Multi-Well Subsurface Study of the Stratigraphic Sequence of the Potter Formation in the Midway-Sunset Field, Kern County, California

A. S. Wylie Jr., L. S. Foulk, and T. H. Nilsen

To understand the stratigraphic nature of the Potter Formation reservoirs, a multi-well study along a west-east cross-section was done using dipmeter, Formation MicroScanner, and FMI^TM (Fullbore Formation Microlmager) data. Thermal EOR wells are drilled only into the heavy oil- bearing portion of the reservoir, thus each well does not penetrate the complete Potter sequence, but penetrates successively younger sandstone and conglomerate members from west to east. Wireline logs and continuous core data were used for correlation and calibration of the dip and image data.

The image data revealed detailed stratification, bedding, and sedimentary structures, identifying conglomeratic, bioturbated and stratified sequences. Correlation with continuous core clarified which features were more interpretive. The image data, available on three of the eleven wells, was then correlated to dipmeter data, both in the form of computed dip data and interpolated electrical images. Each of the eleven wells penetrated only one or two members of the Potter Formation. Using the dip data, it was possible to reconstruct a true stratigraphic thickness type log of the Potter Formation. The interpreted stratigraphic data, revealing bedded, bioturbated, and conglomeratic depositional systems was combined into a single type log of the Potter Formation. The resultant type log can be used for various sequence stratigraphic, engineering, and thermal EOR reservoir characterization applications in the Midway-Sunset Field.

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