Rectorite drilling fluid: high-temperature resistance for geothermal applications

Abstract

This study aims to resolve some existing limitations of geothermal drilling and exploration of high-temperature drilling fluid systems, such as complex formulation, inconvenient preparation, inappropriate selection of additives, unstable high-temperature performance, and high costs, through theoretical, experimental, and microstructural analysis. The slurry-making ability of several relevant clay minerals were theoretically analyzed based on their slurry-making performance and rheological behavior under various high-temperature environments (i.e., 180, 200, and 220 °C). Rectorite was selected as the appropriate slurry-making clay mineral and was modified organically using a single colloidal material (LP). In addition, suitable high-temperature additives were selected to improve the performance of the drilling fluid system by reducing filtration loss and preventing borehole collapse during geothermal drilling. The proposed drilling fluid system exhibited a simple system structure, excellent rheological performance under high temperatures, reduced filtration loss, and inhibitory and anti-pollution characteristics. The microstructure of rectorite was analyzed using x-ray diffraction, infrared spectrometry, and environmental scanning electron microscopy. It was verified that the microstructural mechanisms improved the temperature resistance of the drilling fluid system, thus helping to solve the critical problems in high-temperature geothermal well drilling and other production processes.