Resource potential, explorative prospect and favorable direction for natural gas in deep formation of China.

Natural gas contained in deep formation is a respect with strategic importance for hydrocarbon exploration in China, which presents a low exploration degree(18.46%). It indicates that there is confirmative necessity and research value for clarifying the resource potential and ascertaining the favorable explorative direction. From elaborating the present condition in exploration for natural gas resource, methodologies including hydrocarbon generation, analogy and statistics are applied based on the result of the 4^th round of resource assessment of PetroChina, which indicates there is a huge total amount of resource potential.lt occupies a predominant position as 55% (20.31 ×10¹²m³)of the totalamount of resource potential for natural gas.The anisotropic characteristic is presented in the respect of resource distribution.Sichuan, Tarim and Songliao Basins are recognized as the relatively more concentrated (76.70%) in resource potential.Similar feature in anisotropy also exists in the respect of lithology,carbonates occupies 57.27% of the proved reservoir of natural gas contained in deep formations, which mainly correlates to the marine strata of Paleozoic cratons in the center and west basins. In the respect of remaining resource, it is quite abundant (16.56×10¹²m³). 76.07% of the remaining resource is contained in three main basins such as Sichuan, Songliao and Tarim Basins.In these basins, the favorable directions to further exploration for natural gas in deep formations are acquired as the clastic and volcanic reservoir from Jurassic to Cretaceous formed in the fault depression of Songliao Basin.Favorable exploration direction includes the dolomite reservoir of the lithological facie as mound and shoal in the center of paleo-uplift in Sichuan Basin, bioclaslic limestone and dolomite reservoir in the facies of reef flat contained in Changxing and Feixianguan Formations in the north and northwest of Sichuan Basin,the dolomite reservoir from Devonian to Lower Permian in the west of Sichuan Basin, the Ordovician dolomite reservoir in the facies of mound and shoal in the center of Tarim Basin, and the Cretaceous clastic reservoir in Kuche Depression of Tarim Basin, etc., which consequently reveals the prominent prospect for natural gas contained in deep formations. [ABSTRACT FROM AUTHOR]