Fault Deformation Features and Reservoir controlling Mechanisms of Xujiaweizi Fault Depression in Songliao Basin
Received date: 2012-05-12
Revised date: 2012-08-17
Online published: 2012-12-10
Xujiaweizi fault depression is a dustpan\|shape graben which ruptures at the west and overlaps at the east.Two kinds of fault have a significant controlling effect on the gas accumulation,namely extensional fault and strike-slip fault.The extensional fault system controls the basin boundary and the distribution of effective hydrocarbon kitchen.The distribution of the Shahezi coal is controlled by the NS transtensional fault named Xuxi fault and the NNE faults,which is an effective hydrocarbon kitchen.The strike\|slip faults are the channels of volcanic eruption.Xuzhong fault and Xudong fault control the volcanoes′ distribution in the first and third members of Yingcheng Formation,while the NNE faults intersected with them have the effect of inducing volcanic eruption.And the scale of the volcanic is the largest at the intersection.Xuzhong fault has a strong movement from the late Quantou to early Qingshankou,whose dextral strike slip deformation makes the volcanic rock to form a great number of fractures,especially at the fault intersection,forming high quality reservoir.Xudong fault has no obvious activity at this moment,where high quality reservoir is not controlled by fractures.The intense activities combined with abundant gas generation and expulsion from the Shahezi source rocks make the faults as gas |source faults.Xuzhong fault is the most significant gas source fault.Gas accumulates at the footwall of gas source faults because of the lithology juxtaposition.The trend of Xuzhong fault changes,so the gas distributes like a “sine curve” around the Xuzhong fault.Inverted faults and cap rocks control the layer of gas enrichment.The top lithology of volcanic rock named “mix litholoty” has a good sealing quality,which seals the gas at the volcanic rock reservoir at the area lack of inverted faults.In the inverted faults area,the gas in volcanic rock is easily adjusted to Fuyang oil layer sealed by regional cap rocks,Qingshankou Formation.And the adjustment happened at the late deposition stage of Mingshui Formation.Strike slip fault is the controlling factor of gas accumulation.There is no strong inversion at the end of Mingshui deposition,which is crucial for preservation.
LI Yu-ying, FU Xiao-fei, ZHANG Ming-xue . Fault Deformation Features and Reservoir controlling Mechanisms of Xujiaweizi Fault Depression in Songliao Basin[J]. Natural Gas Geoscience, 2012 , 23(6) : 979 -988 . DOI: 10.11764/j.issn.1672-1926.2012.06.979
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