18 Well Area Of Fengcheng Oilfield Of Qigu Formation Of Jurassic Of Sedimentary Facies Research

Windy City field is located in the northern end of the northwestern margin of the Junggar Basin, about 130km northeast from Karamay, administrative subordination Karamay City. In the north of Sahara Alat is bounded by mountains, east Xiazijie border, west of the town of Urho. Regional structure located on the northwest edge of the Junggar Basin, Ukraine-summer red summer north rupture disc on fault-fold belt, Mesozoic overlap pinch out to bring the North to break Wulanlinge is bounded to the south with the northern slope Mahu things oilfield about 24km, north-south width of 13km, the average ground elevation of about 300m, is a typical inland basin of arid desert oilfield. Here, the study area is mainly about heavy Fengcheng oilfield Well Area 18 2013 annual capacity of built-up areas of research Jurassic horizons statistically Qigu.Wuxia fault-fold belt is slipping pleated-the leading edge of faults associated with anticlinal structure mode, the leading edge of the Permian affected within two concealed faults, uneven intervals along the base, increasing the depth of the south east direction. Growth reverse fault, fault-related folds, faults recoil as the main deformation characteristics, the main fault was "flying geese" type of arrangement, having cut twist properties. Jurassic stratigraphic distribution of the overall thickness was thinner in the north south to the basin thickening wedge distribution, bottom-up development Badaowan (J1b), Sangonghe (J1s) and Qigu (J3q) (Xishanyao missing). The main types of sedimentary facies of braided river delta sedimentary characteristics.Because Qigu and overburden and underlying strata showed unconformity overlying strata Cretaceous spit glutenite and underlying strata of Jurassic Sangonghe top lime mudstone Valley Luqun bottom or Badaowan top seam as division marker bed, top and bottom boundaries can be determined accordingly Qigu group. Qigu development of two transgressive shale formation and development of the region, which can be divided into the Qigu J3ql, J3q2, J3q3 three sections based on lithology, electrical and cycle characteristics, which in the study area are J3q1 eroded away, J3q21 mainly local Northwest, J3q2 can be divided into J3q21, J3q22-1, J3q22-2, J3q22-3 four small layer; J3q3 can be further divided J3q31, J3q32, J3q33 three small layers.In high resolution sequence underlying science as the theoretical basis, the study area can be divided into two medium-term cycles have seven short-term cycles. According core description coring wells, drilling and logging data, the first phase of the study area is divided into rock conglomerate, coarse sandstone, sandstone, fine sandstone, fine sandstone, argillaceous sandstone and mudstone with seven types, and according to rock phase histogram single well, well profile and associated rocks of the small plane distribution of rock layers to understand the purpose of developing all directions relative to the rock layers of cloth and regional characteristics of rock’s faces.The old studies think Qigu sedimentary facies of braided river, river development has stranded, beach heart, floodplain, river flood lakes, natural levee, crevasse splay microfacies, there are a few people think that meandering river deposition. We find that, based on previous research on many braided river can not explain the phenomenon:(1) J3q2 development of a large set of thick-bedded fine sandstone (also a study area oil lithology), (2) advanced by coring observation shows that the number of gray shale thickness of 10 m (3) sandstones into visible waves rippled bedding, (4) development of bulk Star pyrite grains (5) Qigu general display clear lake transgressive deposition processThereby Through comprehensive analysis of cores, sedimentary sequence, laboratory analysis and logging think Qigu a set of braided river delta sedimentary body, braided river delta plain, and braided river delta front facies, partial see former Delta. Wherein the braided river delta plain succession braided river characteristics, retention and development of river, beach heart, floodplain microfacies, braided river delta front underwater distributary development main channel, underwater distributary channel times, between the Bay tributaries, mouth bar microfacies, in addition to the northwest of the study area to see local distal bar and front delta mud interbedded. Plain where Heart was the dominant part of the beach, developmental parallel bedding, cross bedding and other product side, showing little muddy sand binary structure; underwater distributary channel deposits to the leading edge of the main body, the type of structure is rich, there are staggered bedding, parallel bedding and ripples into waves bedding, etc., common bottom surface erosion.Provenance direction aspect ancient geography, color mudstone, conglomerate thickness, gravel than distribution, heavy minerals, mineral maturity comprehensive analyzes judgment, that the main sources of north-west and north provenance direction in the study area.Qigu formation of the overall display as the rising lake level process, which has emerged inside the lake level more than once a lifting of change. J3q3 lake level to rise early and late emergence of the rise and fall constantly alternating, forming a reddish brown, brown, gray mudstone gradual transition, J3q22-3 lake level continues to rise, forming a body underwater deposits, appears at the top of the stable mudstone, once a large lake flooding surface, J3q22-1+J3q22-2 lake level continues to rise, a row of fine sandstone thickness up to 30 meters, in J3q2 late heavy appears near 017 wells in the study area near the northwest edge of the wind 40 m mudstone and argillaceous siltstone. In this, Qigu is divided into two medium-term cycles and seven short-term cycle, sedimentary evolution of the transition to a braided river delta plain to the delta front and delta.By analyzing the deposition of drilled oil test data and the corresponding layers of micro phase contrast study area braided river delta plain beach sand heart and front subaqueous distributary channel sand body is a good place for the oil and gas reservoirs. Stranded between the river and the river Glutenite thin sand poor, or even become non-reservoir and the tributaries from the inter-bay mud play the interbeds role.