Experimental Study On Physical Simulation Of Interlayer Interference Seepage In Low Permeability Reservoir

XL oilfield block belongs to low permeability heterogeneous reservoir.It has been waterflooding for more than 30 years since it was put into development.The comprehensive water cut has reached more than 82% and the recovery degree is about 30%.Due to the difference of sedimentary rhythm and physical properties,the horizontal and vertical waterflooding are not balanced in the process of waterflooding development,and the development effect is restricted.At present,there is a lack of intuitive quantitative research on the analysis of vertical and plane production contradiction constraints of low permeability reservoir in this block.According to the characteristics of low permeability and heterogeneous reservoir in the target block,the physical boundary of interzonal interference caused by multilayer coproduction in the target block was determined through plate physical model displacement experiment,microscopic CT scanning experiment under different displacement states,and parallel displacement experiment of natural core with different permeability levels.The adaptability of amplifying production pressure difference and deoxygenated air flooding to reduce interlayer interference was explored.Four and five sets of reservoir plate model displacement experiments with the same permeability difference show that the recovery degree of separate injection and production is higher than that of combined injection and production.Compared with the four sets of reservoirs,the difference between combined injection and separate injection and separate injection is smaller,but the recovery degree of the core with the lowest permeability of the five sets of reservoirs is 0,which indicates that the increase of the number of sets leads to the greater permeability difference,and the high permeability core has more obvious influence on the low permeability core.The CT scanning results of cores at different displacement stages show that the greater the permeability of cores is,the greater the change of oil saturation of cores before and after displacement,that is,the higher the recovery degree of cores is.The greater the permeability difference of parallel experimental cores,the greater the influence of high permeability cores on the recovery of low permeability cores.Reservoirs with core pore radius less than 3μm are difficult to deploy.By comparing the experimental results of parallel displacement of 2,3,4 and 5 natural cores,the reasonable development layer limit is 4 sets of reservoir co-production.When 4 sets of reservoir co-production,each layer can be used to different degrees,which can maximize the development potential of each layer.The reservoirs with permeability below 7m D,12 m D～23m D and 23 m D～33m D are divided into one layer combination,which can effectively reduce the influence of interzonal interference.Compared with the differential pressure of amplified production,the effect of deoxygenated air flooding on the recovery degree of parallel core is more obvious.The research results are helpful to improve the understanding of the displacement mechanism and seepage law of the target oilfield,and have certain guiding significance for the actual field development and the optimal development mode.