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4D Seismic in Deep Water at the Dikanza Field, Offshore Angola, West Africa
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 72nd EAGE Conference and Exhibition incorporating SPE EUROPEC 2010, Jun 2010, cp-161-00393
- ISBN: 978-90-73781-86-3
Abstract
A 4D seismic program was acquired over the Dikanza field with the objectives of monitoring water sweep, OWC movement, gas exsolution and to identify infill well opportunities to optimize the field’s depletion and ultimate recovery. The baseline survey was acquired in 2002 and a subsequent monitor survey in 2008 approximately two and a half years after the start of production in 2005. Excellent seismic repeatability was achieved with a NRMS value of around 0.12 measured in an interval above the reservoir. Dramatic production related 4D effects were observed consisting of strong reflectivity changes and large time shifts associated with gas exsolution, water injection, water sweep and increases in pore pressure due to water injection. The observed responses were validated by forward modelling and comparison to well production data. The 4D data generally confirmed the effectiveness of water sweep in the field and showed excellent agreement with the production data. It confirmed the presence of off-axis channel systems and indicated the presence of stratigraphic barriers to fluid flow. The interpreted 4D response will be integrated into the geologic model to improve the simulation and history match of field performance and to optimize future producer and water injector locations.