TOTAL Exploration & Production has been active in cold environmentssince 1970 (i.e. drilling in the Arctic Islands in Canada) and has beenoperating the Russian Kharyaga field since 1999. For its first experiences inthose challenging conditions, TOTAL applied its internal rules andspecifications that were not aimed at this kind of environments but to"classic" prospects, the main assets being in the Guinea Golf, in the NorthSea, the Middle East and in South East Asia. As the prospects and TOTAL'sportfolio have developed in areas where temperatures are below -15°C, such asKashagan field in Kazakhstan or Yamal in Russia, an "Extreme Cold" taskforcewas put together several years ago. The aim is to gather feedbacks from thepast and to centralize the Research & Development activities to look forinnovative solutions for the future and on-going projects. The workgroup isorganized around several panels, one of those being the Health and Safetyaspects for the operations in Extreme Cold conditions. From partnership throughJIPs, internal research and workshops with affiliates (mainly in Norway, Russiaor Canada), and projects teams, it has been decided to produce internalguidelines in order to define and harmonize the practices, acknowledging thateach field has its own meteorological constraints, and to gather the resultsfrom the multiple actions carried out by TOTAL headquarters or affiliates. Themethodology and the risk analysis performed to obtain a common technical basiswill be here presented.
Direct Electrical Heating (DEH) of flowlines is a flow assurance technologythat facilitates development of fields in arctic regions, fields with longsubsea tiebacks, fields with heavy oil, and marginally profitable offshorefields. By allowing for operation in conditions outside of the hydrateregion and/or above the wax appearance temperature, DEH opens up areas ofdevelopment not otherwise considered viable by production companies and cansignificantly reduce CAPEX and OPEX for already-viable fields. It isproposed for Arctic field development, where a colder subsea temperaturecompounds typical flow assurance difficulties and where traditional chemicalinjection becomes difficult or cost prohibitive to manage.
This paper provides an explanation of Electric Flowline Heating (EFH), bothDirect and Indirect Electrical Heating, including how the technology works, thedifferent types of systems, and the modes of operation. A listing ofcurrently installed systems is also provided. The purpose and benefits ofDEH are discussed, including prevention and remediation of hydrate and paraffinformation, improving the flow of heavy oil, extended shutdowns without the useof chemical injection or hot oil circulation, reduction of infrastructure forsuch chemical injection and hot oil circulation, the handling of high water-cutduring tail end production periods, and planning for third-party tie-ins withpoorly-defined composition. A case study is presented to illustrate some ofthese benefits.
As awareness of DEH's benefits grows, so does interest in applying it to thechallenging environment of the Arctic. This paper discusses some of thechallenges of designing and installing an Arctic DEH system, as well as othertechnology-stretch applications such as whether DEH can be used for hydrateplug remediation (after the plug has formed), whether it can be used incontinuous flowing conditions, and how to maximize the length of a DEH-heatedsegment.
Poedjono, Benny (Schlumberger) | Beck, Nathan (Schlumberger) | Buchanan, Andrew (Eni Petroleum Co.) | Brink, Jason (Eni Petroleum Co.) | Longo, Joseph (Eni Petroleum Co.) | Finn, Carol A. (U.S. Geological Survey) | Worthington, E. William (U.S. Geological Survey)
Geomagnetic referencing is becoming an increasingly attractive alternativeto north-seeking gyroscopic surveys to achieve the precise wellbore positioningessential for success in today's complex drilling programs. However, thegreater magnitude of variations in the geomagnetic environment at higherlatitudes makes the application of geomagnetic referencing in those areas morechallenging.
Precise, real-time data on those variations from relatively nearby magneticobservatories can be crucial to achieving the required accuracy, butconstructing and operating an observatory in these often harsh environmentsposes a number of significant challenges. Operational since March 2010, theDeadhorse Magnetic Observatory (DED), located in Deadhorse, Alaska, was createdthrough collaboration between the United States Geological Survey (USGS) and aleading oilfield services supply company. DED was designed to produce real-timegeomagnetic data at the required level of accuracy, and to do so reliably underthe extreme temperatures and harsh weather conditions often experienced in thearea.
The observatory will serve a number of key scientific communities as well asthe oilfield drilling industry, and has already played a vital role in thesuccess of several commercial ventures in the area, providing essential,accurate data while offering significant cost and time savings, compared withtraditional surveying techniques.
