Investigation on Plugging and Profile Control of Polymer Microspheres as a Displacement Fluid in Enhanced Oil Recovery.

Xiangrong Nie,Yunyi Hou,Yi Cao,Yanlong He,Junbin Chen,Shaomin Yuan,Jinyuan Zhang,Wenjing Zhao

doi:10.3390/polym11121993

Abstract

Polymer microspheres (PMs) are used as a new material to recover residual oil left in unswept oil areas after secondary recovery methods. The fact that the PMs plug the macropores causes the flow direction of the injection fluid to be transferred from macropores to micropores. In order to investigate the plugging and profile control mechanisms of PMs in reservoirs, four kinds of PMs with different particle sizes and four kinds of artificial cores with different permeability were selected for flooding tests, including plugging experiments and profile control experiments. The pore throat size distribution of cores was characterized by nuclear magnetic resonance (NMR) technology. The particle size distribution of PMs used in the experiment was characterized using a laser particle size analyzer. The results showed that there are six matching relationships existing simultaneously between pore throats and PMs based on theoretical analysis, which are completely plugging, single plugging, bridge plugging, smooth passing, deposition, and deformable passing. A key principle for optimizing PMs in profile control is that the particle size of the selected PMs can enter the high permeability layer well, but it is difficult for it to enter the low permeability layer. The results of this paper provide a theoretical basis for the optimal particle size of PMs during the oil field profile control process.

Highlights

Once the oil field is in the high water-cut stage, oil–water distribution in the reservoir becomes complicated, and reservoir heterogeneity becomes severe, causing water to bypass small pores and low-permeability layers, flowing along the large pores and high-permeability layers
In order to toaccurately accuratelycharacterize characterizethe the matching relationship between polymer microspheres porepore throats, the pore throat radius distribution curves of four were transformed into pore and throats, the pore throat radius distribution curves ofcores four cores were transformed intothroat pore diameter distribution curves, and the same diagrams were drawn with the particle size distribution throat diameter distribution curves, and the same diagrams were drawn with the particle size curves of four polymer microspheres, as shown inas
We focused on plugging and profile control of Polymer microspheres (PMs) in porous media using physical

Summary

Introduction

Once the oil field is in the high water-cut stage, oil–water distribution in the reservoir becomes complicated, and reservoir heterogeneity becomes severe, causing water to bypass small pores and low-permeability layers, flowing along the large pores and high-permeability layers. The remaining oil in the small pores and the low-permeability strips cannot be displaced, forming an ineffective water circulation [1,2]. In order to further enhance oil recovery (EOR), it is possible to increase the sweep factor and oil displacement efficiency of the injected fluid. Profile control technology expands the sweep factor of the injected fluid by plugging the high permeability layer [3,4,5]. The traditional profile control agent only works in the near-well zone, and the subsequent.

Methods

Results

Discussion

Conclusion