Research And Evaluation Of Environmental Protection Synthetic Drilling Fluid System

Environment-friendly compound drilling fluid is a kind of ester-based drilling fluid.The drilling fluid system is made by mixing self-made corn oil biodiesel and isopropyl oleate as the base fluid in a certain proportion and through the optimization of each treatment agent.This kind of drilling fluid has similar properties to oil-based drilling fluid,the base fluid is non-toxic and degradable,and the toxicity of the prepared drilling fluid system conforms to the toxic allowable value of pollutants in offshore oil exploration and development,and has good degradability,and has broad application prospects.In this paper,the formulation of environmental protection synthetic base drilling fluid system is developed and optimized by using oilfield chemistry knowledge and drilling fluid process principle.On the basis of the self-made biodiesel and the determination of related properties,the defect of low temperature fluidity of biodiesel was analyzed,and this problem was solved.The mixture was mixed with isopropyl oleate,and the mixture was used as the base fluid of environment-friendly synthetic base drilling fluid.Optimize the treatment agent compatible with it and determine its optimal dosage.The final basic formula is:V（synthetic base solution）:V（25%Ca Cl₂ aqueous solution）=90:10+2%emulsifier 5+3%auxiliary emulsion 1+25%Ca Cl₂ solution+1%Ca O+1%1#organic soil+2%2#wetting agent+1%3#stripping agent+2%organic lignite+1%oxidized asphalt+2%OSD-2+barite.The optimized drilling fluid system has a temperature resistance of 180℃and a density upper limit of 2.2 g/cm³.Based on the existing experimental conditions,the related properties of the optimized environmental protection synthetic base drilling fluid system were evaluated.The experimental results show that the drilling fluid system has a low density and is suitable for underbalanced or low-pressure formation drilling operations.Environment-friendly synthetic base drilling fluid system can resist 10%clean water and 15%inferior soil.Its lubrication performance is better than that of white oil based drilling fluid.The reservoir protection performance is inferior to white oil-based drilling fluid.The biodegradation rate of environmental protection synthetic drilling fluid system is relatively high,and the biological toxicity meets the allowable value of Marine pollutant discharge standard.Due to its superior environmental performance,it is worthy of further study and extensive promotion.Based on the theory,the environmental protection synthetic base drilling fluid system is systematically analyzed and discussed.The shortcomings of ester based drilling fluid are suggested and its application prospect is forecasted.