| Xiuwu Basin has a good hydrocarbon-generating material basis,but it is relatively weak in the research of controlling factors of shale gas accumulation.This paper establishes a sequence stratigraphic framework from the perspective of sedimentary and tectonic evolution on the control of shale gas accumulation.Based on the data obtained from the field section,drilling,logging,analysis and seismic data in the study area,combined with the regional geological background,the control of shale gas accumulation in the Lower Cambrian sedimentary and tectonic evolution of the Xiuwu Basin was clarified.During SQ2 and SQ3,there was a strong reducibility;the bioproductivity was highest in the SQ3.The hydrothermal silicon is present in most layers SQ2 and SQ3.Hydrothermal activity enhances the reducibility of the water body and increases the productivity of the organism,thereby controlling the enrichment of organic matter and further affecting the enrichment of shale gas.SQ2 and SQ3 are the favorable Cambrian shale gas development zones in the study area.Tectonic evolution plays an important role in the control of shale gas content The history of tectonic evolution in the Xiuwu Basin is divided into six stages.Caledonian,Hercynian,and Indosinian settlements dominated;the Indosinian-Yanshan early research area was uplifted,developed a thrust fault,and natural gas began to migrate along faults;In the late Yanshanian-early Himalayan period,the stress of the shale changed from squeezing to extension,natural gas migrated and the late Himalayan stresses changed from extension to compression and migration.The best matching period for shale gas generation,reservoir capacity,direct capping and indirect capping are the key moment for shale gas enrichment.The key time of the shale of the Wangyinpu FormationKuanyintang Formation is Middle-Period—Jurassic,and the end time is long.The shale gas content is low,which is unfavorable to the enrichment of shale gases. |
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