New Understandings of Natural Gas Accumulation and Distribution with Prediction of Favorable Exploration Plays in China

The in-depth research in this paper indicates that the accumulation and distribution of natural gas is characterized by cylicity, sequentiality, balance, traceability and multiphase, namely each tectonic sedimentary cycle signifies one gas accumulation system; in each system the generation, migration, accumulation of natural gas are characterized by a certain series; the significant factor for gas accumulation is the balance between migration force and resistance; the closer the distance from hydrocarbon source rocks, the higher the gas accumulation efficiency is, so the multiphase accumulation of gas is its feature in the long geological history. A large gas field is generally controlled by five features in its forming and distribution. The inner hydrocarbon source rocks and adjacent to the source rock area, unconformity zones and faulted anticlinal belts are favorable areas for large gas fields distribution. In addition to unconformity zones and faulted anticlinal belts that have been found more like these nowadays, the inner source area and proximal realm should be the domains for petroleum exploration in the future. The Carboniferous-Permian in southeastern Ordos basin, the Triassic in southwestern Sichuan basin and the Jurassic in Kuqa depression of Tarim basin which haven't got a major breakthrough could be the significant plays for next exploration of petroleum.