Abstract
The concept of the hydrodynamic characteristic size of polymer was proposed in this study, to characterize the size of aggregates of many polymer molecules in the polymer percolation process. The hydrodynamic characteristic sizes of polymers used in the target block S were examined by employing microporous membrane filtration method, and the factors were studied. Natural core flow experiments were conducted in order to set up the flow matching relationship plate. According to the flow matching plate, the relationship between the hydrodynamic characteristic size of polymer and pore throat radius obtained from core mercury injection data was found. And several suitable polymers for different reservoirs permeability were given. The experimental results of microporous membrane filtration indicated that the hydrodynamic characteristic size of polymer maintained a good nonlinear relationship with polymer viscosity; the value increased as the molecular weight and concentration of the polymer increased and increased as the salinity of dilution water decreased. Additionally, the hydrodynamic characteristic size decreased as the pressure increased, so the hydrodynamic characteristic size ought to be determined based on the pressure of the target block. In the core flow studies, good matching of polymer and formation was identified as polymer flow pressure gradient lower than the fracture pressure gradient of formation. In this case, good matching that was the pore throat radius should be larger than 10 times the hydrodynamic characteristic size of polymer in this study. Using relationship, more matching relationship between the hydrodynamic characteristic sizes of polymer solutions and the pore throat radius of target block was determined.
Highlights
Polymer flooding is a quite advanced technique for enhancing oil recovery
The effect of polymer flooding can be strengthened by using high molecular weight and high concentration of polymer, but except for the molecular weight and concentration of polymer, the size of the polymer is related to some other factors, such as the dilution water, injection pressure, and viscosity
The results indicated that, when the polymer KYPAM-II solution passed through nuclepore films with different pore diameters, the figure of the filtration curves, the solution viscosity and concentration before and after filtration, and the size variation of the solution molecular clews differed
Summary
Polymer flooding is a quite advanced technique for enhancing oil recovery. For polymer flooding, the water-soluble polymers are used for increasing the injection liquid viscosity to improve the mobility ratio and reduce water phase permeability, so as to enhance the oil recovery [1,2,3,4].The effect of polymer flooding can be strengthened by using high molecular weight and high concentration of polymer, but except for the molecular weight and concentration of polymer, the size of the polymer is related to some other factors, such as the dilution water, injection pressure, and viscosity. Polymer flooding is a quite advanced technique for enhancing oil recovery. The water-soluble polymers are used for increasing the injection liquid viscosity to improve the mobility ratio and reduce water phase permeability, so as to enhance the oil recovery [1,2,3,4]. For the polymer flooding, the polymer which has good relation with the pore throat size should be selected [5,6,7,8]. The results indicated that, when the polymer KYPAM-II solution passed through nuclepore films with different pore diameters, the figure of the filtration curves, the solution viscosity and concentration before and after filtration, and the size variation of the solution molecular clews differed
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