minimum of 1,500 feet per NTL 2000-G20. Slight turbidity and burial from sediment settling would be expected but these would have short-term, localized and negligible impacts to epifaunal or infaunal communities. The proposed Cascade wells and their respective jumper connectors are not located within a high probability area for archeological resources. Furthermore, the shipwreck that was identified will not be impacted by the proposed project.
19(c).5 Impacts from Wastes Sent to Shore The majority of wastes sent to shore would consist of municipal garbage associated with personnel on the FPSO, Shuttle Vessels, and drilling rig. Other wastes would consist of

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Petrobras America Inc. Page 19-59 Development Operations Coordination Document Cascade / Chinook Development Project waste oil from machinery. These wastes would be transported to onshore waste disposal facilities in Louisiana and Texas via supply boats. No expansions of the existing onshore waste disposal facilities would be required. Refer to Section 7(a) and Appendix 7 for additional details. The proposed Cascade wells and their respective jumper connectors would have no environmental effects on offshore or nearshore coastal resources as a result of the wastes sent to shore.
19(c).6 Marine and Coastal Resources

Coastal Birds Proposed activities are located well offshore in the Gulf of Mexico. Other than transient individuals, the project area is not expected to be in a high use area by birds. Shuttle vessels from the FPSO to existing ports will use existing shipping lanes. No significant impacts to coastal birds are likely from well development production.

Fish Resources and Essential Fish Habitat The proposed project is in over 8,000 feet (2,446.5 meters) of water depth and is no longer in a blanket designation of EFH. The project area does retain EFH designation for some specific species: shark, tuna, swordfish, and sailfish. The benthic fish population that could be in the direct vicinity of the project’s seafloor activities is very low in density and restricted to species that live below 8,200 feet (2,508 meters): oceanic bathypelagics while species within the water column above the specific seafloor project site would be ocean pelagic species above 656 feet (200 meters) and mesopelagics using the water column between 656 to 3,280.8 feet (200 to 1,000 meters). Shuttle vessels will utilize existing commercial shipping lanes in shallower water areas. Any impacts would be temporary, and associated with minimal disturbance during construction /well drilling. No significant impacts to fish resources and EFH are likely from well development production.

Sea Turtles Sea turtles are found through the Gulf of Mexico. Based on the water depth at the Cascade Field location, only sea turtles in the project area would be considered transient, either migrating through the area, or foraging. Shuttle Vessels will be using existing shipping lanes into existing port facilities, which will minimize potential impacts in the richer shallow water habitats of the Gulf of Mexico. Impacts would be limited to inadvertent vessel collision with an individual.

Coastal Habitats The project is located 165 miles (265.5 km) from the nearest coastline, which is Louisiana. Sensitive coastal habitats include beaches and dunes and barrier islands. A large scale inadvertent oil release at the well site would take 30 days to travel to beaches and islands as per oil spill risk analysis undertaken for the FPSO (MMS 2008). Therefore, lengthy spill travel times and large dilution factors would be involved for

### 19 Environmental Impact Analysis (EIA)

Page 19-60 Petrobras America Inc. Development Operations Coordination Document Cascade / Chinook Development Project significant dispersion of an accidental spill prior to reaching a coastline from any of the Cascade well locations proposed. No new navigation channels would be required for this project. Primary potential impacts to coastal habitats would be from shuttle vessel traffic and inadvertent spills since onshore facilities are existing facilities. No onshore, near shore construction activities are part of proposed Cascade Field, drilling, completion and production activities, therefore no impacts are anticipated. Seagrass beds, another sensitive coastal habitat are located behind barrier islands. Therefore, likelihood of impact from an inadvertent oil spill is low. Nonetheless, as demonstrated during the Deepwater Horizon accident, these sensitive resources are susceptible to impacts from inadvertent spills. Areas of Special Concern Areas of Special Concern include marine protected areas. The proposed project is not located in or near a marine protected area. However, the Gulf of Mexico is considered an area of special concern. As such, a principal impacting factor would be a significant inadvertent spill. Fate of hydrocarbons in the Gulf of Mexico is largely uncertain (Ramseur 2010) following BP’s Deepwater Horizon oil spill of 200 million gallons (4.9 million barrels) of crude oil. According to a Congressional Research study, the fate of spilled oil was as follows: human intervention (direct recovery 17%; in-situ burning 5%; skimming 3%; chemical dispersal 16%), natural processes (natural dispersal 13%; evaporated or dissolved 24%), and other 22% remaining in the water column, settling to the seafloor, mixing with sediments, ingested by microbes, or collected during shore clean-up activities. Oiled shorelines (classified as light, moderate, or heavily oiled) were estimated to extent approximately 700 miles (1,127 km) in Louisiana, Mississippi, Alabama, and Florida. According to studies following the 1979 Ixtoc oil spill, approximately 25% of that oil settled on the bottom of the Gulf of Mexico. Monitoring and other mitigation measures identified in Section 12 would reduce impacts.

Tourism and Recreation The GOM supports diverse and valuable commercial and recreational fisheries; beaches, wetlands and barrier island natural resources that support local and state-wide tourism economics and recreational opportunities for the public. Primary concern to tourism and recreation is effects from inadvertent spill that could cause 1) change in fish distribution and abundance; 2) reduced catches of finfish and shellfish; 3) inability to access fishing areas; 4) loss/damage to fishing equipment; 5) reduced market value of a fishery, i.e. public perception of contamination. Shipping and Transportation No port modifications are required as part of the proposed project. PAI will be using existing ports that currently accommodate commercial traffic and no additional facilities or facility expansions are required for this project. Shuttle vessels would use existing shipping lanes and no modifications to shipping would be required. Therefore, no impacts to shipping and transportation are likely.

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Petrobras America Inc. Page 19-61 Development Operations Coordination Document Cascade / Chinook Development Project The Cascade Field wells and their associated jumper connectors would not be expected to have significant environmental effects on marine and coastal resources.
19(c).7 Accidents and Spills The FPSO EIS indicates that FPSO-unique spill risks comprise only 5% of the total risk for this kind of development (MMS 2001). The remaining 95% of spill risks would not be unique to FPSO operations and would be equally likely to have similar outcomes on atension leg platform or other deepwater production facility. Of the total potential FPSOunique spills, it is estimated that approximately 94% of a spill volume would be more likely to occur during oil transfers from the FPSO to the Shuttle Vessel and from the Shuttle Vessel’s transit to shore. A well blowout scenario is addressed in Section 2 (j) and oil spill information is provided in Section 9. An Oil Spill Risk Analysis was undertaken and is in Appendix 5. The proposed project site for the Cascade wells is more than 100 miles (161 km) away from established shipping lanes, which occur closer to the
coast. An attendant vessel with fire fighting capability could also be a significant resource in the event of a fire on the FPSO or Shuttle Vessel. Lifesaving capabilities on an attendant vessel would be able to assist in the event of a man overboard or helicopter accident in the vicinity of the FPSO as previously addressed in the initial DOCD. The FPSO would also disconnect from the mooring and riser system for hurricanes and named storms, providing a step change reduction in risks to people, the environment, and assets regarding hurricane avoidance. Refer to Sections 1(f) and 2(e) for more information regarding the disconnectable feature of the FPSO and the associated pollution prevention controls that PAI will utilize. Small spill less than 1,000 barrels would be expected to have a short term, non-significant impact to marine water quality. Larger spills, however, could impact marine water quality more significantly. This is not expected to affect coastal resources due to the site’s distance from shore and the expected response activities that would occur in event of a spill (Ji et al., 2007). According to the worst case discharge analysis evaluated seafloor intervention which anticipated 21 days to kill a well blow out resulting in a potential discharge of 325,017 barrels and a relief well would take longer, an estimated 110 days resulting in a potential discharge of 1,702,470 barrels. However, the chance of a large spill is extremely unlikely given the controls that PAI will put in place. The accidental release of synthetic-based drilling fluids and blowouts could have temporary localized impacts on marine water quality. Refer to Sections 1(f) to review additional pollution prevention measures and Section 9 to review oil spill response planning. Depending on the size of a spill, accidents would have the potential to result in short term adverse impacts on sperm whales but these impacts would likely be sublethal (NOAA 2002). Sea turtles may be more affected by spills, especially large ones, but this would not affect the species’ population to survive and recover from any loss (NOAA 2002). The proposed Cascade wells would not result in different impacts from those assessed in the FPSO EIS. Potential effects of impacts from other marine vessels would not be

### 19 Environmental Impact Analysis (EIA)

Page 19-62 Petrobras America Inc. Development Operations Coordination Document Cascade / Chinook Development Project expected due to the small number of vessels that use the Gulfmex No. 2 lightering zone far from the project site, the distance of the project to established shipping lanes, and because a dedicated field tug would maintain a constant watch onsite to prevent such a situation from occurring. Military Warning Areas in the Central Gulf of Mexico would be transited by marine support vessels, Shuttle Vessels, and helicopters. This would be mitigated by following the Military Areas Stipulation for these lease blocks, which requires that PAI enter into an agreement with the command headquarters prior to commencing any traffic in one of the military warning areas. This would prevent any conflicts between PAI and military operations. Therefore, no impacts to military operations are expected.
19(c).8 Other Impacts Identified No impacts are expected on socioeconomic and human resources such as coastal infrastructure, navigation and port usage, or recreational resources. The direct and indirect expenditures of the project would have a minor and temporary positive impact on the economic activities around the support facility at Port Fourchon. This project would have no effects on minority or low income populations. Nor would there be any secondary impacts to coastal resources or populations as a result of land-based support activities, use of infrastructure, or traffic.


### 19(d) Environmental Hazards
A number of environmental hazards exist in this area of the GoM: geological, meteorological such as named hurricanes; and strong currents that could impact the project and are described below.
19(d).1 Geological Hazards The primary geological hazards that could affect a deepwater well development include variable sediment types, steep slopes, high sedimentation rates, gas hydrates at or near the seafloor, interstitial gas, faulting, carbonate areas, salt and shale mobilization, and mud flows (MMS 2001). The GEMS Shallow Hazards Report for Facilities and the Summary of Environmental Conditions for Cascade / Chinook in Appendix 2 describes the potential hazards and how they will be mitigated.
19(d).2 Hydrogen Sulfide Determination The Cascade / Chinook fields were analyzed and addressed in the initial DOCD. H 2 

### S is not present in significant quantities in the project area. The reservoirs will be designated “H 2 

### S Absent” subject to MMS approval.
19(d).3 Loop Current and Deep Ocean Currents The Loop Current is the dominant circulation feature in the GoM, entering through the Yucatan Channel and exiting through the Florida Straits. The MMS-funded DeSoto Canyon Eddy Intrusion Study (Hamilton et al . 2000) was undertaken to take current and

### 19 Environmental Impact Analysis (EIA)

Petrobras America Inc. Page 19-63 Development Operations Coordination Document Cascade / Chinook Development Project temperature measurements at British Petroleum’s Atwater Block 618, which is located at the base of the Sigsbee Escarpment in water depths of approximately 6,561 feet (2,000 m). This is approximately 50 miles (80.5 km) north-northeast of the Cascade / Chinook Development area. The data showed unusual deep current flows that were typical of topographic Rossby waves (TRWs); however, the energy levels of TRWs in the study area were exceptional, while their duration was short compared to other areas of the Gulf (Hamilton et al . 2003)

. There are suggestions that deepwater currents are a result of TRWs that are generated westward by Loop Current fluctuations, Loop Current eddy shedding events, or the movement of Loop Current eddies (Hamilton et al . 2003). These waves are most likely to affect the central and eastern portions of the GoM but the generation mechanisms for them are not well understood (Hamilton et al . 2003). The Sigsbee Escarpment was the primary focus of the above study, and similar conditions are expected in the Walker Ridge area. It is known that significant currents (up to 2 knots) occur along the base of the Sigsbee Escarpment (Bryant et al . 2004). The evidence for this is also found in the form of mega-furrows, which occur throughout the Cascade / Chinook development area and are the result of high speed currents that have built up these sediments over thousands of years. Refer to the geophysical report in Appendix 2 for additional information. In addition to TRWs, density currents associated with the leaching of exposed salt along the escarpment add to the complex current conditions in this area (Bryant et al . 2004). Refer also to Section 19(c).4. The FPSO is designed to remain on station for 1.) a 100-year return winter storm with a 1-year return loop current and 2.) a 100-year return loop current with a 1-year return winter storm. PAI has access to data collected on the Loop Current and would know days in advance if a significant Loop Current event, such as a topographic Rossby wave, is expected to occur near the location of the Cascade Field while the proposed activities are underway. The associated drill ship could thus respond accordingly by disconnecting if the thresholds are met. PAI would also measure ocean currents at the site as required by NTL 2007-G17, Deepwater Ocean Current Monitoring on Floating Facilities.
19(d).4 Hurricanes and Named Storms Hurricane season in the Atlantic basin officially runs from June 1 through November 30; however, about 75% of the Category 3 or stronger hurricanes occur in August and September. Over the last few years, oil and gas activities in the GoM have been significantly disrupted by several major hurricanes, including Lili (in 2002), Ivan (2004), Katrina (2005), Rita (2005) and Ike (2008). Hurricane Ike affected 49 of the 3,800 offshore oil and gas platforms in the Gulf. At one point just prior to Katrina’s landfall, 79% of Gulf platforms were evacuated and 1.4 million barrels of oil per day (95% of normal Gulf OCS daily production) and 8.8 billion cubic feet of gas per day (88% of normal Gulf OCS production) were shut in. Katrina destroyed 44 platforms as it passed over the region, including some deepwater projects that were under construction. As Rita passed over, 93% of platforms were evacuated with the shut-in of 100% and 81% of normal daily oil and natural gas production,

### 19 Environmental Impact Analysis (EIA)

Page 19-64 Petrobras America Inc. Development Operations Coordination Document Cascade / Chinook Development Project respectively. Sixty-nine platforms were destroyed by Hurricane Rita (Energy Information Agency 2006). In addition to upstream impacts, the hurricanes had significant impacts on midstream and downstream infrastructure. Four hundred fifty-seven underwater pipelines were damaged, and the Louisiana Offshore Oil Port temporarily stopped accepting shipments during the 2005 storms. Some onshore crude oil refineries and natural gas processing facilities also suffered heavy damage. After Katrina hit Louisiana, nearly 2 million barrels per day of refinery capacity were shut down either due to direct damage or interruption of power supplies. More than 4.9 million barrels per day of refinery capacity were shut down after Hurricane Rita hit the Texas coast (Energy Information Agency 2006; see also MMS 2006b). Hurricanes Rita and Katrina resulted in the destruction of more than 100 platforms, which were all in shallow water except for a facility located in Green Canyon block 237 (French et al. 2006). MMS issued NTL 2009-G13, which provides operators with additional guidance to ensure that production platforms, drilling and workover rigs, and other equipment and facilities on the OCS are secured during hurricane seasons in the GoM. PAI will utilize an FPSO which will have a single point mooring system which will allow for full passive weathervaning. The single point mooring system will have a disconnectable feature which will allow the FPSO to disconnect and motor away from named storms and hurricanes under her own power, returning for re-connection when it is safe to do so. The disconnectable feature provides a step change reduction in risk regarding the protection of people, the environment, and assets. After disconnection, the turret buoy (which is attached to the FPSO mooring lines, FSHRs, and umbilicals) will be left behind in a submerged condition out of harms way of the environment conditions at the surface. Drill ships associated with the proposed operations on the Cascade Field may also respond by disconnecting if certain thresholds are met.
19(d).5 Operating Environmental Criteria for Product Offloading PAI has defined more conservative environmental operating criteria for FPSO offloading relative to the maximum operational conditions for GoM lightering operations as specified in 33 CFR 156.320. Parameters for shuttle approach and connection as well as offloading are summarized in Table 2-7 located in Section 2(e).


