| Junggar basin, one of large oil and gas basins in China northwest. Major tectonic units in China-part of the Junggar block. The Tianshan orogenic belt, East and west Junggar and Altai mountains surrounded the Hercynian fold. An area of130,900square kilometers. Above Junggar Triassic basin is Mesozoic and Cenozoic unified continental sedimentary basins. Composite overlay with the underlying Paleozoic Partition of Sea-land transition of sedimentary basins. therefore, This is a large composite superimposed basin.The Jimsar oilfield Ji7Wellblock located in the eastern Junggar Basin Jimsar depression East Slope, Jimsar depression was Jimsar fracture、the LaoZhuang bend fracture、SanTai fracture、west to fracture and some small and medium-sized faults clamping, east by stratigraphic control, by the western area, the area and east deep slope belt to form. With the east slope of Permian, for a large tectonic stratigraphic traps.The area experienced the Hercynian, Indosinian, Yanshan, Himalaya and other periods of tectonic movement. The work area of fracture development, formed BaoZi fracture, auspicious003well rupture,007Wells at south east fracture, auspicious and well for the skeleton of the fault fracture broken order form tectonic belt, is typical of lithologic reservoir-structure. In Early Permian, Jimsar Sag have strong tectonic subsidence, and as a relatively independent sedimentary unit, in the Carboniferous substrate receiving thick general temple group deposition, the general thickness of50～750m. In the Late Permian, development of a delta-lacustrine deposits, formed the most important Pingdiquan formation source rock. Late Permian Jimsar sag as the northeast slope of Bogeda Piedmont depression, two Permian Wutonggou formation to three Permian sedimentary stability of garden of leek, thickness of250～470m, is the major oil producing zone of Jimsar sag. The late Indosinian tectonic movement in eastern Qitai that raised strong rise, resulting in east slope of Permian Triassic, varying degrees of erosion, the Jurassic and the lower strata unconformity contact. At the end of the Jurassic of yanshan movement Ⅱ to suffer from severe erosion of Jurassic, Jimsar depression to the south west direction atrophy, and only in the remaining eight bay, group, thickness100～300m. The Cretaceous, independent of depression pattern disappeared, Yanshan Ⅲ episode of tectonic motion effects, Southeast of Jimsar depression angle gradually decreasing, Cretaceous in Ji5, Ji15well first-line pinchout. Enter the Cenozoic, Himalaya sport and result in the whole of tilted strata from east to west, to the east gradually thinning.Now we research reservoir characteristic in order to further implement that top oil and gas reservoirs distribution and reservoir oil and gsa production capacity,to determine the oil and gas reservoir types and reserves dimensions of Permian wutonggou formation of the Ji7well area in Jimsar sag.Bottom-up in Ji7area drill strata is:Permian general temple group (P2j), Pingdiquan group (P2P), Wutong group (P3wt); Jurassic eight bay group (Jib), three in Sangonghe Formation (J1S), Xishanyao group (J2x group), Toutun River (J2t); ancient Near system (E), Neogene (N) and Quaternary (Q). Drilling and seismic prediction with the whole Permian Pingdiquan group of Permian, general temple group, Wutonggou formation thickness variation, which reflect the general temple group during the deposition source mainly comes from the ancient East West bulges and southern Fukang fracture zone, Pingdiquan group and Wutonggou formation sedimentary source mainly comes from the ancient West protruding southeast the Department of. Therefore, the east slope is Wutonggou formation sand body is relatively developed regions.The objective layer is wutonggou formation in Ji7well area,overlying the eight bay group and underlying Pingdiquan formation are unconformable contact,that is divided into P3wt1and P3wt2two sections.Where P3Wti is subdivided into P3Wt11and2two sand group, P3Wt2is subdivided into P3wt2and P3wt22two sand group. P3Wt11further subdivided into P3wt11-1and P3wti1-2two sand layer, P3wt12further subdivided into P3wt12-1, P3wt12-2and P3wt12-3three sand layer; P3Wt21further subdivided into P3wt21-12and P3wt21-3three sand layer, P3wt22further subdivided into P3wt22-2and P3wt22-3three sand layer.The main reservoir is the P3wt22and P3wt11Objective layer Wutonggou formation lithology and reservoir characteristics are as follows:Wutong group Wu paragraph two (P3wt2):in the thick, thick layer of gray mudstone, sandy mudstone with medium thick siltstone; bottom is a thick layer of fine sandstone, sandstone, rudaceous sandstone and conglomerate, is the main oil-bearing series. With the underlying strata conformity contact.Wutong group Wu paragraph one (P3wt1):gray mudstone, sandy mudstone with medium thick glutenite, rudaceous sandstone, divided into three sand groups:P3wt11, P3wt12, P3wt13. The P3wt12oil-bearing sand group Ji19well area of main oil-bearing series, with the underlying strata unconformity contact.Wu paragraph two of sand body continuity is well, distribution basically stable, Ji7well area of main oil layers, the study of oil-bearing series for Permian Wutonggou formation in paragraph two (P3wt2). From the current Ji7well area have been drilling reflect P3wt2sand body sedimentary characteristics, thickness of sand from south to north, from east to west, thinning.Wutong group structure from the vertical perspective, is a under thick and up thin cycle, and North Station, south sand deposition pattern is similar to. From the plane of the change of view, Wutonggou formation in the depression by the sediment source areas of the braided river delta facies into northwestern front Delta mud.Ji7well area in paragraph two (P3wt2) reservoir lithology is mainly in coarse grained lithic sandstone. Particles of rock detritus, containing a small amount of mineral composition. Clastic to felsite (21.4%), tuff (18.6%), followed by the Flint (13.3%), andesite, rhyolite (9.88%)(7.17%); mineral composition mainly quartz and feldspar (9.64%)(4.82%). Clastic particles sorting good; for the first round corners; the pore cementation is the main type of cementation.Reservoir cements for small amounts of calcite and siderite.Mixed base content of1.3%,is mainly smectite mixed layer,followed by kaolinited and chlorite,see a small amount of illite.According to a144porosity and permeability analysis data,reservoir porosity and permeability on average18.97%, average16.99mD.According to69porosity and permeability analysis data that comes from Ji7and Ji8well,reservoir porosity an average of19.97%,with an average of46.78mD for permeability,is a low porosity,low permeability sandstone reservoir.Cast thin section analysis of reservoir pore are the main types of remaining intergranular (87%), followed by intragranular dissolved pores (13%), trace intercrystalline pore. The average pore diameter of13μm～332μm, an average of81.9μm; Faces rate is0.08%～10.92%, average of3.92%; pore coordination number0～3. Displacement pressure is0.006MPa～2.56MPa,0.21MPa on average; median saturation pressure is5.3MPa～20.48MPa,13.5MPa on average; the maximum pore throat radius of0.27μm～116.67μm, average of16.05μm; saturation median radius is0.034μm～0.132μ m, average of0.062μm; unsaturated percentage of pore volume is36.8%～76.65%, average of53.79%. |
PDF Full Text Request