The Accumulation Mechanism And Accumulation Mode Of The Tight Sandstone Gas Reservoir In The Thrust Belt Of Kuqa Depression

The thrust belt of Kuqa Depression is the enrichment zone of the tight sandstone gas.So study the accumulation mechanism and accumulation model of the tight sandstone gas reservoir in the thrust belt of Kuqa depression and predict the favorable areas for accumulation are very meanful for the next step of exploration and development in the study area.Based on the analysis of diagenesis evolution,the recovery of porosity evolution history,the hydrocarbon filling history,the experiment inclusion analysis,we analyzed typical tight sandstone gas reservoir in middle and eastern area in the thrust belt of Kuqa depression.During the study,we found out that the typical tight sandstone gas reservoir can be divided into three types: tight conventional gas reservoir,tight deep basin gas reservoir and tight composite sandstone reservoir.The tight conventional gas reservoir's(eg.Dina 2 gas reservoir and Keshen 2 gas reservoir)reservoir-forming dynamic is buoyancy.And the accumulation mechanism is gas charge and formed the conventional gas reservoir at first,then the reservoir tightened because of the compaction and cementation.Tight deep basin gas reservoir's(eg.Dibei gas reservoir)reservoir-forming dynamic is expansion pressure.The accumulation mechanism is the gas charged into the tight sandstone reservoir next to the source rock.The last type is tight composite sandstone reservoir(eg.Dabei 1 gas reservoir).It is the complex of the first two types.The reservoir-forming dynamic is buoyancy at early stage and expansion pressure at last stage.There are gas charged before and after the reservoir tightened.Different type of tight sandstone gases has different accumulation mode.Using T-CDMS prediction method and T-PLDS prediction method can predict the favorable zone of tight gas reservoir development of study area.The favorable zone of tight deep basin gas reservoir are the Dibei slope belt,the western and southern part of Yangxia sag in Jurassic reservoirs.The favorable zone of tight composite sandstone reservoir are the Dibei slope belt and eastern part of Yangxia sag in Jurassic reservoirs.The favorable zone of tight conventional gas reservoir are western part of Yangxia sag in Jurassic reservoirs and the middle part of Kelasu structural belt Cretaceous reservoirs.