NON-TECHNICAL SUMMARY

Transcription

1 NON-TECHNICAL SUMMARY S1 INTRODUCTION This Environmental Statement (ES) Addendum presents the findings of the Environment Impact Assessment (EIA) conducted by TOTAL E&P UK Limited (TOTAL) for the development of the Islay field in UK Continental Shelf (UKCS) block 3/15 in the northern North Sea. Originally, the development of the Islay field, initially known as Jura East, was included as a part of the Forvie and Jura Area Field Development, for which an umbrella ES has been prepared and approved. Islay has since been classified as a separate field and therefore, as determined by the Department of Energy and Climate Change (DECC), requires a separate ES. This will take the form of a slimline ES addendum that refers back to the original umbrella ES prepared for the Forvie and Jura fields. This Addendum to the Forvie and Jura Area Field Development ES has been undertaken in compliance with the Offshore Petroleum Production and Pipelines (Assessment of Environmental Effects) Regulations 1999 (as amended). S2 ALTERNATIVES/DECISIONS REMAINING TO BE MADE Environmental impacts have been considered throughout the option selection process for the development of the Forvie and Jura area, including what is now known as the Islay field, and these are documented in the original umbrella ES. Regarding the current Islay development, several further options have been considered and several decisions still remain to be made. The routing of the pipeline and umbilical and the requirement for seabed preparatory works prior to installation have been considered. Some decisions are still to be made however, including the method of pipeline installation, which is directly related to the type of pipeline. Two pipelines are currently being considered; a reeled 6 / 10 conventional pipeline option i.e. a 6 pipeline that sits within a 10 carrier pipe, along with a separate 5 umbilical line, and a 30 bundle, in which all the pipelines are contained. The type of pipeline chosen will influence the degree of seabed preparatory work required. The conventional option has been carried forward in this ES due to the potentially higher environmental impacts. S3 PROJECT DESCRIPTION The Islay field is situated 150 km east of Shetland Islands, 400 km east of Aberdeen and approximately 550 m from the UK/Norway transboundary line. The Islay exploration well 30/15-12 which has already been drilled, is located at N and E, in a water depth of 122 m. The Islay field is a gas/condensate prospect. The well was drilled by the Transocean John Shaw semi-submersible drilling rig in January The total well duration was days to enable the well to be fully drilled, cored, logged and completed for future tie-in. Water based mud was used to drill all the Islay well sections and cuttings were discharged at the seabed for the top hole sections and directly into the water column via the cuttings disposal caisson for all the other hole sections. The well was suspended after completion operations and presently has a xmas tree structure installed. The development will consist of a single well tied back with a 6 km subsea pipeline and separate umbilical line to the existing Forvie subsea manifold, which will direct production via an existing pipeline to the Alwyn North installation. Two pipeline end manifold structures will be installed, one at either end of the pipeline which will provide a number of metering and control facilities. The seabed topography local to Islay will have an influence on the subsea equipment. The Islay well has been drilled on a sloping section of seabed with the upslope in the direction of the Forvie manifold. Preparatory work is required prior to the installation of the subsea piplines in order to ensure a free draining profile along the entire Islay pipeline route. Modifications to the seabed include excavation by dredging, rock dumping and the use of prefabricated, height adjustable sleepers. Page xiii

