Research On Faults Characteristics And Its Control On Gas Accumulation Of Xujiaweizi Fault Depression

The Xujiaweizi rifting is the important gas-bearing rifting in the northern deep layers of Songliao Basin,with the progressive discovery of deep volcanic gas reservoir,has become the the major block of gas exploration in Daqing Oilfield.Because of complex structure in rifting,the control modes of the structure and fracture on gas was not clear enough,limit the development of the deep gas.In this paper,based on the seismic interpretation data of continuous working area in Xujiaweizi rifting,while taking well logging?gas testing and other information,to research the characteristic of fracture structure and its role of natural gas accumulation in Xujiaweizi rifting.In this paper,from two angles of the systematic analysis of tectonic feature and tectonic evolution in Xujiaweizi rifting,the Xuxi fault is main boundary fault that it controls the formation of the rifting,the Xuzhong fault and the Xudong fault respectively control the centers of volcanic rock eructation in Yingl Member and Ying3 Member,the thickness of volcanic crater is larger,after tectonic movement fractures are created to improve physical property,can be used as a reservoir.Whlie in the rifting,the roles of faults forming and activing during different periods for gas reservoir are different.The faults that are active during the stage of Qingshankuo deposition can be used as gas source faults,though the Xuzhong fault has no vertical sealing ability after accumulation,cap rock sealing is not damaged,laterally,mudstone and conglomerate in thrown wall resist the parallel migration of gas,so the Xuzhong falutfor natural gas not only has a conducting role,also has a shielding effect.after main accumulation stages,faulting activity during reversion stage has a fixing effect on gas,adjusting part of the volcanic rock gas reservoir to the upper strata,then accumulation will be in Quantou Group and Denglouku Group by secondary migration.