Monitoring the Movement of CO 2 at the Upper Spraberry Reservoir Using Well Logs Gokul Lakshman Texas A&M University Pioneer Natural Resources
Dec 22, 2015
Monitoring the Movement of CO2 at the Upper Spraberry Reservoir Using Well Logs
Gokul LakshmanTexas A&M University
Pioneer Natural Resources
Outline Pilot Information
Location Pilot Design Pilot Highlights Upper Spraberry Makeup
CO2 Flood Mechanism Log Monitoring
Objectives and Tools Used Looking Inside CNL tool What the logs have to say?
Decision Analysis Production Outlook Conclusions and Future Scope
Glasscock Co
Reagan CoUpton Co
Midland Co
Martin Co
Cany
on R
eef
Carr
iers
CO2 S
uppl
y
Cany
on R
eef
Carr
iers
CO2 S
uppl
y
O’Daniel
Shackelford
Driver
MerchantNorth
Pembrook
Benedum
Pembrook
Aldwell
Sherrod
Preston
MidkiffTippett
Location
Pilot Design
Producers
CO2 Injectors
Observationwells
Water Injectors
N
Pilot Goal
To evaluate the technical and economical feasibility of using CO2 as a tertiary recovery agent in the low permeability, fractured sandstone of the Spraberry Trend
Pilot Objectives
Collection and Analysis of pilot performance data To understand vertical and horizontal heterogeneities To determine optimal usage of CO2
Comparison of waterflood and CO2 flood performance Work within the limitations of allocated budget
Spraberry Reservoir : Looks Complicated??
CO2 Flood Mechanism
CO2+OIL OILHEAVIER FRACTIONS
1550 PSI
CO2
1U
3U
4U
2U
5U
7045
7230
PAY ZONES
CO2
Key Operating Targets
• CO2 Injection Rate= 91MSCF/D• Average Reservoir Pressure= 2300PSI• Target Water Injection Rate= 250BPD
Log Monitoring of CO2 flood – A Forensic science
Objectives
Monitoring the movement of CO2 in the formation
Calculation of the saturation of fluids
Logging Tools Used
Compensated Neutron Log Array Induction Log
Enter Tool Physics
CNL TOOL
H+Formation
Gamma Rays
Thermalized neutrons
SSD
SOURCE
SSLS
LSD
Logging Runs Conducted
Total HCPV to be injected : 22HCPV(128MMCF)How much has been injected until now:76MMSCF
RUNS MONTHS
1 Jan
2 Feb
3 Mar
4 Apr
5 Jun
6 Aug
7 Dec
Feb 22nd Start of CO2 Injection
Successive Neutron porosity decrease observed-Jan to Dec Well 49
1u
2u
3u
4u
5u
Gas entry
What the logs have to say ?
1u Frequency Distributions in Well #49Jan-Mar Distribution 1u
0
5
10
15
20
25
0.02
5-0.
038
0.03
8-0.
050
0.05
0-0.
063
0.06
3-0.
075
0.07
5-0.
088
0.08
8-0.
100
0.10
0-0.
113
0.11
3-0.
125
0.12
5-0.
138
0.13
8-0.
150
0.15
0-0.
163
0.16
3-0.
175
0.17
5-0.
188
0.18
8-0.
200
0.20
0-0.
213
0.21
3-0.
225
Neutron Porosity Distribution
Rel
ativ
e fr
equ
ency
0102030405060708090100
Cu
mu
lati
ve
freq
uen
cy
Jan rel freq Mar rel freq jan cum freq mar cum freq
1
2
Jan-Apr Distribution 1u
0
5
10
15
20
25
Neutron Porosity Distribution
Rel
ativ
e F
req
uen
cy
0102030405060708090100
Cu
mu
lati
v F
req
uen
cy
Jan rel.freq Apr Rel.freq Jan Cum freq Apr Rel.freq
1
2
Jan June Distribution 1u
0
5
10
15
20
25
0.02
5-0.
038
0.03
8-0.
050
0.05
0-0.
063
0.06
3-0.
075
0.07
5-0.
088
0.08
8-0.
100
0.10
0-0.
113
0.11
3-0.
125
0.12
5-0.
