Experimental and kinetic modelling studies on the gas hydrate inhibition effect of PVP K-90 in drilling fluids

The hydrate inhibitors play a very important role in preventing hydrate growth inside the drilling fluid systems, which is desirable for smooth drilling operation. It has been demonstrated in several scenarios that the water-soluble polymer such as polyvinyl pyrrolidone (PVP K-90) efficiently reduces hydrate formation rates. In this study, the influence of on hydrate inhibition in predesigned drilling fluids in presence of a mixture gas of methane, ethane and propane has been investigated. As the concentration of the PVP K-90 increase, the induction time continues to increase. The rheological studies of drilling fluids conducted at different temperature and pressure condition with varying concentration of indicates their better performance. The chemical structure of polymer is a single 5-membered lactam ring attached to a carbon backbone which is responsible for the inhi-bition effect of the drilling fluid samples. The large concentration range tested allows unprecedented visuali-zation of the shifting of formation rate in compare to pure water. Hydrate formation rate appears to reduce as concentration of increases from 0.1 wt% to 0.7 wt%. The results suggest that increasing the concentration of the inhibitor up to 0.7 wt% may reach to a level that saturates all the growth sites and there are enough PVP K-90 molecules available to block the hydrate crystal growth, which significantly reduces the formation rate. The experimental investigation offers new understanding of the operational mechanics of kinetic hydrate inhibitor (KHI) in drilling operations.