The Canyon Express project involves a commingled tieback of three dry gas fields, owned and operated by different companies, through a jointly owned twin 12" flowline tieback to a third party host platform at 56 miles distance. It is also the world's deepest development at 2200 m/7200 ft. Design rate is 500 mmscfd. In the design/construction phase of a challenging project such as Canyon Express, a project team attempts to identify what operational challenges will be faced and how they are to be designed for and managed. The start-up and operational phases show how well anticipated problems have been managed, and bring to light unexpected problems. This paper presents an overview of the key operational problems anticipated in the Canyon Express project design phase, and whether they did actually occur during and after start-up. It will also discuss the operational experience gained during the commissioning and early production life phases, and the unexpected problems that arose. Operational Experience Discussed Flowline dewatering and pigging Flow assurance strategy & hydrate prevention Pipeline liquid inventory management Methanol recovery system and methanol inventory Management Flowline solids production Subsea methanol filter blockages Significance of Subject Matter. The depth and tie-back distance of the Canyon Express fields pose significant flow assurance and other operational challenges. The operational experience gained in this development are valuable lessons learned for the development concepts and operating strategies of future long distance, deep water subsea tie-backs. Introduction The Canyon Express system is a joint development of three Gulf of Mexico deep water gas fields: King's Peak, operated by BP Americas, Inc.; Aconcagua, operated by TotalFinaElf E&P USA, Inc.; and Camden Hills, operated by Marathon Oil Company. The three fields are located in 6500' to 7200' of water, and are tied into the Canyon Express pipeline system operated by TotalFinaElf. The pipeline system consists of 57 mile long twin 12" flowlines, a main electro-hydraulic umbilical system, and a 2-7/8" diameter single methanol distribution line (SMDL). The King's Peak field comprises 3 wells, the Aconcagua field 4 wells, and the Camden Hills field 2 wells. The gas produced from the three fields is a very dry gas, containing >99% methane, with up to 0.5% carbon dioxide, and a condensate yield of around 0.75 to 1 bbl/mmscf. The fields jointly have the potential to produce 450-500 mmscfd of gas. The two 12" flowlines are tied back to a processing platform in 300' of water. This platform, Canyon Station, is owned and operated by Williams Field Services. The subsea control system and methanol injection facilities are also located on Canyon Station. Methanol is stored on Canyon Station in three legs of the structure, the total capacity amounting to approximately 2400 bbl. Methanol is continuously injected at the subsea wells to prevent hydrate formation; injection rates are currently around 800-1200 bbl per day, with a design maximum of 1900 bbl per day. Gas produced from the flowlines is separated from the liquids in two-phase HP separators, then dehydrated in a conventional process prior to export through three separate export lines.
The Shetland Gas Plant (SGP) is a 500 MMSCFD capacity gas plant located at Sullom Voe on the Shetland Islands. It receives reservoir fluids, via twin 143km multiphase flowlines, directly from the Laggan-Tormore fields which are located 125km north-west of the Shetland Islands in approximately 600m water depth. Fluids arriving at the SGP are separated into gas and liquid phases. The gas is processed and then exported to St Fergus gas processing plant via the SIRGE and FUKA pipelines. The liquid phases are separated and the condensate is exported to the BP Sullom Voe facility for stabilisation and export by tanker. The aqueous phase (rich MEG) is regenerated at SGP to produce lean MEG for reinjection subsea, a by-product of the regeneration process is produced water. The produced water is then fed to the Effluent Water Treatment Plant (EWTP) for processing prior to being discharged to Yell Sound via a 3.75km pipeline. The effluent water treatment package was designed by SUEZ Eau Industrielle (patented design). The effluent water is required to meet strict discharge specifications as part of the operating consents, e.g. Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), MEG, Benzene, Total Suspended Solids (TSS), etc. The Effluent Water Treatment Plant (EWTP) consists of 3 stages of treatment: physical, chemical and biological. The physical treatment contains; – A Corrugated Plate Interceptor, which uses gravity to separate the free oil from the produced water; – A Stripping Column, which removes BTEX (Benzene, Toluene, Ethylbenzene, Xylenes) and volatile hydrocarbons entrained in the water via transfer to fuel gas. The chemical treatment contains; – A Dissolved Air Flotation Treatment Unit, to remove any residual free oil and TSS utilising flocculants and coagulants. The biological treatment contains; – A Biological Aerated Flooded Filter (BAFF) Unit, which is an aerobic biological filtration process whereby a biomass (bacteria) give biological degradation of soluble organics while simultaneously removing suspended solids via filtration. The biological process removes the remaining MEG and BTEX and has the ability to handle varying loads of COD and BOD. The EWTP has been in operation since the start up of the SGP in February 2016. The paper will discuss: – The initial challenges faced during start up and the first year of operation and how these were overcome; – Current operation of the process including ongoing challenges and areas of success.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.