Water resistivity (Rw) values computed from the spontaneous potential (SP) log frequently yield low values for the Minnelusa formation of the Powder River Basin, Wyoming when compared with Rw values determined directly from water samples. These anomalies arise when conventional SP analysis techniques for obtaining Rw are fallowed. Therefore, a new technique for determining the SSP deflection and a new equation which salves for Rw have been developed.1 

To construct and validate the new technique and equation, a complete appraisal of the current methods of obtaining estimates for water resistivity has been provided. A substantial number of wells, which produced 100% water upon testing and span a large cross-sectional area of the basin, were analyzed. In addition, oil producing wells have been included to verify Rw estimates for intervals bearing hydrocarbons.

Using this new procedure has resulted in significant improvements in the accurate evaluation of the hydrocarbon potential of a prospective interval within this formation.

You can access this article if you purchase or spend a download.