In iceberg prone regions, subsea substructures placed on the seabed are atrisk of impacts from free-floating and scouring iceberg keels. Here themethodology for assessing iceberg loads and two mitigation strategies aredescribed. The iceberg load model was an extension of previous work forestimating iceberg impact loads on offshore surface-piercing structures.Components of the algorithms were modified such that global design loads fromkeel contacts account for the change in contact location (i.e., longer leverarm in the vertical direction resulting in greater rotation effects). Theiceberg eccentricity model and the relationship between contact area andpenetration distance were also modified to account for iceberg keel contactswith a generic low profile structure on the seabed. One concept considered wasa single wellhead structure fitted with a special weak shear link incorporatedinto the design at the expected scour level. The shear link, or failure joint,would act as a mechanical fuse designed to fail in a combination of shear,tension and buckling during keel loading. The failure joint minimizes downholestructural response during iceberg keel loading on the production tree. Thedesigned failure mechanism would allow the well to be re-entered by protectingthe well casing from damage. Another concept considered was a steel truncatedcone structure installed over the well installation and fixed to the seabed byone of several identified foundation concepts. The protection structure absorbsenergy through crushing of the ice keel and encourages the iceberg to deflectaround and over the structure. The steel structure would be designed accordingto ultimate limit states accounting for energy absorption through elastic andplastic deformation of the structure. Design loads would correspond to anAbnormal Level Ice Event (ALIE) with an annual exceedance probability of 10-4.The size of the frame is governed by the size of the wellhead and tree system,Remotely Operated Vehicle (ROV) access requirements, and slope to encourageiceberg keel deflection. Piles may be the best option for securing a protectionstructure to the seabed, especially if a local vessel can be sourced to performthe installation. As an alternative to piles, using a drill rig to install wellcasings may be an option; however, market conditions for drilling rigs maydictate economic feasibility.
Subsea tiebacks are becomingincreasingly prevalent in oil and gas field developments. As the accessibilityof the production from wellheads becomes more difficult, the need for subseacompression and pumping increases. Compression and pumping require significantpower which can be distributed and controlled from a HVSS (High-Voltage SubseaSubstation). The viability of an Arctic field development will be determined bythe reliability of all elements in the tieback and in particular, thecentralized subsea power distribution system.
We present numerical results arising from a parameterization of wave-iceinteractions in a two-dimensional ice-ocean model of the Fram Strait (HYCOM:HYbrid Coordinate Ocean Model). The model takes wave predictions/hindcasts fromthe WAM wave model and these waves are advected into the ice, breaking it asthey go. They in turn are attenuated by the ice using the model of Bennetts andSquire (2012). We use a truncated power law for the floe size distribution,following the observations of Toyota et al. (2011). The maximum floe size isdetermined by the dominant wavelength in the ice field. The maximum valueincreases with distance from the ice edge as shorter waves are attenuated morestrongly than long ones. At some distance from the ice edge, breaking is nolonger able to occur, and this marks the end of the Marginal Ice Zone(MIZ).
Consequently, we now have a model that predicts the expected floe size andwave intensity at any point in the ice, something that current wave models areunable to do at present, and which is a notable weakness. Recognizing that acombination of large waves and ice can be extremely hazardous, Arctic operatorswho need to know both wave and ice conditions in ice-infested areas will usethe model as a forecasting tool when it is fully operational.
This paper characterizes the processes that presently occur during freeze-upin the Alaskan Beaufort and Chukchi Seas, based on joint-industryinvestigations conducted in 2009-10, 2010-11, and 2011-12. The studies weredesigned to address five specific objectives: (1) describe the ice conditionsthat evolve during the freeze-up and early winter seasons; (2) locate and mapfeatures of potential importance for offshore exploration and productionactivities, including ice movement lines, leads, polynyas, first-year ridgesand rubble fields, and multi-year floes; (3) locate and quantify ice pile-upson natural shorelines and man-made structures; (4) correlate significantchanges in the ice cover with the corresponding meteorological conditions; and(5) compare present-day freeze-up processes with those that occurred in the1980s. Each study included an analysis of meteorological data, ice charts, andsatellite imagery in concert with a series of aerial reconnaissance missions.The study findings are presented in seven categories: (1) air temperatures, (2)first-year ice growth, (3) the timing of freeze-up, (4) landfast ice, (5)multi-year ice, (6) ice pile-ups, and (7) extraordinary ice features discoveredoff the Chukchi Sea coast.