### 19(e) Alternatives
PAI evaluated an alternative to installation of the gas export pipeline in Phase 1 during early conceptual design. Rather than seek BOEM approval for low volume gas flaring for the early stages of Phase 1, PAI decided to install the gas export pipeline during the early stages of Phase 1 to eliminate such flaring. The gas export line will be ready for utilization at first oil production and will minimize impact to the environment. With the development of previous wells in the Cascade/Chinook Development Area there are no other least damaging practicable alternatives.

### 19 Environmental Impact Analysis (EIA)

Petrobras America Inc. Page 19-65 Development Operations Coordination Document Cascade / Chinook Development Project 

### 19(f) Mitigation Measures
Section 1(f) describes the most important safety and pollution prevention controls that PAI will utilize to mitigate the potential for any adverse effects to GoM resources. Such controls are generally aimed at minimizing the frequency and magnitude of oil spills. The effective implementation of such industry proven controls will effectively eliminate the potential for large oil spills which could have an impact to GoM resources. See also Section 12 for mitigation measures.


### 19(g) Consultation and Coordination

Meeting Contacts Minerals Management Service (MMS), 2006, Meeting between MMS Gulf of Mexico Region staff (Russell Hoshman; Michael Tolbert, Plans; Manny Gagliano, Pipelines; Ronald Bowser; Holly Karrigan; Christy Bohannon; Mike Conner, Field Operations; B.J. Kruse, Field Operations; Mike Saucier; Houma District; Bryan Domangue, Houma District; Glenn Woltman; Nick Wetzel, Plans; Carole Current, Leasing and Environment; Stephen Kovacs; Dennis Chew, Leasing and Environment; and Ed Richardson, NEPA lead) and PAI staff (Luiz Souza, FPU Production and Operation Manager; Gus Cassity, Phase 1 Coordinator; Mike Bigler, Corporate HSE Coordinator; Cheryl Saha, Land Manager; Partha Ganguly, Millennium Technical Consultants; Wanda Richmond, J. Connor Consulting, Inc.; and Carliane Johnson, Ecology and Environment, Inc.) on September 6, 2006 in New Orleans, LA to provide an introduction to the Cascade / Chinook project and discuss the regulatory framework for FPSOs. State of Louisiana, 2007, Meeting between Louisiana Department of Natural Resources (DNR) Coastal Management Division (CMD) staff (Brian Marcks; Jeff Harris; Agaha Brass; and Gregory DuCote) and PAI staff (Mike Bigler, Corporate HSE Coordinator and Carliane Johnson, Ecology and Environment, Inc.) on February 12, 2007 in Baton Rouge, LA to provide an introduction to the Cascade / Chinook project and to better understand any concerns by the State of Louisiana. State of Texas, 2007, Meeting between State of Texas staff (Tammy Brooks, Texas General Land Office; Jesse Solis, Texas General Land Office; Leslie Savage, Railroad Commission of Texas; David Nuckels, Texas Department of Transportation; Jarrett (Woody) Woodrow, Texas Parks and Wildlife Department; and Cherie O’Brien, Texas Parks and Wildlife Department) and PAI staff (Mike Bigler, Corporate HSE Coordinator and Carliane Johnson, Ecology and Environment, Inc.) on March 19, 2007 in Austin, TX to provide an introduction to the Cascade / Chinook project and to better understand any concerns by the State of Texas.

### 19 Environmental Impact Analysis (EIA)

Page 19-66 Petrobras America Inc. Development Operations Coordination Document Cascade / Chinook Development Project Telephone and E-mail Contacts Dunlap, K. 2011, Personal communication, Karen Dunlap Plans Section, BOEM, New Orleans telephone conversation with G Collins regarding greenhouse gas reporting, frequency of environmental monitoring, extent and duration of oil spill analysis, and meeting February 28, 2011. Dunlap, K. 2011, email, Karen Dunlap, Plans Section, BOEM, New Orleans email with Greg Roland regarding Supplemental DOCD required, requested NTL 2010-N06 information, expanded radius for biological survey, OSRP comparison, CZM review, and AGOV review. Anderson, C., 2006, Personal communication, Cheryl Anderson, Operations Research Analyst, Engineering and Research Branch, Engineering and Operations Division, Mineral Management Service, Herndon, VA, telephone conversation on June 21, 2006 regarding world wide oil spill records, with Davey Crawley, Ecology & Environment Inc., Pensacola, FL. Boland, G., 2006, Personal communication, Greg Boland, Leasing and Environment Section, Minerals Management Service, New Orleans, LA, telephone conversations on August 10 and October 20, 2006 regarding the geophysical mapping surveys and interpretation of 3D seismic to determine the presence of chemosynthetic communities, with Carliane Johnson, Ecology and Environment, Inc., Arlington, VA. Breeding, D., G. Goeke and G. Kozlowski, 2007, Personal communication, Darice Breeding, Gary Goeke, and Greg Kozlowski, Minerals Management Service, New Orleans, LA, telephone conference call on May 1, 2007 regarding the quantity to consider for a worst-case discharge, with Mike Bigler, PAI., Houston, TX and Carliane Johnson, Ecology and Environment, Inc., Arlington, VA. Breeding, D., 2006, Personal communication, Darice Breeding, Minerals Management Service, New Orleans, LA, E-mail correspondence in July 2006 regarding U.S. and Mexico oil and hazardous spill response agreements, with Carliane Johnson, Ecology and Environment, Inc., Arlington, VA. Clark, Tricia, 2006, Personal communication, Co-chair of the Industry Taskforce on Offshore Lightering (ITOL) Group, Houston, TX, telephone conversation on August 8, 2006 regarding lightering operations, with Jeff Hammond, Ecology and Environment, Inc., Buffalo, NY.
Conner, M., 2006, Personal communication, Mike Conner, Technical Assessment and Operations Support Section, Minerals Management Service, New Orleans, LA, telephone conversation on August 21, 2006 regarding the scheduling of an introductory meeting with MMS, PAI officials, and others to discuss the Cascade / Chinook project, with Carliane Johnson, Ecology and Environment, Inc., Arlington, VA.

### 19 Environmental Impact Analysis (EIA)

Petrobras America Inc. Page 19-67 Development Operations Coordination Document Cascade / Chinook Development Project Current, C., 2007, Personal communication, Dr. Carole Current, Oceanographer, Minerals Management Service, New Orleans, LA, E-mail correspondence and phone communication between October 2006 and April, 2007 regarding oil spill risk analysis (OSRA) modeling runs for hypothetical spill in the Cascade / Chinook development blocks of Walker Ridge, with Carliane Johnson, Ecology and Environment, Inc., Arlington, VA. Cushing, J., 2006, Personal communication, John Cushing, Commander United States Coast Guard, Washington, DC, telephone conversations on June 14, July 6 and July 25, 2006 regarding the use of articulated tug barges (ATBs) in the Gulf of Mexico, U.S. shipbuilding capacity for tanker construction, and regulatory differences between ATBs and shuttle tankers, with Jeff Hammond, Ecology & Environment Inc., Buffalo, NY. Goeke, G., 2006, Personal communication, Gary Goeke, NEPA Specialist, Minerals Management Service, New Orleans, LA, telephone conversation on June 28, 2006 regarding the sufficiency of data from 3D seismic versus side scan sonar to determine the presence of chemosynthetic communities, with Carliane Johnson, Ecology and Environment, Inc., Arlington, VA. Hefren, F., 2006, Personal communication, Fred Hefren, Minerals Management Service, New Orleans, LA, E-mail correspondence on June 22, 2006 regarding deepwater current monitoring requirements, with Carliane Johnson, Ecology and Environment, Inc., Arlington, VA. Henry, C., 2006, Personal communication, Charlie Henry, National Oceanic and Atmospheric Administration, New Orleans, LA, telephone conversation on August 4, 2006 regarding the oil spill models used by NOAA, with Solange Silva, Ecology and Environment, Inc., Houston, TX. Herkhof, D., 2007, Personal communication, Dirk Herkhof, Meteorologist, Minerals Management Service, New Orleans, LA, telephone conversation on February 26, 2007 regarding the air emissions analysis, with William Vasil, Ecology and Environment, Inc., New York, NY. __________, 2006, Personal communication, Dirk Herkhof, Meteorologist, Minerals Management Service, New Orleans, LA, telephone conversation on December 29, 2006 regarding air emissions modeling that would be required if air emissions exceed thresholds, with William Vasil, Ecology and Environment, Inc., New York, NY. Irion, J., 2006, Personal communication, Dr. Jack Irion, Archeologist, Minerals Management Service, New Orleans, LA, telephone conversation on July 17, 2006 regarding surveying techniques for identifying archeological sites, with Carliane Johnson, Ecology and Environment, Inc., Arlington, VA.

### 19 Environmental Impact Analysis (EIA)

Page 19-68 Petrobras America Inc. Development Operations Coordination Document Cascade / Chinook Development Project Kozlowski, G, 2007, Personal communication, Gregory Kozlowski, Environmental Protection Specialist, Minerals Management Service, New Orleans, LA, E-mail correspondence on May 8 and May 9, 2007 regarding questions on the use of MMS Form 137 and obtaining a copy of the stipulations from Lease Sale 157, with Carliane Johnson, Ecology and Environment, Inc., Arlington, VA.
Ramos, J., 2006, Personal communication, Jeff Ramos, Commander United States Coast Guard, New Orleans, LA, telephone conversations on June 13 and August 2, 2006 regarding articulated tug barge operations in the Gulf of Mexico, whether there have been any lightering accidents in Gulfmex No. 2 area, and whether regulations are proposed for the use of FPSOs, with Jeff Hammond, Ecology & Environment Inc., Buffalo, NY.
Richardson, G.E., 2006, Personal communication, G. Ed Richardson, Mineral Management Service, New Orleans, LA, telephone conversation on July 13, 2006 regarding NEPA implications of segmenting aspects of the Cascade / Chinook project, with Carliane D. Johnson, Ecology & Environment Inc., Arlington, VA. Shedd, W., 2006, Personal communication, Dr. William Shedd, Geophysicist, Minerals Management Service, New Orleans, LA, telephone conversation on August 10, 2006 regarding the geophysical mapping surveys and interpretation of 3D seismic to determine the presence of chemosynthetic communities, with Carliane Johnson, Ecology and Environment, Inc., Arlington, VA. Violetta, E., 2006, Personal communication, Captain Ernesto Violetta, Oil Spill or Incident Primary Qualified Individual, American Eagle Tankers, Houston, TX, telephone conversation on August 8, 2006 regarding lightering operations, with Jeff Hammond, Ecology & Environment Inc., Buffalo, NY. Wade, P., 2007, Personal communication, Peggy Wade, U.S. Environmental Protection Agency Region 6, telephone conversation on February 21, 2007 regarding the potential impact of a project that could add mobile source emissions to the Houston/Galveston non-attainment area, telephone conversation with William Daughdrill, Ecology and Environment, Inc., Pensacola, FL.
Wilson, Scott, 2007, Personal communication, Scott Wilson, Environmental Scientist, U.S. Environmental Protection Agency, Region 6, Dallas, TX, E-mail correspondence on January 25, 2007 regarding regulations for cooling water intake structures on offshore oil and gas facilities, with Carliane Johnson, Ecology and Environment, Inc., Arlington, VA.
__________, 2006, Personal communication, Scott Wilson, Environmental Scientist, U.S. Environmental Protection Agency, Region 6, Dallas, TX, telephone conversation on December 1, 2006 regarding thermal discharges, with Carliane Johnson, Ecology and Environment, Inc., Arlington, VA.

### 19 Environmental Impact Analysis (EIA)

Petrobras America Inc. Page 19-69 Development Operations Coordination Document Cascade / Chinook Development Project __________, 2006, Personal communication, Scott Wilson, Environmental Scientist, U.S. Environmental Protection Agency, Region 6, Dallas, TX, telephone conversation on July 12, 2006 regarding the reissuance of the NPDES GP after the current GP expires in November 2007, with Thierry Garcy, Ecology and Environment, Inc., New York, NY. Wright R., 2006, Personal communication, Rusty Wright, Oil Spill Program Administrator, Minerals Management Service, New Orleans, LA, telephone conversation on July 6, 2006 regarding the Oil Spill Risk Analysis Model (OSRAM) and the use of worst case discharge response scenarios for the Oil Spill Response Plan, with Jeff Hammond, Ecology and Environment, Inc., Buffalo, NY.


### 19(h) List of Preparers
The PAI representatives responsible for overall review of this EIA are: Gregory D.Roland Regulatory Compliance Area Manager Petrobras America Inc. 10350 Richmond Ave, Suite 1400 Houston, Texas 77042 Phone: 713-808-2881

Solange Silva, Ph.D. Walker Ridge Regulatory Advisor Petrobras America Inc. 10350 Richmond Ave., Suite 1400 Houston, Texas 77042 Phone: 713-808-3004 The contractor responsible for preparing this EIA is: Georganna Collins Project Manager Ecology & Environment, Inc. 2 Riverway, Suite 625 Houston, Texas 77056 Phone: 713-344-3000 Ext. 3505

### 19 Environmental Impact Analysis (EIA)

Page 19-70 Petrobras America Inc. Development Operations Coordination Document Cascade / Chinook Development Project Table 19-20 identifies E&E contributors to the preparation of this EIA.

Table 19-20 – E&E Contributors to EIA

Name Role Project Responsibility

Mike Donnelly Project Director Principal Reviewer / Quality Assurance

Georganna Collins Project Manager Project Management and Document Development

Lisa Richard Administrative Specialist Document Production

Bill Vasil Air Specialist Air Emissions Analysis

Paul VanKerkhove Air Specialist Air Emissions Analysis

Jeff Hammond Maritime Support Vessel Requirements and Data Collection

Jennifer Harris Planner Socioeconomic Analysis

Valerie Meyer Biologist Coastal Zone Consistency Assessment

David Trimm Fisheries Biologist Fisheries

David Crawley Environmental Scientist Storm Data/Coastal Resources

Holli Brandt GIS Graphics

Greg Coniglio GIS Graphics



### 19(i) References
Barras, John A., 2006, Land area change in coastal Louisiana after the 2005 hurricanes— a series of three maps: U.S. Geological Survey Open-File Report 06-1274. Baumgartner, M.F., K.D. Mullin, L.N. May, and T.D. Leming, 2001, Cetacean Habitats in the Northern Gulf of Mexico, Fisheries Bulletin , Vol. 99, pp. 219-239. Benfield, M.C. and R.F. Shaw, 2005, Potential spatial and temporal vulnerability of pelagic fish assemblages in the Gulf of Mexico to surface oil spills associated with deepwater petroleum development, OCS Study MMS 2005-012, U.S. Dept. of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA.
Block, Barbara A., Heidi Dewar, Susanna B. Blackwell, Thomas D. Williams, Eric D. Prince, Charles J. Farwell, Andre Boustany, Steven L. H. Teo, Andrew Seitz, Andreas Walli, and Douglas Fudge, 2001, Migratory Movements, Depth Preferences, and Thermal Biology of Atlantic Bluefin Tuna, Science, 17 August 2001, Vol. 293, Downloaded from www.sciencemag.org on May 8, 2007.

