Experimental Study Of Remaining Oil Distribution Of Thick Oil Reservoir And EOR Strategies

LD10-1 is offshore thick reservoir,limited by time and space and other factors,unlike onshore oil field,offshore oil development usually take the high-speed development method.LD10-1 is facing high water-cut,high recovery degree,oil production rate decline,etc.Water flooding is complicated and the effectiveness of early polymer flooding need further verification.Remaining oil distribution is lack of accurate understanding and the validity of polymer/surfactant flooding as a successor of early polymer flooding need to be verified.In this paper,the basic physical parameters of polymer is determinated which was injected in LD10-1,and water flooding,polymer flooding relative permeability curve is determinated.Deduced similarity criterion thick reservoir under water flooding,and design the displacement experiment of visible plate model under the control of similar criteria.Designed and manufactured visible plate model with reference to the typical well group of LD10-1.Integrated use different-scale physical simulation experiment(visible plate model oil displacement experiments,parallel heterogeneous core displacement experiment and glass etching model microscopic oil displacement experiment),the law of water flooding,remaining oil distribution of early polymer flooding is studied.Performance and influential factors of polymer/surfactant flooding after polymer flooding is studied.The microscopic displacement mechanism of polymer polymer/surfactant flooding is studied.Studies show that polymer solution rheological model is power-law model,and the higher concentration,the stronger viscosifying ability and non-Newtonian behavior.Resistance factor and residual resistance coefficient increased with increasing polymer concentration and decreasing core permeability.Oil relative permeability curve of water flooding and polymer flooding is consistent with the trend.Polymer can reduce water relative permeability during high water saturation.The law of water flooding is affected by reservoir rhythmic,permeability ratio,distribution of the interlayers and perforation layer.Since the difference between the permeability layer,watered-out occurs in the high permeable layers.Water gravity segregation occurs in the high permeable layers,so the degree of watered-out is higher in the bottom of the high permeable layer.Early polymer flooding can adapt to the heterogeneity of formation,reduce remaining oil in the middle and low permeable layer,and enhance oil recovery.Enrichment of remaining oil occur low permeable layer near the production well.Polymer/surfactant flooding after polymer flooding can be further enhanced oil recovery,water-cut 85% of polymer flooding,slug injection 0.3PV is more reasonable.After early polymer flooding,the type residual oil is film and columnar residual oil.Due to synergistic effect of polymer and surfactant,polymer/surfactant flooding can activate residual oil after early polymer flooding.