Deep Panuke Project Description - Encana

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2.9.2 Pipeline Leak PreventionThe pipeline design philosophy, in accordance with CNSOPB regulations, incorporates designs for:internal pressure containment; dropped objects protection; fatigue; spanning; and hook, pull or snagloads due to fishing activities. The pipeline will be designed to withstand impacts from conventionalmobile fishing gear in accordance with the Det Norske Veritas (DNV) Guideline No. 13, InterferenceBetween Trawl Gear and Pipelines, September, 1997. During the operational phase, inspections arecarried out as part of the Annual Survey to ensure that the pipeline integrity is maintained.Leak detection for the pipeline will be carried out by the use of mass balancing. This method usesprocess conditions at either end of the pipeline along with gas composition to calculate the mass enteringthe pipeline and exiting it. The M&NP custody transfer meter along with onshore instruments will beutilized to gather flow, temperature and pressure measurements. Similarly on the MOPU, the flow,temperature, and pressure will be used in conjunction with the gas composition to calculate the massentering the pipeline. The onshore measurements along with the offshore gas composition will be usedto calculate the mass exiting the pipeline. The mass entering and exiting the pipeline will be used todetect leaks. The leak detection system will be designed accordingly for the export option selected.In the event that a leak is confirmed, the pipeline has a series of shutdown valves that will isolate thepipeline from the M&NP pipeline and the MOPU to prevent additional hydrocarbons from entering thesystem.2.9.3 Blowout Prevention SafeguardsThere are many safeguards in place to prevent blowouts or uncontrolled releases of hydrocarbons duringthe various stages of a wellbore’s life cycle. The equipment used to drill, complete and workover awellbore is essentially the same regardless of whether it is an injection or production well. Also, there isa separate set of permanently installed equipment that is used during the production or injection phase ofthe life cycle.The objective during the drilling of the well is to provide a wellbore through the selected reservoirinterval in the safest and most efficient manner. Several strings of pipe (casing) are set at increasinglydeeper depths to achieve this goal. The first section of pipe, the conductor, is set to approximately 75 mbelow the seafloor with no well control or blowout prevention equipment. For the next hole section(surface hole), a large diverter assembly is installed on top of the conductor pipe. This provides a meansto divert any shallow gas that may be encountered over the side of the rig in a controlled manner untilthe mud weight can be increased to control the flow. The probability of encountering shallow gas duringthis hole section is unlikely since the rig is positioned to avoid any shallow gas anomalies based on ashallow seismic survey.Deep Panuke Volume 4 (Environmental Assessment Report)• November 2006 2-58
Once the surface section has been drilled and cased, blowout preventers are installed which canwithstand/holdback the reservoir pressures expected during the drilling process should a well controlincident occur. The primary method of well control is the hydrostatic pressure exerted by the column ofmud in the wellbore. The density of the mud that is used to drill the hole section is tailored to ensure thatthe ingress of wellbore hydrocarbons is prohibited. If the density of this fluid is too low a “kick” occursby which an amount of reservoir fluid enters the wellbore. As soon as this kick is detected, the well isshut in and monitored to determine the conditions surrounding the kick. The BOPs are used to shut inthe well. Once the well is shut in, the mud is circulated to bring the reservoir fluids to surface. Thehydrocarbons are vented or burnt at the flare in a controlled manner. The density of the mud is increasedthe appropriate amount and the drilling process may begin again.These blowout prevention safeguards are well-known operational procedures for which standardindustry practices are in place. EnCana’s Well Control Manual deals with these types of situations and isconstantly updated based on the most recent technological innovations. All personnel are trained on acontinuous basis and exercises and drills are routinely performed during operations on the drilling rig.During the production or injection life of a well, there are several safety measures in place to insure nouncontrolled release of hydrocarbons occur. The primary prevention mechanism within an offshorewellbore is the surface-controlled subsurface safety valve (SC-SSSV). The fail-close valve has a controlline to surface that is constantly pressured to keep the valve open. In the case of an accident, the ESDprocedure would have the valve close as soon as the hydraulic pressure is removed from the line. Allreservoir fluids are contained within the production or injection tree on top of the wellhead. This tree(series of fail-close surface valves) is connected to the tubing string within the wellbore that is used totransport the fluids to or from the reservoir. The SC-SSSV is an integral part of the tubing string usuallylocated at a depth below the seafloor. At the bottom of the tubing string, a production packer is placedbetween the tubing and casing to prevent migration of reservoir fluids in the annulus (space between thetubing and casing). This equipment provides a fit for purpose design conduit for the fluids to be removedfrom or injected into the reservoir.2.9.4 Flowline ProtectionThe flowlines design philosophy, in accordance with CNSOPB regulations, incorporates designs forinternal pressure containment, dropped objects protection, fatigue and spanning. The flowlines will beburied to avoid impacts from conventional mobile fishing gear and their locations will be charted.During the operational phase, inspections will be carried out as part of the Annual Survey to ensure thatthe pipeline integrity is maintained. Environmental and safety protection systems, such as emergencyshutdown (ESD) valves, will be provided on the flowlines.Deep Panuke Volume 4 (Environmental Assessment Report)• November 2006 2-59
Page 1 and 2:
2 PROJECT DESCRIPTIONThis section p
Page 3 and 4:
Potential Radioactive Components: T
Page 5 and 6:
2.2.2 Subsea Wells and FlowlinesThe
Page 10 and 11: 2.2.3.1 M&NP OptionThe proposed pip
Page 12 and 13: The onshore portion of the pipeline
Page 14 and 15: 2.3 Construction and Installation2.
Page 16 and 17: 2.3.2 Export PipelineA proposed pip
Page 18 and 19: A dedicated subsea umbilical will b
Page 20 and 21: Table 2.2 Construction MethodsCateg
Page 22 and 23: These subsea structures may be fast
Page 24 and 25: For the new production and injectio
Page 26 and 27: Figure 2.8Typical Production Well S
Page 28 and 29: 2.3.8.1 Drilling Fluid ProgramWater
Page 30 and 31: Table 2.4 Hydrostatic Fluid Dischar
Page 32 and 33: Acid GasInjectionFeed GasCompressio
Page 34 and 35: Although the M&NP Option is the onl
Page 36 and 37: Spent TEG has no measurable H 2 S a
Page 38 and 39: Table 2.7 Water CompositionComponen
Page 40 and 41: 2.4.2 Utilities2.4.2.1 Electrical P
Page 42 and 43: will be designed considering emerge
Page 44 and 45: zones over the pipeline although th
Page 46 and 47: 2.7 Emissions and DischargesEnCana
Page 48 and 49: Table 2.8 Routine Project Emissions
Page 50 and 51: 2.7.1.1 Air PollutantsThe following
Page 52 and 53: esult in eye irritation, respirator
Page 54 and 55: Typically, a re-entry and completio
Page 56 and 57: 2.7.5.3 Deck DrainageDuring constru
Page 60 and 61: 2.9.5 Subsea Protection StructuresT
Page 62 and 63: • consider concept alternatives f
Page 64 and 65: Table 2.10Centre Substructure Type
Page 66 and 67: is much more weather-dependent than
Page 68 and 69: Table 2.11 Processing Location Alte
Page 70 and 71: After carefully considering the con
Page 72 and 73: Flaring acid gas consists of direct
Page 74 and 75: Table 2.13Produced Water Disposal A
Page 76 and 77: Therefore, injection into an annula
Page 78 and 79: Use of a dedicated condensate pipel
Page 80 and 81: is taken offshore on a special lay
Page 82: Table 2.15Acid Gas Injection Locati
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Deep Panuke Project Description - Encana

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