DESIGN AND IMPLEMENTATION OF A CO2 FLOOD UTILIZING ADVANCED RESERVOIR CHARACTERIZATION AND HORIZONTAL INJECTION WELLS IN A SHALLOW SHELF CARBONATE APPROACHING.

DESIGN AND IMPLEMENTATION OF A CO2 FLOOD UTILIZING ADVANCED RESERVOIR

CHARACTERIZATION AND HORIZONTAL INJECTION WELLS IN A SHALLOW SHELF

CARBONATE APPROACHING WATERFLOOD DEPLETION

DESIGN AND IMPLEMENTATION OF A CO2 FLOOD UTILIZING ADVANCED RESERVOIR

CHARACTERIZATION AND HORIZONTAL INJECTION WELLS IN A SHALLOW SHELF

CARBONATE APPROACHING WATERFLOOD DEPLETION

•Based On DOE Report # DOE/BC/14991R36

•Presented by M. K. Moshell, P.E. 12/12/02

0

100

1stQtr

3rdQtr

EastWestNorth

Cooperative Agreement Number: DE-FC22-94BC14991

Participant Organization: Phillips Petroleum Company

4001 Penbrook

Odessa, Texas 79762

(Now ConocoPhillips)

Date of Report: 09/01/2002

Award Date: 06/03/1994

Completion Date: 07/01/2001

Special “Thanks” to

Michelle Navarette

Project Purpose:

To economically design an optimum carbon dioxide (CO2) flood for a mature waterflood nearing

its economic abandonment.

The original project utilized advanced reservoir characterization and CO2 horizontal injection wells

as the primary methods to redevelop the South Cowden Unit (SCU), Ector County, Texas.

The Unit was a mature waterflood with water cut exceeding 95%. Oil must be mobilized through the use of a miscible or near-miscible fluid to recover significant additional reserves. Also, because the unit is relatively small, it does not have the benefit of economies of scale inherent in normal larger scale projects. Thus, new and innovative methods are required to reduce investment and operating costs.

Two primary methods planned to accomplish improved economics were use of :

1) Reservoir characterization to design and restrict the flood to the higher quality rock in the unit, and

2) Use of horizontal injection wells to cut investment and operating costs

Property Details

Low permeability San Andres reservoir, 4,600’

At Eastern edge of San Andres productive trend on Central Basin Platform

~ 2200 Acres in Unit, ~500 Acres CO2 Flood area

20 Acres /wellbore on edges

10 Acres/wellbore in thicker pay area of Unit

Slow waterflood processing rate

Economic limit and abandonment was predicted for 1999

Early ResultsEarly Results

•The first two lateral CO2 injectors were drilled in the thickest portion of the reservoir

•Oil production response to that injection was less than predicted

•Laterals were drilled from existing producers

•Additional injectors were drilled as vertical wells

feet1000. 0. 1000. 2000. 3000. 4000. 5000.

Scale 1:8000.

