Study On Enriching Regularity About The Remaining Oil Of Shahejie Formation In Liuzhong Area Of Jidong Oilfield

Shahejie Formation reservoir in Liuzhong area of Jidong oilfield is a medium porosity and medium permeability sandy conglomerate reservoir.It has been explored in1980 and developed for about 40 years.At present,the water cut of the oilfield is very high and the oil production rate is low.To get more oil from the reservoir,it is urgent to tap the potential of remaining oil.In this thesis,the original oil-water differential distribution of reservoir is studied by integrating core,seismic data as well as logging data;From the sedimentary characteristics of the study area,the connectivity of single sandbody is studied.Combined with the development well data,the relationship between the connectivity of single sandbody and well pattern is analyzed;The interlayer and interlayer contradictions of the main development strata and the distribution of preferential percolation path are analyzed to deepen the understanding of the oil-water movement contradictions in the development process;Combined with geological modeling and numerical reservoir simulation,and enriching regularity about the remaining oil is comprehensively revealed.The thesis has achieved the following results:(1)The reservoir of Shahejie Formation in Liuzhong area is mainly underwater distributary channel sandstone.The original oil-water distribution is controlled by the structure and lithology.Oil are mainly concentrated in the high part of the fault edge.The oil sandbody is limited by the development degree of sandstone,and the distribution is point and strip.(2)The vertical stacking styles of single sand bodies mainly include separation type and shear stacking type,and the plane stacking styles include side cutting type,flank contact type,estuary bar contact type and inter Bay contact type.The connectivity between single sand bodies of shear stacking type and side cutting type is good,the estuary bar contact type is weakly connected,and the separation type,flank contact type and inter Bay contact type are not connected.The multi-layer combined injection and production in the study area has low injection production efficiency,single effective direction,imperfect injection production well pattern and low oil displacement efficiency.(3)The study area has fast sedimentary transformation and strong reservoir heterogeneity.Taking the I ～ III oil gourp as an example,the heterogeneity between reservoir layers is very prone to single-layer breakthrough,and the remaining oil is concentrated in the relatively low permeability reservoir.There is strong heterogeneity in the layer.The rhythmicity is mainly positive rhythm,and the proportion of composite rhythm and homogeneous rhythm is very low.The bottom part of positive rhythm is efficiently flooding.The plane is seriously heterogeneous,and the permeability distribution is directional.High permeability areas are distributed on the mainstream belt of underwater distributary channel.It is easy to develop dominant seepage units after long-term water injection.(4)Combined with geological modeling and numerical reservoir simulation,the vertical remaining oil distribution of I ～ III oil group in Liu 1 fault is mainly controlled by the inter layer physical property difference and rhythmicity.The main oil layers have good physical properties,strong water absorption capacity,thus they are easy for water drive.High remaining oil saturation exists in oil reservoir with poor porosity and permeability.Positive rhythm is mostly developed in the oil layer,and the upper part has the high saturation of the remaining oil.There are four types of plane remaining oil distribution,including local high parts blocked by closed faults or controlled by positive microstructure,areas with poor physical properties controlled by sedimentary phase transformation,areas around water flooded path caused by dominant seepage channels and areas with imperfect well pattern.The remaining oil of oil group Ⅰ and Ⅱ is mainly caused by the imperfect well pattern due to the small area of oil sandbody.The remaining oil of oil group III is mainly distributed in areas with poor physical properties due to the high viscosity of crude oil and poor water flooding effect.