An autonomously self-gel-breaking, highly reservoir protective completion fluid tailored for gel-free processing in multi-lateral well construction

Abstract

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.