The Fugro group of companies have been engaged in geophysical and hydrographic mapping projects in the Caspian Sea since 1994. The works done to date, using the full range of modern geophysical systems, has begun to reveal the complexity and variety of seabed and sub-seabed features and geohazards to be found in this significant area for new exploration investment. This paper describes some of the main findings particular to the Caspian Sea, with examples from Fugro mapping surveys. Recommendations are made for issues to be considered when planning future survey work in this province.
Since 1994, Fugro companies have been the most active Western contractors in geophysical survey and geotechnical sampling in the Caspian Sea. Working in Azeri Turkmeni and Khazakhstani waters, programmes of geophysical and hydrographic surveys, plus geotechnical and geochemical sampling, have been undertaken for the various western/local consortia and joint venture operations becoming established. Taking advantage of lessons learned in the North Sea and elsewhere, these new operators, led by the pioneering Azebarjan International Oil Company (AIOC), have commissioned a series of systematic and planned surveys and sampling programmes to support long term development.
The Caspian has been a major hydrocarbon province for many years, with an extensive but aged infrastructure in place to exploit the vast early discoveries of oil and gas reserves. This infrastructure, developed greatly in the Soviet era, has lacked maintenance, investment and the latest modern technology. This has resulted in an enormous backlog of reconstruction and redevelopment work. Modern oil exploration and development technologies are now being brought into play, with western expertise being used, together with increasing contributions from local Caspian personnel, in Azerbarjan and elsewhere.
The Caspian is the largest body of inland water in the world. It does not have any significant tidal cycle, but the water level does change, due to a number of factors including climatic variations and the variable influx of water from more than 125 rivers, the largest of which are the Volga and Kura rivers. Some of these rivers are controlled by dams, and thus the water level is influenced by man-made events. The full range of sea level changes have included major rises in level over recent years (Fig 2). This has resulted in whole docksides, in Azerbarjan and Turkmenistan, being flooded by the rising water.
The Caspian enjoys a range of sea conditions similar to the North Sea, but with more extremes. Poor sea state due to the strong and unpredictable winds that blow from November to March, cause long periods of weather downtime for many marine operations.
The Caspian is divided into three distinct topographic regions; the North, Central and South. The Apsheron Sill is located between the Central and Southern basins, and is an asymmetric anticline in cross section, with a steep southern slope and gently dipping northern slope.
The Apsheron Sill is a continental margin, between continental (granitic) basement rock to the north, and oceanic (basaltic) basement rock to the south