### 19 Environmental Impact Analysis (EIA)

Petrobras America Inc. Page 19-71 Development Operations Coordination Document Cascade / Chinook Development Project Boehm, P., D. Turton, A. Raval, D. Caudle, D. French, N. Rabalais, R. Spies, and J. Johnson, 2001, Deepwater Program: Literature Review, Environmental Risks of Chemical Products Used in Gulf of Mexico Deepwater Oil and Gas Operations, Volume I: Technical Report, OCS Study MMS 2001a-011, U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA.
Boland, G., C. Current, M. Gravois, M. Metcalf, and E. Peuler, 2004, Fate and Effects of a Spill of Synthetic-Based Drilling Fluid at Mississippi Canyon Block 778, OCS Report MMS 2004-039, U.S. Department of the Interior, Minerals Management Service, New Orleans, LA. Bryant, W., N. Slowey, S. DiMarco, D. Bean, and D. Berti, 2004, Deep-sea furrows: Physical characteristics, mechanisms of formation and associated environmental processes, Final Report (August 2003 – September 2004) to Research Partnership to Secure Energy for America, Subcontract No. R-505, Sugar Land, TX, report accessible on the web at http://otrc.tamu.edu/pages/furrows.htm

. Buck, E.H., 2000, Management of U.S. Fisheries for Highly Migratory Species, Congressional Research Service, Report for Congress RL30535, Washington, DC. Clark, Tricia, 2006, personal communication, Co-chair of the Industry Taskforce on Offshore Lightering (ITOL) Group, Houston, TX telephone interview with Jeff Hammond, Ecology and Environment, Inc., Buffalo, NY, August 8, 2006. Coastal Marine Institute and Minerals Management Service (CMI/MMS), 2002, Lafourche Parish and Port Fourchon, Louisiana: Effects of the Outer Continental Shelf Petroleum Industry on the Economy and Public Services, Part 2, Coastal Marine Institute, Louisiana State University, Baton Rouge, LA and U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. 1435-01-96-CT-30660-19945. Congressional Research Service (CRS). 2006. U.S. International Borders: Brief Facts. CRS Report for Congress. Order Code RS21729. Updated November 9, 2006. Received through the CRS Web. www.fas.org/sgp/crs/misc/RS21729.pdf Accessed 21 February 2011. Continental Shelf Associates, Inc., and Texas A&M University, Geochemical and Environmental Research Group (CSA and Texas A&M), 2001, Mississippi/Alabama Pinnacle Trend Ecosystem Monitoring, Final Synthesis Report, OCS Study MMS 2001-080, U.S. Department of the Interior, Geological Survey, Biological Resources Division, USGS BSR 2001-0007 and Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. Continental Shelf Associates, Inc. (CSA), 2002, Deepwater Program: Bluewater Fishing and OCS Activity, Interactions between the Fishing and Petroleum Industries in Deepwaters of the Gulf of Mexico, OCS Study MMS 2002-078, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA.

### 19 Environmental Impact Analysis (EIA)

Page 19-72 Petrobras America Inc. Development Operations Coordination Document Cascade / Chinook Development Project __________, 2000, Deepwater Gulf of Mexico Environmental and Socioeconomic Data Search and Literature Synthesis , Volume I: Narrative Report, OCS Study MMS 2000-049, U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. Cordes, E.E., 2006, Ecology of Gulf of Mexico Deep-Sea Hard-ground Communities, NOAA Expedition to the Deep Slope, http://www.oceanexplorer.noaa.gov/explorations/06mexico/background/hardgrou nds/hardgrounds.html

. Coston-Clements, L, L.R. Settle, D. E. Hoss, and F.A. Cross, 1991, Utilization of the Sargassum Habitat by Marine Invertebrates and Vertebrates - A Review, NOAA Technical Memorandum NMFS-SEFSC-296, NOAA National Marine Fisheries Service, Southeast Fisheries Science Center, Beaufort, NC. Couvillion, B.R., Barras, J.A., Steyer, G.D., Sleavin, William, Fischer, Michelle, Beck, Holly, Trahan, Nadine, Griffin, Brad, and Heckman, David, 2011, Land area change in coastal Louisiana from 1932 to 2010: U.S. Geological Survey Scientific Investigations Map 3164, scale 1:265,000, 12 p. pamphlet. Dagorn, Laurent, Kim N. Holland, Jean-Pierre Hallier, March Taguet, Gala Moreno, Gorka Sancho, David G. Itano, Riaz Aumeeruddy, Charlotte Girard, Julien Million, and Alain Fonteneau, 2006, Deep diving behavior observed in yellowfin tuna ( Thunnus albacares ), Aquatic Living Resources 19, 85–88 (2006), Article published by EDP Sciences and available at http://www.edpsciences.org/alr

. Dahl, T.E. 2010. Status and trends of wetlands in the conterminous United States 2004 to 2009. U.S. Department of the Interior, Fish and Wildlife Service, Washington, D.C. 82 pp. Davis, R. W., W.E. Evans, and B. Würsig (eds), 2000, Cetaceans, Sea Turtles and Seabirds in the Northern Gulf of Mexico: Distribution, Abundance and Habitat Associations, Volumes I and II, prepared by Texas A&M University at Galveston and the National Marine Fisheries Service, U.S. Department of the Interior, Geological Survey, Biological Resources Division, USGS/BRD/CR—1999-0006 and Minerals Management Service, Gulf of Mexico OCS Region OCS Study MMS 2000-002 and MMS 2000-003, New Orleans, LA. Department of the Navy, 2003, Marine Resource Assessment for the Eastern Gulf of Mexico Testing and Training Areas, Final Report, Prepared for Department of the Navy, Commander in Chief, US Atlantic Fleet, Norfolk, VA Contract Number 62470-95-D-1160, Task Order Number 0053, by Geo-Marine, Inc., Plano, TX. Energy Information Agency, 2006, The Impact of Tropical Cyclones on Gulf of Mexico Oil and Natural Gas Production, Short-term Energy Outlook released on June 7, 2006 from the National Energy Information Center, report accessible on the web
at: http://www.eia.doe.gov/emeu/steo/pub/pdf/hurricanes.pdf

.

### 19 Environmental Impact Analysis (EIA)

Petrobras America Inc. Page 19-73 Development Operations Coordination Document Cascade / Chinook Development Project Enright, J.M., R. Gearhart II, D. Jones, and J. Enright, 2006, Study to Conduct National Register of Historic Places Evaluations of Submerged Sites on the Gulf of Mexico Outer Continental Shelf, OCS Study MMS 2006-036, U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. Environmental Protection Agency (EPA), 2006, AirData, U.S. Environmental Protection Agency air quality data from state ambient air monitoring programs (2002-2006) http://www.epa.gov/air/data/geosel.html , Web site last updated September 26, 2006. Federal Register Notice, 2005, Fisheries of the Caribbean, Gulf of Mexico, and South Atlantic; Gulf of Mexico Essential Fish Habitat Amendment, Federal Register, Volume 70, Number 178, Thursday, September 15, 2005, National Marine Fisheries Service, Southeast Regional Office, St. Petersburg, FL. Felder, Darryl L and David K. Camp, 2009. Gulf of Mexico Origin, Waters, and Biota: Volume 1, Biodiversity, Texas A&M University Press, College Station, Texas. Florida Museum of Natural History, 2007, Biological Profiles: Ichthyology, last updated January 29, 2007, http://www.flmnh.ufl.edu/fish/Education/bioprofile.htm

, Accessed February 1, 2007. French, Leanne S., G. Ed Richardson, Eric G. Kazanis, Tara M. Montgomery, Christy M. Bohannon, and Michael P. Gravois, 2006, Deepwater Gulf of Mexico 2006: America’s Expanding Frontier, OCS Report MMS 2006-022, U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. Gallaway, B.J., J.G. Cole, and L.R. Martin, 2001, The Deep Sea Gulf of Mexico: An Overview and Guide, OCS Study MMS 2001-065, U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. Garcia, H. E., R. A. Locarnini, T. P. Boyer, and J. I. Antonov, 2010. World Ocean Atlas 2009, Volume 3: Dissolved Oxygen, Apparent Oxygen Utilization, and Oxygen Saturation. S. Levitus, Ed. NOAA Atlas NESDIS 70, U.S. Government Printing Office, Washington, D.C., 344 pp. Geoscience Earth & Marine Services, Inc. (GEMS), 2007, Seafloor and Geologic Assessment Cascade and Chinook Development Areas Bocks 160-162, 203-208, 247-252, 293-295, 337-338, 381-382, 425-426, & 469-470 Walker Ridge Area Gulf of Mexico, Report submitted to Petrobras America Inc., Houston, TX.

### 19 Environmental Impact Analysis (EIA)

Page 19-74 Petrobras America Inc. Development Operations Coordination Document Cascade / Chinook Development Project Gulf of Mexico Fishery Management Council (GMFMC), 2005. Final Generic Amendment Number 3 – Addressing Essential Fish Habitat Requirements, Habitat Areas of Particular Concern, and Adverse Effects of Fishing in the following Fishery Management Plans of the Gulf of Mexico: Shrimp Fishery of the Gulf of Mexico; Red Drum Fishery of the Gulf of Mexico; Reef Fish Fishery of the Gulf of Mexico; Coastal Migratory Pelagic Resources (Mackerels) in the of the Gulf of Mexico and South Atlantic; Stone Crab Fishery of the Gulf of Mexico; Spiny Lobster in the Gulf of Mexico; Coral and Coral Reefs of the Gulf of Mexico. Gulf of Mexico Fishery Management Council, Tampa, FL. Halbouty, M.T. 1967. Salt Domes, Gulf Region of the United States and Mexico. Gulf Publishing. Houston. 425p. Hamilton, P., J.J. Singer, E. Waddell, and K. Donohue, 2003, Deepwater Observations in the Northern Gulf of Mexico from In-Situ Current Meters and PIES. Final Report. Volume II: Technical Report, OCS Study MMS 2003-049, US Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. Hamilton, P., T. J. Berger, J. H. Churchill, R. R. Leben, T. N. Lee, J. Singer, W. Sturges, and E. Waddell, 2000, Desoto Canyon Eddy Intrusion Study; Final Report, Volume II: Technical Report, OCS Study MMS 2000-080, US Department of the Interior, Minerals Management Service Gulf of Mexico OCS Region, New Orleans, LA. Heemstra, P.C. and J.E. Randall, 1993, Groupers of the World (Family Serranidae

, Subfamily Epinephelinae), Food and Agricultural Organization of the United Nations, Fisheries Synopsis , No. 125, Vol. 16. Hoff J., Mackay, D. Wania F., Jia C. 1995. Development of Models Describing the Distributions of Organic Chemicals in Cold Ecosystems. Synopsis of Research Conducted Under the 1994/95 Northern Contaminants Program. DIAND Ottawa 73:39-44. Hoggard, Wayne. 1991. First Recorded Turtle Nesting on Mississippi’s Man-Made Beach. Marine Turtle Newsletter 52:11-12. http://www.seaturtle.org/mtn/archives/mtn52/mtn52p11.shtml Accessed 22 February 2011. Ji, Zhen-Gang, Walter R. Johnson, Charles F. Marshall, and Eileen M. Lear (Editor), 2007, Oil-Spill Risk Analysis: Contingency Planning Statistics for Gulf of Mexico OCS Activities, U.S. Department of the Interior Minerals Management Service, Environmental Division, Herndon, VA.
Jochens, A. E., L. C. Bender, S. F. DiMarco, J. W. Morse, M. C. Kennicutt II, M. K. Howard, and W. D. Nowlin, Jr., 2005, Understanding the Processes that Maintain the Oxygen Levels in the Deep Gulf of Mexico: Synthesis Report, OCS Study MMS 2005-032, U.S. Dept. of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA.

### 19 Environmental Impact Analysis (EIA)

Petrobras America Inc. Page 19-75 Development Operations Coordination Document Cascade / Chinook Development Project Lee, Y.-D. and R.A. George, 2004, High-resolution geological AUV survey results across a portion of the eastern Sigsbee Escarpment, The American Association of Petroleum Geologists (AAPG) Bulletin, Vol. 88, No. 6 (June 2004), pp. 747-764. MacDonald, I.R., R. Arvidson, R.S. Carney, C. F. Fisher, N.L. Guinasso Jr., S. Joye, P. Montagna, J.W. Morse, D.C. Nelson, E. Powell, W. Sager, R. Sassen, S. Schaeffer, and G.A. Wolff, 2002, Stability and Change in Gulf of Mexico Chemosynthetic Communities: Final Report, Contract 14-35-001-31813, U.S. Dept. Interior, Minerals Management Service Gulf of Mexico OCS Region, New Orleans, LA. McKay, M., J. Nides, and D. Vigil (eds), 2002, Proceedings: Gulf of Mexico Fish and Fisheries: Bringing Together New and Recent Research, Prepared under MMS contract by University of New Orleans, Office of Conference Services, New Orleans, Louisiana, OCS Study 2002-004. Mendelssohn IA and Lin Q. 2003. Development of bioremediation for oil spill clean up in coastal wetlands. US Department of Interior Mineral Management Service, GOM, OSC Region. 89 pp. Merrill. W.1983. Reefs and banks of the Northern Gulf of Mexico: Their Geological, Biological, and Physical Dynamics. TAMU. Dept. of Oceanography. Final Report. Minerals Management Service (MMS) 2008. Site-specific Environmental Assessment for an FPSO Facility. Evaluation of Petrobras America Inc.’s Initial Development Operations Coordination Document, N-9015. Cascade-Chinook Project; Walker Ridge Blocks 205, 206, 249, 250, 425, 426, 469 and 470. _________, 2006a, Outer Continental Shelf Oil & Gas Leasing Program: 2007-2012, Draft Environmental Impact Statement, MMS OCS Report 2006-004, U.S. Department of the Interior, Minerals Management Service, Herndon, VA. __________, 2006b, Environmental Assessment for the Proposed OCS Lease Sale 200,Western Gulf of Mexico, 2006, MMS Report No. 2006-016, MMS Gulf of Mexico OCS Region, New Orleans, LA. __________, 2005, Proposed OCS Lease Sale 198, Central Gulf of Mexico, Environmental Assessment, OCS EIS/EA MMS 2005-059, US Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA
__________, 2004, Supply Network for Deepwater Oil and Gas Development in the Gulf of Mexico: An Empirical Analysis of Demand for Port Services , Final Report, OCS MMS 2004-047, US Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA.

