Abstract:
In order to clarify the exploration potential of deep natural gas in Qaidam Basin, based on seismic, geological and drilling data, the enrichment conditions of deep natural gas reservoir in Qaidam Basin are comprehensively analyzed from the aspects of source rock, reservoir, structure and reservoir formation, and the favorable exploration direction of deep natural gas is defined. The results show that two sets of high-quality gas sources of Jurassic and Paleogene are developed in the deep layer of Qaidam Basin, with high degree of evolution and strong gas generation capacity; Three types of reservoirs including bedrock, clastic rock and lacustrine carbonate are developed in the deep layer, and many types of pores such as primary pores, dissolution pores and fractures are developed, which provides a broad storage space for the enrichment of deep gas reservoirs; The multi-stage tectonic activities developed the faults in the basin, formed a variety of dredging systems dominated by faults, and provided a high-quality channel for gas migration. Qaidam source rock has the characteristics of early and multi-stage filling, and the structural formation period matches the natural gas generation period. In particular, the crude oil generated in the early stage is conducive to deep buried cracking and gas generation in the later stage, with strong gas generation capacity and great resource potential. The widely developed salt rock, argillaceous rock and abnormally high pressure layer in the deep layer of the basin are conducive to the preservation of deep natural gas. The traps around the hydrocarbon generating sag developed by deep and large faults are favorable areas for deep natural gas accumulation. The deep layers of Piedmont paleouplift, abdominal structural belt in the north margin of Qaidam and Yxiongling structural belt in West Ring of Qaidam are favorable exploration directions for deep natural gas.