Laboratory research and application of high-temperature resistant oil-based drilling fluid
In response to the drilling and completion challenges in the third spudding section of the YJ3-X ultra-deep and highly deviated well,such as fracture development,high risk of lost circulation,long displacement in deviated well sections,difficulties in carrying sand,high friction torque,and prolonged downhole casing operations,the existing high-temperature resistant oil-based drilling fluid system in the laboratory are optimized.This optimization primarily involved enhancing the emulsifier.The simulations to assess potential well risks in a near-well complex scenario are conducted and the drilling fluid system's performance regarding anti-cuttings pollution and saltwater pollution are evaluated.The experimental results indicate that the optimized high-temperature resistant oil-based drilling fluid has excellent rheological properties,temperature resistance up to 180℃,demulsification voltage up to 1 366 V,high temperature and high pressure filtration loss as low as 2 mL,resistance to cuttings pollution up to 20%,resistance to CaCl2 brine pollution up to 30%,and settlement factor of 0.52 after standing for 120 h,which can meet the operation requirements of various complex downhole environments.Field applications further demonstrate that the optimized high-temperature resistant oil-based drilling fluid exhibits stable rheology,low viscosity,strong thixotropy,excellent borehole cleanliness,reduced friction during tripping and casing operations,and stable borehole wall.These attributes make it particularly well-suited to the operational needs of highly deviated deep wells in the YJ block.
ultra-deep and highly deviated welloil-based drilling fluidborehole cleaninganti-pollutionreducing friction
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