Water-Based Drilling Mud (WBM)
Definition - What does Water-Based Drilling Mud (WBM) mean?
Water-based drilling mud (WBM), otherwise known as water-based drilling fluid, has freshwater or saltwater as its major mixing medium, unlike oil-based drilling fluid in which oil is the major mixing medium. Additives such as polymers are added to change the density, viscosity, control circulation loss, and other parameters as required for the project.
WBMs are cheap and environmentally friendly. Drilling fluids are an important part of a trenchless pipeline installation project and is customized to the prevalent ground conditions in the path of the bore, requiring extensive geotechnical and soil investigation before arriving at the correct mix of additives.
Trenchlesspedia explains Water-Based Drilling Mud (WBM)
The primary constituent of drilling fluid is water, and additives constitute only about 3-4%. The quality of water will also affect the final drilling mud because water has to be sourced from creeks, rivers or the city. Additives will be more effective when the pH of the water on the pH scale is between 8.5 and 9.5; calcium content should be below 100 parts per million (ppm).
The main constituent of drilling fluid is bentonite which is a mineral found in clay beds. When combined with water it forms a cake-like texture that helps seal the borehole walls, preventing the drilling fluid from escaping through crevices in the borehole wall leading to frac-out.
The support provided by the slurry also keeps the borehole from collapsing.