Experimental study on constant rheology water-based drilling fluids with different types of base slurries

With increasing seawater depth, the temperature progressively decreases, reaching approximately 4°C at significant depths at the seabed mud line. In such low-temperature conditions, the viscosity and shear force of the drilling fluid experience a considerable increase. Conversely, during drilling operations with circulation, the temperature of the drilling fluid in the riser pipe rises, leading to a reduction in viscosity. The key component in marine deepwater water-based drilling fluids is the base slurries, which is primarily responsible for enhancing viscosity and shear, reducing fluid loss, and ensuring wellbore integrity and wall construction. The preparation of the drilling fluid involves initially mixing the base slurries with water in a predetermined ratio to create a base slurry, to which various treatment agents are subsequently added. It is essential to maintain the stability of the base slurry&s;s rheological properties within a temperature range of 4°C to 65°C to ensure the constant rheology of marine deepwater water-based drilling fluids.