Yuzhang Liu

Investigation on the Adaptability of the Polymer Microspheres for Fluid Flow Diversion in Porous Media

Large amounts of water producing from producers have been a great concern for petroleum engineers. In an attempt to inhibit water production and promote oil productivity, various water control agents and techniques have been devised for enhanced oil recovery purpose for decades with some good successes reported commercially. Mainly field-targeted specifically, however, these chemicals are limited in expansive reservoir applications for failing to tolerate harsh formation conditions of high temperature (HT) and high salinity (HS). Besides, their low injectivity is also another proper impediment. In this presentation, we synthesized a new agent of polymer microspheres using inverse emulsion polymerization technique to divert fluid patterns in deep porous media for reservoirs encountered recovery enhancement problems. These microspheres are made to tolerate HT and HS conditions, and can be pumped into deep pore space with relative ease. With the help of nuclear magnetic resonance (NMR) and nuclear pore membrane filtration techniques, a series of experimental procedures were conducted to test the adaptability of newly produced polymer microspheres to targeted pore structure in enhancing the sweeping efficiency of injection fluids. Both laboratory core tests and NMR data show good characteristics of polymer microspheres in modifying injection profile, demonstrating a good capability to divert fluid flow patterns in deep porous media and enhance oil productivity.

The Viscoelastic Effect of Polymer on Tracer Dispersion

Polymer flooding works as the main enhance oil recovery method in China, but tracer test interpretation during and after polymer flooding still uses the technology of water flooding. And a lot of problems exposed in the application Experimental study of tracer dispersion in viscoelastic fluid through porous media isreported. We use different viscoelastic non-Newtonian fluid with the same shear shinning properties as the carrier fluid. It is evident that viscoelastic property is also the key factor influences the velocity field and the dispersivity in non-Newtonian fluid. High Peclet number yields the enhancement of the viscoelastic effect on the dispersivity of the tracer. Compared to pure viscous fluid, polymer viscoelasticity may lead to a larger vortex and, thus, a larger sweeping volume and speed field difference which leads to a higher dispersivity.

Investigation of Pore-Scale dispersion in Polymer Flooding

Local displacement in polymer flooding is significantly affected by mixing taking place in the medium. Despite decades of research on mixing and dispersion, there remain questions about the amount of mixing occurring at pore-scale, especially for non Newtonian fluid. This study has investigated the local mixing experimentally as well as computationally. Tracer dispersion in Newtonian and shear-thinning fluids flowing through sand pack has been carried out experimentally using classical transmission dispersion. Transmission dispersion increases markedly with the shear thinning index of the fluid at all Peclet numbers.