Othman Amro, Aljawad Murtada Saleh, Kamal Muhammad Shahzad, Mahmoud Mohamed, Patil Shirish, Alkhowaildi Mustafa
Department of Petroleum Engineering, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia.
Center for Integrative Petroleum Research, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia.
ACS Omega. 2022 Aug 24;7(35):31318-31326. doi: 10.1021/acsomega.2c03606. eCollection 2022 Sep 6.
Freshwater is usually used in hydraulic fracturing as it is less damaging to the formation and is compatible with the chemical additives. In recent years, seawater has been the subject of extensive research to reduce freshwater consumption. The study aims to optimize the rheology of seawater-based fracturing fluid with chemical additives that reduce the formation damage. The studied formulation consists of a polymer, a crosslinker, and a chelating agent to reduce seawater hardness. We used a standard industry rheometer to perform the rheology tests. By comparing five distinct grades [hydroxypropyl guar (HPG) and carboxymethyl hydroxypropyl guar (CMHPG)], we selected the guar derivative with the best rheological performance in seawater. Five different polymers (0.6 wt %) were hydrated with seawater and freshwater to select the suitable one. Then, the best performing polymer was chosen to be tested with (1.6, 4, and 8 wt %) , -dicarboxymethyl glutamic acid GLDA chelating agent and 1 wt % zirconium crosslinker. In the first part, the testing parameters were 120 °C temperature, 500 psi pressure, and 100 1/s shear rate. Then, the same formulations were tested at a ramped temperature between 25 and 120 °C. We observed that higher and more stable viscosity levels can be achieved by adding the GLDA after polymer hydration. In seawater, an instantaneous crosslinking occurs once the crosslinker is added even at room temperature, while in freshwater, the crosslinker is activated by ramping the temperature. We noted that, in the presence of a crosslinker, small changes in the chelating agent concentration have a considerable impact on the fluid rheology, as demonstrated in ramped temperature results. It is observed that the viscosities are higher and more persistent at lower concentrations of GLDA than at higher concentrations. The study shows the rheological response when different chemical additives are mixed in saline water for hydraulic fracturing applications.
由于淡水对地层的损害较小且与化学添加剂相容，因此在水力压裂中通常使用淡水。近年来，海水已成为减少淡水消耗的广泛研究对象。该研究旨在通过使用减少地层损害的化学添加剂来优化海水基压裂液的流变学性能。所研究的配方由一种聚合物、一种交联剂和一种螯合剂组成，以降低海水硬度。我们使用标准的工业流变仪进行流变学测试。通过比较五种不同等级的[羟丙基瓜尔胶（HPG）和羧甲基羟丙基瓜尔胶（CMHPG）]，我们选择了在海水中流变性能最佳的瓜尔胶衍生物。将五种不同的聚合物（0.6重量%）与海水和淡水进行水合，以选择合适的聚合物。然后，选择性能最佳的聚合物与（1.6、4和8重量%）的二羧甲基谷氨酸（GLDA）螯合剂和1重量%的锆交联剂一起进行测试。在第一部分中，测试参数为120℃温度、500 psi压力和100 1/s剪切速率。然后，在25至120℃的升温温度下对相同的配方进行测试。我们观察到，在聚合物水合后添加GLDA可以实现更高且更稳定的粘度水平。在海水中，即使在室温下添加交联剂也会立即发生交联，而在淡水中，交联剂通过升温来激活。我们注意到，在存在交联剂的情况下，螯合剂浓度的微小变化对流体流变学有相当大的影响，如升温温度结果所示。可以观察到，在较低浓度的GLDA下，粘度比在较高浓度下更高且更持久。该研究展示了在盐水用于水力压裂应用时，不同化学添加剂混合后的流变学响应。
