The Study Of Oil-water Distribution And Core Area Evaluation On Putaohua Oil Layer In Pubei Oilfield Of Daqing Placanticline

The Pubei Oilfield is structurally located on the Putaohua structure in the southern part of the Daqing placanticline area in the central depression of the Songliao Basin.The Putaohua oil layer is the key development level in the study area.However,with the successive development of the main block,the potential for subsequent development is insufficient,and it is urgent to expand the favorable potential area.In this paper,using the sedimentology,petroleum geology,logging geology,etc.,the structural characteristics,fault characteristics,reservoir sedimentary characteristics,oil-water distribution law,main control factors of oil-water distribution and potential for external expansion are studied in depth.On the basis of delineating the oil-water envelope of the main body of the structure,the extent of the potential expansion area is given,which has important guiding significance for the remaining oil exploitation of the entire oilfield.Firstly,the paper analyzes the structural characteristics and fault characteristics of the study area,and summarizes three types of fault development.The type I fault is used as the boundary condition of 7 independent fault blocks in the Putaohua oil layer of the study area,and the type II and III faults are used as occlusion conditions to subdivide these seven independent fault blocks into 15 single traps.Then,using the reservoir section method,sub-layer projection method and probability statistical method to calibrate the oil bottom and water top of each single trap,and the vertical distribution of oil and water distribution in the Putaohua oil layer of the Pubei Oilfield is obtained.The oil and water envelope of the study area is delineated.Three main controlling factors of oil-water distribution law are summarized: 1)the structure controls the height of oil column and oil-water distribution.The oil-water differentiation is better in steep slope area,with a shallower oil-water interface and a lower oil column height.2)The fault concentrated belt has an antiformal structure to control the plane gathering site of oil and gas.In this study area,the area of the fault concentrated belt with a antiformal structure of more than 20 meters can develop into a favorable oil-concentrating part;3)the net-to-gross ratio affects the sandbody connectivity and the vertical differentiation of oil and water.The net-to-gross ratio and the coincidence rate of oil-water distribution have a positive linear correlation.The result shows that the oil-water consistency rate exceeds 90% when the sand-to-ground ratio is greater than 12%,On the basis of the research of oil-water distribution,the expansion of the development zone and the optimization of the favorable target area were carried out.The unexplored area within the oil-water envelope of the Putaohua oil-layer is used as the external expansion potential area,and four favorable targets were identified.It provided guidance for the increase of storage and stability in the high water cut period of the Pubei Oilfield.