Study on filter cake strengthening of STJ plant gum drilling fluid

Abstract:

Borehole wall collapse and other issues frequently occur during drilling in complex fractured formations. To prevent such accidents and improve core recovery， wireline coring drilling is commonly used， which requires solid-free drilling fluids with excellent anti-collapse performance. The STJ plant gum drilling fluid is an environmentally friendly solid-free drilling fluid； however， the filter cake formed by it is sparse， which fails to meet the requirements of borehole wall protection. Aiming at the problem of sparse filter cake of the STJ plant gum drilling fluid， this study took the STJ plant gum drilling fluid as the base fluid， combined with the ideal packing theory， and employed research methods such as laboratory experiments and microscopic analysis to optimize the selection of filling materials and their proportions， as well as to investigate the filter cake strengthening mechanism of the plant gum drilling fluid. Experimental results indicate that the solid-free drilling fluid formulated with 2% STJ+3% YT-1+2% YT-2+3% YT-3 exhibits a significant reduction in filtration loss. The filter cake formed by this drilling fluid is denser and flatter， and its borehole wall protection performance is greatly enhanced. Micron-sized filling materials form a dense filter cake through particle gradation， which is consistent with the ideal packing theory. This research provides an environmentally friendly and efficient solution for drilling in complex formations.