The Analysis Of The Distribution And Controlling Factors Of The Furukawa Oil Reservoir In Fuxian Formation-Yan9Oil-bearing Formation In Wuqi Area

Wuqi area is located in the mid-western of Shanbei slope, Ordos Basin. Fuxianformation-Yan9oil-bearing formation is one of main productive layers of Jurassicreservoir. The distribution of Jurassic reservoir is controlled by palaeogeomorphologybackground. Using the method of impression to recover palaeogeomorphology shapeof Wuqi area, Ordos Basin, and combining with the existing results of oil and gasexploration, a conclusion is achieved that palaeogeomorphology plays an importantcontrolling role in the reservoir. Then the distribution features and controlling factorsof the furukawa oil reservoirs is concerned, and the accumulation model issummarized. On this basis, forecast and evaluate of the favorable area is completed.Each period of the top surface of Fuxian formation-Yan9oil-bearing formationin Wuqi area is the Western-leaning monoclinic structure. On that background,nose-like structures and slightly uplifts are developed. The top surface structure hasobvious inheritance in each period. By applying the method of impression to recoverand characterize the paleogeomorphology, four paleogeomorphology units are divided,they are Corrosion valley, mound, slope zone and low monadnock. The ancient oilreservoirs is mainly aggregated in three specific location of slope, including high peakof low monadnock, the source of secondary furukawa and the position of secondarymound mouth cut by the three-level and four-level furukawa. When pressure directionproduced by slops on both sides in the river valley is superimposed with the pressurealong the SW-NE direction generated by regional monoclinal strata, resultant forcedifference generated will lead to the difference in the oil and gas migration and theobvious difference of the reservoir stratas on both sides in the river valley. Thenorth-east bank of the Mengshan furukawa reservoir is mainly the Yan9oil-bearing formation of upper Jurassic, the south-west bank is mainly the Fuxian formation oflower Jurassic and the Yan10oil-bearing formation. So the control factors ofreservoir is proposed of group Fuxian Formation-Yan9oil-bearing formation inwuqi area: geomorphologic background, structure leading, lithological control,hydraulic drive, top of the sand, low monadnock at the slope zone, source of subprimeriver, secondary mound mouth. The reservoir-forming pattern is consisted of lowmonadnock control, slope control, mixed control and sandstone lens control.