Improved Reservoir Management of Heavy Oil Assets Using Biomarker Variability in Sidewall Cores and Produced Oils: An Example From the Cymric Field, Kern County, California

Henry A. Legarre, Mark A. McCaffrey, and Scott J. Johnson

Development of biodegraded oil accumulations can be optimized by using geochemical indicators of variations in the extent of biodegradation. Biodegradation typically reduces oil producibility by increasing oil viscosity. Using the Cymric Field substantially over extremely short vertical distances (feet) in shallow, low-permeability reservoirs. These variations can be mapped laterally for more than a mile using reservoir sidewall core extract compositions. The relationship between oil viscosity and biomarker biodegradation parameters can be calibrated from analyses of produced oils. These relationships can then be used to convert sidewall core biomarker parameters into quantitative predictions of lateral and vertical changes in oil viscosity and gravity. These compositiona variations can be used to optimize the placement of new wells and well completion intervals, as well as to assess the relative production from discrete zones. We discuss how this new technique can be used to optimize field development, including parameters such as (1) the placement of completion intervals, (2) the thickness of steam injection intervals, and (3) the spacing between injection intervals in the same well.

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