Outer Continental Shelf Title V and PSD Permit Application

Process Description 2-1 ENVIRON 

## 2 Process Description

As discussed previously, Statoil is applying for a Title V and PSD permit to authorize the proposed operation of either the Developer (Operating Scenario 1) or the Discoverer Americas (Operating Scenario 2) deep water drilling vessel and its associated support fleet to perform exploration activities in Statoil’s Desoto Canyon lease blocks, which are located east of the 87 degree, 30 minute Longitude on the Outer Continental Shelf (OCS) of the Gulf of Mexico.
Sections 2.1 and 2.2 below summarize the Developer and Discoverer Americas , respectively, and their associated support vessel operations.



### 2.1 Developer

The Developer is a dynamically positioned semi-submersi ble drill rig. Semi-submersible drill rigs are configured with large buoyant pontoon structures below the water surface and slender columns passing through the water surface supporting a platform deck above the sea surface. With its hull structure submerged at a deep draft, the semi-submersible is less affected by wave loadings than a typical vessel. Semi-submersible platforms can be ballasted up or down by altering the amount of flooding in buoyancy tanks. Please see Figure 2 which documents the configuration of the Developer drilling vessel.

A dynamically positioned drill vessel is a vessel that is equipped with a computer controlled system to automatically maintain a vessel' s position and heading by using the vessel’s own propellers and thrusters. Therefore, no anchors are necessary for this type of vessel. Position reference sensors, combined with wind sensors, motion sensors, and gyro compasses, provide information to the computer pertaining to the vessel's position and the magnitude and direction of environmental forces affecting its position.

The Developer is equipped with eight main engines that drive respective electricity producing generators. These generators provide electricity for equipment onboard the vessel. Notably, the generators provide electricity for the electric motors that provide propulsion for the vessel. Additionally, the Developer is equipped with two cementing unit engines; an emergency generator engine; life and rescue boats; and storage vessels containing fuel and waste oil. The Developer will also include forklifts to support limited supply movements onboard the vessel. Furthermore, the Developer will be supported by various vessels operating within 25 miles of the drill vessel. The support vessels associated with the Developer will include crew boats and offshore support vessels (OSVs), which will transport supplies and materials to the drill vessel as needed. Lastly, crew and time-sensitive supplies will be transported to and from the Developer via helicopters. Note that the Developer will not require towing or anchoring vessels because the drilling vessel is self-powered and it will be directionally positioned at the drilling

location.

To begin exploratory drilling operations, the drill vessel travels to the designated location and deploys beacons on the seabed floor. Referencing these beacons, the vessel is able to maintain position dynamically using its thrusters and thereby allowing drilling operations to commence. While positioning the vessel in the correct location, work begins in order to spud the well. “Spudding” in, or to "spud" a well, means to initiate drilling operations at a location. To accomplish this, a short length of pipe (~200 feet) with a 36-inch outside diameter (OD), called the jetpipe, is conveyed (or run) to the seabed floor using a smaller multi-purpose pipeOuter Continental Shelf Title V and PSD Permit Application