2 An insulated sump section will be positioned on the down-sloping seabed beyond the well location. Water accumulating in this sump section can then be dosed with methanol within a practicably achievable timescale as part of a hydrate management strategy. Producing fluids from the Islay field will result in a number of impacts on the Alwyn North B, and the Dunbar installation will require a number of modifications. The use and discharge of chemicals will be revised to suit anticipated flow rates from the Islay well. Any use and discharge of chemicals, including treatment philosophies, will be included in the Alwyn Area PON 15D. S4 ENVIRONMENT S4.1 Introduction It is important to understand the environmental features on which the proposed development may have an influence or be influenced by. Both the physical and biological aspects of the offshore marine environment are discussed, together with socio-economic factors relevant to the area. A full environmental description that included the area of the proposed Islay development was provided in the Forvie and Jura Area Development ES (TOTAL 2004). For the purposes of this ES addendum, an update of key environmental sensitivities in the area has been provided including details of recent route and environmental survey work. S4.2 PHYSICAL AND BIOLOGICAL ENVIRONMENT S4.2.1 Bathymetry and seabed features The water depth across the entire pipeline route ranges from 105 m to 122 m, with the suspended Islay well sitting at a depth of 122 m. The seabed slopes gradually to 108 m from the Islay well towards the Forvie manifold over a distance of 0.5 km. A number of seabed features have been reported along the proposed route, including anchor scars and a small number of minor depressions close to the Islay well. However, these features can be attributed to variations in seabed topography rather than to changes in seabed composition. S4.2.2 Seabed sediments The seabed sediments, similar along the entire proposed pipeline route, are composed of dark grey silty fine sand with varying amounts of shell fragments and coarser grained material. General total hydrocarbon levels are within typically expected background levels for the sediment type encountered in the northern North Sea. Heavy metal analysis showed levels were within typical background levels. S4.2.3 Benthic communities FUGRO (2010) reported a diverse but sparsely distributed epifauna along the proposed pipeline route. Visible fauna observed along the pipeline route included numerous anemones, a seapen (Virgularia mirabilis), a sea urchin and hermit crabs. A survey conducted in 2005 (FUGRO, 2006) found that infauna present was characteristic of those found in fine sands in this region of the North Sea. The dominant species recorded were polychaete worms, crustaceans, molluscs and echinoderms. S4.3 CONSERVATION INTERESTS There are no seabed features that correspond with habitats of interest or concern listed in Annex I of the Habitats Directive along the proposed pipeline route. The nearest features, reefs and submarine structures made by leaking gases, are located 100 km and 40 km from the development area respectively. The nearest area of search (AoS) where additional special areas of conservation (SACs) may be sited, is the reef east of Shetland Isles, approximately 110 km from the Islay well. It is unlikely that coastal conservation sites would be affected by any aspect of the proposed project given the distance of the Islay development from the coast. Page xiv

3 S5 EIA PROCESS AND METHODOLOGY The environmental impact assessment (EIA) has been conducted in accordance with the Offshore Petroleum Production and Pipelines (Assessment of Environmental Effects) Regulations 1999 (as amended). This ES will form part of an addendum to the original Forvie and Jura Area Development ES (2004) and, following on from consultations with DECC, their scientific advisors and with the Scottish Fishermen s Federation (SFF), will cover the drilling programme retrospectively, the revised pipeline route and impacts at the receiving installation (Alwyn). Based on this information, the impacts identified for further assessment are discussed in the following sections: Atmospheric emissions; Discharges to sea; Seabed impacts, and Noise. S6 ATMOSPHERIC EMISSIONS The key potential sources of atmospheric emissions include: Vessel activities during pipelines and subsea structures installation, and Increased combustion and flare emissions at Alwyn North. The gases produced from the planned emissions have the potential to contribute to a variety of environmental effects, including global warming (greenhouse gases), acidification (acid rain) and local air pollution. All vessels employed during installation activities will comply with the Merchant Shipping (Prevention of Air Pollution from Ships) Regulations 2008, which will reduce the level of pollutants entering the atmosphere. Furthermore, all combustion equipment will be subject, under the conditions of the PPC permit, to monitoring and inspection to ensure an effective maintenance regime is in place and to ensure that all combustion equipment runs as efficiently as possible. Effects on local air quality are not expected due to the dispersive nature of the offshore environment. Locally elevated concentrations of emissions will be short lived and are unlikely to be detectable even a short distance away from any of the activities. Following start-up of the Islay well, there is not expected to be any increase to daily routine flaring volumes and subsequently there will be no cumulative emissions generated in relation to flaring. The contribution to total annual United Kingdom emissions on an annual basis from subsea installation and pipelay and Alwyn North production is very small (0.12%). No significant transboundary or cumulative effects are envisaged. S7 DISCHARGES TO SEA The potential discharges to sea identified for the proposed Islay well tie-back include well suspension chemicals, chemicals used for pipeline hydro-testing and produced water operational discharges. Under the Offshore Chemical Regulations 2002, permits to use and discharge chemicals shall be applied for through the submission of a PON15C. The PON15C serves as an application for a permit for the use and discharge of chemicals during the installation, hydro-testing, commissioning, maintenance, repair and decommissioning of a pipeline. Alwyn North has an OPPC life permit in accordance with the Petroleum Activities (Oil Pollution Prevention and Control) Regulations These discharge permits are continually reviewed to ensure they adequately cover their discharges. A variation will be submitted to the current Alwyn Area PON15D chemical permit, to take account of the possible addition of chemical applications or an increase in the volume of use of existing applications. Page xv