138
0.13
8-0.
150
0.15
0-0.
163
0.16
3-0.
175
0.17
5-0.
188
0.18
8-0.
200
0.20
0-0.
213
0.21
3-0.
225
Neutron Porosity Distribution
Rel
ativ
e F
req
uen
cy
0102030405060708090100
Cu
mu
lati
ve
freq
uen
cy
Jan rel.freq Jun rel.freq jan cum.freq jun cum.freq
Jan-Aug distribution 1u
0
5
10
15
20
25
Neutron Porosity distribution
Rel
ativ
e Fr
eque
ncy
0102030405060708090100
Cum
ulat
ive
Freq
uenc
y
Jan rel.freq Aug.rel.freq Jan cum.freq aug rel.freq
1
2
Frequency Distribution-Well 49 5u(Jan-Mar)
0
5
10
15
20
25
30
0.02
5-0.0
38
0.03
8-0.0
50
0.05
0-0.0
63
0.06
3-0.0
75
0.07
5-0.0
88
0.08
8-0.1
00
0.10
0-0.1
13
0.11
3-0.1
25
0.12
5-0.1
38
0.13
8-0.1
50
0.15
0-0.1
63
0.16
3-0.1
75
0.17
5-0.1
88
0.18
8-0.2
00
0.20
0-0.2
13
0102030405060708090100
jan rel freq mar rel freq jan cum freq mar cum freq
Frequency Distribution-Well 49 5u(Jan-Apr)
0
5
10
15
20
25
30
0102030405060708090100
jan rel freq apr rel freq jan cum freq apr cum freq
Frequency Distribution-Well 49 5u(Jan-Jun)
0
5
10
15
20
25
30
0.02
5-0.0
38
0.03
8-0.0
50
0.05
0-0.0
63
0.06
3-0.0
75
0.07
5-0.0
88
0.08
8-0.1
00
0.10
0-0.1
13
0.11
3-0.1
25
0.12
5-0.1
38
0.13
8-0.1
50
0.15
0-0.1
63
0.16
3-0.1
75
0.17
5-0.1
88
0.18
8-0.2
00
0.20
0-0.2
13
0
20
40
60
80
100
jan rel freq jun rel freq jan cum freq jun cum freq
Frequency Distribution-Well 49 5u(Jan-Aug)
0
5
10
15
20
25
30
0
20
40
60
80
100
120
jan rel freq aug rel freq jan cum freq aug cum freq
5u Frequency Distributions in Well #49
Decision Analysis--Lets be practical?
Oil in tank-Is it significant??
Whether a nominal PV of CO2 has been injected ?
Have Log So Responses Been Stabilized
Cease CO2 Injection
Production Outlook -Cumulative CO2 Injection
0
10000
20000
30000
40000
50000
60000
70000
80000
09-Jan-01 28-Feb-01 19-Apr-01 08-Jun-01 28-Jul-01 16-Sep-01 05-Nov-01 25-Dec-01 13-Feb-02
Time (Days)
Cu
mu
lativ
e o
f CO
2 In
j/Pro
d (M
cf)
Cumulative of CO2 Injection Cumulative of CO2 Production Cumulative of CO2 at A#1
0
10
20
30
40
50
60
01/09/2001 02/28/2001 04/19/2001 06/08/2001 07/28/2001 09/16/2001 11/05/2001 12/25/2001 02/13/2002
Time (Date)
Oil
Pro
du
ctio
n R
ate
(BB
LS
/D)
A#1 #38, 39 and 40 Series3 Series4
Series5 Series6 Series7 Series8
Series9 Series10
CO2 Injection Started
(2/26/2001) 7/20/2001 8/21/2001 10/2/2001 11/6/2001 12/8/2001 1/3/2001
Are we still getting enough oil in the tank??
Conclusions• From neutron porosity logs there is indication of gas movement in all layers• More Logging runs required to get a clear picture of CO2 movement
My present status of research
Trying to calculate Sg using count rates Awaiting more data from field
What I plan to achieve? Calculate Sg for all layers Compute extent of vertical displacement of CO2 using log
analysis Predict the horizontal movement of CO2 using tracers and gas
compositions at different wells