Research On Displacement Mechanism And Effect Evaluation For Well Pattern Adjustment With Heterogeneous Combination Flooding After Polymer Flooding

As a new following technique for reservoir after polymer flooding to enhance oilrecovery, well pattern adjustment with heterogeneous combination flooding after polymerflooding now is in the pilot experiment stage, and the displacement mechanism and effectevaluation is still not known. So it is important to analyse the displacement mechanism and toevaluate the development effect, which can popularize the application and enhance oilrecovery.Based on the numerical simulation method and physical simulation method,displacement mechanism is proposed, which includes the amplifyication of well patternadjustment on heterogeneous combination flooding and the synergia of three chemical agents.From the analysis on remaining oil distribution, responding remaining oil distribution,enhanced oil recovery, enhanced oil recovery ratio and the sweep efficiency, it is discoveredthat the well pattern adjustment and the heterogeneous combination flooding has the sameeffect on enhancing oil recovery in the displacement method of well pattern adjustment withheterogeneous combination flooding after polymer flooding, while the well patternadjustment amplify the heterogeneous combination flooding’s effect on enhancing oilrecovery. The displacement efficiency of heterogeneous combination flooding is larger thansurfactant flooding, while the sweep efficiency is larger than PPG flooding and polymerflooding. The enchanced oil recovery of heterogeneous combination flooding is larger thanthe total enhanced oil recovery of the surfactant flooding, the PPG flooding and the polymerflooding, which illustrate the synergia of three chemical agents.On the basis of the analysis of production and injection performance of the pilot test area,the quantitative characterization of displacement effect is established. The production wells at different positions have been analysed from the aspects of water cut, daily oil production anddaily liquid production, while the new production wells between production well rows andinjection well rows respond obviously. The injection wells at different positions have beenanalysed from the aspects of injection pressure and daily water injection, while the injectionpressure of every injection wells are keeping rising while the daily water injection remainsconstant.Based on the existing effect evaluation index, the specialized index for well patternadjustment with heterogeneous combination flooding after polymer flooding is established,which includes pressure liquid index, hall curve and pressure improvement value. Pressureliquid index can reflect the characteristic of the chemical agent injection period. Apparentresistance factor of the injection well can be calculated by pressure liquid index and hall curve,while the results are similar. Pressure improvement values establish the corresponding relationof the injection wells and the responding production wells.