Evaluation Of Shawan Reservoir On The Foreland Slope Zone Of South Margin Of Junggar Basin

Junggar basin is located in the north of the north of Xingjiang Uygur Autonomous Region, closed to the northeast of Qinggil mountain and Kelameil mountain,closed to the south of Tianshan mountain,closed to the northwest of Zaire mountain and Halaalate mountain. The distance from east to west is about 700km,and the distance from north to south is about 320 km. The total area is about 13×104 km2.Foreland slope area in the Southern Junggar Basin is the area, which located from north of the lowest regional structural boundary of the northern thrust structural belt foredeep to the south of the front uplift area, including northern Sikeshu depression, Chepaizi region, Mosuowan region, and Fukang depression. The northern limit of it is the pinchout boundary of northern Shawan formation. It has been mainly formed in himalayan movement. The lengh of the foreland slope zone of Southern Junggar Basin is about 500km from east to west, and 150km from north to south. The structural characteristic of the foreland slope zone of Southern Junggar Basin is high in the south and low in the north. The research of the west of foreland slope area in the Southern Junggar Basin mainly includes northern Sikeshu depression, the east of Chepaizi arch, Hongche fault belt, and the west of Shawan depression. The study area has large resource potentiality.Firstly,this study systematic and comprehensively collected 2D seismic data,log infornation,log data,testing data and core analysis and testing data from the main study area. Secondly,based on core observation,data analysis,cast thin slice,scanning electronic microscope,X-ray diffraction,mercury data,to in-depth study of petrology features,physical properties characteristics,pore structure characteristics,diagenetic characteristics and control factors of reservoir development of Shawan group of the southern margin of Junggar basin. Finally,application of porosity and permeability histogram to understand distribution characteristics,established Porosity interpretation model,draw the porosity and permeability contour map in the study area,explore the control factors of reservoir physical properties,classification evaluation of reservoir development zone in the study area,and summarizes the reservoir development regularities.Through this study,the understanding of study area mainly included in these following points.(1)The reservoir is mainly composed of feldspathic clastic sandstone. The cuttings content is relatively high,but rock composition maturity is more lower than average that between 0.5% and 1.5%. The adglutinate mainly composed to calcite and pyrite,in the northeast Shawan,and have a bit of gypse. The gypse is distributed in a dot,and select separation is bad-middle level.(2)The pore types of Shawan group are mainly included in primary intergranular pore and intergranular pore,and have a bit of dissolution pore. The whole throat have little pore and little throat.It also have fewer neck down pore and slice throat. The pore-structure mainly included in type II medium pore and medium throat and type Ⅲmedium pore and medium throat,except for type I macroporous and coarse throat.(3)The experience of diagenesis in Shanwan group are mainly included in compaction,dissolution,cementation and metasomatism. According to the characteristics of authigenic mineral assemblages and the index for the thermal maturity of organic matter,combined with slice observation from the study area,to divided into the early diagenesis B stage-middle diagenesisAl. The stronger compaction can reduce the reservoir characteristic. The cement that included in kaolinite,siliceous cement,and carbonate minerals have a great influence on reservoir characteristic. The cuttings and feldspar create dissolution,but they have little impact on characteristic. Therefore,the dissolution have little impact on improve the porosity and permeability.(4)The sedimentation via the function of clastic rock structure, composition, particle size to control reservoir physical property. On the whole, the physical properties of underwater distributary channelsand body is the best.The compositional maturity of interdistributary bay sand body is lower, and the properties is poor. In the meanwhile, even if the source direction and the sedimentary environment are identical, but the physical properties are different.(5)The advantage phase belt of reservoir development is located in delta front. The mainly advantage reservoir phase belt type are underwater distributary channel,mouth bar,shore and shallow lake sand flat,far bar.