Enhancing Oil Recovery from Low-Permeability Reservoirs with a Thermoviscosifying Water-Soluble Polymer

• Published in: Molecules (Basel, Switzerland) Vol. 26; no. 24; p. 7468
• Main Authors: Zhang, Xiaoqin, Li, Bo, Pan, Feng, Su, Xin, Feng, Yujun
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 09.12.2021; MDPI
• Subjects: Aging; Calcium ions; Calcium permeability; Enhanced oil recovery; Feasibility studies; Flooding; Floods; Laboratories; Magnesium; Membrane permeability; Molecular weight; Oil; Oil and gas fields; Oil field equipment; Oil fields; Oil recovery; Oil reservoirs; Permeability; Petroleum production; Polyacrylamide; polymer flooding; Polymers; Porous media; Propagation (polymerization); Reservoirs; Salinity tolerance; Salt tolerance; smart polymer; Surface water; Thermal stability; thermoviscosifying polymer; Viscosity; Water chemistry; Water flooding; Water soluble polymers; water-soluble polymer; water-soluble polymer; thermoviscosifying polymer; enhanced oil recovery; smart polymer; polymer flooding
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules26247468

Water-soluble polymers, mainly partially hydrolyzed polyacrylamide (HPAM), have been used in the enhanced oil recovery (EOR) process. However, the poor salt tolerance, weak thermal stability and unsatisfactory injectivity impede its use in low-permeability hostile oil reservoirs. Here, we examined the adaptivity of a thermoviscosifying polymer (TVP) in comparison with HPAM for chemical EOR under simulated conditions (45 °C, 4500 mg/L salinity containing 65 mg/L Ca and Mg ) of low-permeability oil reservoirs in Daqing Oilfield. The results show that the viscosity of the 0.1% TVP solution can reach 48 mPa·s, six times that of HPAM. After 90 days of thermal aging at 45 °C, the TVP solution had 71% viscosity retention, 18% higher than that of the HPAM solution. While both polymer solutions could smoothly propagate in porous media, with permeability of around 100 milliDarcy, TVP exhibited stronger mobility reduction and permeability reduction than HPAM. After 0.7 pore volume of 0.1% polymer solution was injected, TVP achieved an incremental oil recovery factor of 13.64% after water flooding, 3.54% higher than that of HPAM under identical conditions. All these results demonstrate that TVP has great potential to be used in low-permeability oil reservoirs for chemical EOR.