In the following a description of production activities related to the Solsort West Lobe wells are presented.
6.1 Production from the Solsort West Lobe wells
The current project development plan with South Arne as host platform anticipates first oil exported from Solsort West Lobe wells in 2023.
The production profile during the expected lifetime of Solsort is shown in Figure 6-1.
Figure 6-1 Indicative production profile from the Solsort West Lobe, over the life-time of the field with a maxi-mum allowable oil rate of 14000 BPD. Production of oil and gas is expected to reach a maximaxi-mum within the first 3 years of production, after which it will gradually decline. Water production is expected to increase grad-ually during the lifetime of the field.
The multiphase production will be transported from South Arne wellhead platform North to the South Arne wellhead platform East and from there commingled with other South Arne production to the processing facilities on South Arne main Platform. Processing will take place on the South Arne platform.
The stabilized oil will be stored at a sub-sea tank and exported via loading to tankers. Gas will be exported through the existing gas export pipeline to the Danish onshore gas treatment plant in Nybro. Any excess natural gas liquids will be utilized offshore as fuel.
The production profile after tie-in of Solsort West Lobe wells is shown in
Figure 6-2 Total production for both South Arne and Solsort West lobe wells.
6.2 Maintenance 6.2.1 Wells
Solsort West Lobe wells will require regular intervention over the field life like the other South Arne wells at the South Arne wellhead platform North.
It is expected that the maintenance of the Solsort West Lobe wells is covered by the planned maintenance of wells for the South Arne wells.
6.3 Discharge of produced water
During the processing at the host platform, where oil and gas is extracted from the multiphase production, the remaining produced water mixed with treated seawater is transported back to South Arne North Well Head platform for injected into the reservoir at the Solsort injection well to maintain a high pressure in the reservoir and thereby ensuring a high oil recovery.
Discharge of produced water is not expected to increase due to the tie-in of the Solsort West Lobe production well.
The discharge of produced water is expected to be limited due to high produced water reinjection above 80%
at South Arne supported by the improvement of the water injection system.
6.3.1 Production phase chemicals
The use of chemicals is evaluated continuously balancing technology, economy and impacts on environment and work environment.
All Solsort West Lobe chemical injection requirements are supplied from South Arne. It is expected that new dedicated scale inhibitor pumps are required at WHPN to accommodate Solsort West Lobe injection rates.
Indicative chemical injection requirements are summarised below. Chemicals in use at South Arne for the same service are assumed to be suitable for Solsort:
• Scale inhibitors to prevent mineral coating on steel surfaces.
• Corrosion inhibitors to protect the steel in the processing equipment from corrosion.
• H2S and oxygen scavengers to remove H2S from the produced gas, to meet the specifications. Not clarified yet whether this product will be relevant to use.
• Biocides
• Wax inhibitors and dissolvers to prevent precipitation of wax on cold surfaces
• Sodium hypochlorite as a bactericide.
• Antifoam to secure separation of oil and water.
• Demulsifier to enhance the separation of oil and water in the separators.
• Flocculant to enhance the processing.
Estimated use of
As can be seen in the table above the amounts of expected used and discharged chemicals will be lower compared to the amounts from South Arne EIA (2007). The discharge of red chemicals will increase with a factor 2 not due to the Solsort tie-in but due to the changes classification of sodium hypochlorite.
Hydraulic oil will be used in a closed system for wellhead control panel and actuated valves. As this is a closed loop system, there will be no discharge to sea. The expected volume is <100 litre in total and this is installed
onshore as part of the equipment purchase. No replacement of oil hydraulic oil is expected over the lifetime of field.
6.4 Emissions
The multiphase is transported to the South Arne wellhead platform East and further to the South Arne main platform, where the processing of the oil gas and water takes place. In relation to the production emissions to air will be generated from fuel gas, flare gas and diesel combustion. A temporary higher amount of flaring may be expected during tie-in of the Solsort West Lobe wells compared to normal production flaring.
The tie-in of Solsort West Lobe wells will be within the existing production capacity on South Arne. It is assumed that the emissions to air are proportional to the production volume for diesel and fuel gas and is within the existing approvals for South Arne.
6.5 NORM
It is a general experience and well-known that offshore oil production in the North Sea is associated with contamination of certain parts of the processing equipment by small amounts of natural radioactive constitu-ents in the reservoir, which are transported to the surface along with the extracted oil and/or particles. This material with low-level radioactivity is known as NORM (Naturally Occurring Radioactive Material).
NORM will most likely also be present at the Solsort West Lobe field and will have to be handled, stored and disposed of in accordance with the Radiation Protection Act administered by Sundhedsstyrelsen, Strålebeskyt-telse, SIS (see section 3.4)
6.6 Human Health
Establishment of large structures can have direct or indirect impact on human health and their possibilities for use of recreational areas.
The typical impacts would be noise, visual effects, impacts on the humans possibilities for use of culture, na-ture etc.
The offshore oil and gas installation are too far from shore to result in impact on human health from the activ-ities taking place both during construction, operation and decommissioning.