Deep Panuke Project Description - Encana

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Typically, a re-entry and completion of existing wells will be conducted as follows:1. Remove temporary abandonment caps and convert mudline suspension system to subsea wellhead.2. Install high pressure riser to rig tension deck and BOP stack.3. Drill out 340mm casing cement plugs and pull bridge plugs using suspension brine.4. Confirm well is secure and remove high pressure riser and BOP stack and install subsea productiontree.5. Drill out 245mm casing cement plugs and pull bridge plugs using suspension brine, change tools.6. Drill out 178mm casing cement plugs and pull bridge plugs using suspension brine.7. Filter and clean suspension brine to completion fluid specifications.8. Install the completion tubing/equipment.9. Provide underbalance and allow the well to flow to surface removing all completion fluids untilburnable gas at surface prior to handover to production.10. Secure the well and move the rig to the next well location and repeat the process.Spent WBM and associated drill cuttings will be discharged in accordance with the OWTG (NEB et al.2002).The conservative case of five new wells using WBM for all hole sections has been modelled with resultspresented in Appendix D.2.7.4.2 Drill Waste Discharge Behaviour and ModellingWhen cuttings and mud are discharged, the fine materials in the discharge form a turbidity plume nearthe sea surface, but the bulk of the material (cuttings) drops to the seabed with the fine materials beingstripped from the plume as it descends. Typically, a cuttings pile forms on the seabed near the dischargepoint. However, in high energy environments, like the Deep Panuke site, cuttings and fine particles andassociated metals, such as barium, are more likely to disperse rather than settle (refer to Appendix D).Barite is typically used to increase the density of the drilling fluid. It is also used to build small volumesof high density slugs used to trip drill pipe out of the hole dry. The type of drilling fluids used for DeepPanuke wells will be salt-based and the density will be adjusted by increasing the concentration of salt inthe drilling fluid. Therefore, the use of barite will be minimized and generally only used for thepreparation of high density slugs to pull the drill pipe out of the hole dry.Oceanographic plume modelling for discharge of mud and cuttings at sea was conducted for surfacedischarge of WBM. See Section 2.3.4 for further details. The modelling of drill mud and cuttingsdischarges is based on the following assumed operational processes and volumes shown in Table 2.9.Modelling results of ocean disposal of drill waste discharges are presented in Appendix D.Deep Panuke Volume 4 (Environmental Assessment Report)• November 2006 2-54
Table 2.9 Deep Panuke Potential Drilling Waste Discharge SummaryEach New One New Each Re-entry Total DischargesProduction Well Injection Well Production WellSeabed release of WBM associated 131 131 0 656cuttings (m 3 )Surface release of WBM associated 427 356 0 2062cuttings (m 3 )Seabed release of WBM on180 180 0 900cuttings (m 3 )Surface release of WBM on64 53 0 309cuttings (m 3 )Surface release of WBM (bulk mud 700 600 0 3400release) (m 3 )Surface release of completion fluid 1000 300 300 5500(m 3 )Notes:All volumes are approximations that represent each well’s discharges.Using a conservative approach to dispersion modelling, it is assumed four existing wells will be re-completed using completion fluid (“reentry”production wells), and four new production wells and one new injection well will be drilled using WBM with overboard discharge.The completion fluid is a brine (NaCl) with various additives for oxygen scavengers, H 2 S scavengers and corrosion protection in somecases.Prior to use, all chemicals will be screened using the CNSOPB Offshore Chemical Selection Guidelines2.7.5 Effluent Discharges2.7.5.1 Produced WaterProduced water management is described in Section 2.4.1.8. Produced water will be treated to a targetdispersed oil concentration of 25 mg/L (30-day weighted average). The OWTG specify a 30-dayweighted average of 30 mg/L. Refer to Appendix D for results of produced water dispersion modelling.2.7.5.2 Cooling WaterThe cooling system will use seawater to indirectly cool a circulating medium (40% ethylene glycol, 60%water (volume)) solution. The cooling water flow rate will be constant at 2,400 m 3 /hr and will have atemperature approximately 15°C above background water temperature. It will be mixed with producedwater before discharge.The seawater is treated with chlorine generated by a sodium hypochlorite generator to prevent/reduce thegrowth of marine biological growth. The design chlorine concentration at the seawater lift pump inlet is 2ppm (1 ppm during normal operation with an increase during periods of high larval mussel concentration).The residual free chlorine concentration at the outlet will normally be below 0.25 ppm. The combinedproduced water and cooling water stream exit temperature will not exceed 25 o C above ambient.Deep Panuke Volume 4 (Environmental Assessment Report)• November 2006 2-55
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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 56 and 57: 2.7.5.3 Deck DrainageDuring constru
Page 58 and 59: 2.9.2 Pipeline Leak PreventionThe p
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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