LEGEND

Active Water Injection Well

Proposed Locations

Proposed WIW to Convert to POW

TA'd or SI Prod. Well

P & A Prod. Well

Wells To Be Shut In

Prop. CO2 Inj.(WAG)/Currently Active WI

TA'd WIW

Active Prod. Oil Well

P & A WIW

D&A or P&A - Oil

rowen 1/00

msb PRO97CGD.GPF

12

7

8

9

13

18

17

16

EMMONS UNIT

S. COWDEN UNIT

112

114

101A

103

104

105

106

108

109

110

201

203W

204

111

116W

122

102A

127

208

132

210

209

131

107

215W

135

136

202

140

142

213

217

218

4-02

3-03

3-01

3-04

3-05W

3-06

3-07

8-02

8-03

8-04W

8-05

8-06

8-08W

8-09W

7-01

7-02

7-03W

7-04W

7-05

1-01

1-02

1-03

1-04

2-01

2-02

2-03

2-04

2-05

2-07

2-08

2-09

2-10

2-11

2-12

2-13W

5-01W5-02

5-03

5-04W5-05

6-01

6-02

6-03W

6-05

6-06

6-07

6-08

6-10

6-11W

6-12W

6-09A7-06

7-085-07

7-09

2-15W

8-10

8-13

6-13

2-17

8-14

6-14

1-07

1-05

9-03

8-16

8-12

1-06

6-16W

8-18

6-178-17

6-18

2-202-19W

4-03W

6-19

2-22

2-212-23

5-08

3-02

8-15W

5-06W9-02W

6-20

2-24

8-19

2-25

6-23

6-21

7-10

2-18

8-02

9-01

6-227-12

6-24

7-13

7-15

6-04

205

123

128

211

143

146W

2-26W

2-27W

6-C25H7-C11H

6-26W

6-28W

6-27W

PHASE I - SHORT RADIUS DRILLING

Original TrajectoriesActual Trajectories

Challenges – Phase 2Challenges – Phase 2

•Inject CO2 at higher rates to improve flood economics

•Keep CO2 injection within the target reservoir layers

•Increase total production rate without fracturing out of zone

a

South Cowden Unit

Cumulative CO2 Injection

0

2

4

6

8

10

12

14

16

Jul-9

6

Oct

-96

Jan-

97

Apr

-97

Jul-9

7

Oct

-97

Jan-

98

Apr

-98

Jul-9

8

Oct

-98

Jan-

99

Apr

-99

Jul-9

9

Oct

-99

Jan-

00

Apr

-00

Jul-0

0

Oct

-00

Jan-

01

Apr

-01

Jul-0

1

Oct

-01

Jan-

02

Apr

-02

BC

F

Purchased CO2 Total Injection Recycled CO2

South Cowden Unit CO2 Utilization

01020304050607080

Jan-

97

May

-97

Sep

-97

Jan-

98

May

-98

Sep

-98

Jan-

99

May

-99

Sep

-99

Jan-

00

May

-00

Sep

-00

Jan-

01

May

-01

Sep

-01

Jan-

02

May

-02In

stan

tan

eou

s C

O2

Inje

ctio

n, M

CF

Per

Te

rtia

ry B

bl R

eco

vere

d

Gross, Total Injection Net, Purchase Only

Tertiary Recovery vs. CO2 Injection

0.000

0.001

0.002

0.003

0.004

0.005

0.006

0.007

0.000 0.010 0.020 0.030 0.040 0.050 0.060 0.070

CO2 Injection, Fraction of HCPV

Tert

itar

y R

eco

very

, Fra

ctio

n o

f O

OIP

Oil Recovery Summary MMSTBO % OOIP

PROJECT AREA

Estimated Original Oil in Place, Project Area 86.5

Most Likely Estimated Ultimate Tertiary recovery 3.7 4.3

UNIT

Estimated Original Oil in Place, Unit* 117 100

Estimated ultimate oil recovery, Primary + Secondary** 35.8 30.6

Cumulative recovery to 6/30/02 36.3 31.0

Cumulative Tertiary recovery to 6/30/02 0.6 0.5

Est. Ultimate Primary + Secondary + Tertiary 39.5 33.8

Most Likely Estimated Ultimate Tertiary recovery 3.7 3.2

High Side Estimated Ultimate Tertiary recovery 4.5 3.8

12/11/02 Update

Current Production

680 BOPD

2,800 MCFD

5,500 BWPD

Oil production has been rising steadily since April 2002

(April 2002 = 600 BOPD)

ConclusionsConclusions

•Reservoir characterization partially successful

•Simulation provided a forecast which was too optimistic on total liquid production and BOPD

•Ultimate Tertiary Oil recovery ~ 40% of predicted

•Liquid production rate still too low

ConclusionsConclusions

•Oil response good where CO2 Injection rate is maintained at target injection rates

•Overall oil response is poor due to inability to maintain CO2 injection rate in-zone in most injectors

•Water injection for gas mobility control in the future will slow flood even more