The Study On Rheological Properties Of The Produced Fluids In Polymer Flooding Wells

With the development of the oilfield during the middle and later period,as one of the enhanced oil recovery methods,polymer flooding technology has been widely applied in the oilfield. Polymer flooding is different with waterflooding especially in wells containing polymer in their fluid productions, the presence of the polymer has a huge impact on rheological properties of the fluid. Therefore, the rheological properties of the produced fluid must be studied furtherly in order to improve the process design and management of such wells.Based on the literature survey, experiments were done to study the rheological properties of the produced fluids. Firstly, the rheological properties of the polymer were researched, the existing theoretical predictions and models were listed, influences of some factors on the apparent viscosity of the polymer were studied based on experiments, the facters included temperature, polymer concentrations, shear rate and different ions(Na+, K+, Mg2+, Ca2+). A new method was proposed to calculate the apparent viscosity of the polymer by regressing the experiment data.Secondly, based on the theory of the phase inversion for oil-water emulsions, experiments were done to study the inversion points of the produced fluids, factors that affect the inversion points, such as temperature, polymer concentrations and salinity were analyzed which offers a basis of determining the type of emulsions.Finally, the rheological properties of the produced fluids are studied, an qualitative analysis of factors that affect the apparent viscosity of the produced fluids, such as temperature, shear rate, polymer concentrations, water content and different ions(Na+, K+, Mg2+, Ca2+) were analyzed. Experimental data were used to evaluate the viscosity prediction models. The Richardson model and the Vand model are preferred to calculate the relative viscosity of the produced fluids. Combined with the polymer viscosity model founded before, the model to calculate the apparent viscosity of the produced fluids in polymer flooding wells was founded. Verified by the experimental data and field data, the model has high accuracy.