--> ABSTRACT: Hydrocarbon Transport and Shearing Processes in the Antelope Shale, Monterey Formation, San Joaquin Valley, California, by S. K. Dholakia, A. Aydin, D. D. Pollard, and M. D. Zoback; #91019 (1996)

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Hydrocarbon Transport and Shearing Processes in the Antelope Shale, Monterey Formation, San Joaquin Valley, California

S. K. Dholakia, A. Aydin, D. D. Pollard, and M. D. Zoback

An essential component of the development and management of a fractured reservoir is the basic understanding of the fracture system and its effect on hydrocarbon flow. In the Antelope Shale, a siliceous shale member of the Monterey Formation in the Buena Vista Hills field (BVH), San Joaquin alley (SJV), the relationship between the fracture system and hydrocarbon productivity is poorly understood. An integrative approach, employing both eological and geophysical methods, to fracture characterization in the Antelope Shale is important for a better understanding of the connected fracture network and for identifying hydrocarbon-carrying fractures. This knowledge will aid in future reservoir management plans for the BVH field, specifically CO2 enhanced oil recovery from the existing reservoir.

Field studies of the Antelope Shale at Chico Martinez Creek in the SJV demonstrate the importance of shearing processes for the migration of hydrocarbons. Hydrocarbons primarily occur in brecciated zones which are oriented parallel to bedding. The internal architecture of early stage breccia zones is well-organized with sets of hydrocarbon-stained fractures oriented both at high angles and parallel to bedding. In later stage breccia zones, internal organization is disrupted and consists of fragments of the host rock surrounded by hydrocarbons. Subsurface studies which include core and FMS data demonstrate comparable shear-related features in the Monterey Formation. Oil-stained breccia zones are observed in core from the Antelope Shale from a field near BVH. Breccia zones are documente in FMS data from offshore Monterey fields and similar features are being sought in FMS data from SJV in the Antelope Shale.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California