The gas accumulation process in Western Sichuan Foreland Basin

The Western Sichuan Foreland Basin developed Upper Triassic coal measure source rock, which mainly generated gases. There exist several reservoir-cap combinations for natural gas preservation. So the Western Sichuan has abundant natural gas resource. The gases belong to coal-typed and the occurrence controlled by paleo-uplift, the buried gas source faults that connect the source rock and reservoir and the beneficial reservoirs. The Southern Sichuan Foreland Basin had endured several times of gas accumulation. The gases mainly accumulated during Laramide and Himalaya orogenies, gas pool adjusting during Himalaya. Gases from Triassic coaly source rock accumulated during Laramide and original gas pool formed. During Himalaya, thrusting movement promoted the shallow reservoir storage ability. The faults produced acted as pathway in connecting shallow traps and some deep gas pools. In this way, the deep original gas pool, mainly Upper Triassic gas reservoirs, had been adjusted and shallow gas pools had been formed in the Jurassic at the same time.