SS FA- Why Use Kinetic Hydrate Inhibitor

Abstract

A number of gas fields have been developed in the Middle East, Offshore Western Australia and in the Asia-Pacific region for the last five years as the demand for Liquefied Natural Gas (LNG) has grown tremendously worldwide. Most of these gas field production systems consist of long subsea flowlines, which are flowing with three phase fluids gas, condensate and water. The cold temperatures of the subsea environment pose a flow assurance risk to production, especially for hydrate blockages.The only solution currently being considered to address the risk for hydrate blockages in gas fields is the usage of Kinetic Hydrate Inhibitors (KHIs), not Anti-Agglomerate Low Dose Hydrate Inhibitors (AAHIs). The most significant production concern for all producers associated with this production scenario is that the performance of the KHI is compromised in the presence of the Corrosion Inhibitor (CI). The reason for not considering the AAHIs for this application, whose performance is not compromised by the corrosion inhibitor, is the general belief that these chemistries are predominantly water soluble and therefore increase the toxicity of the produced water.The published literature to-date is focused on understanding the interactions between the KHI and the CI chemistries to solve the incompatibility issue. The lack of literature to-date showcasing the success of such an understanding warrants a solution with a different perspective. Data is available for new generation chemistries currently being used in the industry that show greater than 99% oil solubility and would hence overcome the toxicity concern that was valid for the first generation AAHI chemistry.This new generation chemistry was tested by Heriot-Watt University in the United Kingdom (UK) that shows the product effectiveness up to 90% water cut at a reasonable subcooling, applicable for these subsea flowlines in discussion. The performance at these high water cuts will make this new generation chemistry more applicable for these subsea flowlines without the risk of hydrate blockages.

Exploring Kinetic Hydrate Inhibitor Test Methods and Conditions Using a Multicell Steel Rocker Rig

“…Another factor that can affect reliability is traces of chemicals or surface conditioning that might affect the next KHI test. For example, some corrosion inhibitors are known to affect KHI performance and by design these can be difficult to remove completely from the cell walls. − Therefore, thorough and consistent cleaning of the inside of the rocking cells is also important to avoid this problem.…”

Can cyclopentane hydrate formation be used to screen the performance of surfactants as LDHI anti-agglomerants at atmospheric pressure?

“…This liquid phase is usually a hydrocarbon phase although surfactants have been claimed to act as AAs at 90% water cut or even with no liquid hydrocarbon phase present at all. (Gao, 2009;Alapati et al, 2010;York and Firoozabadi, 2009;Sun and Firoozabadi, 2014;Sun et al, 2015). Nearly all field applications for AA use have accompanying liquid hydrocarbons.…”

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) …”