This presentation discusses two new methods for re-evaluating conventional logs from low resistivity formations in mature fields in order to detect intervals of by-passed pay, especially those in laminated formations.
The first method involves the modeling of resistivity anisotropy in neighboring wells, with different deviation angles, through the same formation. This allows vertical and horizontal resistivity logs to be computed and used in a laminated shaly sand interpretation.
The second method uses low resolution modeling of different component layers in a formation which is too complex for other interpretation techniques to work. Fluid saturations are derived using separate saturation height functions for each rock type and synthetic resistivity logs are calculated and compared with recorded logs to verify the modeling results.
These techniques can be used to distinguish laminated from non-laminated formations, they produce results which have significantly lower uncertainty than conventional interpretations and are also better suited to upscaling for reservoir modeling.
The new techniques have been successfully applied in various formations in the Asia-Pacific region and examples are presented which demonstrate the different modelling processes available.