Successful Field Application of an Inhibitor Concentration Detection System in Optimising the Kinetic Hydrate Inhibitor (KHI) Injection Rates and Reducing the Risks Associated with Hydrate Blockage

Abstract

TX 75083-3836, U.S.A., fax +1-972-952-9435. AbstractCurrently, hydrate inhibitors are injected at the pipelines upstream based on the calculated/measured hydrate phase boundary, water cut, worst pressure and temperature conditions, and the amount of inhibitor lost to non-aqueous phases. In general, no means of controlling and monitoring are available along the pipeline and/or downstream to assess the degree of inhibition. Often high safety margins are considered to accommodate for the uncertainties in the above parameters and to ensure gas hydrate risks are eliminated. However, despite these efforts hydrates do still form and this can result in considerable economical and safety concerns. As a result of a joint industry project, a novel device based on electrical conductivity and sonic velocity (C-V technique) has been developed for monitoring the hydrate safety margin to optimise inhibitor injection rates. The system determines the amount of inhibitors (e.g., salt, KHI, methanol, MEG, etc…) in the aqueous phase and the degree of inhibition they can provide. The device has been successfully applied in determining the amount of KHI in produced water from the Dolphin field in Qatar. Compared to conventional chemical techniques the device is much faster (less than 3 minutes) and less labour intensive and there is no chemical requirement. In this presentation, the results of the trial of this device in determining KHI concentration in produced water are described. The results shows that this new technique is very fast and reliable, optimising the KHI injection rate, improving the economy and reliability of hydrate inhibition strategy, and minimising the impact on the environment.

Solvent Synergists for Improved Kinetic Hydrate Inhibitor Performance of Poly(N-vinylcaprolactam)

“…Many oil and gas operations meet the conditions needed for gas hydrate formation to occur. Gas hydrate formation can jeopardize oil and gas production if not treated. − One way of treating gas hydrates is by the utilization of low-dosage hydrate inhibitors (LDHIs) and, more specifically, the subgroup kinetic hydrate inhibitors (KHIs) …”

A Novel Technique for Monitoring Hydrate Safety Margin

“…The field evaluations of the C-V technique were in various applications such as monitoring of MeOH and MEG injection rates, measuring high MEG concentrations for MEG regeneration units, and monitoring KHI concentrations in pipelines. Lavallie et al (2009) reported the evaluation results in Dolphin Energy and suggested that the C-V device is a simple and reliable device for measuring KHI concentrations compared to conventional chemical analysis method.…”

Further Investigation of Solvent Synergists for Improved Performance of Poly(N-vinylcaprolactam)-Based Kinetic Hydrate Inhibitors

“…In gas hydrates, gases of certain molecular weight stabilize hydrogen-bonded molecular water cages. Thus, if suitable low-molecular weight hydrocarbon gases combine with water under specific conditions of temperature and pressure, typically favoring conditions at temperature and pressure in the ranges of <25 °C and >30 bar, respectively, gas hydrates will form. − These requirements are not uncommon to encounter when producing or transporting oil and gas, and if it is left untreated, formation of gas hydrate plugs can occur, potentially jeopardizing operations and posing health hazards. − Therefore, it is important to treat the system in such a manner that the risk for forming gas hydrate plugs is eliminated. There exist multiple measures to handle and treat gas hydrate; one of them is the utilization of chemicals, more specifically, low-dosage hydrate inhibitors (LDHIs) and subgroup kinetic hydrate inhibitors (KHIs) …”