Zhang Yanze, Ali Wajid, Dehghanpour Hassan
Department of Civil and Environmental Engineering, School of Mining and Petroleum Engineering, University of Alberta, Edmonton, Alberta T6G 2W2, Canada.
Gels. 2025 Feb 22;11(3):158. doi: 10.3390/gels11030158.
The petroleum industry seeks to optimize the reuse of flowback and produced water (FPW) in hydraulic fracturing to reduce environmental impacts and costs. This study investigates how controlling divalent cations in FPW influences its rheological properties and proppant carrying capacity, both of which are crucial for efficient fracturing. Synthetic FPW, modified to simulate treated and untreated conditions, was analyzed to determine the impact of gel-based additives such as anionic polyacrylamide-based friction reducers (FRs). Results indicate that removing divalent cations increases relaxation times from 0.12 s in untreated FPW to 1.00 s in a 1 gallon per thousand gallons (gpt) FR solution, demonstrating improved viscoelastic gel characteristics. However, these changes do not significantly increase proppant carrying capacity. Even with relaxation times increasing to 4.5 s at higher FR dosages (3 gpt), the treated FPW still does not achieve the relaxation time observed in FR solutions using deionized (DI) water, which remain above 10 s. The removal of divalent cations from FPW resulted in only minor changes to its shear viscosity, with a modest 15% increase that was not enough to significantly affect the settling velocity of the proppant. Thus, removal of divalent cations can positively influence rheological behavior; it does not necessarily improve proppant transport efficiency in hydraulic fracturing operations.
石油行业致力于优化水力压裂中返排液和采出水（FPW）的再利用，以减少环境影响和成本。本研究调查了控制FPW中的二价阳离子如何影响其流变特性和支撑剂携带能力，这两者对于高效压裂都至关重要。对经过改性以模拟处理和未处理条件的合成FPW进行了分析，以确定基于凝胶的添加剂（如阴离子聚丙烯酰胺基减阻剂（FRs））的影响。结果表明，去除二价阳离子会使松弛时间从未处理的FPW中的0.12秒增加到每千加仑1加仑（gpt）FR溶液中的1.00秒，表明粘弹性凝胶特性得到改善。然而，这些变化并未显著提高支撑剂携带能力。即使在较高的FR剂量（3 gpt）下松弛时间增加到4.5秒，处理后的FPW仍未达到使用去离子（DI）水的FR溶液中观察到的超过10秒的松弛时间。从FPW中去除二价阳离子仅使其剪切粘度发生微小变化，适度增加了15%，不足以显著影响支撑剂的沉降速度。因此，去除二价阳离子可以对流变行为产生积极影响；但不一定能提高水力压裂作业中支撑剂的输送效率。
