Solidification of Slag Mud Cake that Improves Cementation Quality of the Second Bonding Interface

Poor solidification of filter cake results in poor cementation quality of the second bonding interface (between filter cake and cement sheath). Technology for the solidification of slag mud cake is presented to try to improve the cementation quality of the second bonding interface. This technology is based on the characteristics of slag, which can be activated by alkali. Several studies have been conducted, including:effects of slag mud cake on the cementation performance of the second bonding interface; flushing fluid for this technology; and phase composition and functioning mechanism of filter cake inspected using XRD. The studies show that the slag mud cake solidification technology helps improve the cementation quality and the cementation morphology of the second bonding interface. The flushing fluid further improves the cementation quality. Slag mud cake, having the potential of being solidified, after penetration and pre-activation by the flushing fluid, exchanges matters with cement slurry. Both the slag mud cake and the cement during this course hydrate simultaneously, producing C-S-H gels which encapsulate and link solid particles and fill the spaces among cement particles, making the filter cake and cement sheath solidify as a whole. It has been proved that this technology, when used in combination with the designed flushing fluid, is beneficial to the improvement of the cementation quality of the second bonding interface. These studies are of importance to the use of inorganic gel materials in drilling fluids, especially the recycling of industrial wastes.