Modification and Application of Waste Shaddock Peel as a Green Additive for Water-Based Drilling Fluid

To develop an eco-friendly drilling fluid additive, shaddock peel was modified and was used in waterbased drilling fluid in this work. The shaddock peel has obvious effects on rheological properties, filtration, and wall formation of drilling fluid. It also displays the inhibition of clay swelling, while the shaddock peel slurry is easy to ferment, mildew and so on. The performance of the shaddock peel slurry and moldy/fermented shaddock peel slurry in water-based drilling fluid were compared, which shows that the efficiency, such as the AV and PV, decrease obviously by more than 50%. The swelling rate of bentonite in the water extraction of moldy/fermented shaddock peel in 90 min is about 62%, which is obviously higher than the swelling rate of the non-mildew/fermented shaddock peel water extract, 46%. Then preservative was evaluated in shaddock peel slurry modified drilling fluid. The result indicates that the effect of moldy/fermentation on the viscosity and the inhibition of shaddock peel was obviously inhibited by the preservative. The combined sodium benzoate and formaldehyde can protect the shaddock peel slurry from mildew and fermentation, which can keep the performance of shaddock peel slurry in the drilling fluid.