2022 Volume 2 Issue 2 Pages 41-54
As one of the distribution areas of the oldest organic shale in China, Yanshan area contained a Middle-Upper Proterozoic sedimentary succession, in which the exploration of shale oil and gas resources is of great significance. To investigate shale oil and gas accumulation conditions and resources potential of the Middle-Upper Proterozoic strata, here we carried out total organic carbon (TOC) analysis, equal vitrinite reflectance (Ro) measurement, Porosity and permeability, and isothermal adsorption experiments on shale samples collected from Xinglong-Kuancheng area. Organic shale-bearing strata in this area include Chuanlinggou, Hongshuizhuang, and Xiamaling Formations, of which Hongshuizhuang and Xiamaling Formations develop organic shales better. Due to favorable sedimentary environments, Honghongzhuang and Xiamaling Formations have large shale thickness values, with ranges of 20-140 m and 100-300 m, respectively. A large number of oil seepages in the field outcrop provide direct evidence for hydrocarbon generation in this set of strata. Organic shales with TOC greater than 2.0% are widely distributed and have high hydrocarbon generation ability. The thermal evolution degree of shale organic matter is from low maturity to over maturity and Ro generally ranges from 0.6% to 2.2%. Especially, the maturity of organic matter in Xiamaling Formation varies greatly with the distance from diabase dikes. Hongshuizhuang and Xiamaling Formation shales are characterized by ultra-low porosity and permeability, indicating a good development potential. From the perspective of shale oil and gas accumulation conditions, this study demonstrates the good resources potential of Hongshuizhuang and Xiamaling Formations. The North Hebei Depression is a favorable area for shale oil and gas exploration.