The Return of Kinetic Hydrate Inhibitors

Kinetic hydrate inhibitors (KHIs) have been serving the petroleum industry for many years. They are normally used at dose rates of <3% of the produced water, resulting in considerable savings in CAPEX/OPEX. However, several uncertainties and challenges have prevented their more widespread usage, including a lack of consistent test protocols, poor repeatability of test results, concerns over performance under shut-in conditions, the potential risk of hydrate formation at the top of the pipelines, and relatively low cloud points/fouling issues, which can cause problems in produced water handling/reinjection (PWRI) and/or monoethylene glycol (MEG) regeneration schemes. In this communication, we present the latest developments related to KHIs, including the results of a testing technique based on crystal growth inhibition that produces reliable and repeatable results, KHI performance under shut-in conditions, risk of hydrates at the top of pipelines, and a technique for removing KHIs from produced water prior to PWRI or MEG regeneration. We also demonstrate that it is possible to predict the potential suitability of KHI-based solutions for any specific field application prior to even starting the experimental campaign and/or designing a KHI + THI combination (where THI denotes thermodynamic hydrate inhibitor). Results show that MEG is an excellent synergist for the KHIs investigated, and 1% KHI can replace large quantities of MEG. Considering the fact that many of the operational challenges and uncertainties associated with KHIs have recently been addressed and that there are excellent opportunities for combining KHIs with MEG, we expect resurgence in KHIs as a reliable and economical option for preventing gas hydrate problems. This could have significant economic and environmental impact, as well as extend the life of petroleum reservoirs.