Cao Xiaoqin, Shi Yiwen, Li Wenzhi, Zeng Peiyun, Zheng Zhuo, Feng Yujun, Yin Hongyao
Polymer Research Institute, State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu 610065, China.
Sichuan University-Pittsburgh Institute, Sichuan University, Chengdu 610065, China.
ACS Omega. 2021 Sep 21;6(39):25421-25429. doi: 10.1021/acsomega.1c03394. eCollection 2021 Oct 5.
The increasing energy demand has prompted engineers to explore deeper wells where rich oil and gas reserves exist. However, the high-temperature and high-salt conditions have impeded the further application of traditional water-based fracturing fluids in such reservoirs. Therefore, it is urgent to develop fracturing fluids that are suitable for such geographic characteristics. In this study, for the first time, a novel synthetic polymer, poly-(acrylamide--acrylic acid--2-acrylamido-2-methyl-1-propanesulfonic acid) (P3A), was investigated as a rheological modifier for water-based fracturing fluids in high-temperature and high-salt conditions and compared with a guar gum system. Results showed that the apparent viscosity increased with increasing P3A and guar gum concentrations, and the thickening ability of P3A was much better than that of guar gum. Despite the better shear and temperature resistance and proppant suspension ability of guar gum fluids in high-temperature and saturated salt conditions, plentiful solid residues after gel-breaking have prevented their progress in the petroleum industry. P3A fluids have no residues, but the unsatisfying proppant suspension capability and high dosage encourage us to promote their rheological performance via interaction with an organic zirconium crosslinker. Infrared spectroscopy and scanning electron microscopy were applied to guarantee the successful reaction of P3A with the crosslinker. The subsequent investigation indicated that the transformed fracturing fluid exhibited remarkably improved thickening capability and satisfying rheological performance in terms of temperature and shear resistance and proppant-carrying ability as well as gel-breaking results in a high-temperature and saturated salt environment. All of the above results suggest the potential application of crosslinked P3A in hydraulic fracturing for the reservoirs with hostile conditions, and this article also provides a new orientation for synthetic polymers utilized in the oil and gas industry.
不断增长的能源需求促使工程师们去勘探更深的油井，这些油井蕴藏着丰富的油气资源。然而，高温和高盐条件阻碍了传统水基压裂液在这类油藏中的进一步应用。因此，开发适合此类地理特征的压裂液迫在眉睫。在本研究中，首次对一种新型合成聚合物聚（丙烯酰胺-丙烯酸-2-丙烯酰胺基-2-甲基丙烷磺酸）（P3A）作为高温高盐条件下水基压裂液的流变改性剂进行了研究，并与瓜尔胶体系进行了比较。结果表明，表观粘度随P3A和瓜尔胶浓度的增加而增大，且P3A的增稠能力远优于瓜尔胶。尽管瓜尔胶压裂液在高温饱和盐条件下具有较好的抗剪切和抗温能力以及支撑剂悬浮能力，但破胶后大量的固体残渣阻碍了它们在石油工业中的发展。P3A压裂液没有残渣，但支撑剂悬浮能力不理想且用量大，这促使我们通过与有机锆交联剂相互作用来改善其流变性能。采用红外光谱和扫描电子显微镜来确保P3A与交联剂成功反应。随后的研究表明，改性后的压裂液在高温饱和盐环境下，在增稠能力、抗温抗剪切性能、支撑剂携带能力以及破胶效果方面均表现出显著改善的流变性能。上述所有结果表明交联P3A在恶劣条件油藏水力压裂中的潜在应用价值，本文也为油气工业中合成聚合物的应用提供了新的方向。
