Study On High Temperature Water-in-oil Emulsion Drilling Fluid

In recent years,anti-high temperature oil-based drilling fluids used in deep well deilling have become a research hotspots at home and abroad.Among them,the study of anti-high temperature fluid loss additive and the oil-based drilling fluid composed of fluid loss agents as the core treatment agent are the most important.Although the foreign countries have anti-high temperature fliud loss additive,they are limited by technical secrets.Oil-based drilling fluid mainly uses bitumen and its derivative as fliud loss additive at home,the kind is single and solid content is high.Therefore,it is very urgent to study the polymer fliud loss additive and compose oil-based drilling fluid.Among them,the study of anti-high temperature fluid loss agents and the oil-based drilling fluid composed of fluid loss agents as the core treatment agent are the most important.Fluid loss additive which was the key treating agent in oil-based drilling fliud was mainly researched.Chosing eighteen alkyl two methyl allyl ammonium chloride(C18DMAAC)and styrene(St)as reactive monomers,using ammonium persul and sodium hydrogen sulfite fate as initiator by free radical polymerization,synthesizes a oil-based drilling fluid loss agent JFL-1.The optimal synthesis conditions of JFL-1 were determined by single factor experiment:the dosage of initiator is 4.0%,the monomer concentration is 40.0%,the monomer ratio of C-gDMAAC and St is 1:7,the reaction temperature is 60?,the reaction time is 6h,the dosage of crosslinking agent is 1.0%,the dosage of emulsifier is 4.0%.JFL-1 was characterized by infrared spectroscopy,molecular weight distribution and thermogravimetric analysis.The results showed that the molecular structure,morphology and the molecular weight of the synthesized product were in good agreement with the expected design.At the same time,evaluating temperature resistance and analysising mechanism.The results showed that JFL-1 can make the distribution of particles more uniform in the drilling fluid and form thin and dense filter cake,which can significantly reduce the filtration volume of drilling fluid and could be stable at 180?.On the base of JFL-1,by optimizing the oil-base drilling fluid with main and auxiliary emulsifier,organic soil,wetting agent,strpping agent and orther auxiliary agent and determining the oil-water ratio and the dosage of calcium oxide prepares a set of high temperature oil-wrapped water emulsion drilling fluid.The formula is diesel(0#)+ solution of 20%(?)CaCl2(the ratio of oil and water was 8 to 2)+ 3%main emulsifier MOEMUL + 3%auxiliary emulsifier MOCOAT + 3%fluid loss agent JFL-1 +3%organic soil EN-301 + 1%CaO + 1.5%wetting agent DF-FSWET + 0.5%?2%strpping agent TQ-1 + heavy stone.The formula can be used to prepare oil-based drilling fluid with a density range of 0.90 g/cm3 to 1.60 g/cm3 and could be stable at 160 ? and has good sedimentation stability and pollution resistance.