High-temperature resistant oil-based drilling fluid system for leakage prevention and plugging based on temperature-sensitive rheology modifier

To address the challenges of the oil-based drilling fluid system’s deteriorating rheological properties and insufficient plugging pressure resistance under high-low temperature cycling conditions in the Yaha gas storage reservoir drilling, a temperature-sensitive high-temperature thickener, RHT, was developed. Optimized plugging materials and supporting agents were selected to construct a high-temperature resistant oil-based drilling fluid system. Characterization methods, including infrared spectroscopy, nuclear magnetic resonance hydrogen spectra, thermogravimetric analysis, and differential scanning calorimetry (DSC), were used to analyze RHT’s molecular structure, thermal stability, and temperature-sensitive characteristics in depth. The systematic evaluation of its rheological control in emulsions and oil-based drilling fluids was conducted. Experimental results showed that RHT significantly improved the shear-thinning and thixotropic properties of the emulsion, demonstrating excellent rheological control capabilities under high-low temperature cycling conditions. At 80 ℃, the dynamic yield stress increased by 87% without any increase in plastic viscosity; at 220 ℃, the dynamic yield stress increased by 220%, with a dynamic plastic ratio of 0.49 Pa/(m Pa·s). The drilling fluid system maintained strong rock-carrying capacity after aging at 220 ℃ and effectively sealed 20~40 mesh sand beds and 1~3 mm cracks, achieving a maximum pressure resistance of 8 MPa. In the field application of the Yaha gas storage reservoir well X, this system significantly enhanced the rock-carrying and plugging performance of the drilling fluid, reducing complexities such as fluid loss and stuck pipe incidents, thereby providing strong technical support for the efficient development of the Yaha gas storage reservoir.