Study On Reservior Characteristics Of Triassic Karamay Formation In Taibei Sag,turpan-hami Basin

The Triassic reservoirs in Taibei Sag of Tuha basin are the key target strata for exploration and development in Tuha oilfield,and important exploration breakthroughs have been made.However,the distribution of sedimentary facies and the distribution of high-quality reservoirs of the Triassic Karamay formation in Taibei sag are not clear at present.In order to better guide the exploration of oil and gas fields,it is necessary to study it.The sedimentary facies of Karamay formation is studied by using core data and logging data.The results show that the sedimentary facies of the Triassic Karamay formation are mainly Braided River Delta and shore shallow lake facies.The braided river delta front subfacies is of great thickness,and has a high sand ratio.It has a mat like distribution at the edge of the sag,and has a wide distribution and further progress.By means of thin section observation,mercury injection experiment analysis,cathodoluminescence and SEM observation,etc.The rock type of Karamay formation is mostly lithic arkose.The maturity of rock and mineral is low to medium,and the contact between particles is mainly point line contact.The reservoir space of Karamay formation is divided into pore and fracture.The pores are mainly residual intergranular pores and intergranular dissolved pores.Reservoir physical properties show the characteristics of good in the South and good in the north and good in the West and East.The reservoir of Karamay formation has experienced compaction,cementation,dissolution,metasomatism and other diagenesis.According to the characteristics of mineral particles,vitrinite reflectance,it is judged that it is in a stage of middle diagenesis.The diagenetic evolution sequence of Karamay formation is summed up by using the microscopic characteristics.Furthermore,the law of pore evolution is studied.Compaction and cementation play a destructive role in pores,while dissolution will improve the reservoir physical properties.The reservoir of Karamay formation is evaluated and predicted by using the four parameters of sandstone thickness,sand land ratio,porosity and permeability.The reservoir is divided into four types.The high-quality reservoirs of type I and II are mainly distributed in the braided river delta front of the convex front and the Northern Piedmont of the sag.According to the hydrocarbon accumulation conditions,the favorable exploration zones and drilling targets are optimized.