### Noble Energy, Inc. Page B-1

Revised Exploration Plan 10/6/2011 Mississippi Canyon 948 & 949 (OCS-G 28030 & 32363) 

## Section B
General Information

A. Applications and Permits No additional applications or permits are required to conduct the activities proposed herein.

B. Drilling Fluids

Type of Drilling Fluid Estimated Volume of Drilling Fluid to be used per Well Water-based 43,000 bbls Synthetic-based 14,000 bbls

C. New or Unusual Technology Noble does not propose to use any new or unusual technology to carry out the proposed exploration
activities.

D. Bonding Statement The bond requirements for the activities and facilities proposed in this EP are satisfied by an area-wide bond, furnished and maintained according to 30 CFR 256, subpart I; NTL No. 2000-G16, "Guidelines for General Lease Surety Bonds;" and National NTL No. 2003-N06, "Supplemental Bond Procedures".

E. Oil Spill Financial Responsibility (OSFR) Noble Energy, Inc., BOEMRE company number 02237, has demonstrated oil spill financial responsibility for the facilities proposed in this EP according to 30 CFR Part 253; and NTL No. 99-N01, "Guidelines for Oil Spill Financial Responsibility for Covered Facilities".

F. Deepwater Well Control Statement Noble Energy, Inc., BOEMRE company number 02237, has the financial capability to drill a relief well and conduct other emergency well control operations.

G. Blowout Scenario This information is addressed under separate cover in the NTL 2010-N06, worst case discharge package submitted along with this revised exploration plan.

### Noble Energy, Inc. Page C-1

Revised Exploration Plan 10/6/2011 Mississippi Canyon 948 & 949 (OCS-G 28030 & 32363) 

## Section C Geological and Geophysical Information

A. Geological Description Proprietary Data

B. Structure Contour Map Proprietary Data

C. Interpreted 3-D Seismic Lines Proprietary Data

D. Geological Structure Cross-Section Maps Proprietary Data

E. Shallow Hazards Report A shallow hazards survey was conducted over Mississippi Canyon 948. Locations F, G and H are within 50 feet of each other, therefore the site clearance letter is intended to cover all three locations.

F. Shallow Hazards Assessment Utilizing the 3D seismic exploration data, a shallow hazards assessment was prepared for the proposed surface locations, and is included as Attachment C-4. The shallow hazards assessments of the proposed well locations are also included in the “Wellsite Discussion” section of the combined Shallow Hazards Assessment, Benthic Communities Evaluation, and Archeological Resource Survey being submitted with this EP. The initial plans for this project were to use a moored rig, therefore the assessment mentions anchor considerations. The rig for this project has changed and will be a dynamically positioned rig.

G. High-Resolution Seismic Lines Proprietary Data

H. Stratigraphic Column Proprietary Data

I. Time vs. Depth Table Proprietary Data10615 SHADOW WOOD DRIVE
SUITE 200 HOUSTON, TEXAS 77043 Phone: (713) 468-14 10

Fax: (713) 468-1438
E-mail: gems@gemsinc.com

March 21, 2011 Project No. 0609-1659

Noble Energy, Inc. 100 Glenborough, Suite 100 Houston, TX 77067

Attention: Mr. Jonas E. Harrell



### Site Clearance Letter Proposed Wellsite F Block 948 (OCS G-28030) Mississippi Canyon Area
Gulf of Mexico

Geoscience Earth & Marine Services, Inc. ® , (GEMS) was contracted by Noble Energy, Inc., (Nob le) to prepare a Site Clearance Letter for the Proposed We llsite F in Block 948 (OCS G-28030), Mississippi Canyon (MC) area. This letter addresses specific s eafloor and subsurface conditions near the proposed location to a depth of about 3,600 ft below the mud line (bml). Our assessment is based on findings provided within the main body of the geohazard repo rt “Geologic and Stratigraphic Assessment, Block 94 8 (OCS G-28030), Mississippi Canyon Area, Gulf of Mex ico” (GEMS, 2007; Project No. 0407-1324). The text, maps, and figures included in the report prov ide detail to the regional geology of the Study Are a. This letter supplements the report with details pertaini ng directly to the proposed wellsite.

The following report complies with the Bureau of Oc ean Energy Management, Regulation, and Enforcement (BOEMRE) Notice to Lessees (NTL’s) 2008 -G04, 2008-G05, and 2009-G40, (MMS, 2008a,b and 2010). Block 948, Mississippi Canyon Area, is located in g rid 16 of the BOEMRE’s Grid Map for ROV Surveys (MMS, 2008c); therefore, activities at the proposed wellsite will not be required to follo w NTL 2008-G06 with respect to pre- and post-spud ROV visual inspection surveys.

