A2-1

Appendix for Chapter 2

Appendix for Chapter 2

Table of Contents

2.1 Drilling from a Floating Vessel ............................................................................................................................A2-3

2.2 Drilling Procedures for Point Sal .........................................................................................................................A2-5

2.3 Drilling Procedures for Purisima Point ................................................................................................................A2-5

2.4 Drilling Procedures for Bonito Unit .....................................................................................................................A2-6

2.5 Drilling Procedures for Gato Canyon Unit ..........................................................................................................A2-7
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Delineation Drilling Activities Offshore Santa Barbara County
A2-3

Appendix for Chapter 2

Appendix 2

APPENDIX 2.1 DRILLING FROM A

FLOATING VESSEL

This paper discusses the sequential steps of drilling a well from a floating vessel. The sequence of events

in this description is commonly used; however, is not

necessarily followed for every well drilled from a floating vessel. For a guideline system, the typical steps

used to drill the well are as follows: spudding the well,

running the structural casing, installing the Diverter

System and the Conductor Casing, running the blowout preventor (BOP) stack, completing the well, and

plugging and abandoning the well.

Spudding the Well:

The first step in drilling from a floating vessel is

to lower the temporary guide base to the ocean floor.

The temporary guide base is a heavy steel device with

an opening in the center and four cables called guidelines attached to its four outside corners. A drill pipe

is fitted into the center opening to lower the guide

base to the ocean bottom. The drill pipe is removed

and pulled back up to the semi-submersible leaving

the temporary guide base on the ocean bottom with

the four guidelines running back up to the rig.

With the temporary guide base in position, the

hole for the structural casing is drilled. The bit is made

up on drill collars and drill pipe as usual; however, a

guide frame is installed on a drill collar near the bottom. The guide frame has two to four arms where the

guidelines are threaded. As the bit and drill stem are

lowered into the water, the guidelines keep the guide

frame, drill stem and drill bit in line with the center

opening in the temporary guide base.

When the drill bit reaches the seafloor, circulation and drilling begin, and the hole for the structural

casing is made. As the drill grinds and gouges rock

into small pieces or cuttings, drilling mud is used to

move cuttings away from the bit to the ocean floor. A

remotely operated vehicle (ROV) is often used to observe returns on the ocean floor. Drilling mud is ejected

out of nozzles in the bit with great speed and pressure.

Running the Structural Casing:

The next step is to put the permanent guide base

and the structural casing in place. It is called structural casing because it provides lateral support for the

BOP stack. The structural casing is lowered into the

water and down the hole one joint at a time. A guide

frame is attached to one of the bottom joints of structural casing and is used to guide the casing into the

center opening of the temporary guide base and into

the borehole. The permanent guide base is attached to

the top of the topmost structural casing joint and the

guidelines threaded through the guideposts. After the

final joint of structural casing is run down the guidelines into the hole, the permanent guide structure and

housing are landed in the temporary guide base. The

permanent guide base provides a structural base for

additional casing strings and additional equipment,

such as the BOP stack, that are run later.

Next, the structural casing is cemented in the

hole. To cement the structural casing, a drill pipe is

lowered down inside the structural casing to a point

near the bottom where it is connected to a fluid-tight

seal. Cement is pumped down the inside of the drill

pipe. Because of the fluid-tight seal, the cement goes

out the bottom of the structural casing and back up

the annular space between the wall of the hole and the

outside of the casing. Again, cement returns are taken

on the ocean floor and may be observed with a ROV

camera.

Installing the Diverter System and the Conductor Casing:

A hole is drilled for the conductor casing after

the cement sets. Once again, the drill bit is guided by

the guide frame and guidewires down to the guide base.

The hole for the conductor casing is a few inches in

diameter smaller than the inside diameter of the structural casing.

Before the hole for the conductor casing is started,

the shoe of the conductor casing is drilled out. A marine riser fitted with a subsea dump valve is run and
A2-4

Delineation Drilling Activities Offshore Santa Barbara County

latched onto the structural casings wellhead housing.

The next steps are to install the diverter and diverter

system and then to test the operation of the subsea

dump valve.

A diverter system is installed to negate the hazards associated with drilling in shallow gas zones. If

shallow gas is encountered, the diverter system will

direct the well bore fluids and the high volumes of

low-pressure gas overboard and downwind from the

semi-submersible.

