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Suggested Citation:"APPENDIX C: RESERVIOR CHARACTERIZATION." National Research Council. 1996. Maintaining Oil Production from Marginal Fields: A Review of the Department of Energy's Reservoir Class Program. Washington, DC: The National Academies Press. doi: 10.17226/9143.
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C

Reservoir Characterization

Reservoirs range from simple to complex based on their geologic origins. All reservoirs are characterized by some degree of heterogeneity (variability) of properties (porosity, permeability, fluid saturations, etc.) on a variety of scales (Figure C.1). The more complex a reservoir is, the higher its degree of heterogeneity and the more difficult it is to predict the occurrence and producibility of hydrocarbons. Reservoir characterization therefore is necessary in order to understand and predict the occurrence and producibility of hydrocarbons from a reservoir.

Reservoir characterization involves a large component of interpretation. Most producing wells are four to twelve inches in diameter, and most well logs provide constraints on data about rocks six to twelve inches away from the well bore. Therefore, wells provide information about a very small fraction of a reservoir, and hence good interpretation is needed to estimate characteristics of the vast majority of the reservoir located between wells. High-quality reservoir characterization is needed to accurately interpret data from wells and infer the distribution of flow units between wells. Techniques for reservoir characterization include core analysis, wireline log analysis, 3D reflection seismic data, crosswell tomography, vertical seismic profiles (VSPs), transient pressure analysis, tracers, 3D geological modeling, geostatistical modeling of reservoirs, production history matching, fracture analysis, and reservoir fluid analysis (PVT analyses).

Because wells provide information on such a small fraction of the res-

Suggested Citation:"APPENDIX C: RESERVIOR CHARACTERIZATION." National Research Council. 1996. Maintaining Oil Production from Marginal Fields: A Review of the Department of Energy's Reservoir Class Program. Washington, DC: The National Academies Press. doi: 10.17226/9143.
×

FIGURE C.1 Levels of reservoir heterogeneity. From: Tyler, N., 1988, New Oil from Old Fields. Geotimes vol. 33, no. 7, p. 9. Reprinted by permission of the American Geological Institute.

ervoir, integration of geophysical and engineering data with geological well information is required to give the best interpretation possible. Geophysical techniques can provide information about a large fraction of the reservoir. Conventional 3D seismic data can provide structural data for an entire reservoir, but conventional surface seismic data can only image bodies of rock approximately 100 by 100 by 100 feet. Seismic data cannot, therefore, directly provide data on many of the most important reservoir properties like porosity, permeability, and fluid saturations. And while other geophysical techniques like crosswell tomography can give much finer resolution, they also do not directly provide information on porosity, permeability, and fluid saturations. Fluid flow and pressure data from wells can provide much data on bulk properties of fluid flow within a reservoir. In general, the most accurate and comprehensive estimate of reservoir characteristics results from the integration of geologic, engineering, and geophysical data.

Suggested Citation:"APPENDIX C: RESERVIOR CHARACTERIZATION." National Research Council. 1996. Maintaining Oil Production from Marginal Fields: A Review of the Department of Energy's Reservoir Class Program. Washington, DC: The National Academies Press. doi: 10.17226/9143.
×

TABLE C.1 GOALS OF RESERVOIR CHARACTERIZATION

MAJOR PURPOSE OF RESERVOIR CHARACTERIZATION: LOCATION OF INFILL WELLS

Project No.

Contractor

Area

Purpose

Class 1

4

Texas Bureau of Economic Geology

Frio Formation

No field demonstration

6

Diversified Operating Corporation

Sooner Field

Infill and recompletion locations

9

Sierra Energy Company

Frontier Formation

Locations of horizontal well to intersect fractures

11

University of Kansas

Savonburg and Stewart Fields

Locate infill wells and design waterflood

12

Oklahoma Geological Survey

Fluvial-dominated deltaic reservoirs in Oklahoma

Classification of reservoirs and recovery technologies being used

14

Utah Geological Survey

Bluebell Field

Locate infill wells and zones to recomplete in existing wells

Class 2

16

Fina Oil and Chemical Co.

Clearfork Reservoir

Locate infill wells and redefine waterflood **

17

Laguna Petroleum Co.

Foster and S. Cowden Fields

Locate infill wells and redefine waterflood

18

Luff Exploration Co.

