Geoscience unlocks the treasures of Africa's hydrocarbon resources

lobal key to discoveries in Africa is extensive geoscience surveys of the region that require a broad portfolio of technologies.

Insights: Global key to discoveries in Africa is extensive geoscience surveys of the region that require a broad portfolio of technologies - Steve Toothill, VP New Ventures and Chief Geologist, CGG speaks to us.

Exploration in Africa has been continuing throughout the downturn. CGG has had at least one vessel acquiring data offshore Africa almost continuously for the past two to three years. “We have also acquired data onshore in Angola and Namibia, and are currently surveying to support the construction of the pipeline from Lake Albert in Uganda to the Indian Ocean in Tanzania,” Steve Toothill, VP New Ventures and Geoscience at CGG, said. “We have just completed acquisition of 15,400km2 of multi-client 3D data over the Beira High in the outer Zambezi Basin, the first phase of up to 40,000km2 to be acquired offshore Mozambique. We have also been acquiring proprietary surveys offshore West Africa, for example in Senegal and Mauritania.”

In addition to processing data for its multi-client group, CGG’s subsurface imaging teams have also been processing and reprocessing several proprietary surveys, including 4D offshore Angola, multi-component nodes processing offshore Nigeria and towed streamer work from a number of countries. “Our airborne multi-physics division has completed a project in Tanzania in partnership with TPDC to explore the East Africa rift basins and attract investment to the region,” Toothill added. 
A mixture of technologies

High-quality multi-client data packages can be a major attraction to oil companies looking to invest in a region. CGG has taken the lead in Mozambique starting an ambitious multi-client 3D seismic programme in the Zambezi Basin. A similar project started a few years ago in Gabon has led to two discoveries recently announced by Petronas and Repsol.

“We aim to use the latest, state-of-the-art technology on all our surveys, including multi-client surveys, in order to produce the best possible images,” Toothill continued. “Our recent Gabon survey was acquired using BroadSeis broadband technology for the maximum bandwidth and optimal low-frequency signal.”

The survey was processed through the latest high-end velocity modelling and pre-stack depth imaging techniques, including Full-Waveform Inversion (FWI) and high-definition tomography. CGG’s new Mozambique survey will also be processed through a broadband sequence including FWI.
For on-shore areas, CGG has developed LiteSeis, which is perfectly suited to the Southern and Eastern Africa regions, minimising the environmental footprint by using existing access where possible. LiteSeis vibroseis operations use the latest Sercel UNITE and WTU-508 cableless recording equipment and Nomad 15 broadband mini-vibrator to ensure the best possible flexibility, coverage and data quality.

“Our Falcon high resolution airborne gravity system has been very successful in the East Africa rift system and in the coastal basins,” Toothill added. “It provides the resolution that is required to focus seismic on structures with high potential.” 

Ready for action

Following several years of decline of investment in exploration, the tide seems to be turning in Africa. Industry has already gone through a process of reform and cost reduction. Higher oil prices and more favourable terms will attract more investment in the region given that there are still many basins both on and off-shore that are under explored with less than one well per 5,000 sq km. CGG is about to embark on a major regional 2D programme offshore East Africa including the Mozambique Channel which will help to open up the region for future exploration.