About This Item

Share This Item

The AAPG/Datapages Combined Publications Database

AAPG Bulletin

Abstract

DOI:10.1306/10241111030

Production-induced fault compartmentalization at Elk Hills field, California

Alan P. Morris,1 Kevin J. Smart,2 David A. Ferrill,3 Nathaniel E. Reish,4 Peter F. Cowell5

1Department of Earth, Material, and Planetary Sciences, Geosciences and Engineering Division, Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas; [email protected]
2Department of Earth, Material, and Planetary Sciences, Geosciences and Engineering Division, Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas; [email protected]
3Department of Earth, Material, and Planetary Sciences, Geosciences and Engineering Division, Southwest Research Institute, 6220 Culebra Road, San Antonio, Texas; [email protected]
4Occidental of Elk Hills, Occidental Petroleum Corporation, 10800 Stockdale Highway, Bakersfield, California; [email protected]
5Occidental of Elk Hills, Occidental Petroleum Corporation, 10800 Stockdale Highway, Bakersfield, California; [email protected]

ABSTRACT

Mature and aging clastic-dominated hydrocarbon fields commonly become increasingly difficult to produce, causing lower economic return than initially forecast. A major cause of this reduced economic viability is compartmentalization, defined as limitation on the ability to produce hydrocarbons resulting from permeability barriers within a field. Three primary causes of compartmentalization are structural variations in permeability, stratigraphic variations in permeability, and permeability reduction resulting from compaction adjacent to producing wellbores. Recognition and delineation of compartmentalization permit formulation of development and depletion plans to maximize recovery and economic value. Here, we examine one of 52 reservoir-scale faults that compartmentalize the eastern shallow oil zone (ESOZ), Elk Hills field, California. Using well-log, stratigraphic, structural, and pressure data, we apply standard fault seal analyses to the selected fault. Results are compared with known pressure conditions across the fault and show the fault capable of supporting pressure differentials two to three times those expected from standard static fault seal measures. Although this observation could be used as a basis for local calibration of standard fault seal measures for a dynamic seal, such an approach assumes that these fault seal mechanisms are in fact the cause of sealing behavior. Alternatively, one of the most significant changes in ESOZ reservoir conditions over the production lifetime of the field is the reduction of fluid pressure from approximately 1500 to approximately 200 psi (from sim10.27 to sim1.37 MPa). Decreasing fluid pressure would have driven stress states acting on faults in the reservoir from critical (near or at slip) to stable (nonslipping) conditions. Critically stressed faults and fractures are more transmissive than those that are noncritically stressed. We propose that decreasing fluid pressure can cause faults to become less leaky, causing production-induced reservoir compartmentalization.

Pay-Per-View Purchase Options

The article is available through a document delivery service. Explain these Purchase Options.

Watermarked PDF Document: $14
Open PDF Document: $24

AAPG Member?

Please login with your Member username and password.

Members of AAPG receive access to the full AAPG Bulletin Archives as part of their membership. For more information, contact the AAPG Membership Department at [email protected].