Study On Reservoir Sand Body Architecture Of Upper Paleozoic He 8 Member In X Well Area,Ordos Basin

With the deepening of exploration and development in the X well area of Yanchang Gas Field in the south of Ordos Basin,He 8 member of Permian Shihezi Formation is the main exploration and development layer in the area.In order to further improve the efficiency of gas production,the research focus should be on the development of small beds to the single sand body inside the channel.To solve this problem,this paper takes the X well area of Yanchang Gas Field as the research object,uses the sedimentology and the principle of reservoir architecture to carry out the identification and architecture study of the single genetic channel sand body in the study area,establishes the three-dimensional reservoir geological model,and realizes the quantitative and visual research and prediction of the reservoir sand body of He 8 Member.The deposition of He 8 member in the study area is mainly affected by the provenances from the north and northeast directions.The delta front subfacies deposition has five microfacies:underwater distributary channel,underwater interdistributary bay,underwater natural dike,sheet sand and estuary bar.Because the estuary bar is often eroded by underwater distributary channel or the channel itself migrates and wobbles unfixed,the estuary bar is scoured or undeveloped.With the dense well pattern X-01 well and X-02 well,the underwater distributary channel sand body as the main body of the configuration,the vertical staging,horizontal demarcation mark and the contact relationship of the single underwater distributary channel are systematically analyzed,and the plane distribution characteristics of the single underwater distributary channel are further described in detail,and the quantitative prediction model of the size of the sand body of the single underwater distributary channel is established.According to the internal configuration anatomy of underwater distributary channel sand body in the study area,the internal configuration elements of underwater distributary channel mainly include foredeposit and foredeposit,and foredeposit and foredeposit are mainly foredeposit type and accretion type.The foredeposit dip angle is generally 0～8 °,the foredeposit thickness is0.4-0.8m,and the foredeposit width is generally equal to or less than the channel width,and the thickness is between 1-4m.The quantitative prediction model of single channel sand body size and the internal configuration anatomy of the channel provide important theoretical basis for the prediction of single channel sand body in the area with sparse well pattern in the later period,and provide guidance for the formulation of subsequent waterflood development scheme.On the basis of reservoir configuration,this paper uses sequential Gaussian simulation method of random modeling to complete three-dimensional reservoir geological modeling of the He 8 member in well area X-01 and X-02,and establishes the layer model,structural model,lithofacies model and reservoir parameter model of the two well areas.In this way,the distribution characteristics of sand bodies and reservoir physical properties can be displayed more intuitively and clearly in the three-dimensional space.The three-dimensional geological model is well comparable with the geological knowledge and actual geological conditions,which has certain guiding significance for the subsequent gas reservoir development in the study area.