Appraisal of a Supergiant: The Kashagan Field, North Caspian Basin, Kazakhstan

By

 W. Zempolich¹, C. Alberti¹

(1) Agip Kazakhstan North Caspian Operation Co. N.V, The Hague, Netherlands

 The Kashagan field is located on the North Caspian Sea, offshore Kazakhstan and is one the largest discoveries made in the last several decades. The structure was successfully tested by the Kashagan-East1 and Kashagan-West1 exploration wells, which penetrated a significant oil column in late Devonian-Carboniferous platform carbonates. The Kashagan structure developed as an isolated carbonate platform and is approximately 75 km length and 35 km width. Due to its areal extent and complexity of the reservoir, further appraisal is required to determine the true size of the Kashagan resource. Challenges of the appraisal program include operating in shallow, ecologically-sensitive waters subjected to harsh winter and ice conditions.

The Kashagan appraisal program includes acquisition of a state-of-the-art 3D seismic dataset and a sequence of wells which are designed to assess the potential of the structure as rapidly as possible. Due to water depths that range from 3 to 8 m, approximately 1600 km2 of OBC seismic data will be acquired and processed to better image the reservoir. Appraisal wells have been strategically located to test the geological model and to assess reservoir quality across the structure. Well logs, core data and vertical seismic profiles are also used to tie in the 3D seismic data set in order to correlate reservoir intervals between wells.

The Kashagan-East2 and Kashagan-East3 appraisal wells support the presence of a platform rim with enhanced reservoir quality and strengthen the geological model. Further drilling and integration with 3D seismic will allow for continuing definition of the resource.