### 19 Environmental Impact Analysis (EIA)

Page 19-76 Petrobras America Inc. Development Operations Coordination Document Cascade / Chinook Development Project __________, 2002, Gulf of Mexico OCS Oil and Gas Lease Sales: 2003-2007, Central Planning Area Sales 185, 190, 194, 198, and 201; Western Planning Area Sales 187, 192, 196, and 200, Final Environmental Impact Statement, OCS EIS/EA MMS 2002-052, US Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. __________, 2002b. Stability and Change in Gulf of Mexico Chemosynthetic Communities. Volume 1. Executive Summary. US Dept of Interior. Gulf of Mexico, OCS Region. __________, 2001, Proposed Use of Floating Production, Storage, and Offloading Systems On the Gulf of Mexico Outer Continental Shelf, Western and Central Planning Areas, Final Environmental Impact Statement, OCS EIS/EA MMS 2000-090, US Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA, 1435-01-99-CT-30962.
__________, 2000, Gulf of Mexico Deepwater Operations and Activities, Environmental Assessment, OCS EIS/EA MMS 2000-001, U.S. Department of the Interior, Minerals Management Service, Gulf Mexico OCS Region, New Orleans, Louisiana,.
__________, 1996, Distribution and Abundance of Cetaceans in the North-Central and Western Gulf of Mexico, Final Report. Volume 1, OCS Study MMS 96-0026, Gulf of Mexico OCS Region. New Orleans, LA.
Moulton, D. W., T. E. Dahl and D. M. Dall. 1997. Texas coastal wetlands status and trends, mid-1950s to early 1990s. Albuquerque, New Mexico, United States Department of the Interior, Fish and Wildlife Service, Southwestern Region: 32
pp. Nakamura, I., 1985, Billfishes of the World, Food and Agricultural Organization of the United Nations, Fisheries Synopsis , 5(125), p. 65. National Biodiversity Information Infrastructure 2011. http://www.nbii.gov/portal/server.pt?open=512&objID=1950&mode=2&in_hi_us erid=2&cached=true , accessed September 23, 2011. National Incident Command Joint Analysis Group (JAG) 2011. Review of Preliminary Data to Examine Oxygen Levels In the Vicinity of MC252#1 May 8 to August 9, 2010. http://www.noaa.gov/sciencemissions/bpoilspill.html. National Oceanic and Atmospheric Administration (NOAA). 2011. Flower Garden Banks National Marine Sanctuary. http://flowergarden.noaa.gov/welcome.html Accessed 22 February 2011

. National Oceanic and Atmospheric Administration (NOAA). 2011. Science Missions and data. http://www.noaa.gov/sciencemissions/bpoilspill.html , accessed September 23, 2011.

### 19 Environmental Impact Analysis (EIA)

Petrobras America Inc. Page 19-77 Development Operations Coordination Document Cascade / Chinook Development Project National Oceanic and Atmospheric Administration (NOAA) 2011. Gulf of Mexico Biodiversity http://www.nbii.gov/portal/server.pt/community/gulf_of_mexico_biodiversity/19 50/marine_vertebrates/7249 , accessed September 23, 2011. National Oceanic and Atmospheric Administration (NOAA), 2007a, web-based communication from the National Marine Fisheries Service, Fisheries Statistics and Economics Division, Silver Spring, MD, http://www.st.nmfs.gov/. National Oceanic and Atmospheric Administration (NOAA), 2007a, NOAA Fisheries: Office of Science & Technology, webpage at http://www.st.nmfs.gov/st1/commercial/ , accessed January 31, 2007. __________, 2007b, NOAA Fisheries Office of Protected Resources, webpage at http://www.nmfs.noaa.gov/pr/species/concern/ , accessed January 26, 2007. __________, 2002, Biological Opinion for Gulf of Mexico Outer Continental Shelf Multi-lease Sale (185, 187, 190, 192, 194, 196, 198, 200, 201), F/SER/2002/00718, NOAA National Marine Fisheries Service, Southeast Regional Office, St. Petersburg, FL. __________, 1999, Final Fishery Management Plan for Atlantic Tuna, Swordfish, and Sharks, NOAA National Marine Fisheries Service, Office of Sustainable Fisheries, Highly Migratory Species Management Division, Silver Spring, Maryland. Pearson, C.E., S.R. James, Jr., M.C. Krivor, S.D. El Darragi, and L. Cunningham, 2003,Refining and Revising the Gulf of Mexico Outer Continental Shelf Region HighProbability Model for Historic Shipwrecks: Final report. Volume I: Executive Summary (OCS Study MMS 2003-060) and Volume II: Technical Narrative (OCS Study MMS 2003-061), U.S. Dept. of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. Petrobras America Inc., (PAI) 2006, Level I Basis of Design, Cascade Phased Development Project, I-ET-7040.2-1000-941-001-0, Petrobras America Inc., Houston, TX.

Ribic et al. 1997. Ribic, C.A., R. Davis, N. Hess, and D. Peake. 1997. Distribution of Seabirds in the Northern Gulf of Mexico in Relation to Mesoscale Features: Initial Observations. ICES Journal of Marine Science 54:545–55. Russell, R. W. 2005. Interactions between Migrating Birds and Offshore Oil and Gas Platforms in the Northern Gulf of Mexico. Final Report. (OCS Study MMS 2005- 009.) Minerals Management Service, Gulf of Mexico OCS Region. New Orleans, LA. 348 pages. Available online: http://www.gomr.mms.gov/homepg/regulate/environ/studies/2005/2005-009.pdf

. Sonoma Technology Inc., 2004, Breton Aerometric Monitoring Program, October 2000- November 2001, Petaluma, CA.

### 19 Environmental Impact Analysis (EIA)

Page 19-78 Petrobras America Inc. Development Operations Coordination Document Cascade / Chinook Development Project Texas Parks and Wildlife Department (TPWD). 2007. Texas Gems – Flower Garden Banks National Marine Sanctuary. http://www.tpwd.state.tx.us/landwater/water/conservation/txgems/flowerga/index. phtml Accessed 22 February 2011. TDI-Brooks International, Inc., 2005, Investigations of Chemosynthetic Communities on the Lower Continental Slope of the Gulf of Mexico, News Item, September 2005, http://www.tdi-bi.com/what's_new/sept05/chemoIII/Chemo%20write%20up.pdf

. U.S. Census Bureau. 2000. United States Census 2000. Decennial Census. Available through the American FactFinder: http://factfinder.census.gov/home/saff/main.html?_lang=en Accessed 17 February 2011. U.S. Census Bureau. 2007. 2007 Economic Census and Surveys. Available through the American FactFinder: http://factfinder.census.gov/home/saff/main.html?_lang=en Accessed 17 February 2011.

U.S. Census Bureau. 2010. United States Census 2010. Decennial Census. Available through the new American FactFinder: http://factfinder2.census.gov/main.html Accessed 17 February 2011. U.S. Department of Labor Statistics. 2010. Local Area Unemployment Statistics. Databases, Tables & Calculators by Subject. Bureau of Labor Statistics. http://www.bls.gov/data/ Accessed 21 February 2011. United States Fish and Wildlife Service (USFWS), 2002, Wildlife and Fisheries , 50 CFR, Chapter 1, Section 10.13, List of Migratory Birds. __________, 2000, Appendix V: West Indian Manatee ( Trichechus manatus latirostris ): Florida Stock, Online at http://www.nmfs.noaa.gov/pr/pdfs/sars/westindianmanatee_florida.pdf

, USFWS North Florida Field Office, Jacksonville, FL. __________,. 2010. Sea Turtle Information. North Florida Ecological Services Office. http://www.fws.gov/northflorida/SeaTurtles/seaturtle-info.htm Accessed 22 February 2011. U.S. National Park Service. 2010. Current Sea Turtle Nesting Season. Padre Island National Seashore. http://www.nps.gov/pais/naturescience/current-season.htm Accessed 22 February 2011. United States Geological Survey, 1995, U.S. Geological Survey Programs in Louisiana, Fact Sheet FS-018-95, Department of the Interior, US Geological Survey, Baton Rouge, LA. University of Michigan, 2003, Animal Diversity Web, sponsored in part by the Interagency Education Research Initiative, the Homeland Foundation, and the University of Michigan Museum of Zoology, http://animaldiversity.ummz.umich.edu/.

### 19 Environmental Impact Analysis (EIA)

Petrobras America Inc. Page 19-79 Development Operations Coordination Document Cascade / Chinook Development Project Waring, Gordon T., Elizabeth Josephson, Carol P. Fairfield, and Katherine Maze-Foley (Editors), 2007, U.S. Atlantic and Gulf of Mexico Marine Mammal Stock Assessments – 2006 (2 nd 

### Edition), Web version posted April 24, 2007 at http://www.nefsc.noaa.gov/nefsc/publications/tm/tm201/ , National Oceanic and Atmospheric Administration (NOAA) Northeast Fisheries Science Center, Woods Hole, MA. Würsig, B., T. A. Jefferson, and D. J. Schmidly, 2000, The Marine Mammals of the Gulf of Mexico, Texas A&M University Press, College Station, TX.

### 19 Environmental Impact Analysis (EIA)

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### Petrobras America Inc. Page 20-1

Development Operations Coordination Document Cascade / Chinook Development Project 

# 20 Administrative Information
20(a) Exempted Information Description
PAI has determined that the following information in Table 20-1 is considered proprietary and will therefore not be included in the public version of the SDOCD.

Table 20-1 – Proprietary Information

Description Section

BHL, TVD, and MD information in Plan Information Forms 1(a), 1(b)

Production rates 2(c)

Geological and geophysical information 3 (a), 3(b), 3(c), 3(d), 3(e), 3(f)

Hydrogen Sulfide Classification 4(b)

Reservoir Information and Exploratory Well Results 5(b)

Topographic Features Map 6(b)

Archeological Resources Information and Figure 19(b).15

Geological and geophysical information Appendix 2-B

Worst-Case Discharge Evaluation Appendix 6



### 20(b) Bibliography
The following citations were used in the DOCD. This list excludes citations that were used in the EIA contained in Section 19. Ji, Zhen-Gang, Walter R. Johnson, Charles F. Marshall, and Eileen M. Lear (Editor), 2007, Oil-Spill Risk Analysis: Contingency Planning Statistics for Gulf of Mexico OCS Activities, U.S. Department of the Interior Minerals Management Service, Environmental Division, Herndon, VA.

### 20 Administrative Information

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### Petrobras America, Inc. Development Operations Coordination Document Cascade / Chinook Development Project



# APPENDIX 1

C ascade / Chinook S OP A pprovals

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### Petrobras America, Inc. Development Operations Coordination Document Cascade / Chinook Development Project



# APPENDIX 1a

Approved DWOP - 18 August 2009

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### Petrobras America, Inc. Development Operations Coordination Document Cascade / Chinook Development Project



# APPENDIX 2a

GEMS Summary of Environmental Conditions for Cascade and Chinook

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### Petrobras America, Inc. Development Operations Coordination Document Cascade / Chinook Development Project



# APPENDIX 2b

GEMS Shallow Hazards Report for Facilities - P ublic Version

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# Seafloor and Geologic Assessment Cascade and Chinook Development Areas Blocks 160-162, 203-208, 247-252, 293-295, 337-338, 381-382, 425-426, & 469-470 Walker Ridge Area Gulf of Mexico

Report submitted to 

# Petrobras America Inc. Houston, Texas by Geoscience Earth & Marine Services ® 

## , Inc. Houston, Texas

PUBLIC COPY

Project No. 1106_1257b 10615 Shadow Wood Dr., Suite 200 Houston, Texas 77043 (713) 468-1410 phone

(713) 468-1438 fax gems@gemsinc.com10615 SHADOW WOOD DRIVE SUITE 200 HOUSTON, TEXAS 77043 Phone: (713) 468-1410 Fax: (713) 468-1438 E-mail: gems@gemsinc.com

June 6, 2007 Project No. 1106_1257b

Petrobras America Inc. Walker Ridge EPS-Subsea Engineering 2101 City West Blvd. Bldg 3, Suite 300 Houston, Texas 77042

Attention: Mr. Kazuhiko Kochi



### SEAFLOOR AND SHALLOW GEOLOGIC ASSESSMENT CASCADE AND CHINOOK DEVELOPMENT AREAS BLOCKS 160-162, 203-208, 247-252, 293-295, 337-338, 381-382, 425-426, & 469-470 WALKER RIDGE AREA, GULF OF MEXICO

Geoscience Earth & Marine Services ® , Inc., (GEMS) is pleased to provide Petrobras America Inc. (PAI) with our geophysical and geotechnical evalua tion of the Cascade and Chinook development areas in the Walker Ridge Area (WR) of the Gulf of Mexico. The purpose of this report is to define seafloor and shallow geologic/geotechnical conditi ons and constraints relevant to future development of the Cascade and Chinook areas, as well as along proposed tie-back and export flowlines and umbilicals routes. The Cascade development is composed of two drill centers, located in WR Blocks 206 and 249, that tie-back to a floating production, storage, and offloading vessel (FPSO) in WR Block 249, having anchors in WR Blocks 250, 293, and 294, and pipelines and umbilical s traversing portions of WR Blocks 206, 249, 250 293, and 294. The Chinook development is composed of a drill center located in WR Block 425. Dual flowlines, with associated umbilicals, crossing WR Blocks 293, 337, 371, and 425, will tie-back ~11.5 miles to the Cascade FPSO. The report complies with requirements set forth by th e United States Minerals Management Service (MMS) in government publications Notice-to-Lessees 2000-G20 (MMS, 2000), Notice-to-Lessees 2002-G01 (MMS, 2002), and Notice-to-Lessees 2007-G01 (MMS, 2007). This report is in accordance with Purchase Order 7000000549 dated 14 November, 2006

. We appreciate the opportunity to be of service to PAI on this project and look forward to working closely with you as this landmark project progresses. Sincerely,

GEOSCIENCE EARTH & MARINE SERVICES ® , INC.

James F. Keenan John R. Brand, Ph. D Geoscientist Senior Geologist / Projects Manager

Michael J. Kaluza President Distribution: Mr. Kazuhiko Kochi, Petrobras America Inc., Houston, Texas (5)Project No. 1106-1257b TABLE OF CONTENTS



### TABLE OF CONTENTS MAIN TEXT Page



### SUMMARY i

SECTION 1: INTRODUCTION 1

Purpose

.............................................................................................................................. .............................. 2 Available Data

.............................................................................................................................. .................. 2 Proprietary Geophysical Data

............................................................................................................... 2 Proprietary Geotechnical Data

.............................................................................................................. 4 Public Data

.............................................................................................................................. ................ 4 Project Responsibilities

.............................................................................................................................. ... 4 Report Format

.............................................................................................................................. .................. 4



### SECTION 2: REGIONAL GEOLOGIC SETTING 6

Location

.............................................................................................................................. ............................ 6 Lower Continental Slope ................................................................................................................... 7 Structure

.............................................................................................................................. ..................... 7 Stratigraphy

.............................................................................................................................. ............... 7 Sigsbee Escarpment .......................................................................................................................... 9 Structure

.............................................................................................................................. ..................... 9 Stratigraphy

.............................................................................................................................. ............... 9 Upper Continental Rise ..................................................................................................................... 10 Structure

.............................................................................................................................. ..................... 10 Stratigraphy

.............................................................................................................................. ............... 10 Faults

.............................................................................................................................. ................................. 10 Slope Stability

.............................................................................................................................. .................. 11 Seafloor Currents

.............................................................................................................................. ............. 11 Hydrocarbon Migration and Related Seafloor Features

........................................................................... 11 Hydrocarbon Vents

.............................................................................................................................. .. 11 Hydrates

.............................................................................................................................. ..................... 12 Authigenic Carbonates

........................................................................................................................... 12 Chemosynthetic Communities

..................................................................................................................... 12 Shallow Water Flow

.............................................................................................................................. ........ 13 Exploration Activity and Man-Made Structures

....................................................................................... 13



### SECTION 3: SHALLOW GEOLOGIC CONDITIONS IN THE CASCADE DEVELOPMENT AREA 14
Bathymetry and Seafloor Gradient

.............................................................................................................. 14 Physiographic Provinces, Seafloor Morphology, and Stratigraphy

....................................................... 14 Lower Continental Slope (LCS)

........................................................................................................... 15 The Sigsbee Escarpment (SE) ............................................................................................................... 17 The Upper Scarp

.............................................................................................................................. .... 19 The Bench

.............................................................................................................................. ................ 19 The Lower Scarp

.............................................................................................................................. ..... 20 Upper Continental Rise (UCR)

............................................................................................................. 21 Seafloor Furrows

