Deep Panuke Project Description - Encana

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Table 2.7 Water CompositionComponentAbenaki 5 Formation Water (mg/l)Na + 29,163K + 513Ca 2+ 5,885Mg 2+ 950Ba 2+ 8Sr 2+ 448Fe 2+ 0Mn 2+ 0Cl - 55,321-HCO 3 731-CO 3 02-SO 4 1,570Produced water will be treated to a target dispersed oil concentration of 25 mg/L (30-day weightedaverage). The OWTG (NEB et al. 2002) specify a 30-day weighted average of 30 mg/L. The followingis a brief description of the treatment process.Prior to discharge, produced water is treated in several ways. Water from the inlet separator, testseparator, condensate stabilizer surge drum, and stabilizer feed filter coalescers is commingled androuted directly into the produced water feed drum. Water from other LP vessels is typically routed tothe closed drains header, which is routed to the LP flare drum. Liquids from the LP and high-pressure(HP) flare drums are routed to either the inlet or test separators.The function of the water feed drum is to hold produced water until sufficient volume is available toroute to the hydrocyclones. The small amount of gas from this drum is routed to the acid gas injectioncompressor. At the start of the field life, the water rates are anticipated to be very low, such that batchprocessing in the hydrocyclones is likely. As the water rates increase, the flow will be continuous.The hydrocyclones will remove all but trace amounts of liquid hydrocarbons. The hydrocyclones oiloutlet is routed to the closed drains. The water is continuously routed to cartridge-style produced waterpolishers to further reduce trace amounts of liquid hydrocarbons.The water is then heated in the produced water stripper feed preheaters prior to entering the producedwater stripper. The amount of heat will be adjusted to aid in the H 2 S removal capabilities of the strippertower. The produced water stripper tower is a packed counter current gas/liquid stripping column inwhich sweet fuel gas flows upwards counter current to the water to remove H 2 S; preliminary indicationssuggest that H 2 S will be lowered to a concentration between 1 to 2 ppmw. The gas from the stripper isrouted to the acid gas injection compressor.Deep Panuke Volume 4 (Environmental Assessment Report)• November 2006 2-38
The flow to the stripper column will change dramatically over the field life. It may be necessary toprovide flow via recycle or process in batches during low flow periods.The water outlet of the stripper is sampled for oil and H 2 S and routed overboard. The waste gas fromthe produced water stripper will be routed to the acid gas injection compressor for injection. This willbe the normal mode of operation. The plant does have the capability to divert the produced waterstripper gas to the flare in the event of a malfunction of the acid gas injection well and/or compressor. Ifthe produced water stripper gas were flared, it would be a maximum of 980 kg/h of 19.7 MW gascontaining 1.5 mole % H 2 S.The concentrations of amine and TEG in produced water at the outlet to the sea are below thoseconcentrations which would impact marine species. Studies on the eco-toxicity ofmethyldiethanolamine and TEG, undertaken by the manufacturers, indicate that these substances are oflow toxicity to fish and invertebrates in the concentrations present in the produced water discharge andthat these substances are readily bio-degradeable (Woodburn and Stott, undated).Currently the design envisages platform-based laboratory facilities for verification of produced watermeasurements.The produced water will be routed overboard via the discharge caisson where it will mix withapproximately 2,400 m 3 /hr of seawater which is used for process cooling purposes.2.4.1.9 CompressionFor the M&NP Option, the sales gas will be compressed on the platform for delivery to shore. Theexpected sales gas discharge pressure on the platform is approximately 13,000 kPa. The Deep Panukecompressor system is composed of three 7 MW units for a total of 21 MW of compressor power. Thecompressors will be used for sales gas export and feed gas. The feed gas service will be to account fordeclining reservoir pressure. These compressors will be tri-fuel (condensate, fuel gas, and diesel).For the SOEP Subsea Option, the export gas will be compressed on the platform for delivery to theexisting SOEP 660 mm [26 inch] pipeline and subsequently routed to shore. The expected export gasdischarge pressure on the platform is approximately 13,000 kPa. Like the M&NP Option, the DeepPanuke compressor system is composed of three 7 MW units for a total of 21 MW of compressionpower. The compressors will be used for gas export and feed gas. The feed gas service will be toaccount for declining reservoir pressure. These compressors will be dual-fuel (fuel gas and diesel).Deep Panuke Volume 4 (Environmental Assessment Report)• November 2006 2-39
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 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 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

Deep Panuke Project Description - Encana

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