Analysis Of Sedimentary And Tectonic Characteristics And Optimum Selection Of Favorable Targets In Southern Zhangqiang Depression

Zhangqiang sag is a Mesozoic sag in the peripheral basin of Liaohe River.It is distributed in a nearly north-south direction and can be divided into six secondary structural belts from north to south.In recent years,the exploration and development of Zhangqiang sag are mainly concentrated in the northern area.Great achievements have been made in the exploration of the anticlinal structural belt of Changbei fault in the northern area.The main oil layers discovered are the Lower Cretaceous.There are four sets of oil formations in the upper and lower sections of the county formation,Jiufotang formation and Heshahai formation.The exploration degree of the whole southern area of Zhangqiang Depression is still low.According to the comprehensive geological data obtained by predecessors,the southern area has better source-reservoir-cap assemblages,geological conditions for forming various reservoirs and great exploration potential.Based on drilling,seismic and logging data,this study comprehensively evaluates the Shahai Formation in southern Zhangqiang Depression by means of sequence stratigraphy,sedimentary facies,seismic data interpretation and seismic reservoir prediction.Firstly,the sequence stratigraphic framework of the Shahai Formation is established by dividing the third-order sequence and internal system tract through the method of sequence stratigraphy.On this basis,the sedimentary facies analysis is carried out in the study area,from single-well facies to connected-well facies and plane facies analysis step by step,and the sedimentary evolution law of the area is analyzed and the sedimentary model is clarified.Sequence stratigraphic framework and sedimentary model interpret the target horizon of Shahai Formation in the study area,establish seismic stratigraphic framework and fault system,and clarify the structural characteristics of the study area;inversion of logging-constrained seismic data combined with the above research results,reservoir prediction of sand bodies in favorable areas of Shahai Formation,and clarify the distribution characteristics of sand bodies in the target area;finally,combined with the research results of this paper.The favorable areas of Shahai Formation in the southern part of Zhangqiang Depression are comprehensively analyzed and the favorable targets are optimized.