Abstract
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 Ca2+ and Mg2+) 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.
Highlights
Crude oil is a leading fuel source, and provides feedstocks for synthetic polymers
The thickening power in both synthetic fresh brine and synthetic produced fluids, the temperature dependence of the viscosity, the long-term thermal stability, transportation properties, and enhanced oil recovery efficiency of the thermoviscosifying polymer (TVP) were examined in comparison with currently used hydrolyzed polyacrylamide (HPAM) with a similar molecular weight
These results demonstrate that TVP has much stronger thermothickening power than HPAM under the condition of the type III oil layers in Daqing Oilfield
Summary
Crude oil is a leading fuel source, and provides feedstocks for synthetic polymers. Some inorganic salts, mainly K2CO3, are always needed to tune the thermoassociation temperature of TVPs that contain poly(ethylene oxide) (PEO) as side chains [13,14,15,16,17] These drawbacks limit the large-scale manufacturing of TVPs and hinder the acceptance of petroleum engineers, who always desire less expensive, low-dosage, and high-molecular-weight WSPs for EOR use. The thickening power in both synthetic fresh brine and synthetic produced fluids, the temperature dependence of the viscosity, the long-term thermal stability, transportation properties, and enhanced oil recovery efficiency of the TVP were examined in comparison with currently used HPAM with a similar molecular weight
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
