Abstract

As exploration and production move into ever deeper waters, the tools and techniques for assessing the environmental impacts of deepwater projects are being developed.

This paper outlines the various complimentary techniques that BP Angola is using to describe biodiversity and to monitor the environment in water depths ranging from 1200m to over 2000m.These include:

  • wide ranging, snap-shot in time benthic surveys, which are targeted based on the geophysical information we have in the area mainly looking at seabed microfauna, using a variety of physical and photographic sampling techniques, including the deployment of BP Angola's deepwater short term environmental platform.

  • Short range, extended timescale monitoring with Remotely Operated Vehicles of opportunity mainly photographic looking at larger animals, with trials of traps to gather microfauna. The ROV also photographs animals within the water column as it travels between the rig and the well.

  • Observations of marine mammals, turtles, birds and surface visible fish from seismic and survey vessels.

  • Long term (25 years) monitoring of deep ocean environmental processes with the deployment of deep sea environmental platforms; a cooperative project involving Scripps Institution of Oceanography, Aberdeen University, Texas A&M University at Galveston and Southampton Oceanographic Centre. These platforms should help us understand the linkages between deepwater biodiversity and climate change.

The data gathered is used in managing the environmental impacts from our operations and also in our Environmental Impact Assessments.In addition, the data is shared with the wider scientific community and used in local capacity building to ensure added value.

The described techniques represent a major step forward in the characterisation of deepwater environments and are applicable in other deepwater areas.

Introduction

Deepwater is becoming an increasingly important oil province.In 2003, 65% of exploration finds were in water depths greater than 1,000m.At BP, we estimate that over half of the field development projects underway in 2012 will be in water depths of over 1000m and up to 2500m or even deeper.

Very few of the many ecosystems found at depths below 200m have been studied.However, research over the past decade has revealed remarkably high levels of biodiversity associated with many deep-sea ecosystems.

The oil industry is faced with the challenges of:

  • Understanding the deepwater environment sufficiently well to plan and deliver appropriate management measures to reduce the impact of our operations to an agreed acceptable standard.

  • Developing "public trust" in our deep water operations.

  • Balancing the economic and political drivers for "pace" with the need for knowledge of the deep water environments in which we plan to operate.

In common with almost all deep water provinces, there is very little known about the deepwater environments offshore Angola.BP Angola has therefore developed a programme of studies, in collaboration with Angolan and international scientists, to provide information for environmental impact assessments and management, and to enhance the wider knowledge base of deep sea biodiversity.

The Angolan Deepwater Environment

Over 70% of the Earth's surface is ocean.The sea contains most of the higher order biological diversity on Earth, with many millions of species in the seafloor sediments and associated with cold seeps, deep water corals and other features, most of them not yet discovered.

BP's operations in Angola are in Blocks 18 and 31 in water depths of 1,000m to in excess of 2,000m (figure 1).The marine environment is heavily influenced by the Congo River and a number of regional currents.

The Congo River Offshore Plume: The Congo River has the second highest river discharge in the world. The river has an average discharge of 41 000 m[3]/s of water and 41 million metric tonnes per year of suspended sediment.This sediment is carried west north-west in the nearshore waters and south-southwest in the offshore waters.

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