New thoughts of continental gas exploration in Western Sichuan Depression

Located on the edge of Longmengshan thrust-napped belt,the western Sichuan Depression from the Upper Triassic to Jurassic is a set of continental tight-super tight gas-bearing clasolite.Long-term exploration has proven structures and various types of composite traps.Applying the theory of continuous gas reservoir to analyze the target zone,it has been found out that Jurassic in the western Sichuan is a "distal" gas pool and does not have continuous gas reservoir forming conditions.The Xujiahe Formation possesses accumulation conditions and characteristics of continuous gas reservoir.This is particularly true for T3x5 and part of T3x4 which are characterized by shallow burial depth,well-developed pelite,high organic richness,high maturity,large amount of gas generation and general contact with sandstone.Therefore,with the advantages of exploration for both shale gas and tight gas,they possess large exploration potential and are the most practical development areas under current economical and technical conditions.In view of the high exploration degree of the Xujiahe Formation,the enrichment regulation study for continuous gas reservoir is carried out by the combined prediction of geology-logging-seismic technologies,especially with the high-precision 3D seismic data.The application of new techniques such as pre-stack reservoir,fracture gas-bearing property and advanced engineering technologies of drilling,reservoir stimulation and protection is expected to achieve significant breakthroughs.