Hydrate Prevention and Methanol Distribution on Canyon Express

Cooley, C. (Total E&P USA Inc.) | Wallace, B.K. (Marathon Oil Company) | Gudimetla, R. (INTEC Engineering)


The Canyon Express field in deepwater Gulf of Mexico is a development consisting of multiple subsea gas-condensate wells owned by different companies. Each deepwater well (ranging from 6400 to 7250 foot water depth) flows into one of two 57 mile, 12" flowlines which tie the subsea wells to a shallow water host platform on the Continental Shelf. The production from each well is predominantly methane gas but also consists of produced water and condensate. Due to the nature of the production and the combination of high pressures / low temperatures expected, the potential for hydrate formation is a serious concern to system operability. To adequately protect the system against hydrate formation and deposition, injection of hydrate inhibitor (methanol) at each subsea well from a common umbilical system is being employed. Although wet gas metering is being used at each well to measure gas and liquid rate, water content per well cannot be accurately predicted. Thus, a robust methanol injection strategy was required to effectively inhibit hydrate formation. This paper presents the design of the methanol injection system and development of the overall injection strategy. Examples from the early field life of the Canyon Express development will be presented which demonstrate the application of this injection strategy to the system operation.