Study on Multi-scale Toughener for Oil Well Cement

Elastic-plastic cement exhibits significant advantages in coping with downhole alternating stress conditions. Although elastic materials represented by rubber powder and latex can significantly reduce the elastic modulus of cement stone and improve its toughness, they also significantly decrease its compressive strength. Fiber materials have a relatively small impact on the strength of cement stone while toughening it, but most fiber materials negatively affect the ash mixing rate and rheological properties of cement slurry, causing construction difficulties. This study adopts a “micro-meso-macro” material combination method, using inorganic nanotubes, whiskers, and ultra-short basalt fibers in a compound formulation to prepare a multiscale toughening material XEA. Mechanical evaluation shows that compared with ordinary cement stone, the elastic modulus of cement stone with XEA decreases by up to 23.7%, the compressive strength increases by up to 13.7%, and the tensile strength improves by 11.23%. Construction performance evaluation indicates that XEA has no negative effects on the rheological properties, fluid loss, and thickening properties of cement slurry, showing good application prospects.