The Analysis Of The Tight-gas-sandstone Reservoir Of He-8 Stratumin In North-central Ordos Basin

This thesis entitled by The analysis of the Tight-gas-sandstone reservoir of He-8 stratumin in north-central Ordos Basin as the research object,I investigated the research status of tight sandstone gas resource evaluation at home and abroad,and collected work area drilling,logging,well logging,seismic and geological basis of core analysis data,system analyses the types of tight sandstone gas reservoir and its geological characteristics,Summarized the main controlling factors of the gas reservoir in the study area and the accumulation period of time,and on this basis,set up the block of tight sandstone gas reservoir accumulation mode.Paper's main research results and understanding are as follows:1,Hydrocarbon source rocks in the study area are mainly of ShanXi formation and TianYuan formation of acidic coal rock and dark mudstone,organic matter abundance is high,is mature-too mature stage,with a strong ability to generate gas.2,Give priority to with quartz sandstone reservoir rock types,pure quartz sandstone and lithic quartz sandstone,a small amount of feldspar quartz sandstone and lithic feldspar sandstone,classification of pore structure belongs to the poor,and has the characteristics of low permeability reservoirs,the diagenesis of reservoir in this area is a major cause of densification.3,During the early Jurassic,middle Jurassic to early cretaceous is He-8 natural gas accumulation in the key period,the source of nearly vertical migration gas migration is given priority to,the capillary resistance of large lateral migration,its migration distance is small.4,As main control factors of hydrocarbon are source rocks' ability of generated gas,high quality reservoir and gas separated and keep dynamic balance,and so on.5,Accumulation model is reservoir density first stage,the formation of small-scale reservoirs,through the thermal events,a large number of natural gas generation,overpressure,the late hydrocarbon generation type gas proximal short distance migration,in He-8 sand body form large-scale continuous lithologic gas reservoir development area,finally because of tectonic uplift,reduced pressure,adjust the natural gas.