COMPUTER-AIDED WELL LOG CORRELATION

We have devised a computer-aided well log correlation scheme using sequence comparisons originally developed for molecular biology and dynamic programming technique employed in operations research. The combination of these two methods is known as dynamic waveform matching (DWM). Problems encountered in machine correlation of well logs (e.g., bed thickness changes, stratigraphic gaps, pinch-outs, etc.) may be resolved by DWM. We have coded a program, XCORR, to implement our scheme. Manual or machine zonation of the logs is performed first. Then, log attributes (depth, amplitude, shape, etc.) of two logs are compared and matched in a pass. Each matching cycle comprises three passes, thus ensuring optimal global, not local, correlation. We found good correspondence between geologic structures and path diagrams, which are the resulting matrix from the dynamic programming algorithm. Example logs, both synthetic and real, demonstrate the applicability and efficacy of our approach.