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-submersible 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 pipe 
Outer 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 electricity 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 reservoir 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.