Abstract

Careful selection of development locations is essential for various economic reasons. Many of the sandstone reservoirs in South Texas make forecasting production hazardous because effective pay thickness, porosity “cutoffs” and lateral stratigraphic changes complicate the picture. Conventional structure and net sand isopach maps do not always yield the expected results. Permeability feet (Kh) maps are constructed using data derived from electric logs and local geologic knowledge. These appear to show promise in helping in the selection of many new wells.

The purpose of this paper is to show how existing eletric log recordings can be combined with historic reservoir data (pressure build-up tests and production data) in a manner that is mappable and is easily converted to indicate the productivity of new wells. The field example selected to illustrate the method is in the Owen (Olmos) Field in Webb County, Texas.