Research On The Main Controlling Factors Of High Production Of Xujiahe Formation Gas Reservoir In Zitong Area

Zitong area of Northwest Sichuan sag of Xujiahe reservoir has the structure widely exists in abnormal high pressure drilling,Tight sandstone reservoir and strong heterogeneity,oil and gas distribution showed a wide range of longitudinal reservoir,gas and water distribution is complex,the test yield difference is big,fast decreasing pressure and production gas well production characteristics,but also have high and stable yield of wells.Based on the evaluation of the drilling effect of Xujiahe gas reservoir in Zitong depression,based on the analysis of sedimentary facies and reservoir characteristics,we compared the high-yield well and the middle low production well,and The main controlling factors of high yield of gas well are clarified.results reflec:?1?there are two main types of reservoirs,namely,gray cloud,sandstone,conglomerate and metamorphic rock and lithic sandstone.They are generally low porosity,ultra-low porosity and low permeability low permeability reservoirs.T The reservoir type is mainly fractured pore type,followed by pore type and pore fracture type.The development degree of metamorphic lithic sandstone reservoir is controlled mainly by sedimentary microfacies and feldspar content,and the favorable reservoir area is widely distributed,and the gray cloud chip?Gravel rock?is controlled by sedimentary microfacies,calcite cementation and tectonic stress intensity.The favorable reservoir area is mainly distributed in the Weicheng Weicheng structure.?2?The main controlling factors for high yield of the T₃x?4 section of the Zitong area:?Stable development of gravel;?Fracture development;?High porosity reservoir.The main controlling factors for high yield of the T₂x section of the Zitong area:?Sandstone reservoir thickness;?Adequate gas source;?Tydrocarbon reservoir allocation;? High porosity sandstone reservoir;? Fracture development.In addition to geological factors,in view of such abnormal high pressure tight reservoirs,we should select suitable mud system to avoid pollution to reservoirs,and use reasonable perforation measures to achieve the best effect and exploit the productivity of gas wells.