Prediction of Total Organic Carbon Contents of Organic-Rich Shale (Variegated Shale Member and Sarir Formation) Using Passy Technique: Case Study of Cretaceous Age, Eastern Sirte Basin – Libya

Assessment of maturity and total organic carbon (TOC) of source rocks is mainly by core rock samples, though requires high techniques. On the other hand, well logs could provide valuable results during less time consumption. Therefore, this work is conducted to classify the maturity and estimate the total organic carbon (TOC) of the Variegated Shale member (Sarir Formation) and Sirte shale Formation (Cretaceous) by applying the Passy Technique. These formations have a thick sequence and recognized a high content of organic materials over the whole Sirte Basin (Libya). Also, the measured well logs data were taken from four wells, which are located in the Hamiemat trough (Eastern Sirte Basin), Libya. In addition, two values of a level of organic metamorphism (LOM) are used based on the documented Vitrinite Reflectance (Ro) of the study area, which is equal to 7 and 11 of the TOC evaluation. Thus, statistical average values of the estimated TOC demonstrate about 1% of the Sirte shale Formation, and they are passed 2% of the Variegated Shale member (Sarir Formation). Moreover, poor to very good potential for source rock classification within the Variegated Shale member and Sirte Shale Formations. Therefore, all the estimated TOC results by well logs fall within the documented and published studies of the source rock potential assessments of the eastern Sirte Basin, which gives validity to the applied TOC assessment technique. In summary, the gamma-ray (GR), interval travel time (ΔT), and resistivity (R) logs are the logs that have been recorded within the exploration wells of the oil fields in the hydrocarbon profile basins. Hence, the utilization of these logs to save time and cost by the Passy technique, which provides reliable results of the TOC and maturity of the source rocks in early exploration stratigraphic plan studies.