Development and Application of Acid-Resistant Polymer Wellbore Working Fluid System Suitable for CCUS Drilling
During the establishment of the CCUS demonstration zone in FS oilfield,most wells encountered high CO2 gas layers during drilling,resulting in severe acid gas pollution of the drilling fluid,poor rheological properties,thick mud cake,and high resistance rate in electrical logging.When the polymer bentonite drilling fluid currently used is subjected to carbonate and bicarbonate ions,the viscosity shear force increases sharply and the water loss is not controlled,resulting in a mud cake with a maximum thickness of 4 mm and a high risk of sticking.To solve this problem,the acid radical resistant polymer drilling fluid system was formed by optimizing the anti HCO3-and CO32-polymer fluid loss additives and coating agents,optimizing the content of bentonite,strengthening the inhibition of drilling fluid,and changing the drilling fluid system from a moderately dispersed system to a non dispersed system.The system's acid radical resistant,strong inhibition,strong gel protection,low transport content and excellent thixotropy of polymer solved the problem of poor high-temperature rheology,poor stability,strong structural force after a long period of standstill leads to technical difficulties such as difficulty in starting the pump,reducing the risk of underground construction and improving the safety guarantee ability of drilling fluid.
Acid-resistant wellbore working fluidPolymerRheological property
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