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ABSTRACT: Mapping of Reservoir Compartments in the Brea-Olinda Oil Field, Los Angeles Basin, California by Oil Geochemistry

Talukdar, Suhas C.1, Robert Blake2, and Frank W. Smith3
(1) Core Laboratories, Inc, Houston, TX 
(2) Core Laboratories, Inc, Carrollton, TX 
(3) Nuevo Energy Co, Bakersfield, CA

The study demonstrates a successful application of the use of oil gas chromatography (GC) fingerprints to map reservoir compartments in the structurally and stratigraphically complex Brea-Olinda oil field. The field consists of a southwest dipping homocline that steepens northward truncating against a regional fault. The 1060 acres study area that includes Nuevo Energy's Stearns and East Naranjal fee properties in the southeast field margin is divided into nine blocks by crosscutting northeast trending faults. Oils are accumulated in four Miocene turbidite sands and four Pliocene turbidite sands. Comparison of GC fingerprints of 181 oils (multi-zone and single zone production) and 14 oil extracts by star plots and dendograms reveal: (1) the Miocene reservoirs are in widespread vertical and lateral fluid communication across the nine fault blocks and form a large continuous oil pool, and (2) the Pliocene reservoirs (single zone or multi-zone) form numerous discontinuous oil pools distributed within the different fault blocks.

The northeast trending faults crosscutting the Miocene turbidite sands are non-sealing to the large Miocene oil pool present across the properties. Distributions of the discontinuous Pliocene oil pools in the properties are controlled by several permeability barriers such as rapid facies changes, sealing northeast trending faults, and local lateral sealing by tars. All the oils analyzed are of the same source and thermal maturity. GC fingerprints of the oils from the different reservoir compartments are distinct due to variation in the intensity of biodegradation. The study helped in planning the water flood project for the properties.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia