Resource potential, exploration prospects, and favorable direction for natural gas in deep formations in China

Abstract

Natural gas contained in deep formation is a respect with strategic importance for hydrocarbon exploration in china, which presents a low ratio for being discovered only as 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 in the result of the 4th resource assessment of PetroChina, which indicates there is a huge total amount of source potential. It occupies a predominant position as 20.31 × 1012 m3 as 55% of the entire amount of resource potential for natural gas. The anisotropic characteristic is presented in the respect of resource distribution. Sichuan, Tarim and Songliao Basin 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 proves 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 as 16.56 × 1012 m3. 76.07% of the remaining resource is contained in three mains basins as Sichuan, Songliao and Tarim basin. In these basins, the favorable directions to further exploration for natural gas in deep formations are acquired as the clastic and volcanic reservoir from Jurrasic to Cretaceous system formed in the fault depression group of Songliao basin, the dolomite reservoir of the lithological facie as mound and shoal in the center of paleo-uplift in Sichuan Basin, bioclastic limestone and dolomite reservoir in the facies of reef flat contained in Changxing and Feixianguan formation 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 Cretaceous clastic reservoir in Kuche depression of Tarim basin, etc., which consequently reveals the prominent prospect for natural gas contained in deep formations. Keywords: Deep gas, Resource amount, Exploration potential, Resource distribution, Key concerns