After the hole is drilled, the conductor casing is

run down the guidelines and cemented back to the ocean

floor. The top of the conductor is fitted with a highpressure wellhead housing prepared internally to receive subsequent casing strings.

Running the BOP:

The BOP stack is a combination of individual

BOP’s designed to shut in a well under pressure so

that formation fluids that have moved into the wellbore

can be circulated out while continuous control of the

well is maintained. When drilling from a floating vessel, such as a semi-submersible, the BOP stack is

placed on the ocean floor in order to compensate for

vessel motion. Although several steps are taken to

control unusual well conditions before use of the BOP

becomes necessary, the BOP equipment is designed with

reliability as its ultimate criterion since it is considered a last resort for preventing a well kick from becoming a blowout. In addition, the subsea BOP is designed with several redundancies because of its inaccessibility on the ocean floor.

The BOP is normally lowered on the drill pipe.

Once the stack is attached onto the permanent guide

base, the drill pipe is retrieved. Marine riser pipe is

then run and attached to the top of the BOP stack.

The riser pipe serves as a conduit for the drill stem

and drilling mud returns. Once the BOP stack is put

in place on the ocean floor and the stack is function

and pressure tested, drilling to total depth can begin.

The BOP must be tested according to 30 CFR 250.616.

Drilling to Total Depth:

As the hole is drilled, additional casing strings

may be run through the riser and BOP, depending on

the depth of the well. The casings set between the conductor casing and the final production string are called

intermediate casing strings. The total depth of the hole

is drilled beyond the producing formation.

The system responsible for getting drilling mud

down the hole and the cuttings to the surface is called

the circulating system. Mud pumps pick up mud from

mud pits, put it into and down the drill pipe and drill

collars, send it out nozzles in the bit, and move it back

up the hole to the surface with the drill cuttings. The

mud and cuttings return to the surface through the

annular space between the outside of the drill pipe and

the inside of the hole. At the surface, the mud and

cuttings leave the well through a mud return line. At

the end of the return line, mud and cuttings fall onto

a vibrating screen, or shale shaker. The shaker screens

out cuttings but allows liquid to pass through and fall

into the mud pit, where it is once again picked up by

the mud pumps and sent back down the hole. This

circulatory system is continuous and goes on as long

as the bit is drilling.

Completing the Well:

The casings and cement block the hydrocarbons

in the reservoir from flowing into the well. Therefore,

perforations in the casing must be made to allow the

oil or gas to flow into the wellbore. Perforations are

simply holes that are made through the casing and

cement and extend some distance into the formation.

The most common method of perforating is using

shape-charge explosives.

Shaped charges accomplish penetration by creating a jet of high-pressure, high-velocity gas. The

charges are arranged in a tool called a gun that is

lowered into the well opposite the producing zone.

When the gun is in position, the charges are fired by

electronic means from the surface resulting in several

perforations that allow reservoir fluids to flow into

the wellbore.

Plug and Abandonment:

To abandon a well, it must be plugged first. Abandonment plugs generally consist of laying cement plugs

in the wellbore at specified intervals to just below the

ocean floor. The plugs must be set according to the

regulations at 30 CFR 250.700. The plugs are pressure tested as they are installed.

Next, the subsea wellhead and bases must be

recovered. This is accomplished by cutting the casing

strings approximately 15 feet below the mudline. Cutting is usually done with explosives, although, it can

be done by mechanical means.

Modern Drilling Techniques:

Over the years, significant advances have been

made with drilling and completion practices. In recent

years, much success has been achieved through horizontal or near-horizontal wells by exposing the completion interval to more productive formation than is possible with vertical wells. Horizontal drilling is not a

new technology, but rather an existing technology that

has advanced significantly in the last decade.
A2-5

Appendix for Chapter 2

APPENDIX 2.1 REFERENCES

Baker, Ron. 1985. A Primer of Offshore Operations.

2nd Edition. Austin: Petroleum Extension Service, Division of Continuing Education, The

University of Texas at Austin.

Baker, Ron. 1979. A Primer of Oilwell Drilling. 4th

Edition. Austin: Petroleum Extension Service,

The University of Texas at Austin.

Bradley, Howard B. 1992. Petroleum Engineering

Handbook. Texas: Society of Petroleum Engineers.

