Ammonolysis Modified Soybean Lecithin as a Drilling Fluid Lubricant

Soybean lecithin is a derivative of difatty acid glycerophospholipid, whose molecular structure is rich in lubricant adsorption groups, such as phosphate group, hydroxyl and amino group. The difatty acid glyceride in the molecule of the difatty acid glycerophospholipid has very strong hydrophobicity and very low dispersity, makes it difficult to act as a drilling fluid lubricant. By heating the mixture of soybean lecithin, alcohol amine, catalyst and mineral oil dispersant, these chemicals react to produce a modified phospholipid lubricant. The working mechanisms of the ammonolysis (by alcohol amine) modified soybean lecithin was studied with IR and PNMR. The ammonolysis modified soybean lecithin lubricant was tested to determine their performance as a drilling fluid. In the test, the lubricity, high temperature stability, salt and calcium resistance of the new lubricant were compared with those of the other commercially available lubricants. The new lubricant was also tested for its compatibility with the polymer sulfonate drilling fluid and its ability to improve the lubricity of the drilling fluid. The optimum amount of alcohol amine used in the ammonolysis process was determined to be 10%-25%. The alcohol amine can be used to ammonolyze the fatty acid ester in the soybean lecithin to form fatty amide, thereby reducing the content of hydrophobic fatty chain in the soybean lecithin and enhancing its water dispersity. The hydroxyl formed during the ammonolysis can react with the ionic phosphate to form pentacyclic phosphate through lactonization reaction, and the ionic phosphate is thus masked. The modified soybean lecithin lubricant developed has excellent lubricating capacity, good high-temperature resistance, good salt- and calcium-resistance, as well as good compatibility with many water based drilling fluids, making it a potential high performance drilling fluid lubricant.