A Solidifying Mud Loss Control Slurry for Well Drilling in Coal Mine Goafs

A new solidifying mud loss control slurry has been developed for use in well drilling in coal mine goafs where severe mud losses were frequently encountered. The mud loss control slurry is formulated with slag as the solidifying agent, and other additives such as activator and suspending agent etc. This mud loss control slurry has the ability to satisfy the needs of plugging and solidifying when drilling in coal mine goafs characteristic of low density and low temperature. The hydrational mechanism of the mud loss control slurry was verified through laboratory evaluation and micro-structure examination. Under the action of the activator, the vitreous structure of the solidifying agent is broken down, producing various hydrational products. Part of the calcium-rich phase leaves the original structure and fills in the pores of the hydrational products. On the other hand, as the silica-rich phase continues to become hydrated, the hydrational products are filling in the pores of the hydrational product of the calcium-rich phase, thereby making the hydrational products denser and denser. The hydrational products are mainly C—S—H and C—A—S—H gels, rendering the solidified product high compressive strength. Data from simulation tests and field tests have proved that the solidifying mud loss control fluid is able to satisfy the needs of mud loss control in coal mine goafs, and the goal of studying on the mud loss control in coal mine goafs is achieved.