Controlling factors and countermeasures for exploring large and medium-sized gas fields in Sichuan Basin

Abstract

The Sichuan Basin has been known to be rich of oil and gas resources, and after the exploration and development for more than 70 years, oil and gas reservoirs (mainly gas reservoirs) have been widely discovered in 28 strata, and the first complete gas industrial system has been built in this basin. The main constraint factors for the formation of large and medium-sized gas fields in the Sichuan Basin were discussed in this paper, and some favorable exploration targets were proposed. The enrichment of natural gas in the Sichuan Basin has several characteristics including the generation, accumulation, reservoir, preservation and migration of natural gas which were controlled by rift troughs, paleo-uplifts, erosion surfaces, cap rocks and faults, respectively. Near-source hydrocarbon supply, hydrocarbon accumulation in paleo-uplifts, effective reservoirs caused by the dissolution of carbonate rocks at the erosion surface of unconformity, regional stable preservation by cap rocks and migration through deep and large faults were the main controlling factors for natural gas enrichment. Therefore, the exploration activity for large and medium-sized gas fields was suggested to focus on 3 paleo-uplifts, 2 rifted troughs, and the basement faults in the Sichuan Basin. Through optimization, it was concluded that the Sinian to Lower Paleozoic strata, the high-energy phase band of Permian-Triassic and the Leikoupo Formation of Triassic in the marine carbonate area, the tight continental clastic rocks, the volcanic rocks in Permian and the shale gas areas are the favorable fields for further exploring for large and medium-sized gas fields.

Keywords

• enrichment of natural gas
• constraint factors
• large and medium-sized gas fields
• favorable zones
• sichuan basin