APPENDIX 2.2 DRILLING PROCEDURES

FOR POINT SAL UNIT1

Step-by Step Drilling Procedures - Pilot Hole

1) Mix 500 barrels of 14.5-ppg kill mud before

spudding in. Pick up 26 in bit and 36 in hole

opener and drill 36 in hole to 100 feet BML

(below ocean floor). Circulate hole clean, check

for flow, and pick up and run 30 in structural

casing on temporary guide base. Cement 30 in

casing.

2) Drill 26 in hole to 500 feet BML. Circulate hole

clean, check for flow, and POOH to run conductor casing. Pick up 20 in conductor casing

with permanent guide base and low-pressure

wellhead assembly. Circulate and cement the

20in casing. Washout and rig up 21in riser

system with diverter.

3) Drill 17 1⁄2 in surface hole to 1500 feet BML.

Circulate hole clean, POOH with drilling assembly and pick up and run high-pressure

wellhead on 13 3/8 in surface casing. Circulate

and condition the drilling mud and cement the

133

/

8

 in casing back to the mudline. Rig up 18

3⁄4 in BOP system. Perform a complete pressure test of the BOP’s, casing.

4) Drill 123⁄4 in hole to 3200 feet BML (or 500 ft

above oil and gas); set 95

/

8 in-production casing; cement 95

/

8 in-casing.

5) Drill 81⁄2 in hole to TD (6750 feet BML). Possibly conventionally core selected intervals during the drilling process.

6) Evaluate hole with wireline logs. Determine

optimal zone for production testing.

7) Abandon entire 81⁄2 in open hole section.

Step-by step Procedure - Sidetrack Hole

1) Pick up 81⁄2 in bit and polish off cement plug to

shoe of 95

/

8 in-production casing. Kick off with

directional tools and drill 81⁄2 in hole in a

near-horizontal angle for up to 2000feet.

2) Circulate well clean, pick up drill pipe conveyed

logging tools and log open hole. Evaluate hole

with wireline logs to determine optimal testing interval.

3) Pick up 7in-production liner and run in hole.

Set liner with 200ft lap and cement it in place.

4) Pick up 81⁄2 in bit and polish off to top of 7 in

liner lap. Pressure test lap and prepare to complete well for testing.

Well Site Abandonment

Once all drilling and testing operations are complete, a series of cement plugs will be set in the well at

several zones according to MMS approved abandonment procedures. Drilling mud of sufficient density

will be placed between the plugs and will prevent fluid

migration beneath the ocean floor. This procedure

will be approved by the MMS. Casing will be removed

to a depth within 15 feet below the mud line. The

ocean bottom will be cleared of all obstacles.

APPENDIX 2.3 DRILLING PROCEDURES

FOR PURISIMA POINT UNIT1

Step-by Step Drilling Procedures - Pilot Hole

1) Mix 500 barrels of 14.5-ppg kill mud before

spudding in. Pick up 26 in bit and 36 in hole

opener and drill 36 in hole to 100 feet BML

(below ocean floor). Circulate hole clean, check

for flow, and pick up and run 30in structural

casing on temporary guide base. Cement 30 in

casing.

1

 Aera Energy LLC, Point Sal Unit Project Description Information (September 2000), Drilling Operations,

Page 4-2.

1

 Aera Energy LLC Purisima Point Unit Project Description Information (September 2000), Drilling Operations, Page 4-2.
A2-6

Delineation Drilling Activities Offshore Santa Barbara County

2) Drill 26 in hole to 500 feet BML. Circulate hole

clean, check for flow, and POOH to run conductor casing. Pick up 20in conductor casing

with permanent guide base and low-pressure

wellhead assembly. Circulate and cement the

20in casing. Washout and rig up 21in riser

system with diverter.

3) Drill 171/

2 in surface hole to 1500 feet BML.

Circulate hole clean, POOH with drilling assembly and pick up and run high-pressure

wellhead on 133/

8

 in surface casing. Circulate

and condition the drilling mud and cement the

133/

8

 in casing back to the mudline. Rig up 183⁄4

in BOP system. Perform a complete pressure

test of the BOP’s, casing.

4) Drill 123⁄4 in hole to 3200 feet BML (or 500 ft

above oil and gas); set 95/

8 in production casing; cement 95

/

8 in casing.

5) Drill 81⁄2 in hole to TD (6750 feet BML). Possibly conventionally core selected intervals during the drilling process.

