Study On Sedimentary Microfacies Of Putaohua Reservoir In Gu 117 Block Of Puxi Oilfield

The Putaohua reservoir in Puxi Oilfield-Gu117 Block mainly belongs to the first member of Yaojia Formation.Its sedimentary period is controlled by material sources in the Northwest direction.The sedimentary environment is a delta front subfacies with weak energy.The reservoir has the characteristics of thin vertical direction,single sand body thickness mainly distributes in the range of 0-2m and scattered distribution along the source direction in the plane,which brings great difficulty to the fine characterization of reservoir.And this block belongs to data splicing zone.Previous studies lack systematic and fine reservoir characterization of the target strata in this block.Therefore,it is urgent to conduct a complete and systematic study of sedimentary microfacies in this block.This paper is based on the theory of high-resolution sequence isochronism,sedimentary petrology,and comprehensive interpretation of seismic data for the ancient 117 block of the Portuguese-National Oilfield,combined with core data,well logging data and seismic data.The flower oil layer group performs small-scale sedimentary microfacies analysis.Firstly,the target layer of the study area is divided into small layers,Then inversion reservoir prediction in small layers.Finally,The results of the inversion reservoir prediction are used to characterize the distribution of sedimentary microfacies.The results obtained and the understanding are as follows: the high-level isochronism theory is used to guide the target layer into 8 small layers: PI8,PI7,PI6,PI5,PI4,PI3,PI2,PI1;Seismic inversion reservoir prediction using small layers as a unit.Based on the theory of sedimentary petrology,combined with well logging data,logging data,and core photographs,the sedimentary facies types are analyzed.It is believed that the sedimentary facies of the Putaohua oil layer is a delta facies,mainly developing the delta front subfacies,underwater distributary channels,estuary dams,mat sands,Four microfacies types,such as the diversion bay,were combined with the inversion prediction results to characterize the sedimentary microfacies.The analysis of the distribution characteristics of sedimentary microfacies shows that the distribution characteristics of sedimentary microfacies are divided into three categories according to the direction of river channel distribution: the first category,PI8,PI7,PI6,the river channel is distributed from north to south,and the general thickness of sand body 0~2m,the cumulative thickness is up to 11 m,the sand is developed,the sand body is dominated by river sand and mat sand;the second type is PI5,PI4,PI3,the river channel is distributed from northwest to southeast,and the sand body is generally thick.0~2m,the cumulative thickness is up to 5m,the sand body is dominated by river sand;the third type,PI2,PI1,the river channel is distributed from the northwest and north directions to the southeast direction,the sand body is generally 0~2m thick,cumulative thickness The maximum is 8m,and the sand is well developed.The sand body is mainly composed of river sand and mat sand.The distribution of sedimentary microfacies and reservoir sand bodies has a certain role in the next step of oil and gas exploration in the Putaohua oil layer in the study area.