Multi-lateral well construction is in high demand in both petroleum industrial and commercial sectors. Compared with the traditional gel-breaking fluids used in multi-lateral well completion, autonomously self-gel-breaking completion fluids in a certain downhole environment have specific challenges in development and performance. In this work, focus was on self-gel-breaking capacity demonstrating controllably heat-triggered self-degradation of rheological modifier involved in the newly constructed completion fluid. The self-degradation strategy was first analyzed for the fundamental polymeric additives, and then xanthan gum with a high pyruvate content, as the most crucial rheological additive, was provided of special conformational transition from helix to lattice structure due to sidechain mutual repulsion effect, in combination to tests of advanced technologies such as molecular weight, infrared spectroscopy, dynamic viscosity, elastic modulus, and micromorphology. This facile strategy can be applicable for the control of xanthan thermal degradability that directly responses to self-gel-breaking capability of completion fluid. Finally, several key performance such as reservoir protection and self-gel-breaking capability for the newly developed completion fluid were evaluated to validate its promising gel-free application in the construction of multi-lateral wells.

石油工业和商业部门对多分支井建设的需求量很大。与传统的多分支完井液破胶液相比，一定井下环境下的自主自破胶完井液在开发和性能上都面临着特殊的挑战。在这项工作中，重点是自破胶能力，展示了在新建完井液中涉及的流变改性剂的可控热触发自降解。首先分析了基础聚合物添加剂的自降解策略，然后作为最关键的流变添加剂，具有高丙酮酸含量的黄原胶，由于侧链互斥作用，提供了从螺旋结构到晶格结构的特殊构象转变，结合分子量、红外光谱、动态粘度、弹性模量和微观形貌等先进技术的测试。这种简便的策略可用于控制直接响应完井液自破胶能力的黄原胶热降解性。最后，对新开发的完井液的储层保护和自破胶能力等几个关键性能进行了评估，以验证其在多分支井建设中的无凝胶应用前景。