RIASSUNTO
Abstract
Deepwater represents a significant proportion of future oil and gas exploration and production. Scientists have however stated that the deepwater environment is less well understood than the dark side of the moon. At the same time there is increasing pressure from NGOs to postpone deepwater exploration until more is known about potential impacts. In partnership with the marine science community, and via capacity building in Angola, BP has developed and installed the world's first Deepwater Environmental Long-term Observatory System (DELOS) off the coast of Angola. Two environmental monitoring stations were installed, one in the near field and one in the far field 16 kms distant from, and upstream of, any infrastructure. These subsea platforms will be in place for around 25 years and, for the first time ever, will provide scientifically defensible data to distinguish between anthropogenic and natural change in the deep sea. Without this understanding future changes in the deepwater environment could be incorrectly attributed to E&P operations.
The data collected will be fundamental in helping Industry and the scientific community to build a long-term picture of deep-sea processes and ecology. In particular, it will enable us to:
- Measure and monitor deep-sea biological communities
- Monitor the pace of recovery from any unforeseen impacts
- Differentiate between natural & anthropogenic changes and provide a linkage between marine biodiversity & climate change
The development of the system from concept through to fabrication, installation, and first data recovery is outlined including a first use of non-corrosive Glass. Reinforced Plastic (GRP) as the primary structural element for a deepwater subsea facility. The selection of the various instrumentation modules and their application is discussed.
Introduction
The deep-sea environment into which oil and gas operations are gradually extending is generally poorly understood with surveys regularly discovering new habitats and communities of animals previously unknown to science. Industry currently has little understanding of the impacts of our operations beyond continental margin areas. Without this understanding future changes in the deepwater environment could be incorrectly attributed to our operations. There is inevitably a lack of historical data which can be used as basis for baseline knowledge and prediction. It is however apparent that all deep-sea environments support a wide range of animals that contribute significantly to global biodiversity. At the present time, only a limited number of deep ocean sites have been monitored for periods exceeding 5 years (Smith el al 2001; Billet et; al, 2001). At these sites important annual cycles have been observed with considerable variability from year to year and changes in dominant fauna over decadal time scales (Smith et al 2008; Rul et al 2008). In the Pacific, evidence suggests a linkage between the surface
climate and the deep sea, and major climatic events such as El Ninõ/La Ninã have influenced the deep sea floor epibenthic megafauna community (Ruhl et al, 2004; Billet et al, 2009). In an oil and gas production area, it is desirable to distinguish such spontaneous changes from any influences imposed on the deep-sea environment by the oil and gas activities.
This paper discusses the development and deployment of the DELOS system (Deep ocean Environmental Long-term Observatory System) (Walls et al 2005; Bagley et al 2006, 2007)) which will provide long-term environmental monitoring data to both science and the oil industry. DELOS has been deployed in 1400m water depth offshore Angola in the vicinity of the Greater Plutonio oil production field.