Seismic Reservoir Characterization of the Morrow A Sandstone

Thomas L. Davis & Robert D. Benson CSM Scott Wehner, Chaparral Energy, and Michael D. Raines and Roger Freidline, Whiting Oil and Gas Corp

Postle Field, Texas County, Oklahoma

Postle FieldSite of the 24-5 Well

Location of Postle Field

Modified from Johnson Modified from Johnson (1989)(1989)

Postle Field

Morrow Stratigraphic Section

Postle Field – Geologic Setting

Pennsylvanian Morrow (~217Ma) paleogeography. Modified from Bowen and Weimer (2003).

Study Location in the Hovey Morrow Unit

Net Pay A Sand

Postle Reservoir Parameters

•Depth 6100’•Producing formation Upper Morrow sand•Average Thickness 28’ (10-70)•Porosity 17% (10-23)•Permeability 50 mD (20-500)•Soi 70%•Reservoir Temp 140 F•Reservoir pressure Initial 1630 psi•Reservoir Pressure Current 200 - 2300 - 4500 psi•Minimum Miscibility Pressure 2100 psi•Oil Gravity 40 API•Oil FVF orig 1.28•Oil FVF current 1.20•Well spacing 40 Ac (80-Ac 5-spot inj. patterns)•Area 26000 Ac•Cumulative Production 120 MMBO (40% OOIP)•OOIP ~300 MMBO

Motivation

Dry holes drilled

Cross Section

6300 ft

6000 ft

Morrow A

West East

Valley – Fill Sandstones

Binocular Microscope Image

The Morrow Sandstone

Dipole Sonic Log – Postle Field

Where is the Sand?

Acoustic impedance contrast between Morrow sandstone and shale is small (<10%).

The Morrow A is a thin sandstone reservoir below seismic resolution.

Average ~45 ft.

4-D, 9-C Seismic Survey

Field Survey Layout

4-D, 9-C Seismic Acquisition Parameters4-D, 9-C Seismic Acquisition Parameters

Type survey 4-D, 9-C (time-lapse)

Subsurface bin size 55 feet X 55 feet

Number of receiver locations 1920

Number of source locations 1920

Total number of source points 5760

Type receiver spread Stationary: 13,200’ X 13,200’

Instrumentation I/O System IV, 2 ms sample rate, 4/5 sec. record length

Receiver array Single 3-C Digital Sensor(VectorSeis)

Source (P-wave) Vertical vibrator: 6-100 hz linear sweep, 8 sec duration, 4 sweeps

Source (S-wave) Horizontal vibrator: 4-60 hz linear sweep, 8 sec duration, 4 sweeps, one source oriented N-S, one source oriented E-W

Special Thanks to Paragon

Reservoir Characterization Project Phase XII

P Stack S11 Stack800

1500

1500

2850

1300

1050

2500

2000A

P-Wave Synthetic Seismogram Well 17-6

Correlation: 73%

18

P-Wave Inline 50 - Baseline

19

south north

Lateral Scale 2.5 Miles

S11-Wave Synthetic Seismogram

20

Well 17-6

Correlation: 72%

S11 Inline 50 - Baseline

21

Atoka

Morrow Shale

Morrow A

Lateral Scale 2.5 Miles

Postle Seismic Survey

VSP Well Tie

P-Wave Corridor STK March 08 in Inline 45

S-Wave Corridor STK March 08 in Inline 45

Tamimi 2009

P-Wave Max Peak Amplitude

Pmig4Band Pass 30,35Morrow Peak 20 ms CenterCorrelation: 0.42

Wyllie, 2008

S -Impedance

17840

12893

Correlation Coeff .65

Seismic guided Morrow A Sandstone

4000 ft

(ft)

Multicomponent guided Isopach

14

.73 CC

From Pinto2011

Final Map

With 94% correlation to Morrow A thickness of well data. Includes P-P amp, S11 and S22 amplitudes, and time-lapse P-P data

From Minaei, 2011

Thickness (ft)

Where is the CO2 Going?Where is the CO2 Going?

Seismic/Simulation

P-Wave: 1st Monitor-Base

29From Heris 2011

From Zerpa 2011

Seismic/SimulationS11-Wave: 1st Monitor-Base

30

From Heris 2011

From Zerpa 2011

Revitalization of HMU, Postle Field, OK

Discovery

1958 1961

Start of

Production

1974

Start of Waterflood

May 2007

March2008

Dec.2008

February2010

Start of CO2 Flood Baseline

Survey 1st

Monitor

Survey

2nd MonitorSurvey

Seismic Acquisition

(Modified from Heris, 2011)Production history of Postle Field in the RCP area

31

Production History & Field RevitalizationHovey Morrow Unit

1

10

100

1,000

10,000

100,000

Jan-05 Jan-06 Jan-07 Jan-08 Jan-09 Jan-10 Jan-11 Jan-12

Oil Prod., BOPD

H2O Prod., BWPD

CO2 Prod., Mscf/D

H2O Inj., BWPD

CO2 Inj., Mscf/D

2588 BOPD3068

Conclusions

•The Morrow A Sandstone Reservoir is better imaged with shear waves

•Reservoir conformance mapping with shear waves provides the insight to change or adjust the current injection-production pattern to improve CO2 conformance

Reservoir Characterization Project Phase XII

Thanks to RCP Sponsors of Phases XII and XIII