The Research about Back Pressure and Permeability of Heterogeneous Core Affecting Fractional Flow Rate of Plugging Agent

Abstract

In order to improve the selective plugging effect of high pressure layer which was during the process of commingled chemical water plugging in heterogeneous layer. This paper carried out the parallel core group experiment to research influence of back pressure and permeability contrast affecting fractional flow rate of acrylic plugging agent. The experimental results show that for parallel core group with different permeability contrast, with increased of pressure difference, fractional flow rate of the low pressure core gradually increased, indicating that inter-layer pressure difference in core group was main factor affecting fractional flow rate. With pressure difference increased from 0 MPa to 2 MPa, fractional flow rate of low pressure core gradually increased from 0 to 100% when permeability contrast is 12.55, fractional flow rate of low pressure core increased from 0 to 31.5% when permeability contrast is 105.5, fractional flow rate of low-pressure core increased from 0 to 10.5% when permeability contrast is 333.3. According to the experimental results, this paper proposed a proposal for selectively plugging high pressure layer in heterogeneous layer with inter-layer pressure difference and permeability contrast, that is, when permeability contrast was less than 105.5, temporary plugging agent should be injected to plug low pressure layer temporarily, and then water plugging agent was injected to plug high pressure layer. The lab experimental results show that after temporary plugging agent was injected, fractional flow rate of high pressure core increased from 0 to 98.8%, and fractional flow rate of low pressure core decreased from 100% to 1.2%, which achieved experimental purpose of selectively plugging high pressure core.