6) Evaluate hole with wireline logs. Determine

optimal zone for production testing.

7) Abandon entire 81⁄2 in open hole section.

Step-by step Procedure - Sidetrack Hole

1) Pick up 81⁄2 in bit and polish off cement plug

to shoe of 95/

8 in-production casing. Kick off with directional tools and drill 81⁄2 in hole in a near-horizontal

angle for up to 2000 ft.

2) Circulate well clean, pick up drill pipe conveyed logging tools and log open hole. Evaluate hole

with wireline logs to determine optimal testing interval.

3) Pick up 7in-production liner and run in hole.

Set liner with 200-ft lap and cement it in place.

4) Pick up 81⁄2 in bit and polish off to top of 7 in

liner lap. Pressure test lap and prepare to complete

well for testing.

Well Site Abandonment

Once all drilling and testing operations are complete, a series of cement plugs will be set in the well at

several zones according to MMS approved abandonment procedures. Drilling mud of sufficient density

will be placed between the plugs and will prevent fluid

migration beneath the ocean floor. This procedure

will be approved by the MMS. Casing will be removed

to a depth within 15 feet below the mud line. The

ocean bottom will be cleared of all obstacles.

APPENDIX 2.4 DRILLING PROCEDURES

FOR BONITO UNIT1

Step-by Step Drilling Procedures

1. Drill 36 in hole to 160 ft ± below ocean floor

with seawater. Returns to be left on ocean floor.

Run and cement 140 ft of 30 in, 310-lb casing,

30 in wellhead housing, and permanent guide

structure with sufficient cement to fill to ocean

floor.

2. Install diverter and diverter system.

3. Drill 17-1/2 in hole to 500ft below ocean floor.

Run open hole logs. Open hole from 17 1⁄2 in to

26 in.

4. Check for flow. After it is determined that the

well is completely dead, pull marine riser and

run 20 in, 133 LB, K-55 casing and 20 in x 18

3⁄4 in wellhead housing on drill pipe to 500 ft

below ocean floor. Land and lock the 18 3⁄4 in

wellhead housing into the 30 in wellhead housing. Cement the 20 in casing at 500 ft below

ocean floor through drill pipe with sufficient

cement to fill to ocean floor.

5. Run 183⁄4 in, 10,000 psi, Class IV BOP stack

on 21in O.D. marine riser and latch onto the

183⁄4 in wellhead housing. Test BOP per Nuevo

Operating Instruction D-17 and OCS Order No.

22

.

6. Drill 171

/

2

 in hole to 1520 ft below ocean floor

and run open hole logs.

7. Run and cement 133/

8

 in, 61 LB, K-55 buttress

casing at 1,500 ft, below ocean floor with sufficient cement to fill to ocean floor.

8. Drill 121⁄4 in hole to 50 ft below 133/

8

 in shoe

and make leak off test. Drill 121⁄2 in hole to

±4500 ft below ocean floor and run open-hole

logs.

 9. Run 95/

8

 in, 43.5 LB, N-80, buttress casing and

land near ±4500 ft below ocean floor. Land in

183/

4

in wellhead housing and cement with sufficient cement to fill 200 ft above 133

/

8

 in shoe.

1

 Nuevo Engergy Company, Expoloration Program

Overview, Bonito Unit-Southern Santa Maria Basin (September 2000), Drilling Operations, Page 2-11.

2

 OCS Order No. 2 is superceded by the regulations at

30 CFR 250.407.
A2-7

Appendix for Chapter 2

10. Drill 81/

2

 in hole to 50 ft below 95/

8

 in shoe and

make leak-off test.

11 Drill 81/

2 in hole to total depth and run

open-hole logs.

12. Well testing program to be developed pending

evaluation of open-hole logs

Plug and Abandonment Procedure

The proposed wells will be drilled as an expendable well and will be permanently plugged in accordance with abandonment procedures approved by the

MMS. The plug and abandonment will include the following steps:

1. A cement plug will be placed to extend from a

minimum of 100 ft below the bottom to 100 ft

above the top of any oil, gas, and fresh water

zones in the uncased portion of the hole.

2. A cement retainer with backpressure control

will be set between 50 ft and 100 ft above the

95/

8

 in casing shoe. Cement will be displaced to

a level at least 100 ft below the casing shoe

and spotted a minimum of 50 ft above the retainer.

