Optimal Hydrate Management and New Challenges in GoM Deepwater Using "Best in Class" Technologies

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractThis paper presents an overview of BP's approach to Hydrate Management on new Gulf of Mexico (GoM) Deepwater Developments and Operations using the first and second generation (low and high water cut) Anti Agglomerate Low Dosage Hydrate Inhibitors (AA LDHIs). It also describes how these AA LDHIs are used in conjunction with more conventional hydrate management approaches to reach an optimal cost effective field hydrate management solution.The paper also outlines how the challenges outlined by BP and other major oil producers to the oilfield chemical suppliers at various subsea conferences were taken seriously, and how suppliers have risen to these challenges both in terms of cost, chemical technology development and product delivery to the field.Logistics, HSE, chemical injection and life of well operating envelope challenges need careful consideration at all stages of hydrate management and the paper outlines an integrated approach to cover these on a life of asset development. The impact of AA LDHIs and methanol on downstream transportation and refining facilities are also described as well as impacts on crude marketability and crude quality banks.The paper will touch on all these aspects and outline new challenges that are being faced as we move towards High Pressure High Temperature (HPHT) Developments with record water depths and drilling depth challenges.

Characterization of inhibition mechanisms of kinetic hydrate inhibitors using ultrasonic test technique

“…However, it is not unusual that high concentrations of up to 60 mass% methanol and glycol may be required for certain field cases. The need of a large volume of methanol and glycol leads to high cost and raises environmental and logistical concerns (Brustad et al, 2005;Cowie et al, 2005). In contrast, low dosage hydrate inhibitors are a relatively new category of chemical additives that can be active and effective at only a few mass% for typical applications.…”

Hydrate Shell Growth Measured Using NMR

“…10 Generally, industry aims to completely prevent hydrate formation by injecting sufficient quantities of inhibitor chemicals such as monoethylene glycol (MEG) or methanol; however, such an approach becomes increasingly expensive the deeper and further offshore the hydrocarbon exploration and transportation occurs. 11 Accordingly, industry is now moving from complete hydrate avoidance to a risk management approach (that may involve partial inhibition). 4 However, there are still significant knowledge gaps relating to how hydrates form, agglomerate, and plug pipelines, as well as with respect to the exact mechanisms by which various forms of hydrate inhibition, that target these phenomena, operate.…”

“…Generally, industry aims to completely prevent hydrate formation by injecting sufficient quantities of inhibitor chemicals such as monoethylene glycol (MEG) or methanol; however, such an approach becomes increasingly expensive the deeper and further offshore the hydrocarbon exploration and transportation occurs . Accordingly, industry is now moving from complete hydrate avoidance to a risk management approach (that may involve partial inhibition) .…”

A Novel Technique for Monitoring Hydrate Safety Margin

“…THIs such as MeOH and MEG shift the hydrate-phase boundary to a lower temperature and higher pressure by reducing the water activity, allowing the actual field operation conditions to be outside the HSZ. To have sufficient inhibition for some cases, particularly for those with high water cut, high concentrations (up to 60 mass%, hence a large volume) of MeOH and MEG may be required, which can lead to significant increase in capital expenditure and operational expenditure, and can also cause a severe impact on the environment (Brustad et al 2005;Cowie et al 2005). LDHIs are the other group of chemical additives that are usually divided into kinetic hydrate inhibitors (KHIs) and antiagglomerants (Lederhos et al 1996;Notz et al 1996;Mitchell and Talley 1999;Argo et al 2000;Fu et al 2002).…”