| abstract |
Lubricating additives for drilling fluids are prepared from semi-solid highly viscous and/or high molecular weight lubricants, such as polyalkylenes (e.g., polybutene), by steam jet cooking a mixture of starch, water, and the lubricant in order to uniformly suspend micrometer-sized lubricant droplets in an aqueous starch matrix. These additives avoid the need for toxic emulsifiers, surfactants, or short-chain hydrocarbon solvents for dispersing the lubricants. They impart lubricity to drilling fluids (muds) and also inhibit fluid loss in geological formations by enhancing the filtration control properties of the fluid. |