Salt contamination has become the most critical challenge faced by water-based drilling fluids (WDFs) under extreme salinity and high temperatures, which deteriorates rheology and fluid loss properties, causing drilling accidents such as leakage, formation collapse and borehole instability. Herein, we report a salt-responsive zwitterionic polymer (PAMN) and its novel application as a tackifier in brine drilling fluid exploiting the anti-polyelectrolyte effect, in which the zwitterionic polymer molecular chain has undergone a transformation from a collapsed small spherical shape to an extended chain shape corresponding to the increasing ionic strength of the electrolyte. Compared with the saturated brine drilling fluid, the apparent viscosity and plastic viscosity of the saturated brine drilling fluid dispersed with PAMN increased by 542.9% and 925% respectively owing to the charge interaction on the molecular chain of PAMN was shielded by sodium chloride electrolyte, which resulted in the increase of the radius of gyration (Rg) of the PAMN molecular chain. Additionally, the salt response mechanism of zwitterionic polymer PAMN had been revealed by molecular simulation technology, which simulated the radius of gyration, radial distribution function (RDF), mean square displacement (MSD) and energy of molecular chain in water and salt water, respectively. This work demonstrates that the approach can be extensively generalized to a large class of synthetic zwitterionic polymers and can promote the development of various salt-responsive intelligent drilling fluids.

盐分污染已成为极端盐度和高温下水基钻井液（WDF）面临的最关键挑战，这会破坏流变性和流体损失特性，从而导致钻井事故，例如泄漏，地层塌陷和井眼不稳定。在这里，我们报道了盐反应性两性离子聚合物（PAMN）及其在盐水钻井液中作为增粘剂的新应用，它利用了反聚电解质的作用，其中两性离子聚合物分子链经历了从塌陷的小球形到环状延长链的形状，对应于电解质不断增加的离子强度。与饱和盐水钻井液相比，PAMN分散的饱和盐水钻井液的表观粘度和塑性粘度增加了542。PAMN分子链上的电荷相互作用分别使9％和925％被氯化钠电解质所屏蔽，这导致PAMN分子链的回转半径（Rg）增大。此外，通过分子模拟技术揭示了两性离子聚合物PAMN的盐反应机理，该技术分别模拟了水和盐水中分子的回转半径，径向分布函数（RDF），均方位移（MSD）和分子链能量。 。这项工作表明，该方法可以广泛地推广到一大类合成两性离子聚合物，并可以促进各种盐敏感型智能钻井液的开发。这导致PAMN分子链的回转半径（Rg）增大。此外，通过分子模拟技术揭示了两性离子聚合物PAMN的盐响应机理，该技术分别模拟了水和盐水中分子的回转半径，径向分布函数（RDF），均方位移（MSD）和分子链能量。 。这项工作表明，该方法可以广泛地推广到一大类合成两性离子聚合物，并可以促进各种盐敏感型智能钻井液的开发。这导致PAMN分子链的回转半径（Rg）增大。此外，通过分子模拟技术揭示了两性离子聚合物PAMN的盐响应机理，该技术分别模拟了水和盐水中分子的回转半径，径向分布函数（RDF），均方位移（MSD）和分子链能量。 。这项工作表明，该方法可以广泛地推广到一大类合成两性离子聚合物，并可以促进各种盐敏感型智能钻井液的开发。径向分布函数（RDF），均方位移（MSD）和分子链在水和盐水中的能量。这项工作表明，该方法可以广泛地推广到一大类合成两性离子聚合物，并可以促进各种盐敏感型智能钻井液的开发。径向分布函数（RDF），均方位移（MSD）和分子链在水和盐水中的能量。这项工作表明，该方法可以广泛地推广到一大类合成两性离子聚合物，并可以促进各种盐敏感型智能钻井液的开发。