Study of Environmentally Friendly Wild Jujube Pit Powder as a Water-Based Drilling Fluid Additive.

The development of offshore oil and gas requires environmental protection during the drilling process. However, the existing drilling fluid additives cannot form an efficient environmentally friendly drilling fluid system. At the same time, some environmentally friendly drilling fluid additives cannot be widely used due to their high cost and complicated production process. In this paper, a natural material named wild jujube pit powder (WJPP) was used to improve the performance of the drilling fluid for the first time. The viscosity, shear force, shear thinning, rheology, filtration loss, and lubrication properties of the drilling fluid are discussed. By means of microstructure analysis, infrared spectroscopy, thermogravimetric analysis, and particle size analysis, the properties of WJPP and the drilling fluid system containing WJPP (i.e., rheological property, lubrication property, and filtration loss property) were studied. The results show that the microscopic appearance of WJPP was spherical, fibrous, block, and flake, the thermal decomposition temperature was 273.9 °C, and the suspension of WJPP was slightly acidic. WJPP can increase the viscosity, reduce the filtration loss, enhance the shear thinning and thixotropy, and reduce the lubrication coefficient of the drilling fluid. With the decrease in the particle size of WJPP, the shear thinning and thixotropy of the drilling fluid are enhanced, the viscosity and shear force increased, and the filtration loss and lubrication coefficient decreased. With the increase in the dosage, the shear thinning of the drilling fluid was enhanced, the filtration loss and coefficient of friction decreased, the viscosity and shear force increased, while the thixotropy did not change significantly. The microstructure test of mud cake showed that WJPP could form a grid structure. Combined with the blocking action of particles, the structure could prevent water molecules from passing through to reduce the filtration loss. WJPP can improve the rheological property, filtration property, and friction property of the drilling fluid, which has certain application prospects.