Additives for Kinetic Hydrate Inhibitor Formulations To Avoid Polymer Fouling at High Injection Temperatures: Part 1. A Review of Possible Methods

摘要

The main ingredient in kinetic hydrate inhibitor (KHI) formulations is a water-soluble polymer with both hydrophobic and hydrophilic moieties. Many of these KHI polymers have low cloud point (T-cl) and deposition point (T-dp) temperatures. T-dp is often not much higher than T-cl. The low T-dp value can cause unwanted polymer deposition when solutions of the polymers are injected into a hot aqueous well stream, especially high-salinity-produced fluids, which will impact the KHI performance. One way to overcome this problem is to copolymerize the active functional monomers with more hydrophilic monomers. However, this can often cause reduced KHI performance. Previous studies have shown that low T-cl for a polymer could be beneficial for the KHI performance if certain other criteria are met. In this part of our study, we review possible methods to raise the T-dp (and maybe also the T-cl) of a KHI polymer with low T-cl by formulating it with a second additive. The methods include the use of solvents, hydrotropes, classical surfactants, denaturants, osmolytes (antidenaturants), and polymeric dispersants. Some of these additives can also be synergists to boost the KHI performance. Parts 2 and 3 in this series will be reported shortly and will discuss experimental work using these methods, as well as the effect of the best additives on the KHI performance.