4 The majority of chemicals used on the Alwyn North platform are not discharged to the marine environment, as they are re-injected with the produced water. The discharge of minimal additional volumes of chemicals and oil, when the re-injection system is not operational, should be rapidly dispersed in the Alwyn North area. Routine discharge of utility chemicals to the marine environment will take place, but are not influenced by production. No significant negative effects are expected. Similarly, with the management and mitigation measures in place, no transboundary or cumulative impacts are anticipated. S8 SEABED IMPACTS A number of activities have the potential to impact the seabed, including the installation of two pipeline end manifolds, a 10 subsea production pipeline and a separate 5 umbilical line which will be trenched and will run parallel to the production pipeline approximately 20 metres apart. Extensive seabed preparation is necessary for the installation of these facilities to ensure a free draining profile is achieved along the entire Islay pipeline route. The physical footprint of the subsea structures, rock dump, concrete mattressing, sleepers and seabed excavations will have a direct impact on seabed fauna. There is the potential for direct physical injury of benthic species and localised loss of seabed habitat, direct smothering of seabed habitats, re-suspension of sediments, as well as the introduction of a hard substrate, as a consequence of these activities. It is estimated that a 40 m wide corridor of seabed could be directly impacted along the production pipeline and umbilical route. When combined with the physical footprint of the subsea structures, a total estimated direct impact of 240,787 m 2 is expected. The deposit of stabilisation or protection materials such as pipeline protection and free span correction deposits are regulated under the Offshore Petroleum Production and Pipelines (Assessment of Environmental Effects Regulations 1999 (as amended). The placement of pipelines and other seabed infrastructure onto the seabed is regulated under the Petroleum Act Trenching and backfilling of the umbilical line will minimise the long term loss of seabed habitat, the use of a fall pipe for rock dumping will ensure more accurate rock placement, and all excavated material will be deposited at a designated disposal site. Anchored vessels will not be used for installation of subsea facilities therefore eliminating the potential for anchor scars. The area likely to be affected by the pipeline and subsea facilities will be localised to a small area of seabed that is considered to be representative of large expanses of the North Sea. Although the development is located approximately 550 m from the UK/Norway transboundary line, the Islay development will not result in significant negative transboundary or cumulative impacts. S9 NOISE The EC Birds and Habitats Directives make it an offense to deliberately disturb wild animals of a European Protected Species in such as way as to significantly affect the ability of any significant group of animals to survive or breed, or the local distribution or abundance of that species. Impact hammer piling to secure the two pipeline end manifolds to the seabed is the most significant noise source identified in Islay operations and may affect marine mammals in particular. It has the potential to cause physical injury at close ranges and behavioural effects at a considerable distance from activities. Some installation vessels may make use of dynamic positioning systems (DP) which involves the use of a number of thrusters to maintain position. The noise generated from potential piling operations and the use of DP vessels has been considered. A number of management measures can be implemented to reduce the impact of piling operations. TOTAL will discuss planned operations with the Joint Nature Conservation Committee (JNCC) to ensure that the appropriate protocols are developed and agreed and that operational controls are used during pile driving. Page xvi

5 Considering the low number of cetaceans expected to be in the vicinity of the Islay development at any one time, the short period over which piling is likely to occur and the suite of mitigation measures that can be employed following discussions with JNCC, there is not expected to be any significant impact upon marine mammal populations as a result of the Islay development. It is expected that the use of thrusters from the installation and support vessels will present only an incremental increase to existing noise levels. DP thrusters are regularly utilised by sea going vessels and there is likely to be only a very small area of disturbance surrounding the DP source. The potential impacts of noise resulting from an increase in vessel numbers and movement is considered low. S10 CONCLUSIONS During the EIA process, all potential environmental impacts have been identified. Overall it is considered that the project will not have a significant environmental impact. All appropriate environmental consents will be revised and updated as required and management and mitigation measures implemented to ensure impacts are minimised as far as possible. Potential cumulative and transboundary impacts have been identified and assessed. No significant effects have been identified. Page xvii