.............................................................................................................................. .... 22 Seafloor Flukes

.............................................................................................................................. ....... 23 Seafloor Flukes and Furrows

............................................................................................................. 25Project No. 1106-1257b TABLE OF CONTENTS

Topographic Low

.............................................................................................................................. ... 26 Chemosynthetic Communities

..................................................................................................................... 28 LCS Province

.............................................................................................................................. ............ 28 SE Province

.............................................................................................................................. ............... 28 UCR Province

.............................................................................................................................. ........... 28



### SECTION 4: SHALLOW GEOLOGIC CONDITIONS IN THE CHINOOK DEVELOPMENT AREA 30
Bathymetry and Seafloor Gradient

.............................................................................................................. 30 Physiographic Provinces, Seafloor Morphology, and Stratigraphy

....................................................... 30 (UCR) Seafloor Furrows

....................................................................................................................... 31 (UCR) Seafloor Anti-Dunes .................................................................................................................. 31 (UCR) Topographic Low

...................................................................................................................... 32 Geotechnical Data

.............................................................................................................................. ............ 33 Chemosynthetic Communities

..................................................................................................................... 34



### SECTION 5: SEAFLOOR AND SHALLOW GEOLOGIC CONDITIONS OF THE CHINOOK TIE-B ACK PIPELINE CORRIDOR 35
Water Depths and Gradient

.......................................................................................................................... 35 Seafloor Currents

.............................................................................................................................. ............. 35 Seafloor Morphology and Soils

................................................................................................................... 35 Seafloor Anti-dunes

.............................................................................................................................. .. 35 Seafloor Furrows

.............................................................................................................................. ...... 36 Sediments

.............................................................................................................................. .......................... 36 Man-made Features and Conditions

............................................................................................................ 36 GEOLOGIC CONDITIONS ALONG THE PROPOSED WEST FLOWINE ROUTE

..................... 36 Man-made Features and Conditions

............................................................................................................ 37 Chemosynthetic Communities

..................................................................................................................... 37 GEOLOGIC CONDITIONS ALONG THE PROPOSED EAST FLOWINE ROUTE

...................... 37 Man-made Features and Conditions

............................................................................................................ 38 Chemosynthetic Communities

..................................................................................................................... 38



### SECTION 6: FINDINGS AND RECOMMENDATIONS 39
Cascade Development Area

......................................................................................................................... 39 Chinook Development Area

......................................................................................................................... 40 Chinook Tie-Back Corridor

......................................................................................................................... 40 Summary of Geologic and Geotechnical Findings With Respect to Proposed Field Architecture.... 41 Recommendations................................................................................................................ .............. 46



### LIST OF FIGURES Page No.

Figure 1: Location Map ................................................................................................................... 1 Figure 2: Seafloor rendering showi ng outline of the data coverage ............................................... 3 Figure 3: Regional seafloor rendering of th e northwestern Walker Ridge area showing the development areas in relation to major seafloor topographic features .......................... 6 Figure 4: 3-D seismic inline 8100 illustrating the salt related structural setting beneath the Sigsbee Escarpment ................................................................................................. 7 Figure 5: Regional illustration of the Study Area in relation to the major Pleistocene Mississippi River depositional provinces ...................................................................... 8Project No. 1106-1257b TABLE OF CONTENTS



### LIST OF FIGURES (Cont.’)

Page No. Figure 6: Isometric view of the Sigsbee Escarpment in the Cascade area showing slump scarps on the Escarpment and associated debris apron on the Upper Continental Rise ........... 9 Figure 7: Physiographic provinces within the Cascade Development area .................................... 15 Figure 8: The portion of subbottom profiler line 202 displays typical structure and stratigraphy of the Lower Continental Slope province ...................................................................... 16 Figure 9: Geotechnical test results for the LCS province ............................................................... 17 Figure 10: Isometric view of the Sigsbee Escarpment within the Cascade Development area showing a bench separating an upper and lower scarp .................................................. 18 Figure 11: Subbottom Profiler lines perpendicular (left) and parallel (right) to the Sigsbee Escarpment illustrating the varying stratigraphy and highly deformed structure of the Escarpment ........................................................................... 18 Figure 12: Geotechnical test results for the upper scarp of the SE province ................................... 19 Figure 13: Geotechnical test results for the bench of the SE province ............................................ 20 Figure 14: Geotechnical test results for the lower scarp of the SE province ................................... 21 Figure 15: Subbottom profiler line 138 s hows the transition between “fluked” and “Furrowed” seafloor .............................................................................................. 22 Figure 16: Geotechnical test results for the seafloor furrows of the UCR province ........................ 23 Figure 17: Geotechnical test results for the seafloor flukes of the UCR province ........................... 24 Figure 18: Geotechnical test results for the seafloor furrowed furrows of the UCR province ........ 25 Figure 19: Subbottom profiler line within the topographic low shows folded strata in the shallow subsurface. Darker regions on the side-scan mosaic (Maps 2C and 3C) indicate areas where the “triplet” outcrops .................................................................... 27 Figure 20: Composite soil information to estimate conditions for the topographic low Region of the UCR province ......................................................................................... 27 Figure 21: Subbottom profiler line 117 showing mounds in the LCS province .............................. 28 Figure 22: Physiographic sub-provinces within the Chinook Development Area ........................... 30 Figure 23: Subbottom profiler line 641 showing furrows in the Chinook Development Area ........ 31 Figure 24: Subbottom profiler line 641 showing anti-dunes in the Chinook Development Area .......................................................................................... 32 Figure 25: Subbottom profiler line 725 showing anticlines in WR 469 and 470 ............................ 32 Figure 26: Subbottom profiler line 720 showing the topographic low in the Chinook Development area ................................................................................. 33 Figure 27: Geotechnical test results for the Chinook area, UCR province ...................................... 34Project No. 1106-1257b TABLE OF CONTENTS



### LIST OF TABLES

Table No. Table of AUV data coverage .................................................................................................... ............ 1 Table of existing and proposed wells .......................................................................................... ...... 2 List of cores for the LCS province ............................................................................................ ........ 3 List of cores for the upper scarp of the SE province ......................................................................... 4 List of cores for the bench of the SE province ................................................................................ .. 5 List of cores for the lowe r scarp of the SE province ......................................................................... 6 List of cores for the seafloor fu rrows of the UCR province ............................................................. 7 List of cores for the seafloor flukes of the UCR province ................................................................ 8 List of cores for the seafloor furrowed flukes of the UCR province ................................................ 9 List of cores for the Chi nook area, UCR province ........................................................................... 10 Water depth and gradient along the Tie-Back routes ........................................................................ 11 West Tie-Back block crossings ................................................................................................. ........ 12 Water depth and gradient along th e west Tie-Back route ................................................................. 13 East Tie-Back block crossings ................................................................................................. ......... 14 Water depth and gradient along the east Tie-Back route .................................................................. 15 Summary Table ................................................................................................................. ................ 16



### LIST OF MAPS

Map No. Cascade Development Area Base Map, Cascade De velopment Area ............................................................................................ 1A Bathymetry Map, Cascade Development Area ................................................................................. 2A Seafloor Gradient Map, C ascade Developmen t Area ....................................................................... 3A Seafloor Rendering, Cascade Development Area ............................................................................. 4A Isopach Map, Seafloor to “Triplet” ............................................................................................ ....... 5A Structure Map, Sea Surface to Top of Salt ..................................................................................... ... 6A Side-Scan Mosaic, Cascade Development Area ............................................................................... 7A Features Map, Cascade De velopment Area ...................................................................................... 8 A

Chinook Development Area Base Map, Chinook Development Area ........................................................................................... 1B Bathymetry Map, Chinook Development Area ................................................................................ 2B Seafloor Gradient Map, Chinook Development Area ....................................................................... 3B Seafloor Rendering, Chinook Development Area ............................................................................ 4B Isopach Map, Seafloor to “Triplet” ............................................................................................ ....... 5B Side-Scan Mosaic, Chinook Development Area ............................................................................... 6B Features Map, Chinook Development Area ...................................................................................... 7 B

Chinook Tie-Back Corridor Regional Study Map, Chinook Tie-Back .......................................................................................... .... 1C West Flowline Alignment Sheet ......................................................................................2C (Sheet 1 of 2) West Flowline Alignment Sheet ......................................................................................2C (Sheet 2 of 2) East Flowline Alignment Sheet ........................................................................................3C (Sheet 1 of 2) East Flowline Alignment Sheet ........................................................................................3C (Sheet 2 of 2)

Note: Maps are in pockets at rear of report.Project No. 1106-1257b TABLE OF CONTENTS



### LIST OF APPENDICES Appendix A: Side-Scan Sonar Targets Appendix B: Geotechnical Core Logs Appendix C: References Appendix D: Interpretive Procedures Appendix E: R/V Northern Resolution and AUV DescriptionsProject No. 1106-1257b SUMMARY

- i - 

### SUMMARY

Petrobras America Inc. (PAI) contracted Geoscience Earth & Marine Services ® , Inc., (GEMS) to evaluate the geologic and stratigraphic conditions in the Cascade and Chinook development areas in Walker Ridge (WR), Blocks 160-162, 203-208, 247-252, 293-295, 37-338, 381-382, 425-426, and 469- 470. The purpose of this study was to assess the seafloor and shallow geologic conditions at the planned floating production, storage, and offloading (FPSO) facility in WR 249, at the Cascade and Chinook drill centers in WR 206, 249, and 425, along infield pipelin es and umbilicals in portions of WR Blocks 206, 249, 250 293, and 294, and along the proposed flowline and umbilical routes between the Chinook drill center in WR 425 and the FPSO in WR 249. The study was conducted using AUV, 3-D seismic, and shallow geotechnical soil samples to assess the upper 150 ft BML of sediment in the Cascade and Chinook development areas.

General Conditions in the Cascade Development Area

• The geologic and geotechnical conditions obser ved at Chinook appear favorable for field development.

• Water depths in the Cascade Development area ra nge from 5,637 ft in the northeastern corner of WR 247 to 8,510 ft in the north-central part of WR 338.

• The area consists of three geomorphologic provin ces, the Lower Continental Slope, the Sigsbee Escarpment, and the Upper Continental Rise, w ith the Escarpment crossing the northeastern portion of the area.

• The proposed Cascade facilities will be placed be low the Escarpment on the Upper Continental Rise.

• The seafloor above the Escarpment, on the Lowe r Continental Slope, is generally smooth and featureless. The Escarpment seafloor is rugged. The seafloor below the Escarpment is irregular due to seabed furrows and flukes.

• Seafloor gradients range from near 0o above the Sigsbee Escarpment on the Lower Continental Slope to approximately 70° along the steeper porti ons of the Escarpment. The Upper Continental Rise has a low general gradient, however, furrows and flukes can cause locally high gradients.

• The shallow stratigraphy over the area consists ge nerally of parallel bedded hemipelagic clays. Local slump deposits exist at the base of the Escarpment and sands are present along the floors of the furrows.

• Periodic strong seabed currents are responsible for the formation of the furrows and flukes on the Upper Continental Rise. Evidence of significant erosion is also evident on both the Escarpment and Lower Continental Rise. PAI is aware of these conditions and is addressing the placement of seafloor architecture in these areas from a siting and design standpoint.

• Past slope instability along the Escarpment has resulted in deposition of debris aprons which extend up to one mile downslope of the base of th e Escarpment. The nearest proposed facility to the Escarpment is the Cascade East drill center located approximately one mile downslope of the Escarpment. PAI intends to conduct a future, detailed slope stability of the Escarpment with respect to locations of the Cascade facilities.

• Several gas expulsion mounds are identified on th e Lower Continental Slope in northeastern WR 160, more than four miles away from the proposed facilities.

• In the area of the Upper Continental Rise, wher e the Cascade facilities are planned, there are no geologic constraints such as active faulting, gas venting, or hard bottom conditions that would impact field development.Project No. 1106-1257b SUMMARY

- ii - • There is no potential for encountering chemosynthe tic communities near the planned infrastructure. General Conditions in the Chinook Development Area

• The geologic and geotechnical conditions obser ved at Chinook appear favorable for field development.

• Water depths in the Chinook Development area range from 8,607 ft in the northwestern corner of WR 425 to 9,260 ft in the southeastern corner of WR 470.

• Seafloor gradients range from close to 0o over much of the southwestern two-thirds of the area with locally high gradients, approaching 50°, along the si des of furrows in the northeastern third of the

area.

• The shallow stratigraphy over the area consists gene rally of parallel bedded, differentially eroded, hemipelagic clays. Sands are present along the floors of the furrows.

• Seafloor furrows are present in the north, and seafloor anti-dunes are present in the south and southeastern portion of the area. Periodic strong seabed currents are responsible for the formation of the furrows and anti-dunes.

• There are no geologic constraints such as active fa ulting, gas venting, or hard bottom conditions that would impact field development.

• There is no potential for encountering chemosynthetic communities in this area.

General Conditions in the Chin ook Pipelines Tie-Back Corridor

• The geologic and geotechnical conditions app ear favorable for flowline installation and performance, with appropriate engineering design.

• There are two proposed tie-back pipelines and one production umbilical in a corridor between the Chinook development area in WR 425 and the planned Cascade FPSO in WR 249.

• Water depths in the corridor range from -8,820 ft at the planned Chinook wellsite to -8,170 ft at the end of the pipeline route near the Cascade FPSO facility.

• The shallow stratigraphy over the area generally cons ists of differentially eroded, parallel-bedded, hemipelagic clays. Sands are present along the floors of the furrows.

• Seabed gradients in the corridor range from nearly 0o to locally approaching 32° along the sides of furrows. The average gradient along the west and east tie-back routes is 9° and 10°, respectively.

• Irregular seafloor consisting of anti-dunes, furrows , and flukes are present at various locations along the entire length of the corridor.

• A sidescan sonar target (Sonar Contact No. 24) li es about 7 ft from the proposed East Gas Pipeline Route at about Sta. 385+37.94. This target, which has no measurable height, is 4-ft wide, and 10-ft long, and may be modern debris. No other sona r contacts lie directly along the proposed pipeline or umbilical routes.

• An ROV pre-lay survey will confirm the presence of the identified potential man-made debris with respect to Sonar Contact No. 24. The debris can be removed if necessary.

• There are no geologic constraints such as active fa ulting, gas venting, or hard bottom conditions that would impact pipeline lay operations. The potential for encountering chemosynthetic communities is remote.Project No. 1106-1257b SECTION 1

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### SECTION 1: INTRODUCTION
Petrobras America Inc. (PAI) is evaluating development of the Cascade and Chinook fields in the Walker Ridge protraction area (WR) in the Gulf of Mexico (Figures 1 and 2). PAI has proposed placing a floating production, storage, and offloading facility (FPSO) in Block 249 that will service production from the Cascade and Chinook drill centers. The Chinook dr ill center will be a sub-sea tie-back to the Cascade FPSO. The FPSO will also export produced gas along a futu re gas export pipeline route. Included in this report is an assessment of the general shallow geol ogic and geotechnical conditions and engineering constraints in the Cascade and Chinook development areas, and along the proposed Chinook tie-back and Cascade FPSO gas export pipeline routes.

