Criteria for Oil and Gas Bearing Potential of Jurassic Continental Sediments of the Central Part of Junggarian Sedimentary Basin

Successes in the development of oil and gas accumulations in China’s inland sedimentary basins - the Tarim, Junggarian and Sichuan basins - are attracting increasing attention to their thorough and consistent exploration. The most promising, along with traditional sites and accumulations in low-permeable shale strata, is the study of deep-seated complexes (with depths of more than 5 km), the oil and gas content of which is determined to a significant extent by specific geological conditions, which determined both the composition of organic matter and the primary conditions of formation of the reservoirs. One of the most diverse in terms of hydrocarbon accumulation conditions is the Junggarian basin in north-western China and specifically its pre-Lower Cretaceous formations with emphasis on the Lower Jurassic oil-and-gas bearing complex with oil-and-gas-maternal strata of high carbonaceous clayey sediments of the Badaowan Formation (Badaowan). A Detailed study of well sections located in the central part of the Junggarian basin (Che-Mogu anticlinal uplift, wells Y-1, S-1, Z-1) allowed to reconstruct the palaeogeographic setting, sedimentation conditions and reservoir distribution in the Lower Jurassic part of the section at great depths. Analyses of geological history of the basin, along with the rate of sedimentation, made it possible to identify promising zones of their preservation at great depths. Analysis of geochemical indicators (data from pyrolytic studies of organic matter and bitumoids) made it possible to clarify the prospects for oil and gas bearing capacity of the Central Depression and the Che-Mogu uplift of the Junggarian basin.