Experimental study on the inhibition of hydrate decomposition by drilling fluid treatment agents
The impact of conventional drilling fluid treatment agents on hydrate decomposition was ana-lyzed,and the inhibition of hydrate decomposition by different inhibitors was evaluated.Two types of effi-cient hydrate decomposition inhibitors were selected and their mechanisms of action were explored.The results indicate that conventional drilling fluid treatment agents exhibit a certain degree of inhibition of hy-drate decomposition,among which XC has the strongest inhibitory effect on hydrate decomposition,exten-ding the hydrate decomposition time by 21.9％.There is a good linear positive correlation between the decomposition time of hydrates and the apparent viscosity,with a correlation coefficient R2 greater than 0.95.The polyvinylcaprolactam(PVCap)composite product and antifreeze protein were selected to have good hydrate decomposition inhibition effects,with a delay rate of 97.3％and 66.6％.The oxygen atoms in the PVCap seven membered ring structure are prone to hydrogen bonding with water molecules on the surface of the hydrate,forming a stable cage like structure on the surface of the hydrate crystal nucleus.A large number of seven membered rings adsorb to form a layer of coating film,weakening the mass and heat transfer effects brought by external fluids.Antifreeze proteins adsorb to the surface of hydrates through hy-drogen bonding and hydrophobic interactions,reducing the surface area of hydrates and increasing the re-sistance of external fluids to mass and heat transfer to the surface,thereby delaying the decomposition of hydrates.The viscosity effect of commonly used drilling fluid treatment agents on hydrate decomposition inhibition and the two selected high-efficiency hydrate decomposition inhibitors can provide drilling fluid technical support for hydrate formation drilling.
drilling fluiddrilling of hydrate formationshydrate decomposition inhibitor
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