Method To Enhance Oil Recovery In Heterogeneous Formation After Polymer Flooding

Selection of EOR method in the heterogeneous formation after polymer flooding is the main concern in this study.D10-02 is the offshore oilfield in which oil needs to be enhanced after polymer recovery process.Present studies show improvement in oil recovery after polymer flooding.However,remaining oil distribution in the formation is still evident even after polymer flooding.This study intends to suggest the best EOR method and optimizes recovery parameters of an EOR method to improve oil recovery.To achieve the above objectives,core flooding,microscopic simulation and polymer foam flooding were conducted in the laboratory.Water,polymer,and surfactant – polymer(SP)flooding were designed accordingly,and parameter optimization was studied.In an EOR method experiment,flooding sequence starts with water flooding followed by polymer flooding,then SP flooding and lastly polymer flooding.For the purpose of optimizing Surfactant and polymer(SP)slug size,different slug size values were designed and injected in the core sample.Optimization of polymer injection was also studied.Remaining oil distribution in microscopic experiment after water,polymer and SP flooding was observed.With polymer enhanced foam core samples were prepared and recovery sequence were designed.Results show an increment of 9.8% oil recovery in SP injection compared to polymer flooding.This improvement is due to reduction in the IFT with surfactant and mobility control with polymer.Combined effect of polymer and surfactant improve both mobility and micro sweep efficiency which improved entire oil recovery.When SP slug size increased from 0.2PV to 0.3PV,the oil recovery increased by 4.3%,while the increase from 0.3PV to 0.5PV,oil recovery rate increased by 2.5%.Results for injection velocity in the microscopic flooding show that the increase in injection flow rate in the core sample resulted to improving sweep efficiency and reduce residual oil distribution in the sample.Therefore after optimizing the parameters in an SP injection,the oil recovery factor was improved after polymer flooding.This method shows potential for improving oil recovery and cost-effective improvements at D10-02 oilfield.Polymer enhanced foam also shows significant improvement in oil recovery after polymer flooding.