Experimental investigation on highly potent inhibitors of natural gas hydrate in oil-free flow system

Abstract

During the development of marine natural gas hydrates, the decomposed gas and water from the reservoir easily regenerate hydrate near the mudline, causing serious flow assurance risks. We put forward a scheme of compounding a new anti-agglomerant (NAA) suitable for oil-free systems with MEG, evaluated the effect of the compound inhibitor using the self-built flow pipeline and found the performance was positively correlated with the concentration of the two inhibitors alone. However, MEG must be injected in excess to have a good performance, and NAA has the promoting effect in hydrate formation. Simultaneously, we found for the first time that MEG and NAA show a dual relationship of synergy and competition under different proportioning schemes after the combination: when the proportioning of NAA and MEG is (0.01 ∼ 0.025): 10 wt%, the pipeline can maintain a long-term flow state, and the performance is better than that of the single agent. Outside the optimal range, the higher the concentration of NAA was, the worse the inhibition effect. We obtained the optimal proportioning of the two inhibitors, which can effectively reduce the dosage of MEG by more than 50%, and analyzed the mechanism of NAA as a single agent and its combination with MEG.