The Study On Fine Geological Characteristics And Reservoir Evaluation Of Huan305Wellblock In Huanxian Oil District, Longdong Area

Chang81reservoir of Huan305wellblock in Huanxian oil district, Longdongarea, Ordos basin is typical low-porosity and low-permeability reservoir. At present,with the breakthrough of oil exploration of Chang81reservoir and the continuousaccumulation of recognition and data of rolling construction, the probleums ofpetroleum geological knowledge and development of the study area becomeincreasingly prominent. And the overall development effect and construction of theoilfield is always haunted by these problems. Therefore, the fine geologicalcharacteristics and reservoir classification evaluation of the study area should beintimately research, and its exploration potential should be made clear. It providesreference for the development pattern and technical research of the study area.The research object of this paper is Chang81reservoir of Huan305wellblock inHuanxian oil district, Longdong area. Based on the geological data, core data, loggingdata and the production dynamic data of the study area, the research of stratigraphicfine classification and correlation, sand top micro-structural features and sandthickness distribution characteristics, sedimentary micro-facies and diagenesis,reservoir heterogeneity, four characters relationship and second well log interpretation,reservoir parameters distribution characteristics and reservoir classification evaluationof its target layer is carrien out.The research shows that Chang81reservoir of the study area can be divided into3small layers, Chang813, Chang812and Chang811. It is structurally simple as a whole,and presents northeast high and southwest low, and develops small nose-like uplift,which has certain succession. The sand body distributes in band from west-south toeast-north, and on landscape, its ductility and connectivity is good. In the west-southarea, near procenance, the sandstone is thick, and it gets thinning to the east-north.Among the3layers, the sandstone of Chang812is the thickest, and with high oiliness,it is the major reservoir of this area. The study area develops shallow water delta front,and the main sedimentary micro-facies are underwater distributary channel, underwater natural levee and underwater distributary bay. The channel presents fromwest-north to east-north, and disappears to the northeast area. Its main diagenesis iscompaction, pressolution, cementation, metasomatism and dissolution. Theheterogeneity of Chang813and Chang811is strong, and Chang812is medium. In thisarea, the lithology, physical property and oil content can be analyzed and revealed byelectrical characteristics. And there is a good correlation between reservoir physicalproperty and sandstone thickness, sedimentary micro-facies, reservoir heterogeneity.The reservoir of this area can be divided into4categories. Among them, Ⅰ,Ⅱreservoir, with better physical property, general deposits in underwater distributarychannel, and Ⅲ, Ⅳ reservoir, with relatively poor physical property, generaldeposits in underwater distributary channel and underwater natural levee. The goodreservoir of the study area is mainly develops in Chang812, and the most area ofChang813is general reservoir, and Chang811is poor-non reservoir. The conductionand completion of this study can greatly promote the exploration and development ofthe study area, and has great theoretical and practical significance.