The last thing the offshore operators want to see is after all the investments in exploring, drilling and production, they could not flow the hydrocarbon from underground smoothly and efficiently. Among all the offshore flow assurance challenges, in a short time period can hydrate restrict flow and even form a solid plug to block all production. Long deepwater subsea tiebacks are especially problematic due to the high pressures and low temperatures, which would require sufficient quantities of thermodynamic hydrate inhibitors (THI) injection for hydrate mitigation. High THI injection volume can both exacerbate scaling problems by salting out of high TDS brines, and contaminate the exporting hydrocarbon by methanol. All these offshore production challenges, coupled with complicated logistics and HS&E concerns on THI, have being endorsed the development and field deployment of low-dosage hydrate inhibitors (LDHI) in the last decade.
Given the costs associated with remediating problems in offshore systems and the corresponding deferral of production, each new LDHI development is put through a series of rigorous qualification process. This paper will detail the challenges associated with LDHI applications for offshore productions. Efforts at developing and deploying new DLHI products suitable for number of recent offshore applications worldwide with field different requirements will be highlighted. Umbilical and capillary line failure is a major concern in the industry. Best practices to qualify products for umbilical and capillary injection have been rapidly evolving over the last ten years. Stability of LDHI formulations can depend on both temperature and pressure. In particular, high pressure viscometer measurements have proved to be invaluable for determining whether apparent pressure related stability concerns may exist in formulations at cold deepwater temperatures. Moreover, LDHI compatibilities with production fluids, system materials, other production chemicals and no adverse effect on their performance are also the key to its successful field implementation. Subsequently, closely monitored topside tests and field trials are essential to gain insights to the product performance in real systems.