The above-stated Federal lease block is located wit hin a historically significant area (MMS, 2008d); therefore, requirements set forth in NTL 2005-G07 ( MMS, 2005) are applicable. Fugro Geoservices, Inc.

, (2007) conducted an archaeological survey and compi led an assessment for Noble over the Study Area. Their results in regards to the proposed location a re mentioned herein.

The surface location for the proposed F wellsite li es in the southeastern quadrant of Block 948, Mississippi Canyon area, Gulf of Mexico. Noble pro vided the following coordinates for the proposed
location:

Proposed Wellsite F

Spheroid & Datum: Clarke 1866, NAD27 Projection: UTM Zone 16 North Line Reference Block Calls
MC 948 X: 1,076,544 ft Latitude: 28.024469612o N Inline 13143 576 ft FEL Y: 10,173,777 ft Longitude: -88.748218162o W Crossline 11880 4,497 ft FSLProject No. 0609-1659

2 Wellsite MC 948-F



### Attachments

The page-size maps and figures accompanying this le tter were extracted from the main report’s original maps and 3-D data volume. The maps and figures (li sted below) are centered on the proposed well
location.

Map F-1: Bathymetry Map Map F-2: Seafloor Rendering Map F-3: Seafloor Amplitude Rendering Map F-4: Geologic Features Map Figure F-1: Inline 13143 and Crossline 11880 Showin g Conditions Beneath Proposed Wellsite F Figure F-2: Tophole Prognosis Chart, Proposed Wells ite F, Mississippi Canyon Block 948 Figure F-3: Power Spectrum Chart Based on 3-D Data Volume Within 500-ft Radius of Proposed

Wellsite F, Mississippi Canyon Block 948.



### Man-Made Features

Two existing exploration wellsites occur in MC 948 (Maps F-1 through F-4). The MC 948-1 well was spudded on May 19, 2008, but was abandoned within a week because of shallow water flow problems. The wellsite was moved approximately 160 ft to the southwest and MC 948-2 was spudded on May 25, 2008. The MC 948-1 is approximately 3,230 ft south -southwest of the proposed F location. MC 948-2 is approximately 3,325 south-southwest of the proposed location.

The 2-inch, BP fiber-optic cable crosses the northw est corner of MC 948 (Map F-1). The cable runs northeast-southwest. The closest point to the prop osed F location is approximately 13,675 ft. The Mariner 8-inch pipeline and 3-inch umbilical occur east of the location within MC 949 (Map F-1). The lines run approximately north-south through the blo ck. The closest point to the proposed location is approximately 5,725 ft.

An evaluation of high-resolution geophysical data c ollected within MC 948 and the surrounding blocks indicate that the area is clear of any unusual seaf loor targets that could represent shipwreck remains or debris of archeological significance (Fugro Geoserv ices, Inc., 2007).



### Water Depth and Seafloor Conditions

The water depth at the proposed location is approxi mately -6,045 ft (Map F-1). The seafloor at the proposed site dips to the south at approximately 1. 0 ° (1.7%). The proposed location occurs in a relativ ely
flat area where the seafloor is smooth and featurel ess (Maps F-1 and F-2). The near-surface sediments are expected to be normally consolidated, soft clay s forming a drape over the area.


### Deepwater Benthic Communities

There is no evidence of hydrocarbon seepage within 2,000 ft of the proposed location. The potential f or significant, densely-populated deepwater benthic co mmunities within 2,000 ft of the proposed location is negligible. The Seafloor Amplitude Rendering (Map F-3) shows normal or ambient amplitudes along the seabed near the proposed wellsite.



### Stratigraphy

The stratigraphy at the proposed well location is i llustrated on Figures F-1 and F-2. The Tophole Prognosis Chart (Figure F-2) shows the inline annot ated with calculated depths to the various horizons and predicted lithology of the sequences, along wit h their potential for shallow water flow and shallo w gas. In general, the sediments between the seafloo r and the limit of investigation (about 3,624 ft bm l) consist of hemipelagic clays and stratified turbidi tes, interbedded with mass-transport deposits. The stratigraphic sequence above the Top of Salt is lik ely to consist predominantly of clays and silts. Potential sands may occur between 449 ft and 1,351 ft bml. Stratigraphic units within this section co nsist of turbidite and slope-fan deposits that have been modified by submarine slides and mass-wasting event s.Project No. 0609-1659

