| Member 3 of Liushagang in WS17-2 oilfield is a loose sandy conglomerate faulty reservoir with low permeability and strong water sensibility.At present,preliminary research and evaluation are being undertaken before put into production.The main problems for development we are facing include that high-quality reserves are small,the natural energy is not adequate,the tested productivity is low,reservoir heterogeneity and water sensitivity are strong.Therefore,energy feeding measures such as water injection must be taken for effective development of this reservoir.In order to study the seepage mechanism of Wushi sensitivity reservoir and improving water flooding measures as well as provide guidance for energy supplement measures and main development technology of WS reservoir,based on the study of the low permeability sensitive reservoir seepage mechanism and water flooding development effect,the following research is the main things that have been done:(1)A preliminary understanding of the micropore structure of the core has been made by the micro X-CT scanning and the two-dimensional and three-dimensional images of the core core,which lays a foundation for the study of the subsequent digital core.(2)Through conventional mercury injection experiments,the reservoir performance and flow capacity were analyzed by various parameters.It is found that the diameter of the main pore size and the largest contribution rate of the permeability does not coincide.This shows that the pore throat is different from the flow channel,which provides the reservoir space for the oil and water,and the smaller hole roar provides the storage space,and the seepage channel is greatly provided.(3)Through nuclear magnetic resonance(NMR),water sensitive salt sensitivity test,NMR observation before and after centrifugation and NMR observation under different mineralized degrees,the size of pore throat and the size and proportion of the circulated larynx are found,and the interval of the permeability in the third section of the two sections of the Wushi flow,that is,the critical salinity value,is determined.(4)The experiment of overpressure phase seepage drive shows that the effective overburden pressure increases,the isotonic point of phase infiltration curve decreases,and the isotonic point shifts to the left.It shows that the effective overpressure increases,the two phase flow resistance increases,the effective overpressure increases,the pore roar channel becomes smaller,the oil phase effective permeability is reduced in the water flooding process,the flow remaining oil saturation is increased,and the oil displacement efficiency is reduced.And two section of rock oil,Haizhong hydrophilic.(5)Compared with the water flooding oil,the active water flooding oil has better displacement effect and less resistance,the recovery rate is 3.46%and the breakthrough time is 0.05HCPV late.It shows that the active agent has a certain oil displacement performance,which can reduce the viscosity and surface tension of the crude oil,enhance the hydrophilicity of the rock surface,and effectively peel off the oil film on the surface of the rock.The purpose of improving oil recovery is to improve the mobility of formation crude oil.(6)One day after the stew,when the displacement multiple reaches 2 times HCPV,the water content reaches 100%,the formation water displacement efficiency reaches 54.68%,increases 1.22%,the active water displacement efficiency reaches 57.89%,increases 0.97%,and the output of the oil exore at the exit is somewhat increased,and the result can be seen that the stew well is the result of the formation water flooding or the active water flooding.It has little influence.(7)There is a certain effect of high water washing on the increase of oil displacement efficiency.When the formation water drive and active water drive adopt multiple water flooding,the improvement of recovery degree is less than 1%.The improvement is mainly manifested in the early stage of high water washing,and almost no oil displacement ability in the middle and later stages.Therefore,the effect of improving water flooding is not significant by increasing the injection water volume in the late stage of flooding. |
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