Studies On The Reservoir Characteristics Of The Second Member Of Upper Permian Wuerhe Formation Developed In The Manan Area Of The Jungar Basin,Northwest China

The congnormerate reservoir has recently achieved breakthrough in hydrocarbon exploration in the Permian reservoir in the Jungar basin,northwest China.However,the mechanism that control the formation of high-quality congnormerate reservoirs remains a key scientific problem that to be answered for high effective hydrocarbon exploration and development in the Manan area.Former research works indicate that the favorable reservoirs are mainly distributed in the distributary channel at the front of the fan delta systmes,but the plane distribution of the distributary channel and the main controlling factors that form those channels remain unclear.Based on the core,the,the logging data and the seismic profile,the researcher tries to reconstruct the sedimentary processes and summarize the factors that control the plane distribution of the distributary channels in the fan delta systems.The following conclusion can be drawn:1)Three fan delta systems are developed in the study area.The fan delta systems developed in the Karamay and the Baijiantanarea are relatively small in scale,but in high concerntration of the sandstone and the congnormerate.While the fan delta system developed in the Zhongguai area is relatively large in scale,but in low concentration of the sandstone and congnormerate.2)The processes that control the sedimentation of the congnormerate have an important control on the quality of the reservoir.As a result,the argillaceous concertration of the congnormerate controls the reservoir quality.Research results indicate that the argillaceous concentraion of the congnormerate found in the braided channel of the delta plain is bigger than 7%,which resulted in their porosity smaller than 6% and their permeability less than 0.3 m D.In contrast,those argillaceous concertation from the branches and main distributary channels of the fan delta front decreased from 3%?7% to <3%,their porosity increased from 6%-9% to 9%-15%,and their permeability increased from 0.3-10 m D to >10m D.branches of the distributary channel from the delta front fall between and their porosity and permeability lies in,and respectively.the shale content of the primary channel microchannel reservoir in the leading edge subaqueous distributary channel is less than 3%,the porosity is between,and the permeability is greater than 10 m D;3)According to the plane distribution of distibutary channel developed in different part of the fan delta systems and the main factors that control the forming of high quality reservoirs,the reservoirs can be divided into three different types.The best reservoirs(type I)are those from the main distributary channel in the fan delta front,better reservoirs(type?)are developed in the branches of the distributary channel,and those poor reservoirs(type?)are developed in the braided channel at the fan delta plain.