3 Wellsite MC 948-F

Most sand seams encountered within these units are likely to be discontinuous. An interval at the bas e of the section between 1,241 ft and 1,351 ft bml appea rs to be the fill at the base of a channel or failu re zone. Coarse sands may be ponded within this erosional lo w. A unit of sand-prone slope-fan deposits may also ex ist below 2,083 ft bml. Flat-lying turbidites are
interbedded with channelized intervals and mass-tra nsport deposits. Immediately above the salt/sedime nt interface is a rubble-like zone consisting of chaot ic, discontinuous to amorphous reflectors. The
deformation of this zone is the result of salt move ment. The sediments within the zone are probably turbidites and mass-transport deposits consisting o f clays and silts, interspersed with thin, disconti nuous sands.



### Faults

Two buried faults will be penetrated by the Propose d Wellsite F in the shallow section to the limit of investigation (Figures F-1 and F-2). The faults wi ll be encountered at approximately 1,241 ft and 2,0 83 ft bml. Neither fault extends to the seafloor; theref ore, both have been inactive for thousands of years . The fault at 1,241 ft bml occurs at the top of the poss ibly sand-rich fill of an erosional feature.



### Shallow Water Flow

The potential for shallow water flow ranges from ne gligible to high within the stratigraphic sequences between the seafloor and the limit of investigation (about 3,624 ft bml). A low to moderate potential for water flow is generally expected within the turbidi te and slope-fan deposits between 449 ft and 1,351 ft bml. These turbidite and slope-fan deposits appear to be modified by mass-wasting events at the proposed location. Sands encountered in the upper part of this section (449 ft to 975 ft bml) are pro bably discontinuous and are not likely to produce sustain ed flow. Therefore, the potential for overpressured
sand is considered low.

The sequence between Horizon 40 and Horizon 50 is t he source for water flow in the MC 948-1 well to the south. Sand-layers may be thicker and more con tinuous in this sequence and therefore, a "moderate " potential is given the upper part of the unit. The base of the section between 1,241 ft to 1,351 ft i s given a high potential for overpressured sand. This 110 ft interval appears to be the fill in an erosional cu t and shows slightly elevated amplitude returns. Sand la yers and pockets may have ponded in this location.

In addition, a moderate potential for encountering overpressured sands occurs between 2,083 ft and 3,624 ft bml. Potentially thick and continuous san d deposits may exist within these stratified slope- fan deposits.



### Shallow Gas

The potential for encountering shallow gas at the P roposed Wellsite F is generally negligible to low. However, a moderate potential is assigned to the fi ll interval just above Horizon 50 at 1,241 ft bml (Figure F-1 and F-2). The top of this interval is a relatively flat-lying reflector that has some characteristics of a bottom simulating reflector (B SR). It is limited in areal extent and appears off set by
small faults which are not characteristics of a BSR . The amplitude of this reflector is only slightly elevated. If this is the base of hydrate stability then minor concentrations of free gas may occur be neath the interface within the possibly sand-rich fill.

Elsewhere in the section, the well path will not pe netrate any exceptionally high-amplitude events in the 3,624 ft above the Top of Salt (Figure F-1). Sever al high-amplitude anomalies occur in the area of th e proposed site below Horizon 60 to the Top of Salt ( approximately 2,083 ft to 3,624 ft bml). In genera l, these amplitude anomalies appear as elevated sectio ns within relatively stratified turbidite deposits. The nearest high-amplitude event is approximately 2,100 ft north-northwest of the proposed site at approximately 2,850 ft bml (Map F-4). The high-amp litude anomalies near the site suggest a potential increase in minor amounts of solution gas within sa nd-rich layers.Project No. 0609-1659

4 Wellsite MC 948-F



### Power Spectrum

In accordance with NTL 2008-G04 and NTL 2008-G05 (M MS 2008a,b), we have extracted the power spectrum diagram (Figure F-3) from the 3-D seismic data cube. The extraction was generated within a
500-ft radius of the intersection of the inlines an d crosslines at the proposed wellsite. The amplitu de vs. frequency spectrum, generated by the SMT software, was converted to power vs. frequency by squaring the amplitude values as described by J. A. Coffeen, 1978.


