Study Rheological Behavior of Polymer Solution in Different-Medium-Injection-Tools

Abstract

Previous studies showed the difficulty during polymer flooding and the low producing degree for the low permeability layer. To solve the problem, Daqing, the first oil company, puts forward the polymer-separate-layer-injection-technology which separates mass and pressure in a single pipe. This technology mainly increases the control range of injection pressure of fluid by using the annular de-pressure tool, and reasonably distributes the molecular weight of the polymer injected into the thin and poor layers through the shearing of the different-medium-injection-tools. This occurs, in order to take advantage of the shearing thinning property of polymer solution and avoid the energy loss caused by the turbulent flow of polymer solution due to excessive injection rate in different injection tools. Combining rheological property of polymer and local perturbation theory, a rheological model of polymer solution in different-medium-injection-tools is derived and the maximum injection velocity is determined. The ranges of polymer viscosity in different injection tools are mainly determined by the structures of the different injection tools. However, the value of polymer viscosity is mainly determined by the concentration of polymer solution. So, the relation between the molecular weight of polymer and the permeability of layers should be firstly determined, and then the structural parameter combination of the different-medium-injection-tool should be optimized. The results of the study are important for regulating polymer injection parameters in the oilfield which enhances the oil recovery with reduced the cost.

Experimental and numerical simulation study on the flow characteristics and optimization of structural parameters of displacement agent in partial pressure tools

“…However, the numerical simulation method is only based on the gradual accumulation of finite element analysis and calculation of power‐law fluid, and cannot simulate the shearing and stretching effect between molecules. Moreover, the structure of the molecular chain changes at all times during the flow of the polymer solution in the partial pressure tool, resulting in the experimental results being larger than the numerical simulation results . Moreover, the higher the concentration of the polymer solution, the greater the viscosity loss rate of the solution under the action of the partial pressure tool, and the greater the viscosity loss rate of high‐concentration polymer solution with the increase of the flow rate …”

“…Moreover, the structure of the molecular chain changes at all times during the flow of the polymer solution in the partial pressure tool, resulting in the experimental results being larger than the numerical simulation results. 52,53 Moreover, the higher the concentration of the polymer solution, the greater the viscosity loss rate of the solution under the action of the partial pressure tool, and the greater the viscosity loss rate of high-concentration polymer solution with the increase of the flow rate. 54 Figures 8-10 show the velocity nephogram, velocity streamline, and velocity change of polymer solution in the partial pressure tool when the flow rate is 10 m 3 /d, respectively.…”

Extensional Rheological Measurements of Surfactant–Polymer Mixtures

“…One of the effective ways to control the mobility ratio is the use of water-soluble high-molecular-weight polymers, which not only increase water viscosity but also push additional oil by blocking high-permeable water-flooded pores as polymer chains can entangle to form cross-linked 3D networks. Thus, polymer fluids are viscous in nature and exhibit better rheological properties than water; 2 therefore, polymer fluids are often used to improve the rate of oil recovery from reservoirs. However, for the reservoirs with high salinity, salinity of reservoir brine significantly affects the rheological properties of polymer fluids.…”

Experimental Study on the Effect of ASP Flooding on Improving Oil Recovery in Low Permeability Reservoirs Based on a Partial Quality Tool

“…Therefore, under the condition of not changing the structure of the low permeability oil layer and not polluting the oil layer, it is of great significance to use a partial quality tool to improve the oil displacement effect. At this stage, Huang et al [21] constructed the rheological model for polymer solution using the partial quality tool and determined the maximum injection speed of polymers. Their research showed that the structural parameters of the partial quality tool affect the range of apparent viscosity of the polymer solution and directly affect the oil displacement effect of the polymer solution.…”