Lithofacies Modeling Of Sangonghe Formation Reservoir In The Moxizhuang Area Of Junggar Basin

At present,deep clastic reservoir has become the key field of exploration and development in the world,especially in China,which has great exploration and development potential.Because the reservoir is deeply buried,deep clastic reservoir has strong heterogeneity and less drilling data.The prediction of distribution law and high quality reservoir is always a difficult scientific problem.In view of the above scientific problems,the Jurassic System Sangonghe Formation in the Moxizhuang area of the Junggar Basin is selected as the research object to explore the distribution law of high-quality reservoirs.Based on the geological knowledge of the predecessors,combined with seismic,logging;and core data,a three-dimensional sequence stratigraphic framework of the entire region was built,and the types and characteristics of sedimentary microfacies were identified.The characteristics of different types of lithofacies were studies based on predecessors lithofacies classification scheme;the favorable lithofacies types are selected;and select the sensitive logging series of different lithofacies,meanwhile using machine learning algorithms identify lithofacies.Use the stratum slice and seismic attribute fusion technology based on the principles of seismic sedimentology to explain sedimentary facies and establish sedimentary facies models.Based on the lithofacies identified by logging data and constrained by sedimentary microfacies,the reservoir lithofacies model is established by stochastic modeling method.Through the above work,the following results and understandings are mainly obtained.The two third-order depositional sequences(SQ1 and SQ2)are developed from bottom to top of Sangonghe Formation in the study area,and six fourth-order depositional sequences are developed from bottom to top of the third-order depositional sequences,which are subdivided into MC1 to MC6 from bottom to top.The main sedimentary facies are braided river delta plains,braided river delta front subfacies and shore-shallow lake facies,and the main sedimentary microfacies are braided river channels,flood plains,underwater distributary channels,inter-channels,river mouth bar,and sheet sands,etc..Braided channel and underwater distributary channel sand bodies are thicker and widely distributed.Sandstone of the second member of the Sangonghe Formation is mainly divided into poor plastic grain sandstone,plastic rich grain sandstone and calcareous cemented sandstone.It is believed that plastic grain sandstone with more content and better physical properties,is the lithofacies of high-quality reservoir.Using the XGBoost integrated learning algorithm to establish a lithofacies recognition plan in the study area,and the recognition accuracy reaches 88.7%.Based on the sedimentary facies and lithofacies model,it is considered that the braided channel,braid bar,underwater distributary channel and underwater distributary channel developed in the second member 1 of Sangonghe Formation have rich plastic poor granular sandstone,wide distribution and good connectivity.Four favorable areas are identified,which are located in the northeast of the study area,near the Z3 and Z7 wells in the north,near the Z4 well in the west,and near the Z107 and Z108 wells in the southeast.The research results have important guiding significance for the prediction and characterization of deep clastic rock reservoirs and subsequent exploration and development practice.