Evaluation of Well Logs for Recognition of Depositional Sequences: A Case Study from the Permian-Triassic Successions of the Persian Gulf and Coastal Fars Regions

Using of well logs in un-cored wells in order to identify rock strata related features usually has been discussed between the geologists. In this study, firstly, based on drilling cores, depositional sequences and surfaces of the Permo-Triassic successions in the Persian Gulf and Coastal Fars areas are identified. Then, using processed gamma and density well logs (wavelet analysis), in Cyclolog software, sequence stratigraphic surfaces including sequence boundary and maximum flooding surfaces are recognized and compared with the petrographical results. The recognized surfaces based on gamma ray logs are more compatible with the identified surfaces based on depositional facies, than results of density well logs. According to decreasing and increasing trends and turning points on the processed gamma ray and density well logs of the studied wells and fields, several (isochronous) correlatable surfaces are recognized. Rather than gamma ray and density well logs, Sonic, Neutron, Potassium, Thorium, spectral gamma ray and resistivity, are analyzed using wavelet method which gamma, Potassium, Thorium and Neutron well logs show same results.