Pioneer challenge Reduction of MEG consumption using KHI for hydrate control in a deepwater environment offshore Egypt

Abstract

Abstract Hydrate control in a subsea gas environment is a challenge. The West Delta Deep Marine (WDDM) sub-sea gas production and gathering system was designed to use monoethylene glycol (MEG) and methanol injection as the means of controlling hydrate formation in the Sub-sea infrastructure. The produced fluids are transported to shore based processing facilities via two trunk lines, one 36?? and one 24??. The aqueous phase of these fluids, being a mixture of produced water, condensed water, condensate and MEG are separated and processed through a vacuum distillation system to recover the MEG. Due to the high cost for the MEG and the unavailability of the MEG in the country, it was recommended to do something different to reduce the operating cost and maximize the production by reducing the shut down of the wells due to hydrate formation. The first step to reduce or eliminate these problems was to reduce the MEG consumption. This was achieved by using the MEG as a carrier to apply kinetic hydrate inhibitor (KHI) at the well flow lines. This philosophy was applied first in the Sapphire field (offshore Egypt), which has the highest hydrate tendency. The outcome was a 70% reduction in MEG consumption in this field. This paper will explain the preparation, execution of the application of KHI in the Sapphire system and cost benefits. Introduction The formation of natural gas hydrates in gas pipelines and oil production and processing facilities is a major operational challenge for petroleum producers. These hydrates are crystalline, ice-like compounds composed of water and natural gas that form when small hydrocarbon molecules such as methane and ethane are trapped in hydrogen-bonded water cages under conditions of high pressure (typically above 50 bars) and low temperature (typically below 30ºC). The small, individual crystalline cages tend to agglomerate, forming larger hydrate structures that can adhere to surfaces such as internal pipe walls. If allowed to form and grow unchecked, these hydrate crystals can damage the pipeline or lead to blockage of the pipeline to the point of a pipe rupture (17).