Preparation of Microsphere β-cyclodextrin Polymer Filter Loss Reducer for Drilling Fluids

Aiming at the problem of the failure of the environmental-friendly filtration agent at high-temperature, β-cyclodextrin polymer microspheres with β-cyclodextrin as raw materials and ECH as cross-linker were synthesized by inverse emulsion polymerization. Infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, particle distribution and other test methods were used to characterize the structure of the product and evaluate the high-temperature filtration performance. It showed that β-cyclodextrin polymer microspheres have a uniform particle size and good sphericity, with an average particle size of 42.88 μm, and thermal stability is significantly better than β-cyclodextrin. After hot rolling at 180 and 200 ℃, it can effectively reduce the filtration loss of bentonite base slurry, which is better than the typical high-temperature filtration agent. After 200 ℃ hot rolling, the high-temperature and high-pressure filtration loss effect is outstanding. In addition, β-cyclodextrin polymer microspheres have little effect on the rheological properties of drilling fluids. β-cyclodextrin polymer microspheres can absorb a large number of water molecules to form deformable elastic microspheres, reduce the free water of the system, and improve the compressibility of mud cakes. More importantly, β-cyclodextrin polymer microspheres are partial degraded at high temperatures, generating nanoparticles, plugging mud cake pores, and effectively reduce filtration loss. β-cyclodextrin polymer microspheres have excellent high-temperature filtration loss performance, unique mechanism, and show good application prospects.