The Study On Shale Gas Reservoir Of Jurassic In The Xidatan Area In The Northern Margin Of Qaidam Basin

With the continuous development of the national economy, the shortage of oil and gasresources supplement have become increasingly serious. As one of the most importantalternative resources for conventional oil and gas, it has the characteristics of widergas-bearing area, large amount of resources quantity, the production of long life, yield stability,It has become a new highlight in the global oil and gas exploration and development and hasbroad prospects for further exploration and development. The Jurassic strata in Northernmargin of Qaidam Basin widely distributed thick continental mud shale, the mud shale hasrich organic matter content, a certain degree of organic maturity, thick single layer which hasa certain depth and good shale gas reservoir forming condition. The study of reservoir may bethe first to achieve the Chinese continental shale gas exploration breakthrough and open upnew areas for gas exploration in China.Through the field observation of typical geological section, core description and a largenumber of drilling data developed he sedimentary system and its features in study area. Thispaper argues that the lower Jurassic Xiaomeigou formation oil shale deposition is deeplacustrine sediment and the middle Jurassic Shimengou formation oil shale deposition issemi-deep lacustrine sediment.According to the study of tectonic evolution history of Northern margin of Qaidam Basin,this paper concludes the distribution of Jurassic strata in Northern margin of Qaidam Basin.Based on this study and sequence stratigraphy, The Jurassic stratigraphic in Northern marginof Qaidam bottom-up total divided into11sequence interfaces,10third stage sequences.Jurassic mud shale mainly distributed in lower Jurassic Xiaomeigou formation and middleJurassic Shimengou formation, Which respectively correspond to the sequence S3and S8.On the basis of core observation, laboratory analysis, combined with shale gasaccumulation mechanism and its gas reservoir characteristics then study reservoircharacteristics of the two groups mud shale in Jurassic strata. The mineral composition oftwo groups’ mud shale are mainly quartz and clay minerals which favor shale gas adsorptiongathering and fracturing development; Thickness and burial depth of the oil shale are in linewith the conditions of shale gas reservoirs; The reservoir is compact, low porosity and permeability, the reservoir spaces are mainly of secondary pores and fracture developed.At last, I analyzed the material of the gas chromatography logging. The results showedthe ShimengouFormation and the XiaomeigouFormation are all containinggas.The gasreservoirs is similar to the characteristics of shale gas reservoirs. And the result was alsoproved the reservoir characteristics of two groups of shale gas in Xiaomeigou formation andShimengou formation which beneficial to the formation of the well shale gas reservoir instudy area.