Water Based Mud Additives

Drilling muds are mainly divided into two categories: water-based muds (WBM) with water as the continuous phase and oil-based muds (OBM) with oil as the continuous phase. Oil-based muds use crude oil or refined hydrocarbons (such as diesel) as the continuous phase and are thickened by hydrophobically modified bentonite. Compared with water-based muds, oil-based muds perform well in terms of lubricity and reduced fluid loss, but the toxicity of its base fluid needs to be paid attention to.

Water-based muds use water as the continuous phase, and achieve thickening by adding bentonite or polymers, and increase density by dissolving salts or dispersing inorganic minerals of a specific particle size (such as barium sulfate) to balance the pressure of the formation fluid and prevent mud contamination. Due to the low cost of water-based fluids, water-based muds are usually the first choice when performance requirements are met. In the past, water-based muds were mainly used in low-temperature environments because they had poor rheological stability and high fluid loss under high temperature conditions. However, with the development of additives that can maintain stability at high temperatures, water-based muds can now be used in extreme drilling environments. From an environmental perspective, water-based muds are a better choice because their ingredients are relatively less toxic.