Figure 1. Location Map. The Cascade and Chinook development areas, and the tie -back corridor, encompass the following Federal lease blocks in the north-eastern portion of the Walker Ridge area:
Block 117 (OCS-G-21846) Block 247 (OCS-G-20305) Block 295 (Open) Block 160 (OCS-G-21854) Block 248 (OCS-G-18669) Block 337 (Open) Block 161 (OCS-G-18651) Block 249 (OCS-G-16969) Block 338 (Open) Block 162 (Relinquished) Block 250 (O CS-G-16970) Block 381 (Relinquished) Block 203 (OCS-G-23038) Block 251 (OCS -G-18670) Block 382 (Relinquished) Block 204 (OCS-G-18658) Block 252 (O pen) Block 425 (OCS-G-16987) Block 205 (OCS-G-16964) Block 292 (O CS-G-20309) Block 426 (OCS-G-16988) Block 206 (OCS-G-16965) Block 293 (O CS-G-18681) Block 469 (OCS-G-16997) Block 207 (OCS-G-20297) Block 294 (O CS-G-18682) Block 470 (OCS-G-16998) Block 208 (Open) ~ 1 3 2 M I L E SProject No. 1106-1257b SECTION 1

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### Purpose This study identifies the seafloor and shallow subsurface geologic and geotechnical conditions and evaluates engineering constraints within the Cascad e and Chinook development areas. This report also provides identification of conditions and evaluations of constraints specific to the Cascade drill centers, FPSO riser bases and anchors, and infield flowlines and umbilicals, as well as at the Chinook drill center, the proposed tie-back pipeline corridor between th e two development areas, and along two possible Cascade FPSO gas export pipeline options. The results of this study will assist PAI in the pl anning of all seafloor and shallow-founded architecture within, and between, the Cascade and Chinook developm ent areas. This report can also be used for permitting of the tie-back flowline and umbilical route. The report complies with requirements set forth by th e United States Minerals Management Service (MMS) in the following government publications:

• Notice-to-Lessees 2000-G20 (MMS, 2000)

• Notice-to-Lessees 2007-G01 (MMS, 2007a) The planned facilities are not located within a histor ically significant area, where archaeological surveys and assessments are required per NTL 2005-G07 (MMS, 2005).


### Available Data
This assessment results from the analysis of both pr oprietary data specific to the development areas and publicly available data. Proprietary Geophysical Data. An autonomous underwater vehicle (AUV) survey was conducted to assess the seabed and shallow geologic conditions in this area. GEMS worked with PAI to design the survey layout over the respective ar eas. The survey was designed to acquire data for identifying geologic constraints to facilities engineering. The survey m eets or exceeds the requirements set forth in Notice-toLessees 2007-G01 ), MMS, 2007a. PAI contracted C&C Technologies, Inc., (C&C) of Lafayette, Louisiana, to conduct the data acquisition for th e planned geophysical survey. The AUV survey was conducted from December 12, 2006 to January 26, 2007 and collected 1,770 miles of multi-beam echo sounder bathymetry, side-scan sonar, and chirp subbottom profiler data over the following areas:
Area Total Line Miles # Inlines Spacing (m) # Tie-Lines Spacing (m) Cascade Development 1124.60 74 200 31 600 Chinook Development 472.00 67 200 33 400 Chinook Tie-Back Corridor 278.00 13 centers, 50m offset, 100 2 6,800 Table 1. Table of AUV data coverage. The multibeam swathe bathymetry was binned at 3m. The sidescan sonar was reviewed and mosaicked at 1.0m resolution. The chirp subbottom profiler pr ovides an assessment of the shallow stratigraphy do a depth of ~ 125 ft below the seafloor (bsl).

In addition to the AUV data PAI provided a 3-D explor ation seismic depth volume in a SEG-Y format to assist in the study. These data cover approximately 163 square miles in the Walker Ridge area including all or portions of Blocks 160-163, 204-207, 248-251, 293-295, 338, 339, 382, 383, 426, 427, 470, and 471 (Figure 2, page 3, and Figure 3, page 5). The 3-D volume has an inline spacing of 65.62 ft, a crossline spacing of 81.18 ft, was sampled at 16 ft increments, and has a record length of 48,000 ft (0 to 48,000 ft).Project No. 1106-1257b SECTION 1

- 3 - A UV S

U

R

V

E

Y 

## 3-D DEPTH VOLUME X/Y: (ft)

Figure 2. Seafloor rendering show ing outlines of th e data coverage.Project No. 1106-1257b SECTION 1

- 4 - The 3-D data was used to push the geologic interp retations from the AUV survey deeper and ensure complete review of the potential shallow foundation z one. The data confirmed the observations of the AUV and provided information on deeper stratigraphy as well as geologic structure of the Escarpment, the latter of which is essential for planning geotechni cal programs for future slope stability studies. Proprietary Geotechnical Data. GEMS planned a geotechnical program that would define the geotechnical properties throughout the Cascade-Chinook Development areas to support facilities layout and engineering. The primary objective of this study w as to process and interpret the appropriate geotechnical data as required to: 1) define the spatial soil c onditions along the various pipeline segments and mudmat locations; 2) interpret soil parameters needed for pi peline, SCR, and mudmat foundation analyses; 3) make recommendations relative to spatial soil variability and re levant soil properties that should be considered in the foundation analyses to be performed for the planne d production infrastructure; and 4) integrate with existing geophysical data to assess overall feasibility of the proposed field layout. The scope of the project was to acquire seafloor soil samples with the piston corer and 0.5 m box corer around the proposed Cascade-Chinook Development and pe rform geotechnical laboratory testing. TDIBrooks collected 58 piston cores and 57 box cores for the Cascade-Chinook Development in Walker Ridge and Green Canyon Areas for PAI in November and December of 2006. The piston core samples were obtained using a maximum 20-ft long core barrel with an outside diameter of approximately 3.0 in. A 0.3x0.3x0.5 m box corer was used to collect mudline samples. Core locations and water depths are included on the individual cores logs that follow this report in Appendix B. The field investigation was conducted in two legs: the first leg occurred from 25 October to 10 November 2006, using the R/V Justo Sierra, and the second leg occurred from 10 to 18 December, 2006, using the R/V Ferrel . Water depths at the core locations ranged fro m 4,187 to 8,794 ft. Navigation of the vessel was provided with dual differential GPS signals: Thales Geosolutions (Racal) Skyfix and US Coast Guard DGPS.

Public Data. The regional framework for this study was est ablished by referencing public sources such as the MMS and various published technical papers. Re ferences are included in Appendix C. GEMS has compiled a database of information including Fede ral lease blocks of reported chemosynthetic communities, shallow water flow, shipwrecks, obstructi ons, and infrastructure. Regional bathymetry data is from the National Oceanic and Atmospheric Admini stration (NOAA) swath bathymetry with additional data from the Texas A&M Sea Grant program.



### Project Responsibilities
The field operations and office reporting were conducted under the management of GEMS. Dr. John Brand was the overall GEMS project manager fo r this project. C&C conducted the AUV geophysical data acquisition from the M/V Northern Resolution . The C&C Technologies field party manager was Mr. Chas Honea. PAI contracted GEMS to provide QA/ QC for the field operations and to interpret all collected data. Mr. James Keenan was the GEMS QA/ QC personnel on the vessel. Mr. Keenan was also the lead geologist performing the interpretations and re port of the geophysical data. Dr. Brand, Mr. Sanjay Shinde, and Ms. Jill Rivette reviewed the geotechnical data and contributed to the integrated reporting.



### Report Format The remainder of this report is divided into the following sections: Section 2: Regional Geologic Setting Page 6 Section 3: Shallow Geologic Conditions in the Cascade Development Area Page 14 Section 4: Shallow Geologic Conditions in the Chinook Development Area Page 30Project No. 1106-1257b SECTION 1

- 5 - Section 5: Seafloor and Shallow Geologic Conditions of the Chinook Tie Back Pipeline Corridor Page 35 Section 6: Findings and Recommendations Page 39 Appendices follow the main text of this report. A ppendix A contains tables and images of the side-scan sonar targets. Appendix B contains the geotechnical core logs. Appendix C is a list of the references cited. Appendix D describes the mapping and interpretive pro cedures performed for this assessment. Appendix E contains the R/V Northern Resolution and AUV geophysical survey information. Full-size maps are folded and placed in pockets at the end of each section of the report.Project No. 1106-1257b SECTION 2

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### SECTION 2: REGIONAL GEOLOGIC SETTING

The Cascade and Chinook development areas are on th e Upper Continental Rise, just west of the continental slope edge, in the northeastern portion of th e Walker Ridge protraction area (Figures 1 and 2). The Sigsbee Escarpment delineates the boundary between th e continental rise and the continental slope and occupies the northwestern portion of the Cascade area (Figures 1 and 2). The escarpment is the expression of the lobate frontal edge of allochthonous salt masses which form a complex system of salt ridges, overthrust tongues, and steep-sided massifs (Martin and Bouma, 1978). Upslope of the Escarpment the Lower Continental Slope displays a hill and basi n seafloor morphology. Below the Escarpment the continental rise is relatively flat but does display a scalloped and furrowed seafloor due to erosion from bottom currents. The following section defines the study area within the context of the regional morphological and geologic conditions. Man-made f eatures, including exploration and production activity in the general area, are also discussed.


### Location
The Cascade and Chinook development areas are approximately 132 and 150 nautical miles southsouthwest of New Orleans, Louisiana respectively, (F igure 1). The survey areas include three distinct geomorphologic regions: (1) The Lower Continental Slope, (2) The Sigsbee Escarpment and, (3) The Upper Continental Rise (Figures 3 and 4).

Figure 3. Regional seafloor rendering of the northwestern Walker Ridge area showing the development areas in relation to major seafloor topographic features.Project No. 1106-1257b SECTION 2

- 7 - Horizontal Distance (ft)Depth Below Sea Level (ft)



### SALT UPPER CONTINENTAL RISE LOWER CONTINENTAL SLOPE SIGSBEE ESCARPMENT

THRUST FAULTS AT TOE OF ESCARPMENT UPPER SCARP

BENCH

LOWER SCARP
NORMAL FAULTS BENEATH

THE ESCARPMENT FACE Horizontal Distance (ft)Depth Below Sea Level (ft)



### SALT UPPER CONTINENTAL RISE LOWER CONTINENTAL SLOPE SIGSBEE ESCARPMENT

THRUST FAULTS AT TOE OF ESCARPMENT UPPER SCARP

BENCH

LOWER SCARP
NORMAL FAULTS BENEATH

THE ESCARPMENT FACE General Location of proposed Cascade Facilities

Figure 4. 3-D seismic inline 8100 illustra ting the salt related structural se tting beneath the Sigsbee Escarpment. Figure 4 illustrates the basic stratigraphy and struct ure of the different provinces. These provinces are discussed in the following sections. 

### Lower Continental Slope
Much of the Lower Continental Slope along the nor thern Gulf of Mexico margin lies within the Tabular Salt-Minibasin Province as defined by Diegel et al., (1995). This province is described as a region containing extensive salt sheets with intervening deep water, sediment-filled basins. This morphology is consistent to the southern edge of the province, which is the Sigsbee Escarpment.

Structure. Salt tectonics is the dominant process controlling the geologic structure of the Lower Continental Slope. A thick accumulation of the Jurassic aged (160 to 140 million years, B.P.) Louann Salt layer underlies much of the Texas-Louisiana continen tal slope (Lehner, 1969). Initial deformation of the salt layer occurred in the Eocene to early Oligocene (55 to 37 million years, B.P.). Additional loading of the salt during the lower Miocene to middle Pliocene ( 14 to 2.3 million years, B.P.) caused a remobilization of the salt and created spreading across the slope in the form of large amalgamated salt canopies seaward to the Sigsbee Escarpment. The salt masses attempt to achieve isostatic equilibrium with the surrounding sediments, forcing both horizontal and vertical responses. Updip extensional regions are characterized by growth (extensional) faulting. Downdip contractional regions exhibit folding and thrusting at the base of the slope. The mobilization of the salt affected the surrounding sed iments by causing deformation (e.g., faults and/or folds) and by placing a structural control on subse quent sediment depositional patterns. Topographic highs can block the downslope transport of sediments. St ructural lows around diapirs or salt ridges can act as conduits for the transport of sediment downslope and out onto the continental rise. Salt withdrawal basins (Intraslope Basins) can act as traps for the ponding and accumulation of large volumes of sediment (Apps et al., 1994). Stratigraphy. Most of the shallow stratigraphy on the Lo wer Continental Slope is correlated to the Pleistocene (1.8 million years to 11,550 years B.P.) Mi ssissippi River. The Pleistocene Mississippi River depositional province spans a large portion of the central Gulf of Mexico and has been classified into two major depositional systems: the Western Deposystem and the Eastern Deposystem (Winker and Booth, 

# PROPRIETARYProject No. 1106-1257b SECTION 2

- 8 - 2000), Figure 5. Shifts in the depositional focus of th e Mississippi River have been attributed to sea level fluctuations and river meander, which has had a direct impact on the facies assemblages observed across the continental slope (Prather et al., 1998; Winker and Booth, 2000; Damuth et al., 2003).

Figure 5. Regional illustration of the Study Area in relation to the major Pl eistocene Mississippi River depositional provinces. Both the Western and Eastern Deposystems exhibit intraslope fans and shelf margin deltas, as well as subsequent incised valleys and canyons (Winker and Booth, 2000). The sediments were delivered downslope through a fill and spill process of linked intr aslope basins (Steffens, 1993; Prather et al., 1998; Winker and Booth, 2000; Damuth et al., 2003).
Prather et al., (1998) and Winker and Booth (2000) cl assify the sedimentary sections within intraslope basins as bypass and ponded facies. Many basins show a cyclic succession of bypass and ponded facies with the more chaotic bypass facies overlying the layered ponded facies. Bypass facies are generally dominated by mass-transport complexes, channel fill, and overbank deposits. These units are, in large part, sand poor and are thickest in a proximal setting to the major Pleistocene depocenters. Ponded facies generally consist of slope fan de posits and sand-enriched turbidites. The ponded facies dominate down slope in a distal setting from the Pleistocene depo centers. The Cascade and Chinook development areas are located downslope and approximately mid-way between th e two major late Pleistocene slope fan units (i.e., the GB Orange and GC Red units of Winker and Booth, 2000). Therefor e, the layered or ponded units in the shallow section are likely to be predominantly clay -rich and generally sand poor . This is supported by the overall continuity and amplitude character of th e stratigraphic section for the Lower Continental Slope in Figure 4. Cascade and Chinook

Modified from Winker and Booth, 2000.Project No. 1106-1257b SECTION 2

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### Sigsbee Escarpment
The Sigsbee Escarpment is a continuous scarp marking the boundary between the Lower Continental Slope and the Upper Continental Rise al ong the northern margin of the Gulf of Mexico (Figures 3 through 5). It extends continuously over 300 miles from the Perdido Foldbelt in the southwest to the Mississippi Fan in the northeast.

Structure. The Sigsbee Escarpment is a complex topographic and morphologic feature which represents the seaward limit of mobile allochthonous salt (Jacks on and Hudec, 2004). Formation of the Escarpment results from sediment loading on the upper slope causing mobilization of the viscous salt. Through this process, the salt attempts to achieve isostatic e quilibrium with the surrounding sediments, forcing both horizontal and vertical responses. Beneath the Escarpment face the vertical movement of salt results in growth (extensional) faulting. Downdip, contrac tional forces resulting from the horizontal movement of salt result in folding, and more commonly, thrust faulting at the toe of the Escarpment (Figure 4). The Escarpment is underlain by a series of coalescing salt tongues and sheets known as the Sigsbee Nappe. The Escarpment face is characterized by steep slopes and contains numerous faults, slumps, and gullies. Many of the slumps have created mounded debris aprons that extend out onto the adjacent Upper Continental Rise as shown in Figure 6. Several cany ons are identified along the Sigsbee Escarpment within the Walker Ridge area. Two such canyons are, Fa rnella Canyon located approximately 18 miles to the southwest, and Green Canyon located approximately 15 miles to the north of the development areas. The Farnella Canyon and Green Canyon salt re-entrants are relict sediment pathways for Mississippi Riverderived sediments. The canyons were abandoned during episodes of sea level rise and/or geographic shifts in the Pleistocene Mississippi River depocenter.

