The Research On Sedimentary Facies And Prediction For Favorable Area Of The Second And Third Member Of Shahejie Formation In Wangxuzhuang Oil Field,Huanghua Depression

Wangxuzhuang oilfield is located on Nandagang faulted structural zones and second and third member of the Shahejie Formation is major oil-producing interval in the oilfield.At present,it has entered the late high water-cut stage.However,many problems such as complex tectonic fault system,rapid change of sedimentary facies and severe reservoir heterogeneity results in inconsistent stratigraphic division and unclear remaining oil distribution law.Based on core,well logging,borehole log and seismic data and applying principles and methods of sedimentology,this paper carried out research work on stratigraphic correlation,provenance analysis,sedimentary facies analysis,and favorable area prediction for the second and third Member of the Shahejie Formation,which will provide a strong basis for subsequent remaining oil excavation in the oil field.The main achievements of this paper are as follow.1.A new division scheme of development micro-layers in the study area is established.In the past,stratigraphic division and correlation in the study area were conducted in separate blocks.The main fault blocks were generally divided into Es2+Es3 and“Nanzhongduan”were clearly divided into Es2 and Es3.Under the control of marker beds,based on sedimentary cycle and lithologic association,and integrating well log and seismic information,the division and correlation of micro-layers in the entire region were conducted in this study.The second and third Member of the Shahejie Formation are divided into 13 micro-layers.2.The provenance systems analysis has been carried out.By restoring the paleo-geomorphology,combined with the RMS seismic attributes and the distribution characteristics of heavy minerals,the major sediments may originate from Kongdian salient and Koucun-Yangshanmu buried-hill during the deposition of third member of the Shahejie Formation.In addition,Nandagang underwater terrain is secondary provenance at the Es₃Period,which provided sediments for the downthrown side of Nandagang fault.3.The study of sedimentary facies have been conducted.Based on meticulous core observation and description,a large number of log curves were correlated to establish the logging facies template in the study area.On the basis of core facies marker,logging facies and seismic attributes,the research suggests that the main types of sedimentary facies are composed of delta,nearshore subaqueous fan and lacustrine facies.Delta plain and delta front subfacies can be identified in the delta.nearshore subaqueous fan can identify inner fan and middle fan subfacies.The lacustrine facies can be divided into lakeshore-shallow lacustrine subfacies,semi-deep and deep lacustrine subfacies.4.Pridiction for favorable areas has been done.Based on the analysis of favorable traps of paleostructure,combined with development characteristics of sand bodies,types of sedimentary facies,reservoir inversion and oil test data,it is predicted that there are two favorable rolling development zones in q110-2 wellblock and q2 wellblock respectively.