Research on the Influence of CaCO3 Nanoparticle Surface Characteristics on the Performance of Water-Based Drilling Mud

Abstract

Currently, water-based drilling mud used in the drilling process face many issues regarding formation protection and maintaining wellbore stability. A solution to these problems is the addition of nanoparticles to water-based drilling mud, which can improve the fluid loss properties of the drilling mud and reduce formation damage. However, the influence of the different surface properties of nanoparticles on drilling mud is not yet clear. Therefore, the purpose of this study is to investigate the effect of nanoparticle surface properties on the fluid loss of drilling mud and their impact on formation permeability. CaCO3 nanoparticles were used as the characterization material for the drilling mud, and their surfaces were modified with silane coupling agents. Under conditions of an overburden pressure of 19.84 MPa, pore pressure of 6.47 MPa, overbalance pressure of 3.39 MPa, and temperature of 57°C, the fluid loss of different drilling mud and their impact on formation permeability were analyzed. The results showed that non-functionalized CaCO3 nanoparticles, γ-glycidyl ether oxypropyl trimethoxysilane functionalized CaCO3 nanoparticles, and 3-methacryloyloxypropyl trimethoxysilane functionalized CaCO3 nanoparticles reduced the mud loss of the drilling mud by approximately 15%, 37%, and 40%, respectively. After injecting conventional water-based drilling mud and drilling mud with non-functionalized CaCO3 nanoparticles into the core, the core permeability decreased by 50% and 46%, respectively. In contrast, after adding γ-glycidyl ether oxypropyl trimethoxysilane and 3-methacryloyloxypropyl trimethoxysilane functionalized CaCO3 nanoparticles, the core permeability only decreased by 22% and 17%, respectively. This indicates that nanoparticles can reduce the damage caused by drilling mud to the formation, with the surface properties of the nanoparticles having the greatest impact.