### Anchoring Considerations

An anchored drilling vessel is likely to be employe d for the proposed F location. Anchors may extend 12,000 ft to 15,000 ft from the proposed site (Maps F-1 through F-4). The anchors will need to avoid the seafloor crater approximately 10,320 ft to the sout hwest. Elevated seabed amplitudes associated with this expulsion feature suggest active hydrocarbon seepag e and therefore has the potential for chemosyntheti c communities. Minor seabed amplitude events also oc cur along the relatively steep erosional escarpment s to the northwest (Map F-3).

A cable crosses the northwest corner of MC 948. Th e cable is within 13,675 ft of the location. In addition, a pipeline and umbilical crosses MC 949 t o the east of the location. These lines are within 5,725 ft of the proposed location. A 500 ft avoid ance zone has been placed around the cable, pipelin e, and umbilical as well as around the two existing ex ploration wellsites (Maps F-1 through F-4).

No targets of potentially cultural importance were identified in this area (Fugro Geoservices, 2007).



### Closing

The Proposed Wellsite F in Mississippi Canyon, Bloc k 948, generally appears suitable for exploration drilling operations. Engineers should be aware tha t the area has potential for overpressured sand lay ers. Anchors locations must avoid existing cables, pipel ines, and areas of potential chemosynthetic communities. We appreciate the opportunity to be o f service to Noble Energy, Inc., and look forward t o working closely with you on other projects.

Sincerely,

GEOSCIENCE EARTH & MARINE SERVICES, INC.

Thomas W. Neurauter, Ph.D. Daniel Lanier Senior Marine Geologist Vice President Geoscience

Attachments (4 Maps and 3 Figures)
Distribution: Mr. Jonas E. Harrell, Noble Energy, Inc., Houston, TX (5 copies)Project No. 0609-1659

5 Wellsite MC 948-F REFERENCES

Bureau of Ocean Energy Management, Regulation, and Enforcement, 2011, Free ASCII Data Files, published on the BOEMRE Gulf of Mexico Region Homep age, http://www.gomr.boemre.gov/homepg/pubinfo/freeasci/ freedesc.html , Accessed March, 2011.

Coffeen, J. A., 1978, Seismic Exploration Fundament als: PPC Books, a division of Petroleum Publishing Co., Tulsa, Ok. 277 p.

Fugro Geoservices, Inc., 2007, Archaeological Asses sment, Block 948, Mississippi Canyon Area, Gulf of Mexico: Fugro Report No. 2407-5001.

Minerals Management Service, 2005, Notice to lessee s and operators of federal oil, gas, and sulphur leases and pipeline right-of-way holders in the out er continental shelf, Gulf of Mexico OCS region, Archaeological resource surveys and reports: U. S. Department of the Interior, Minerals Management Service, Gulf of Mexico, NTL 2005-G07. Effective D ate July 1, 2005.

Minerals Management Service, 2008a, Notice to lesse es and operators of federal oil, gas, and sulphur leases in the outer continental shelf, Gulf of Mexi co OCS region, information requirements for exploration plans and development operations coordi nation documents: U. S. Department of the Interior, Minerals Management Service, Gulf of Mexico, NTL 20 08-G04. Effective Date May 1, 2008.

Minerals Management Service, 2008b, Notice to lesse es and operators of federal oil, gas, and sulphur leases and pipeline right-of-way holders in the out er continental shelf, Gulf of Mexico OCS region, shallow hazards program: U. S. Department of the In terior, Minerals Management Service, Gulf of Mexico, NTL 2008-G05. Effective Date May 1, 2008.

Minerals Management Service, 2008c, Notice to lesse es and operators of federal oil, gas, and sulphur leases and pipeline right-of-way holders in the out er continental shelf, Gulf of Mexico OCS region, Remotely Operated Vehicle Surveys in Deepwater: U. S. Department of the Interior, Minerals Management Service, Gulf of Mexico, NTL 2008-G06. Effective Date May 26, 2008.

Minerals Management Service, 2008d, Notice to lesse es and operators of federal oil and gas leases and pipeline right-of-way holders on the outer continen tal shelf, Gulf of Mexico OCS region, revisions to the list of OCS lease blocks requiring archaeological r esource surveys and reports: U. S. Department of t he Interior, Minerals Management Service, Gulf of Mexi co, NTL 2008-G20. Effective Date October 20,
2008.

Minerals Management Service, 2010, Notice to lessee s and operators of federal oil and gas leases in th e outer continental shelf, Gulf of Mexico OCS region, Deepwater benthic communities: U. S. Department of the Interior, Minerals Management Service, Gulf of Mexico, NTL 2009-G40. Effective Date January 27,
2010.