Process Description 2-2 ENVIRON (drillpipe), which is typically five to seven inches in OD. The drillpipe is run through the jetpipe, terminating with a drill bit at the end. The drill bit is spaced so that it extends out a few inches from the bottom of the jetpipe. Seawater is pumped through the bit as the jetpipe is lowered into the seabed until approximately ten feet of the jetpipe remains above the seabed floor. The drillpipe is then released from the jetpipe so that the drillbit can be used to drill the exploration well. Seawater or drilling fluid (mud) is pumped down the drillpipe and out of the bit to clean the hole that is generated during the drilling process. Once the drillbit has reached a designated depth, the drillbit is retrieved back to surface, leaving the jetpipe and a section of hole drilled below the jetpipe. Another pipe called the casing is then run through the jetpipe and into the open-hole section. Cement is then pumped around the outside of the casing to cement the casing in place. A slightly smaller drillbit is installed on the drillpipe to drill out any material in the casing, and the “drill” then “case” process is repeated until the desired depth is reached to set the blowout preventer (BOP). Note that all discharges to water that occur throughout the drilling campaign are regulated under the applicable National Pollutant Discharge Elimination System (NPDES) general permit. The BOP is run on pipe called the drilling riser, which is connected to the wellbore at the seabed floor. This arrangement allows a closed loop system in which fluids pumped through the drillbit return to the rig for reuse. The BOP also serves as a safety device protecting against a well “blowout” by sealing off the well by either the use of blind rams or a gate valve. A blowout can occur during the drilling process when an underground high pressure zone is encountered that exceeds the weight of the drilling fluid, potentially releasing fluids and gases to the atmosphere. From the point of installing the BOP, the “drill” and “case” process is continued until objective depth for the well is reached. Casings are run at design intervals according to the subsurface data used to design the well. Each time a casing is run, the next section's casing will be smaller in order to fit inside the casing that has just been
cemented.

Once the well objective depth in the potential oil-bearing reservoir (the “formation”) is achieved an evaluation program is carried out. This evaluation program involves running a series of electronic tools (referred to as “wireline units”) down into the well in order to measure various properties of the formation. Note that the electr icity required by the wireline units is provided by the main generator engines on the vessel. The well bore can now be cased off if desired, or as is often the case in a discovery scenario, the objective section is cemented so that the wellbore can be reused to drill to another part of the rese rvoir by a process known as “sidetracking.” Sidetracking involves departing from a wellbore by using a mechanical downhole deflecting tool called a whipstock or by deflecting off a strong section of cement placed in the wellbore. The “drill” and “case” procedure previously discussed is then followed to progress the sidetrack to a new objective formation.

Upon completion of the exploratory work scope, the well is plugged with cement or mechanical tools. The BOP, riser, and reference beacons are retrieved and then the vessel travels under its own power to the next drill location. Please see Figure 2 for the actual configuration of the Developer.Outer Continental Shelf Title V and PSD Permit Application

Process Description 2-4 ENVIRON 

### 2.2 Discoverer Americas

The Discoverer Americas is a dynamically positioned drill ship. Similar to the Developer , a dynamically positioned drill ship is a vessel that is equipped with a computer controlled system to automatically maintain a vessel's position and heading by using the vessel’s own propellers and thrusters. Therefore, no anchors are necessary for this type of vessel. Position reference sensors, combined with wind sensors, motion sensors, and gyro compasses, provide information to the computer pertaining to the vessel's position and the magnitude and direction of environmental forces affecting its position.

The Discoverer Americas drill ship is equipped with six main engines that drive respective electricity producing generators. These generators provide electricity for equipment onboard the vessel. Additionally, the Discoverer Americas is equipped with an emergency generator to supply power (primary and redundant) to critical equipment in the event of main engine failure; two emergency air compressor engines; life and rescue boats; a hot oil heater; and storage vessels containing fuel and waste oil. The Discoverer Americas will also include forklifts to support limited supply movements onboard the vessel. Furthermore, the Discoverer Americas will be supported by various support vessels operating within 25 miles of the drill ship. The support vessels associated with the Discoverer Americas will include crew boats and OSVs,which will transport supplies and materials to the drill ship as needed. Lastly, crew and timesensitive supplies will be transported to and from the Discoverer Americas via helicopters. Note
that the Discoverer Americas will not require towing or anchoring vessels because the drilling vessel is self-powered and it will be directionally positioned at the drilling location.

The actual drilling process for the Discoverer Americas is fundamentally identical to the process utilized by the Developer , as described above. Additionally, as with the Developer , upon completion of exploratory work at a particular location, the Discoverer Americas travels under its own power to the next drill location. Please see Figure 3 for the actual configuration of the
Discoverer Americas

.