Development and Application of Environment-Friendly Drilling Fluid GREEN-DRILL

Water based drilling fluid GREEN-DRILL has been developed to improve environmental performance of offshore drilling operation through the development of highly efficient eco-friendly plugging agent(GS),water based lubricant(GL),and soluble inhibitor(GG).Lab evaluation tests indicated that the basic properties of the GREEN-DRILL was stable,its inhibition performance was equivalent to that of glycol drilling fluid,the ratio of biochemical oxygen demand to chemical oxygen consumption was 67.5%,and the 72 h median lethal concentration was more than 60,000 mg/L with larva of Mongolia bare abdomen I age,higher than the permissible value of biological toxicity for levelⅠsea area in China,and meeting the national discharge standard.On the other hand,there was not oil film and black floatage in the surface of GREEN-DRILL diluents fluid.Field application in Bohai Oilfield showed that water based drilling fluid GREEN-DRILL could solve the problem of leakage and lost circulation,with stable properties and environment friendly performance.