Barri Assad, Hassan Amjed, Mahmoud Mohamed
Petroleum Engineering Department, College of Petroleum Engineering & Geosciences, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia.
ACS Omega. 2022 Mar 1;7(10):8938-8949. doi: 10.1021/acsomega.1c07329. eCollection 2022 Mar 15.
Chelating agents' solutions were introduced as effective alternatives to strong acids to be used in acid-sensitive situations such as high temperature and salinity conditions. However, limited studies have been conducted to examine the optimum conditions for improving the chelating agent performance. In this study, a comprehensive study of solubility and physical properties of different chelating agents' fluids that are commonly used in the oil upstream applications was performed under different conditions. The optimum concentration ranges at which chelating agents are soluble and effective to provide the best acidizing efficiency are determined. Also, more than 340 data sets were used to develop new empirical models that can help in estimating the chelating agents' properties at wide ranges of concentrations and treatment temperatures. In this work, different experimental measurements were conducted using a pressure of 2000 psi (13.7 MPa) and a temperature of 120 °C (393.15 K). The conducted experiments are density and viscosity measurements, solubility experiments, interfacial tension measurements, computed tomography scan, and coreflooding tests. The used chelating agents are diethylenetriaminepentaacetic acid (DTPA), hydroxyethylenediaminetriacetic acid (HEDTA), and ethylenediaminetetraacetic acid (EDTA). Results revealed that HEDTA and DTPA chelating agents have good solubility at different pH and concentration ranges. However, EDTA showed a limited solubility performance, especially at a concentration greater than 15 wt %. Moreover, the developed correlations provided fast and reliable estimations for the chelating agent density and viscosity, and estimation errors of around 1% were achieved. Also, treating the tight carbonate rocks with the optimized chelating agent solutions showed effective wormholes with a minimum acid volume. Finally, a good match between the actual and predicted pressure drops is achieved, confirming the high reliability of the developed models. Overall, this work can help in designing the stimulation treatment by suggesting the optimum ranges for fluid concentration and solution pH for wide ranges of temperature. Also, the newly developed correlations can be used to provide quick and reliable estimations for the pressure drop and the chelating agent properties at reservoir conditions.
螯合剂溶液被引入作为强酸的有效替代品，用于诸如高温和高盐度等对酸敏感的情况。然而，为研究改善螯合剂性能的最佳条件所开展的研究有限。在本研究中，对上游石油应用中常用的不同螯合剂流体在不同条件下的溶解度和物理性质进行了全面研究。确定了螯合剂可溶解并有效提供最佳酸化效率的最佳浓度范围。此外，使用了340多个数据集来开发新的经验模型，这些模型有助于在广泛的浓度和处理温度范围内估算螯合剂的性质。在这项工作中，实验在2000 psi（13.7 MPa）的压力和120 °C（393.15 K）的温度下进行。所进行的实验包括密度和粘度测量、溶解度实验、界面张力测量、计算机断层扫描以及岩心驱替试验。所使用的螯合剂为二乙烯三胺五乙酸（DTPA）、羟乙二胺三乙酸（HEDTA）和乙二胺四乙酸（EDTA）。结果表明，HEDTA和DTPA螯合剂在不同的pH值和浓度范围内具有良好的溶解度。然而，EDTA的溶解性能有限，尤其是在浓度大于15 wt%时。此外，所建立的关联式能快速可靠地估算螯合剂的密度和粘度，估算误差约为1%。而且，用优化后的螯合剂溶液处理致密碳酸盐岩显示出有效孔洞，且酸体积最小。最后，实际压降与预测压降之间实现了良好匹配，证实了所开发模型的高可靠性。总体而言，这项工作有助于通过为宽温度范围内的流体浓度和溶液pH值建议最佳范围来设计增产处理。此外，新开发的关联式可用于在储层条件下快速可靠地估算压降和螯合剂性质。
