College of Chemistry and Chemical Engineering, Northeast Petroleum University, Daqing, 163318, Heilongjiang, China.
Department of Oil Field Chemistry, China Oilfield Services Ltd., Tianjin, 300450, China.
Sci Rep. 2021 Sep 22;11(1):18870. doi: 10.1038/s41598-021-98379-w.
Polymers are used widely in various kinds of drilling fluid to maintain the proper rheological properties. However, most of them are not available for high-temperature or salt solutions due to poor temperature and salt resistance. To ameliorate the temperature and salt resistance of polymer used in the solid-free water-based drilling fluid, a novel polymer with a kind of "Mesh-Lock" reinforced network cross structure, named PLY-F [main monomer acrylic acid (AA), acrylamide (AM), functional monomers 2-acrylamide-2-methylpropanesulfonic acid (AMPS) N-vinylpyrrolidone (NVP) and CDMAAC] were prepared through free radical polymerization of an aqueous solution of organic cross-linking agent pentaerythritol triallyl ether (PTE) as a cross-linking system, Potassium persulfate (KPS) and sodium bisulfite as the initiator for the first time. The surface morphology, crosslinking architecture and temperature and salt resistance of the PLY-F were fully characterized with several means including SEM, FT-IR, CNMR, dynamic rheology, and long-term thermal stability. The SEM observation indicated that the PLY-F exhibits a regular "Mesh-Lock" reinforced network cross structure. FT-IR, CNMR analysis indicated that the characteristic functional groups of each monomer such as AM, AA, AMPS and NVP were all together in the polymer. The results show that the apparent viscosity retention rate of the PLY-F in the potassium formate solution (with a density of 1.3 g/cm) was more than 80% after heat rolling for 72 h at 200 °C and the plastic viscosity retention rate reached 90.3%. Moreover, the salt resistance of the polymer can reach the density of 1.4 g/cm (potassium formate solution) under 200 °C and the temperature resistance can reach 220 °C under the density of 1.3 g/cm (potassium formate solution). Besides, the PLY-F still has good rheological properties in other saturated solutions (NaCl, HCOONa) under 210 °C.
聚合物被广泛用于各种钻井液中，以保持适当的流变性能。然而，由于耐温耐盐性差，大多数聚合物不适用于高温或盐溶液。为了改善无固相水基钻井液中聚合物的耐温耐盐性，首次通过有机交联剂季戊四醇三烯丙基醚（PTE）水溶液中的自由基聚合，制备了一种新型聚合物，具有一种“网锁”增强网络交联结构，命名为 PLY-F[主要单体丙烯酸（AA）、丙烯酰胺（AM）、功能单体 2-丙烯酰胺-2-甲基丙磺酸（AMPS）、N-乙烯基吡咯烷酮（NVP）和 CDMAAC]。过硫酸钾（KPS）和亚硫酸氢钠作为引发剂。通过 SEM、FT-IR、CNMR、动态流变学和长期热稳定性等多种手段对 PLY-F 的表面形貌、交联结构和耐温耐盐性进行了充分表征。SEM 观察表明，PLY-F 呈现出规则的“网锁”增强网络交联结构。FT-IR、CNMR 分析表明，聚合物中存在 AM、AA、AMPS 和 NVP 等各单体的特征官能团。结果表明，在 200°C 下热滚 72 h 后，PLY-F 在甲酸钾溶液（密度为 1.3 g/cm）中的表观粘度保留率超过 80%，塑性粘度保留率达到 90.3%。此外，聚合物的耐盐性可达到 1.4 g/cm（甲酸钾溶液）的密度，在 1.3 g/cm（甲酸钾溶液）的密度下，耐温性可达 220°C。此外，在 210°C 下，PLY-F 在其他饱和溶液（NaCl、HCOONa）中仍具有良好的流变性。
