微生物-CMC无固相钻井液固壁作用与机理初探

Preliminary study on wall enhancing and mechanism of microbe-CMC solid-free drilling fluid

摘要:

松散破碎性地层孔壁失稳一直是困扰钻探工程界的难题之一，增强该类地层的胶结性，提高其力学性能是有效解决孔壁失稳的技术关键。本文将微生物诱导碳酸钙沉积（MICP）技术与CMC无固相钻井液相结合，构建微生物-CMC无固相钻井液体系。通过岩心浸泡实验、X射线衍射实验（XRD）以及扫描电镜分析两种微观分析手段对微生物-CMC无固相钻井液的固壁作用与机理进行了初探。结果表明：微生物-CMC无固相钻井液对松散破碎性地层具有较明显的加固作用，且作用时间越长，初始菌种浓度越高，钙源浓度越大，固壁效果越好。在固壁过程中，微生物随钻井液渗透进入试样内部，在松散颗粒之间诱导生成碳酸钙晶体，填充孔隙空间，将松散颗粒胶结成整体，并具有一定的力学强度，从而达到加固孔壁的目的。本研究结果为解决松散破碎性地层孔壁失稳提供了新的钻井液技术方案。

Abstract:

Hole wall instability in loose and fractured formations has always been one of the problems that plagued the drilling engineering community. Enhancing this type of formation and improving its mechanical properties are the technical keys to effectively solving the hole wall instability. In this paper， the microbially induced calcium carbonate deposition （MICP） technology is combined with the CMC solid-free drilling liquid phase to construct a microbial-CMC solid-free drilling fluid system. Through core immersion experiment， X-ray diffraction experiment （XRD）， and scanning electron microscopy， two microanalysis methods are used to explore the solid wall effect and microbial-CMC solid-free drilling fluid mechanism. The results show that the microbial-CMC solid-free drilling fluid has a more obvious reinforcement effect on loose and fractured formations. The longer the action time， the higher the initial bacterial concentration and the calcium source concentration， the better the wall-fixing effect. In the process of wall solidification， microorganisms penetrate the inside of the sample with the drilling fluid， induce calcium carbonate crystals between the loose particles， fill the pore space， cement the loose particles into a whole， and have a particular mechanical strength to achieve the reinforcement hole The purpose of the wall. The results of this study solve the problem of hole wall instability in loose and fractured formations and explore new drilling fluid technical solutions.