--> ABSTRACT: Reservoir Characterization of the Potter Sandstone to Optimize Thermal Recovery, Midway-Sunset Field, California, by C. D. Enkins, M. H. Scheihing, D. G. Peck, J. S. Wingard, G. Perez, J. Colliton, L. Vernik, W. T. Fedewa, and R. D. Tucker; #91021 (2010)

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Reservoir Characterization of the Potter Sandstone to Optimize Thermal Recovery, Midway-Sunset Field, California

JENKINS, CRETIES D., MARK H. SCHEIHING, DOUG G. PECK. JEFF S. WINGARD, GODOFREDO PEREZ, JIM COLLITON, and LEV VERNIK, WILLIAM T. FEDEWA and ROGER D. TUCKER

A series of reservoir studies have been conducted in several leases of the Midway-Sunset Field to: (1) evaluate conversion of cyclic areas to continuous steamflood and (2) optimize existing steamfloods. The leases produce from the unconsolidated Potter Sandstone consisting of immature clastics deposited by gravity flow processes in a steep-faced, fan-delta. Reservoir quality lithologies include fine-grained to pebbly sandstones with air permeabilities of several darcies and porosities of 20-35%. Steam barrier lithologies are fine-grained sandstones and siltstones with air permeabilities that are two orders of magnitude lower than reservoir-quality sandstones.

Of critical importance in this reservoir is compartmentalization due to the spatial distribution of barriers to vertical steam movement. Therefore, reservoir description focused on integrating core, wireline log and temperature data to identify and distribute potential barriers using both deterministic mapping and stochastic modeling techniques. In addition, log models of porosity and permeability were developed and saturations were distributed using a saturation:height function.

The resulting 30 model was scaled-up, input to a thermal simulator and validated with performance data prior to making runs. The modeling effort, coupled with well surveillance analysis, provided insights into the recovery mechanisms responsible for variations in lease performance. Based upon the testing of various production scenarios, recommendations were made concerning (1) if and when some leases should be converted from cyclic to continuous steam injection, (2) which areas were bypassed on cyclic and would benefit from streamflooding, (3) when to deepen existing wells, and (4) where to place infill wells and how to complete them.

AAPG Search and Discovery Article #91021©1997 AAPG Annual Convention, Dallas, Texas.