Accumulation process and potential of Jurassic tight sandstone oil and gas in Eastern Yangxia sag of Kuqa Depression

Abstract

The Jurassic tight sandstone oil and gas exploration and development in the eastern Yangxia Sag is a new field. To elucidate the origin, accumulation process and potential of tight oil and gas, the authors have conducted comprehensive analyses employing methodologies encompassing source rocks, oil geochemistry, and fluid inclusions. The results show that the abundance of organic matter of Jurassic source rocks is high, and the type of organic matter is of II-III and in mature evolution stage. The main source rocks of oil and gas are Huangshanjie Formation and Jurassic coal-bearing source rocks. Ahe Formation developed two stages of hydrocarbon charging, and the period is later than the reservoir densification time. Yangxia Formation oil charged before the reservoir densified, and the late gas charged after the reservoir densified. Hydrocarbon generation intensity of Jurassic source rocks has reached the basic conditions for the formation of tight gas reservoirs. Controlled by the difference of source rocks distribution and accumulation process, tight sandstone oil and gas accumulation conditions are better in the depression direction than in the southeast margin area. This study is of practical importance for expanding the exploration field and selecting favorable areas in the eastern Yangxia sag.