Structure Characteristics And Sand Body Distribution Regularities Of Es₃ Middle Submember Of Gaosheng-Leijia Area

Gaosheng-Leijia area is located in the north section of Liaohe west sag, Bohaiwan basin.The target stratum is Es₃ middle submember which coresponding the Dalinghe oil reservoir. Oil and gas has been indicated in Dalinghe oil reservoir, this study is aimed at implement the structure characteristics of the studied area and sand body distribution in order to provide the scientific basis of further search for potential reservoir.The sequence stratigraphic framework of studied area was Established with logging data and completing stratigraphic division of Es₃ middle submember. Dalinghe oil reservoir was divided into Da-I reservoir group and Da-II reservoir group. After horizon calibration, starting structure interpretation of seismic data of studied area. The use of analyzing the structural feature and fault breakpoint location with horizontal slicing and coherence analysis technique, correcting synthetic velocity field by acoustic logging data and finally, establishing high accuracy variable velocity field and drawing structure maps of the top and bottom boundary of main target layers. The analysis of the structure in the area show: the study area mainly presented the structural framework with “lower from north to south and lower from west to east”, divided into east area and west area. The central Gaosheng-uplift and Songjia-chenjia fault determine the structure forms of the study area. Sand body distribution study was processed by the means of wave impendance inversion and sand-ratio inversion combined with the logging data. Da-I reservoir group and Da-II reservoir group have the similar sand body distribution characteristics. The sand bodies mainly surrounding the Songjia-chenjia fault. Da-II reservoir group has bigger and wider sand body distribution than Da-I reservoir group. The best position for development of the sand bodies are Lei64 area,Gao105 area and Gao3618 area, followed by Lei11 area,Gao18 area and Gao3 area.Analysis show that the structural form of Dalinghe reservoir has important influence on the sand body distribution. The thickness and distribution of sand bodies are obviously influenced by the separation of Gaosheng uplift and Songjia-chenjia fault.The overflowing facies sand body distribution form was affected by the Lei11 area structural slope in the south of study area. Structure characteristics of the study area to a great extent control the sediment deposition. Faults and sand bodies form the fault-sandstone combination, which play the roles of migration channels and reservoirs of oil and gas. Trap types of study area are fault-block and sandstone updip-pinch which located in the areas with favorable structural forms and good sand bodies.