SLUMP SCARPS

DEBRIS APRONS


## U P P E R C O N T I N E N T A L R I S E S I G S B E E E S C A R P M E N T

SLUMP SCARPS

DEBRIS APRONS


## U P P E R C O N T I N E N T A L R I S E S I G S B E E E S C A R P M E N T

Figure 6. Isomet view of the Sigsbee Escarpment in the Cascade area showing slump scarps on the Escarpment and associated debris aprons on the Upper Co ntinental Rise. View is looking northwes t. The proposed Cascade facilities are located southeast out of the frame. Stratigraphy. The stratigraphy along the Escarpment is highl y variable, consisting of recently deposited draped and ponded sediments, fault- or failure-exposed older strata, and slump a nd landslide deposits. The ponded drape deposits will likely be soft to very soft Holocene clays overlying s tiffer Pleistocene/PlioceneProject No. 1106-1257b SECTION 2

- 10 - clays. Stiff to very stiff clays are most likely e xposed along fault scarps. Multiple episodes of slumps or debris slides have deposited debris aprons at the base of the Escarpment (Figure 6). These sediments will generally exhibit high variability both laterally between adjacent deposits and vertically within individual deposits. 

### Upper Continental Rise
The Upper Continental Rise extends from the base of the Sigsbee Escarpment out to the abyssal plane. Regionally extensive seafloor bed forms consis ting of furrows, anti-dunes, and other erosion related features on the seafloor have recently been identifie d along the base of the Sigsbee Escarpment in the Green Canyon area (Bryant et al., 2001). These seafloor features are typically longitudinal bed forms that occur in fine-grained sediment caused by erosion fro m bottom currents (Scott et al., 2001). The erosional nature of the furrows indicates the presence of potentially strong bottom currents along the Sigsbee Escarpment. Bottom currents of two knots have been re ported to the east in AT 618 and experimental work near the Bryant Fan to the west indicates the occurre nce of at least two-knot bottom currents (Scott et al., 2001).

Structure. The only dominant structural process affecting the Upper Continental Rise in the development areas is thrust faulting at the base of the Sigsbee Escarpment (see Figure 4). The thrusts are usually duplexes and are typically characterized by reverse disp lacements that eventually die out up-section of the basement decollement. Stratigraphy. The deep water stratigraphy on the Upper Con tinental Rise generally c onsists of alternating units of thick, chaotic reflection sequences with well- stratified, parallel reflection sequences as evident in Figure 4. The chaotic sequences are “expanded” sec tions of rapidly deposite d slumps and landslides sourced from both the Sigsbee Escarpment and distal Lower Continental Slope mass-transport systems during times of lowered sea level. The parallel (be dded) sequences are "condensed sections" composed of hemipelagic and pelagic sediments deposited during times of stable or rising sea level.
The near-surface sediments, or Late Pleistocene-Holocene drape, along the rise is likely very similar to the drape deposits found on the slope above the Escarpment. These sediments consist of very soft, high water content, silty clays, and normally consolidated to slightly under-consolidated (Booth and Dunlap, 1977). This drape was deposited during the Late-Pleistocene-Ho locene epochs. A generic slope soil profile shows a gradual, linear increase in strength with depth al ong with a corresponding decrease in water content. Actual geotechnical properties, however, can differ gr eatly from the generic profile, due to the presence of buried landslides, turbidity flow de posits, faulting, possible presence of gas hydrates, and erosion of the seabed.



### Faults

Extensional faults dominate the northern Gulf of Mexico basin. These faults are primarily listric growth faults that sole into a salt layer and show an increase in displacement with increasing depth. Rowan et al., (1999) describe many salt-related, extensional fault families, including several salt-rooted growth fault families and faults over crests of fold structures, i. e., anticlines. In many instances, growth faults root into the crests of salt diapirs, forming fault-bounded graben and half-graben structures. Many of these graben families can form complex in terconnected patterns on the seafloor. Faults at the edge of the salt structures are contrac tional, i.e., thrust faults near the downdip limit of allochthonous salt bodies. These “toe-thrust” faults counterbalance the updip extension created by the basinward-dipping normal faults (Rowan et al., 1999). Th rust faults are typically characterized by reverse displacement that eventually dies out up-section. Although not as common as extensional faults, strike-slip faults are also observed in the Walker Ridge area of the Gulf of Mexico. These faults are salt-rooted and oriented roughly parallel to the regional seafloor dip. The position and geometry of the strike-slip fa ults suggest that the deformation may connect the extensional normal faults further landward to the c ontractional structures basinward (Rowen et al., 1999).Project No. 1106-1257b SECTION 2

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### Slope Stability
Uplifting of underlying salt can put stress on low-shear strength surface sediments. With continual uplifting and rotation, the surface materials may even tually fail downslope from the uplift. Increases in pore-pressure due to loading and salt motions also c ontribute instability. These failures are characterized by their arcuate shapes with irregular seafloor downslope of the feature. Many of these failures throughout the continental slope region are covered with a drape of Holocene-aged pelagic sediments (Doyle et al., 1992). The presence of a drape over a slump scar and debris fiel d would indicate that the slump event is an ancient feature. A lack of drape would indicate that the la ndslide is a relatively recent feature and slope stability could be of a concern for the area. The exception to th is is where strong currents may erode, or prevent, the deposition of overlying drape, resulting in “fresh-looking” s lide deposits that may in fact be quite old in the geologic record. Detailed studies of the Escarpment s uggest an increase in failures during periods of lowsea level and reduced events duri ng periods of high sea-level.



### Seafloor Currents
The Loop Current is the dominant water circulation in the Gulf of Mexico. The current formed in the middle Miocene when circum-equatorial currents we re blocked by the formation of the Isthmus of Panama, thus redirecting the flow of the Caribbean current into the Gulf of Mexico. Modern-day sea surface currents associated with the Loop Current ar e well documented and are monitored by satellite observations of seafloor altimetry due to their si gnificant impact on deep-water drilling operations. However, the nature of the deep-water currents is more difficult to observe and are not fully understood. Regional mapping of the seafloor in portions of th e Green Canyon and Walker Ridge areas has uncovered regionally extensive bed forms consisting of furrows, anti-dunes, and other related features on the seafloor along the Sigsbee Escarpment (Bryant et al., 2001). These seafloor features are typically longitudinal bed forms that occur in fine-grained sediment caused by erosion from bottom currents (Scott et al., 2001). The furrows extend for miles along the base of the Escarpm ent and, in some places, are present on and above the Escarpment. The erosional nature of the fu rrows demonstrates the presence of potentially strong bottom currents along the Sigsbee Escarpment in the Walk er Ridge area. These currents may, at least in part, originate from strong eddies that spin off the Loop Current and “feel” bottom along the Escarpment. Another hypothesis is that the currents are a r esult of deep-ocean Rossby waves propagating along the Escarpment.



### Hydrocarbon Migration and Related Seafloor Features
Hydrocarbon seepage on the northern Gulf of Mexico slope is widespread (Anderson et al., 1983; Brooks et al., 1985). Thermogenic hydrocarbons are genera lly believed to form at de pths greater than 5 km (>16,400 ft) in the Gulf of Mexico (Kornacki et al ., 1994). Biogenic gas can be generated at shallower depths from the decomposition of organic matter or the degradation of migrating hydrocarbons. Hydrocarbons can migrate vertically along diapiric salt bodies and faults and accumulate at a shallower level if a stratigraphic or structural “trap” is enc ountered. If nothing traps migration, the hydrocarbons will reach the seafloor and be expelled into the water co lumn, in some cases resulting in significant topographic features. Hydrocarbon Vents. The greater the depth of the gas accumula tion beneath the mudline, the more likely pressures greater than hydrostatic may occur (Dutta, 2002). In general, shallow zones (less than a few hundred feet below the mudline) are not expected to have a significant pressure gradient because the low shear strength of the soils at these shallow depths ge nerally prevents any appreciable buildup of pressure. In some instances, pressure in sha llow soils may reach a point where th ey exceed the seal capacity of the soil; thus, releasing gas from the formation that vents upwards and bleeds off pressure. The venting process can be slow and imperceptible at the seabed, or it can be dynamic, forming large topographic features. On the continental slope of the Gulf of Mexico, large blowout craters, mud volcanoes, and mud diapirs have been attributed to th e venting of gas and other fluids (Prior et al., 1989;Project No. 1106-1257b SECTION 2

- 12 - Neurauter and Bryant, 1989; Neurauter and Robert s, 1992). These features are relatively common around salt bodies and major fault scarps. Active hydrocarbon seepage at the seafloor is a possi ble indication of overpressured sediments in the subsurface. Penetrating shallow gas in the near-s urface may create difficult well control conditions, such as, gas kicks, loss of circulation, or well blowouts. It is important to identify shallow trapped gas accumulations so that these areas can be either avoide d or mitigated through an appropriate casing and/or mud program. Hydrates. Hydrates are a solid form of light gases that ha ve been compressed into an ice matrix of water molecules (Kvenvolden and Barnard, 1983). Hydrates may form near gas vents under proper temperature and pressure conditions. Gas hydrates have been found in water depths exceeding 1,500 ft in the northern Gulf of Mexico (Brooks et al., 1989). Gas hydrates can sometimes be detected on seismic data by the presence of bottom simulating reflectors (BSRs). BSRs mimic the seafloor, cross-cut stratigraphy, and are caused by the impedance contrast at the hydrate-gas phase boundary (Holbrook et al., 2002). It is important to note, however, that hydrates can also exist where BSRs are not observed. The presence of gas hydrates in shallo w sediments can affect the geological and physical properties of the seafloor including shear strength, porosity, permeability, fluid composition, and fluid flow (Dillon et al., 1989). Changes to pressure or temperature can allow th e gas hydrates to dissociate, which could become a triggering mechanism for slope failures (Max and Chandra, 1998; Moridis and Kowalsky, 2006). The slumps and slides could pose a threat to pipelines and other bottom founded structures on the seafloor. Drilling into hydrates could alter the temperature regime in the shallow sediments, allowing the hydrates to disassociate and create uncontrolled gas releases, cem ent failure, collapsed casing, and well control problems (Szczepanski et al., 1998; Collett and Dallimore, 2000; Moridis and Kowalsky, 2006). Various reports indicate the presence of hydrates along the continental slope in the Gulf of Mexico. Milkov and Sassen (2001) estimate an area of potential gas hydrate resources that covers portions of the East Breaks, Garden Banks, Green Canyon, Atwate r Valley, Mississippi Canyon, and Walker Ridge protraction areas. Water depths in these portions of th e Gulf of Mexico are suitable for hydrate formation. Authigenic Carbonates. Venting gases may react with the inters titial, near-surface pore water in shallow sediments to produce carbon dioxide and bicarbonates (R oberts et al., 1990). Under proper conditions, this reaction catalyzes the production of calcium and magnesium carbonates. The result is an accumulation of authigenic carbonates creating large caps, or seals, over gaseous sediments and the formation of boulderlike cemented, hard rock outcrops. These lithified surfaces could pose problems for casing penetration or anchor holding. Authigenic rock outcrops have been recognized in many areas along the continental slope in association with diapiric uplifts and seafloor fault scarps. At the seafloor, such hard rock outcrops are commonly associated with textural changes and seafloor amplitude variations on seismic sections.



### Chemosynthetic Communities
No blocks in the Walker Ridge area have been designated by the MMS as having significant chemosynthetic communities (MMS, 2007b). However, there are published accounts of seepage locations within the Walker Ridge area (McConnell and Kendall, 2002; Sassen, 2000). In water depths greater than 400 meters (1,312 ft) in the Gulf of Mexico, there have been an increasing number of chemosynthetic communities found associated with gas seeps and ro ck outcrop zones (MMS, 2000). Chemosynthetic communities are organisms that have a food source, at least in part, from chemosynthesis rather than organic carbon derived from plankton or marine photosynthetic algae. These organisms can form colonies consisting of dense assemblages of tubeworms, clams, and mussels, while others consist of mats or traces of the bacteria Beggiatoa (Brooks et al., 1987; Brooks et al., 1989; Kornacki et al., 1994). The biologic variety and density of chemosynthetic communities has been associated with the flux rate at which hydrocarbons are expelled at the seafloor (Roberts et al., 2001). The MMS has outlined measures thatProject No. 1106-1257b SECTION 2

- 13 - require the operator to protect high-density ch emosynthetic communities from potentially harmful anthropogenic activities (MMS, 2000).



### Shallow Water Flow
Shallow water flow phenomenon has more frequently been observed while drilling through shallow overpressured formations at deepwater sites in the Gu lf of Mexico (Ostermeier et al., 2000). Encountering overpressured sands in the shallow section has been a problem because of the low formation strengths and fracture gradients. It is difficult for drillers to control formation pressures with mud weights when the surrounding formation has a fracture gradient at or less than the mud weight. Water flow originating from these overpressured zones can cause large and long l asting uncontrolled flows, well damage, foundation failure, formation compaction, damaged casing, and re -entry and control problems (Ostermeier et al., 2000). No shallow water flow events have been reported in the Walker Ridge area (MMS, 2007b). As previously stated, the Walker Ridge area lies downslope and betw een the GB Orange and GC Red units (Figure 5, page 7), two late Pleistocene slope fan systems that have been the source of shallow water flow in wells along the upper continental slope (Ostermeier et al., 2000). Because of the distance from the fan systems, this area probably has a low potential for wate r flow in the shallow stratigraphic section.



### Exploration Activity and Man-Made Structures
There are no pipelines or platforms in the study area (MMS, 2007b). The following table lists the wells and proposed locations within and near the study area.

AREA/BLOCK OPERATOR WELL No. STATUS* API #

WR 206 PETROBRAS 2 TA 608124001601 WR 206 PETROBRAS 1 PA 608124000801 WR 425 PETROBRAS 1 PA 608124000200 WR 425 PETROBRAS 2 PA 608124000500 WR 469 PETROBRAS 1 TA 608124001000 WR 165 MARATHON 1 PA 608124000100 WR 29 CHEVRON 3 DSI 608124002300 WR 29 CHEVRON 1 PA 608124001900 WR 29 CHEVRON 2 TA 608124002004 WR 30 MARATHON 1 TA 608124000602 WR 70 CHEVRON 1 PA 608124000000 GC 1001 MARATHON 1 PA 608114029502
Borehole Status as of 04/10/07: DSI = Drilling Suspended; PA = Permanently Abandoned; TA = Temporarily Abandoned Table 2. Table of existing and proposed wells. The proposed Cascade and Chinook facilities have been pla nned to either fully avoid or utilize the existing wells within the development areas.Project No. 1106-1257b SECTION 3

- 14 - 

### SECTION 3: SHALLOW GEOLOGIC CONDITIONS IN THE CASCADE DEVELOPMENT AREA

Petrobras America Inc. (PAI) is evaluating deve lopment of the Cascade area in Walker Ridge Area (WR) in the Gulf of Mexico. PAI has proposed placing a floating production, storage, and offloading facility (FPSO) in Block 249 that will service the C ascade and Chinook drill centers. The FPSO will be the first of its kind in the Gulf of Mexico. The FPSO will also serve as a host for gas export pipelines, the routing of which is still to be determined. The area surveyed for the Cascad e Development area includes all or portions of WR 117, 160-162, 203-207, 247-251, 292-295, and 338 (Map 1A). All of the Cascade facilities are planned to be placed on the Upper Contin ental Rise, south of the Sigsbee Escarpment.



