Study On Flow Field Evaluation And Horizontal Well Control Strategy Of Offshore G Oilfield

Offshore g oilfield is a lithologic structural reservoir deposited in shallow water delta with strong heterogeneity.Horizontal well is the main development well type to develop single sand body in oilfield.After long-term water injection development,it has entered the stage of high water cut and high recovery.After reaching the high water cut stage,the problems of high water cut of horizontal wells and rapid production decline generally exist in oilfields.Through tracer test and profile test of some production wells,it is known that the dominant seepage channel of reservoir is seriously developed,the injection water fingering in the plane of injection production well group is serious,and the water injection and production of horizontal wells are uneven,which seriously restricts the sweep degree of current well pattern.How to accurately characterize the development of the dominant seepage channels of the reservoir and put forward the policies and measures for the classified treatment of horizontal wells is the key to the continuous oil production and water control in the next step.Based on the investigation of the development status of horizontal wells and the application status of control measures in similar oilfields at home and abroad,this paper first analyzes the geological characteristics and development status of the reservoir,and summarizes the current contradictions in oilfield development.Through tracer test and experiment,this paper analyzes the development and evolution mechanism of dominant seepage channels in target oilfield from macro and micro aspects.Aiming at the characteristics of short-term and high-speed development of offshore reservoirs,a flow field characterization method of dominant seepage channels in offshore oilfields is established,and a new index " oil & surface flux ratio" is proposed to characterize the reservoir erosion intensity.With the help of the characteristic value of oil to permeability ratio curve,the flow field grade is divided,and the development opportunity and location of dominant seepage channels in reservoirs are quantitatively characterized and identified by combining with the water cut curve method of horizontal wells.Considering the enrichment degree of remaining oil and the difficulty of driving,the evaluation index of remaining oil flow field "remaining oil potential coefficient" is proposed to evaluate the remaining oil distribution in the target area.Based on the dynamic development analysis of horizontal wells in G oilfield and the seepage field theory,the reasonable control policy limits of horizontal wells in the target area are studied from three dimensions of single well,well group and the whole area.The results show that there are 8 linear water flooded wells,13 single point water flooded wells,10 multi-point water flooded wells and 7 whole section water flooded wells in G oilfield.The results show that the heterogeneity of flow field is reduced,the rising rate of water cut in horizontal wells is obviously inhibited,the injection water utilization rate is increased and the water drive effect is improved after the measures such as "flow field control",vector control "uniform flow field" and "flow field expansion" of unstable water injection are taken.