Liang Ke, Han Peihui, Chen Quansheng, Su Xin, Feng Yujun
Polymer Research Institute, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, P. R. China.
EOR Laboratory, Exploration & Development Research Institute, Daqing Oilfield Limited Company, PetroChina, Daqing 163712, China.
ACS Omega. 2019 Jun 19;4(6):10620-10628. doi: 10.1021/acsomega.9b00717. eCollection 2019 Jun 30.
The synthetic water-soluble polymer, partially hydrolyzed polyacrylamide (HPAM), has been most widely used for enhanced oil recovery (EOR); however, its poor thermal stability and weak salt tolerance impede further application in high-temperature and high-salinity oil reservoirs. To address such deficiencies, three polysaccharides, xanthan gum, diutan gum, and scleroglucan, were examined in comparison with HPAM on rheological behaviors, shearing resistance, long-term thermal stability, and core flooding test. It was found that all of these three polysaccharides were less sensitive to salinity and shearing time, while HPAM showed a monotonous decrease in viscosity with increasing monovalent cations and shearing history. After 90 days of aging at 85 °C and 10.1 × 10 mg·L of total dissolved solids with 1.0 × 10 mg·L of Ca, the viscosity of diutan gum and scleroglucan solutions nearly remained unchanged; on the contrary, the viscosity of xanthan gum and HPAM solutions drops massively. Core flooding tests at 85 °C with the same initial viscosity demonstrated that all polymers showed good transportation in porous media, and 16, 13, and 11% of oil recovery were obtained by diutan gum, scleroglucan, and xanthan gum, respectively, while only 10% was obtained from HPAM. These comparative results may underpin the potential of diutan gum and scleroglucan to be used in the EOR process in HTHS oil reservoirs.
合成水溶性聚合物部分水解聚丙烯酰胺（HPAM）已被最广泛地用于提高采收率（EOR）；然而，其较差的热稳定性和较弱的耐盐性阻碍了其在高温高盐油藏中的进一步应用。为了解决这些不足，对三种多糖，即黄原胶、迪坦胶和硬葡聚糖，与HPAM在流变行为、抗剪切性、长期热稳定性和岩心驱替试验方面进行了比较研究。结果发现，这三种多糖对盐度和剪切时间的敏感性均较低，而HPAM的粘度则随着一价阳离子浓度的增加和剪切历史的延长而单调下降。在85℃、总溶解固体含量为10.1×10mg·L且Ca含量为1.0×10mg·L的条件下老化90天后，迪坦胶和硬葡聚糖溶液的粘度几乎保持不变；相反，黄原胶和HPAM溶液的粘度大幅下降。在85℃下进行的具有相同初始粘度的岩心驱替试验表明，所有聚合物在多孔介质中均表现出良好的运移性能，迪坦胶、硬葡聚糖和黄原胶分别实现了16%、13%和11%的采收率，而HPAM仅实现了10%的采收率。这些对比结果可能为迪坦胶和硬葡聚糖在高温高盐油藏提高采收率过程中的应用潜力提供依据。
