Study on Constant Rheologic Characteristics of Deepwater Synthetic-based Drilling Fluid

With the characteristics of its unique environmental performance,high mechanical drilling speed and borehole stability,synthetic-based drilling fluid has become a commonly used drilling fluid system for offshore oil and gas drilling internationally.In deep water drilling,temperature was changed significantly,this had enormous demands for the rheology of drilling fluids.The rule of influence of synthesis base fluid,organic clay,fluid loss additive and O/W ratio on HMS synthetic-based drilling fluid was studied,and it was compared with that of traditional synthetic-base drilling fluid.The results reveal that the flowability of drilling fluid prepared with low kinematic viscosity of linear alpha olefin(LAO) and special oil is better than that of ester-base drilling fluid.Organic clay and O/W ratio have obvious effects on HMS synthetic-base drilling fluid,while fluid loss additive has a weak affect.Compared with traditional synthetic-base drilling fluid,the rheology of HMS synthetic-base drilling fluid is temperature independent,and its yield point(4℃)/yield point(65℃) is lower than 1.15,it presents good low temperature flowability,it is more suitable for offshore deepwater drilling.