Williston Basin

Locate drilling locations to utilize horizontal drains

19

Michigan Tech. University

Dundee Formation

Locate horizontal wells

23

University of Kansas

Schaben and Bindley Fields

Locate infill wells

24

Utah Geological Survey

Paradox Basin

Locate infill wells and assess viability of waterflood and CO2 flood

**Mid-term project

Suggested Citation:"APPENDIX C: RESERVIOR CHARACTERIZATION." National Research Council. 1996. Maintaining Oil Production from Marginal Fields: A Review of the Department of Energy's Reservoir Class Program. Washington, DC: The National Academies Press. doi: 10.17226/9143.
×

MAJOR PURPOSE OF RESERVOIR CHARACTERIZATION: IMPROVED DESIGN OF A WATERFLOOD OR ADVANCED FLOODING TECHNIQUE

Project No.

Operator

Area

Purpose

Class 1

8

Lomax Exploration Co.

Green River Formation

Waterflood design

11

University of Kansas

Savonburg and Stewart Fields

Waterflood plus infill

12

Oklahoma Geological Survey

Fluvial-dominated deltaic reservoirs in Oklahoma

Classification of reservoir and recovery technologies used

13

University of Tulsa

Glen Pool Field

Waterflood

Class 2

15

Sensor

Anadarko Basin

Gel treatment

16

Fina Oil and Chemical Co.

Clear Fork Reservoir

Locate infill wells and redefine waterflood **

17

Laguna Petroleum Co.

Foster and S. Cowden Fields

Locate infill wells and redefine waterflood

20

Oxy USA, Inc.

Welch Field

Cyclic CO2 flood **

21

Phillips Petroleum Co.

South Cowden Field

Horizontal well for CO2 injection **

22

Texaco E&P, Inc.

Texaco Central Vacuum Unit

CO2 Huff-n-Puff

24

Utah Geological Survey

Paradox Basin

Locate infill wells and assess viability of waterflood and CO2 flood

**Mid-term project

Suggested Citation:"APPENDIX C: RESERVIOR CHARACTERIZATION." National Research Council. 1996. Maintaining Oil Production from Marginal Fields: A Review of the Department of Energy's Reservoir Class Program. Washington, DC: The National Academies Press. doi: 10.17226/9143.
×

LIMITED EMPHASIS ON RESERVOIR CHARACTERIZATION

Project No.

Contractor

Area

Purpose

Class 1

2

Amoco Production Co.

West Hackberry Field

Air injection **

7

Hughes Eastern Corp.

North Blowhorn Creek Field

Microflora and waterflood **

10

Texaco E&P, Inc.

Port Neches Field

CO2 flood with horizontal and vertical wells **

** Mid-term project

Suggested Citation:"APPENDIX C: RESERVIOR CHARACTERIZATION." National Research Council. 1996. Maintaining Oil Production from Marginal Fields: A Review of the Department of Energy's Reservoir Class Program. Washington, DC: The National Academies Press. doi: 10.17226/9143.
×
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Suggested Citation:"APPENDIX C: RESERVIOR CHARACTERIZATION." National Research Council. 1996. Maintaining Oil Production from Marginal Fields: A Review of the Department of Energy's Reservoir Class Program. Washington, DC: The National Academies Press. doi: 10.17226/9143.
×
Page 71
Suggested Citation:"APPENDIX C: RESERVIOR CHARACTERIZATION." National Research Council. 1996. Maintaining Oil Production from Marginal Fields: A Review of the Department of Energy's Reservoir Class Program. Washington, DC: The National Academies Press. doi: 10.17226/9143.
×
Page 72
Suggested Citation:"APPENDIX C: RESERVIOR CHARACTERIZATION." National Research Council. 1996. Maintaining Oil Production from Marginal Fields: A Review of the Department of Energy's Reservoir Class Program. Washington, DC: The National Academies Press. doi: 10.17226/9143.
×
Page 73
Suggested Citation:"APPENDIX C: RESERVIOR CHARACTERIZATION." National Research Council. 1996. Maintaining Oil Production from Marginal Fields: A Review of the Department of Energy's Reservoir Class Program. Washington, DC: The National Academies Press. doi: 10.17226/9143.
×
Page 74
Suggested Citation:"APPENDIX C: RESERVIOR CHARACTERIZATION." National Research Council. 1996. Maintaining Oil Production from Marginal Fields: A Review of the Department of Energy's Reservoir Class Program. Washington, DC: The National Academies Press. doi: 10.17226/9143.
×
Page 75
Suggested Citation:"APPENDIX C: RESERVIOR CHARACTERIZATION." National Research Council. 1996. Maintaining Oil Production from Marginal Fields: A Review of the Department of Energy's Reservoir Class Program. Washington, DC: The National Academies Press. doi: 10.17226/9143.
×
Page 76
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