Further Enhanced Oil Recovery By HPAM/B-PPG Flooding After Polymer Flooding

The conformance control performance after polymer flooding by using the heterogeneous flooding system consisted of branched-preformed particle gel(B-PPG)and polymer were evaluated and optimized through resistance factor tests.Heterogeneous parallel core flooding tests and micro-flooding experiments were carried out to investigate the profile control and EOR ability of the heterogeneous flooding system.The results show that the combination of B-PPG and polymer has both the high viscosity characteristics of polymer and the nature of the viscoelastic particles;therefore the high permeability core can be blocked effectively and high resistance factor and residual resistance factor are obtained.The system has the best blocking performance when polymer and B-PPG are in the proportion of 60:40.The flow ratio of high permeability core and low permeability core can be improved significantly by heterogeneous system flooding after polymer flooding,and the oil recovery in the low permeability core is significantly improved.Micro-flooding experiments show that the main mechanism of improving residual oil recovery after polymer flooding by heterogeneous system is the improvement of the sweep efficiency.The residual oil recovery could be further improved when surfactant was added to the heterogeneous system.