The Adaptability Study Of Polymer Flooding For The Third Class Oil Layer In Daqing Oilfield

The La-Sa-Xing Oilfied has been in the stage of extra high watercut after more than 40years' development. In the subsequent development of polymer flooding, the polymer flooding inthe main oil layers, such as PI, almost finished, and the pilot test of polymer flooding in theSecond Class oil reservoirs also is finished, and now in the stage of industrialized development.Based on the mature technology of polymer flooding in the main, and second class oillayers, the polymer flooding in the three class oil reservoir of Daqing Oilfield is in the stage ofpilot test. The Third Class oil layers is the oil layers and untabulated layers, of which theeffective permeability is less than 100 × 10?3μm2,the effective thickness is less than 1m. For thethin-bad layers and untabulated oil layers, the physical property of oil reservoir is bad, there aremany layers, the remaining oil is greatly dispersed, all of which result in the low productioncapacity of the third infilling wells, high watercut and difficulty of adjustment. Therefore, themethod, which combining the tertiary production with the third inflling, is used to develop theThird Class oil layers.According to the research results, the requirement of injection can be meet through reducingthe relative molecular weight of polymer, but the reduction relative molecular weight of polymercan lead to the worse development result of polymer flooding. So the adaptability study ofrelative molecular weight, geological features of reservoirs and characteristics of pore is vital.The adaptability study of polymer flooding for the Third Class oil Layers in Daqing Oilfieldis presented as follows in the thesis, the overview of geological characteristics of Third Class oilLayers, distribution pattern and mode summary;the microscopic parameters measurement ofpolymers of medium, low relative molecular weight before and after shearing;the compatibilitybetween polymers of medium, low relative molecular weight and core permeability.The conclusions of adaptability study of polymer flooding for the Third Class oil layers are:when selecting the relative molecular weight of polymer for the Third Class oil layers, theinfluence of relative molecular weight of polymer upon the displacement effect, should beconsidered, compatibility between relative molecular weight of polymer and oil layers, andinfluence of clay minerals in low permeability upon permeability are all should be considered.