### Bathymetry and Seafloor Gradient
Water depths in the Cascade Development area ra nge from 5,637 ft in the northeastern corner of WR 247 to 8,510 ft in the north-central part of WR 338 (Map 2A). Above the Escarpment water depths vary from 5,637 ft to about 5,960 ft and are generally shallowest near the Escar pment and deepen to the west and northwest. This occurs along the uplifted of stratigraphic section at the Escarpment that had been caused by the local, shallow emplacement by salt. Wa ter depths deepen rapidly across the Escarpment, averaging a change in elevation of between 2,000 ft and 2,500 ft. Below the Escarpment the water depth generally deepens to the southeast reaching a maximum of 8,510 ft in WR 247. Seafloor gradients range from nearly 0o on the Lowe r Continental Slope up to approximately 70° along the steeper, more rugged portions of the Sigsbee Escarpment (Map 3A). Seabed gradients on the Upper Continental Rise, where the facilities are intended, ar e generally low the central portion of the area. Seafloor gradients above 20° are common in the sout heastern third of the area associated with the sidewalls of seafloor furrows.



### Physiographic Provinces, Seafloor Morphology, and Stratigraphy
The Cascade area displays a variety of seafloor and geologic features resulting from past salt related structural deformation, as well as past and presen t seafloor erosion. The most prominent feature is the Sigsbee Escarpment, which runs roughly north to south through the western part of the area (Map 4A). The Escarpment divides the relatively smooth and gen tly dipping Lower Continental Slope from the Upper Continental Rise. Seafloor currents have significan tly eroded the Upper Continental Rise in the Cascade area, resulting in furrows and flukes on the seafloor. The Escarpment itself has variable gradients and thickness of sedimentary cover overlying older, very s tiff to hard soils. Faulting, in many places along the Escarpment, results in a rough topography, has uplifte d and exposed older strata, and contributed to numerous past failures. Three physiographic provinces have been identified in the Cascade area as illustrated in Figure 7 (next page).

• Lower Continental Slope (LCS) – Shallow seabed dip over most of the area. Soils are normally to slightly over-consolidated clays exhibiting high plasticity and low sensitivity. Occasional faulting and erosion by currents have scoured the very soft, surficial sediments near the top of the Escarpment.

• The Sigsbee Escarpment (SE) – Characterized by high slope angles and rugged topography. Ponded hemipelagic and debris flow sediments o ccur in benched portions of the Escarpment, while stronger sedimen ts are exposed along steep slopes.

• The Upper Continental Rise (UCR) – Generally parallel and continuous undisturbed clayrich stratigraphic section. Seabed topography is variable as a result of erosion by seafloor currents. Seafloor furrows exist to th e east and give way to flukes toward the Escarpment, suggesting a change in current ve locity regime. Soils in this province are differentially eroded, very-soft to soft, highly plastic clays with low to mediumProject No. 1106-1257b SECTION 3

- 15 - sensitivity. A thin drape of foraminifera l sand may be present at the seabed. The Cascade facilities will be placed in this province.

WR 250 WR 251

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Figure 7. Physiographic provinces with in the Cascade Development area. FPS O located in WR 249. DC denotes Drill Center. Gas Export Route will be determined in the future. Each of the three above provinces displays seafloor morphology and shallow structure and stratigraphy quite different from the other provinces. Shallow stratigraphic units are primarily defined from the subbottom profiler data collected by PAI, while deeper stratigraphy and structure were defined utilizing the 3-D depth volume also provided by PAI. Lower Continental Slope (LCS). The LCS province is a benign setting relative to the other two provinces. Seafloor gradients are generally below 6° over most of the province. The shallow stratigraphy, to approximately 260 ft below the mudline (bml) cons ists of well-layered to amorphous reflectors (Map 5 and Figure 8, next page). The base of the surficial unit is identified as the “Triplet” as defined by Brand et al., 2003. Carbon-14 dating of the three distinct silt-ri ch layers indicate that the layers were deposited between ~18.9 – 20.2 ka (1ka=1,000 yrs) slightly before the end of the last lowstand, i.e., Pleistocene/Holocene boundary (Brand et al., 2003). The Tr iplet is an important marker horizon in the area because it both marks the base of the transitional late Pleistocene (low-stand) and current Holocene (high-Project No. 1106-1257b SECTION 3

- 16 - stand) sediments and can be mappe d both above and below the Sigsbee Escarpment. Although the stratum is parallel and continuous, the thickness of sediments above the triplet is variable across the LCS province. Faults are present, caused by the underlying salt movement , and have resulted in the uplift and offset of the sediments above the Triplet, primarily in the northern and southern portions of the province (See Map 5A). The soils are also differentially eroded due to the presence of seabed currents. Below the Triplet the stratigraphy is characterized by intact, parallel continuous reflectors.

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Figure 8. The portion of subbottom profiler line 202 displays ty pical structure and stratigraphy for the Lower Continental Slope province (near top of Escarpment). A number of box cores and short piston core samples were recovered from this physiographic province (Appendix B). Typically the piston core samples were less than 20 ft in length. Table 3 lists the cores in the LCS province. Results of the standard geotechnical testing are presented in Figure 9.

Piston Core Box Core C-ESC-PC-5 CEXP2-BOX5 C-ESC-PC-6 CEXP2-BOX6 CEXP2-PC-3 CEXP2-BOX7 CEXP2-PC-4 CEXP2-BOX8 CEXP2-PC-5 CEXP2-BOX9 CEXP2-PC-9 CEXP2-BOX10 CEXP2-PC-11 CEXP2-BOX13 CEXP2-PC-13 CEXP2-BOX14 CEXP2-PC-14 CEXP2-BOX15 CEXP2-BOX18 CEXP2-BOX20 CEXP2-BOX21 CEXP2-BOX22 CEXP2-BOX23 Table 3. List of cores for the LCS province. 

# PROPRIETARYProject No. 1106-1257b SECTION 3

- 17 - 0 6 12345

Sensitivity

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Figure 9. Geotechnical test results for the LCS province. Soils in the area are generally very soft, highly plas tic, normally to slightly overconsolidated clay. The soils are fairly uniform over the province as is expected from soils that have been differentially eroded and slightly scoured in locations due to currents. There is excellent correlation between the geologic observations and the ground-truth soils data. As can be seen in Figure 9, the moisture content data follows a decreasing trend from generally over 120% at the seafloor to about 70% at 18 ft. Liquidity index (LI) also decreases with depth. Shear strength was measured with miniature vane testing. The results fall within a narrow range and are linearly increasing with depth. The strength of the surficial sedimen ts varies between 40 and 70 psf and increases to about 155 psf at 18-ft depth. The soil sensitivity generally ra nges between 2 and 5 which is typical of very soft, normally consolidated GOM clay. Soil sensitivity is th e ratio of undisturbed to remolded strength and is typically used to indicate sample disturbance. Valu es below 2 can indicate sample disturbance. Figure 9 does show occasional sensitivity results below 2, but in general the sample quality is good with little disturbance. The only potential future facility planned for the LCS is the Export Option 2 Route (see Figure 7). The route has yet to be selected and may never occur. The conditions on the LCS are favorable for pipeline installation and performance. The Sigsbee Escarpment (SE). The Sigsbee Escarpment crosses th e entire Cascade area and separates the LCS province from the UCR province (Figure 7). The Escarpment represents the distal limit of the salt province in the Cascade area with salt located to the west and absent to the east (Map 6A). The topography of the Escarpment is highly variable (Figure 10, next page). Vertical and horizontal movement of the underlying salt has deformed the shallow stratigraphy a nd initiated slope failures. The result of the uplift and deformation is the formation of an escarpment cons isting of a relatively flat bench separating an upper and lower scarp. The upper and lower scarps are rugged, faulted, and steep ly dipping. Faults are salt-rooted, trend parallel to the Escarpment face, and are typically downthrown to the southwest (Map 8A). Throw across the faults is highly variable, but is as much as 20 ft. Numerous slump scarps and gullies incise the lower scarp with debris aprons extending up to about 1 m ile out onto the Upper Continental Rise. 

# PROPRIETARYProject No. 1106-1257b SECTION 3

- 18 - 

### L O W E R S C A R P L O W E R S C A R P U P P E R S C A R P U P P E R S C A R P

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### L O W E R S C A R P L O W E R S C A R P U P P E R S C A R P U P P E R S C A R P

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Figure 10. Isometric view of the Sigsbee Escarpment within the Cascade Development area showing a bench separating an upper and lower scarp. View is lookin g northwest. The proposed Cascade fa cilities are southeast of the frame. Deposition of hemipelagic and mass-transport sediments has covered the Escarpment with a surficial layer of varying thickness. The geophysical data show para llel layered reflectors and amorphous intervals within ponded sediments underlying the bench (Figure 11). Thin to absent drape, or outcropping strata, characterize upper and lower scarps. The multibeam data show furrows present on the Escarpment, indicating seabed currents are actively eroding and re-depositing the surficial sediments.

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Figure 11. Subbottom profiler lines perpendicular (left) and pa rallel (right) to the Sigsbee Escarpment illustrating the varying stratigraphy and highly deformed structure of the Escarpment. Based on the geology, the soil properties of the SE province should cumulatively be either normally consolidated, very soft to soft drape soils, or, overcons olidated stiff to hard older strata. We present the discussion of the soil properties based on the follo wing mapped Escarpment sub-provinces: the Upper Scarp, the Bench, and the Lower Scarp. 

# PROPRIETARYProject No. 1106-1257b SECTION 3

- 19 - The Upper Scarp. Two shallow piston cores were recovered fro m this portion of the SE province. Sample recovery was 5 to 12.5 ft in length. Table (nex t page) lists the cores in the Upper Scarp for the SE province. Results of the standard geotechnical testing are presented in Figure 12.

Piston Core Box Core C-ESC-PC-4 C-ESC-PC-7
Table 4. List of cores for the upper scarp of the SE province.

0 12 2 4 6 8 10

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Figure 12. Geotechnical test results for the upper scarp of the SE province. Figure 12 shows that Core C-ESC-PC-4 exhibits soil char acteristics consistent with a soft drape, and Core C-ESC-PC-7 has soil characteristics consistent with exposed, overconsolidated strata (Appendix B). As mentioned earlier a normally consolidated, soft, ponded soil drape of variable thickness occurs over higher strength overconsolidated soils. Erosion from currents is also likely to redistribute the soft soil drape. The geotechnical data correlates with the geologic cond itions observed from both the shallow high-resolution AUV data and the 3D-seismic data. The moisture content data in Figure 12 follows a sli ghtly decreasing trend. The soft drape soils of the Upper Scarp will have a higher moisture content with surficial results in excess of 100%, but the moisture content will drop rapidly as the old overconsolidated st rata are encountered. The LI also show decreasing trends with depth. The lower LI values corres pond to the higher strength soil. Shear strength was measured with miniature vane testing. The results s how two types of soil conditions: soft drape soils and exposed, overconsolidated soils. Soil sensitivity ra nges from 2 to 7 indicating good sample quality with minimal sample disturbance.

The Bench. The formation of a relatively flat bench separ ates the Upper Scarp from the Lower Scarp. The Bench has occurred from extension, via normal fau lting, of the supra-salt section behind the underlying advancing salt front (see Figure 4). Some of the mate rial eroded by seafloor currents is likely deposited on the bench due to drop in the current velocity as it trav erses over the bench. The overall low gradient of the Bench also allows the preservation of the softer soils. Two piston core samples were recovered from the Bench (see Table , next page). Sample recovery was 11 to 12 ft in length. Results of the standard geotechnical testing are presented in Figure 13. 

# PROPRIETARYProject No. 1106-1257b SECTION 3

- 20 - Piston Core Box Core C-ESC-PC-3 C-ESC-PC-8
Table 5. List of cores for the bench of the SE province.

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Figure 13. Geotechnical test results for the bench of the SE province. As expected, the drape sediments of the Bench ar e normally to slightly overconsolidated, the same as observed on the Upper Scarp. This material is underlai n by the stronger, overconsolidated layer, which is the continuation of the stratigraphic sequence observed in the Upper Scarp.

The moisture content and LI results tend to d ecrease with depth corresponding to the increasing shear strength. Very soft to soft normally consolidated clay was present at both core locations with Core C-ESC-PC-8 encountering the underlying stiffer, overcons olidated soils at ~11 ft (Appendix B). The 3Dseismic data from the Escarpment (shown in Figure 4) suggests as one moves down the Escarpment, and thus deeper in the exposed stratigraphic section, so il strengths should increase. Soils underlying the drape on the Bench are similar to those of the Upper Scarp, with strengths slightly stronger at ~1,000 psf. Soil sensitivity ranged between 2 and 4 with good sample qua lity. The geotechnical data correlates well with the geologic conditions observed from both the shallo w high-resolution AUV and the 3D-seismic data. The trend should continue into the Lower Scarp area. The Lower Scarp. The Lower Scarp sits over the snout of th e underlying salt front, as shown in Figure 4. The shallow soil characteristics of the material encount ered on the Lower Scarp are expected to be similar to those observed for the Upper Scarp and Bench. Two shallow piston core samples were recovered from th e Lower Scarp (see Table , next page). Sample recovery was about 2 and 15 ft in length. Results of the standard geotechnical testing are shown in Figure 14 as well as a more detailed presentation in Appendix B. 

# PROPRIETARYProject No. 1106-1257b SECTION 3

- 21 - Piston Core Box Core C-ESC-PC-2 C-ESC-PC-9
Table 6. List of cores for the lower scarp of the SE province.

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18 16 14 12 10 8 6 4 2Penetration below Seafloor(ft)

Figure 14. Geotechnical test results for the lower scarp of the SE province.
The moisture content and LI data decrease with depth in each individual core corresponding to an increasing shear strength. The measured soil strengths are similar to those observed for the drape and underlying stiffer soils in both the Upper Scarp and Bench area. Core C-ESC-PC-9 illustrates a normally consolidated strength profile expected of the overlying soft drape to about 15 ft. In addition, this core penetrates the underlying stiffer overconsolidated materi al at depth. Core C-ESC-PC-2 also sampled the stiffer, overconsolidated soils of the outcropping strata which appear to be stronger for the Lower Scarp than in the previous two area of the SE province. Soil sensitivity ranged between 2 and 4 with good sample quality. The geotechnical data correlates well with the observed geometry of the stratigraphy and expected relative increase in soil strength within strata exposed near the base of the Escarpment. The only potential future facility that may be placed on the Escarpment is the Gas Export Option 2 pipeline. The final selection of the route is yet to be determined. Engineering of a pipeline route on the Escarpment is feasible. If Option 2 is selected, more detailed studies of the crossing with respect to topography, soils, slope stability, and chemos ynthetic communities should be undertaken.

Upper Continental Rise. The Upper Continental Rise in the Cascade area is defined as an erosional environment. Seafloor currents have scoured and re moved a significant amount of surficial sediments from the area resulting in a seafloor comprised of furrows and flukes. This province is subdivided into four subprovinces (Map 7A) based on the following types of observed seafloor morphology: Seafloor Furrows, Seafloor Flukes, a combination of Seafloor Flukes and Furrows, and a Topographic Low. 

# PROPRIETARY