Blunt, J.D. (ExxonMobil Upstream Research) | Garas, V.Y. (ExxonMobil Upstream Research) | Matskevitch , D.G. (ExxonMobil Upstream Research) | Hamilton, J.M. (ExxonMobil Upstream Research) | Kumaran, K. (ExxonMobil Corporate Strategic Research)
Safe and economic hydrocarbon exploration, development and productionoperations in the high arctic deepwater require a nuanced understanding of thesea ice environment. Robust image analysis techniques provide methods bywhich this nuance can be more objectively characterized and used for decisionmaking while in operations. Morphological segmentation and windowedstatistical analysis are proposed as two approaches that provide usefulinformation on the tactical scale by rapidly characterizing floe fieldmorphology and relative surface roughness. Their use is demonstratedwithin the context of actual high arctic field program data. Results fromthe method application are shown and the benefits and limitations of their useare discussed.
As more attention is paid to the exploration of oil and gas resources in thehigh north, the settlement of the disputed area between Norway and Russia, andthe world's ever-rising demand for energy resources, more and more oilcompanies and suppliers are moving north. For most oil companies, rig and shipoperators and logistics providers, the Arctic represents a new frontier, whereexisting operational systems and technologies are tested to their limits. Thispaper outlines key challenges facing the development of sustainable and safemaritime offshore operation in Arctic waters. The Arctic offers challengesrelated to harsh weather conditions, long distances from bases, limited orabsent infrastructure, a sensitive ecosystem, ensuring safety at sea, potentialoil spills and operations in ice-infested waters. Arctic operations are thussignificantly different from operations in the North Sea. This state of affairsunderlines the need for new or improved organisational and business models forintegrated logistics operations, value chain management and technologicalsolutions that will ensure sustainable and safe maritime operations. It alsodemands optimised design of ships and structures for operation in the Arcticenvironment as well as improved communication infrastructure based onsatellite, terrestrial, ship-to-ship or ad-hoc systems, radar and opticalsatellites. Key features discussed will include ideas and concepts forarea-specific vessel design and multipurpose vessels, with integrated supportand logistics models and systems, base-to-base operation and tailored businessmodels for robust Arctic field operation. The aim is to ensure a holistic andintegrated transport and logistics infrastructure in sparsely populated areaswith extreme weather conditions (polar lows, darkness, fog, ice and icing),including the interplay between vessel technology and the operationalmanagement.
This paper employs finite-element analysis to investigate the performance ofmud line cellars (MLC) in various stratigraphic settings representative for theArctic offshore environment. Numerical results addressing the stability of mudline cellars excavated in sand-prone Arctic marine sediments revealed apotential flow-like mode of failure associated with a high degree of materialdisruption within the failure wedge. On the other hand, the computed potentialfailure mechanism of a mud line cellar excavated in clay-prone Arctic marinesediments is characterized by a sliding block mode of deformation. For theconsidered geotechnical properties of unfrozen Arctic marine sediments,free-standing sand mud line cellars are prone to instability thus requiringadditional lateral support, whereas free-standing clay mud line cellars appearto be stable. The analysis results for a free-standing mud line cellarexcavated in clay with adjacent surcharge at seafloor indicate a progressiveincrease in the size of the potential failure wedge controlling the stabilityof the MLC wall with increasing surcharge horizontal distance relative to themud line cellar location. For surcharge horizontal distances exceeding aspecific threshold, the dominant potential failure mechanism of theMLC-surcharge system in clay undergoes transition from a fully-developedfailure wedge localized at the face of the excavation wall to a more generaltype of bearing capacity failure mechanism developed underneath and in theimmediate vicinity of the loading area of the surcharge that has no significantinfluence on the stability of the MLC wall. Numerical investigations addressingthe performance of a caisson-supported mud line cellar in sand with adjacentsurcharge revealed that the caisson may experience wall bending in combinationwith rigid body rotation due to surcharge-induced lateral soil movements in thevicinity of the mud line cellar.