--> ABSTRACT: "2-Step" Log Analysis of the Spellacy Reservoir in the Giant Midway-Sunset Field, Kern County, California, by David H. Sturm; #91019 (1996)

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"2-Step" Log Analysis of the Spellacy Reservoir in the Giant Midway-Sunset Field, Kern County, California

David H. Sturm

A technique is presented for simple, effective log analysis of (Miocene) "Spellacy" sands and conglomerates of the Santa Margarita Formation at Midway-Sunset Field in Kern County, California. Results are shown graphically on the log display and are quantified for mapping. Requirements are digital wireline data -- in this simple case, just resistivity and porosities -- and flexible log analysis software such as QLA2TM.

The first step of this technique discriminates between reservoir-quality and non-reservoir-quality intervals yielding three color-coded categories. A narrow color-filled column is added to the well log display to graphically communicate the vertical distribution of reservoir-quality and barrier intervals.

The second step performs a fluid analysis on the reservoir-quality category (intervals) yielding three more color-coded categories. The results of the fluid analysis are graphically displayed in a second narrow color-filled column on the well log.

Analysis results are captured from a tabular report for mapping. Quantifiable products include 1) thicknesses: original net pay, current net pay, reservoir quality, total sand, total porosity, phi-H, etc.; 2) averages: original net pay porosity; current net pay porosity, current net pay saturation, current net pay bulk volume oil, etc.; and 3) ratios: thickness of reservoir quality to total sand and thickness of current net pay to total interval.

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