3. Any casing perforations in the 95

/

8

 in casing

will be isolated as per 30 CFR 250, Subpart G.

4. A cement plug at least 150 ft long will be placed

in the 95/

8

 in casing with the top of the plug

within the first 150 ft below the sea floor.

5. The 95

/

8

 in, 133/

8

 in, and 20 in casings will be

cut a minimum of 20 ft below the sea floor and

recovered.

6 The 30 in structural casing will be cut and recovered a minimum of 15 ft below the sea floor.

7. Once all casing and wellhead equipment have

been recovered from the sea floor, a side-scan

sonar survey will be run covering the area

within a 4,000 ft radius of the well to be certain no obstructions remain.

A detailed drilling, casing and cement program

will be contained in the revised Bonito Unit EP to be

submitted in September 2001.

APPENDIX 2.5 DRILLING PROCEDURES

FOR GATO CANYON UNIT1

Based on the information currently at hand, the

following is a general description of the procedures

that will be undertaken to perform the delineation

operations. All operations will be in accordance with

appropriate OCS orders and regulations, Coast Guard

regulations, OSHA regulations and Samedan’s own

safety practices and procedures.

Step by Step Drilling Procedures

a. Drill 36 in hole to 1,005 ft KB (160 ft below

ocean floor); set 30 in structural casing, top of

housing 5 ft above ocean floor; cement 30 in

casing with 1,100 cubic feet of class “G” + 2

percent calcium chloride.

b. Mix and store 500 bbls of 10.2 ppg gel mud

before spudding in.

c. Drill out cement; drill 26 in hole from 1,005 ft

KB to 1,395 ft KB (550 ft below ocean floor);

set 20 in conductor casing; cement 20 in casing with 1,850 cubic feet class “G” + 2 percent

calcium chloride.

d. Test BOP stack, test pipe rams, test blind/shear

rams, test annular preventers.

e. Run BOP stack on 21in riser and land on wellhead, test BOP.

f. Begin formation-logging service

g. Drill out cement, drill 171

/

2

 in hole 10 ft, perform leak-off test; drill to 2,670 ft KB, begin

hole deviation at 2,000 ft KB, 5°/100 ft, heading 073°, run directional tool for continuous

monitoring.

h. Run e-logs at 2,670 ft

i. Run and land 133/

8

 in surface casing at 2,670 ft

KB (1,825 ft below ocean floor); cement 133/

8

in casing with 1,150 cubic feet of Class “G” +

16 percent blended gel + 2 percent calcium

chloride followed by 500 cubic feet of Class “G”

+ 2 percent calcium chloride.

j. Test BOP’s weekly.

k. Drill out cement, run directional and logging

while drilling tools, drill 121

/

4

 in hole to 2,940

ft KB building at 5°/100 ft to maximum angle

1

 Samedan Oil Corporation Gato Canyon Unit, Description of the Proposed Project (August 2000), Drilling

Operations, Page 4-1, August 2000
A2-8

Delineation Drilling Activities Offshore Santa Barbara County

of 57°, drill 121/

2 in hole to 7,523 ft KB, (Top

Monterey target at - 5200 ft).

l. Run logs.

m. Run and set 95

/

8

 in intermediate casing; cement

95/

8

 in casing at 6,550 KB with 1,125 cubic feet

+ 16 percent dry-blended gel, follow with 500

cubic feet Class “G” neat.

n. Run directional and logging-while-drilling tools,

drill 81

/

2

 in hole to TD at 10,802 ft KB (-7,000).

o. Run e-logs.

p. Run and set 7 in liner at 10,802 ft KB (or at

depth determined by log analysis program),

cement liner.

Casing Program

21 in Marine riser to wellhead, from 845 ft KB

30 in Structural at 1,005 ft KB, 160 ft below ocean

floor

20 in Conductor at 1,395 ft KB, 550 ft below ocean

floor

133

/

8

 in Surface casing at 2,670 ft KB, 1825 ft below

ocean floor

95/

8

 in Intermediate casing at 7,523 ft KB (-5200 ft)

Abandonment Procedures

All perforated intervals will be cemented off. A

series of cement plugs will be set in the borehole at

pre-selected depths beneath the ocean floor to prevent

any future leakage. Procedures will be approved by

the MMS. Casing will be removed to a depth of 16 feet

below the ocean floor. The ocean bottom will be surveyed and cleared of all obstacles.