Geology
The block lies in the Lower Congo Basin, which is one of the salt basins that formed along the Atlantic margin following Early Cretaceous continental breakup. Reservoirs were deposited in two major phases: pre- and post-salt deposition.
Pre-Salt Plays
- The primary reservoirs are the Lucula Sandstone of Jurassic to Early Cretaceous age, sealed by shales of the Bucomazi Formation, and the Aptian-aged Chela Sandstone sealed by the Loeme Salt
- The Lucula is equivalent to the main reservoir in the M'Boundi Field in the Congo (Brazzaville).
- The Chela forms the gas reservoir that was encountered by the 123-5 well drilled by Gulf Oil (Cabinda) in 1968.
- Traps - terrace and onlap/pinchout traps.
Post-Salt Plays
- The main reservoir is the Vermelha Sandstone.
- The trap is formed where the sandstones occur in rotated fault blocks, sealed by marine shales.
- This play accounts for a major portion of the production in the offshore area.
- Secondary reservoirs include the Iabe Sandstone and Pinda Limestones, both of which produce offshore, and sandstones in the Lago and Mesa Formations.
Regional activity
The Lower Congo Basin is a prolific oil producer with a total production in excess of 1.3 million BOPD, approximately one-third of which is produced in the Chevron-operated Block O immediately offshore from the Cabinda South Block.
For several decades, offshore oil production platforms have pumped oil to shore-based facilities in Cabinda.
No part of ROC's block is more than 50km from Chevron’s onshore oil processing facility at Malongo.
Permit size
1,073km2
History
- The block is in the Lower Congo Basin, a prolific petroleum province.
- Due to the Angolan civil war, the block had not been explored from the early 1970s until ROC started its activity on the ground in 2005.
- In 2000 ROC agreed to acquire a 45% interest and operatorship in the block and in 2001 received Government approval for the acquisition. In 2002 the civil war ended.
- In 2003 ROC acquired a further 15% in the block.
- In 2004 the PSA was activated.
- In 2005 ROC-operated 2D and 3D seismic surveys marked the effective return of onshore oil exploration activity in Angola after a hiatus of more than 30 years.
- Some oil and gas discoveries and shows were recorded from within the block, despite the pre-1972 wells being drilled on gravity data, surface mapping and old seismic data.
- In April 2009 ROC executed a farmout agreement with Pluspetrol Angola Corporation for the farmout of a 45% interest (56.25% paying interest) in the Block. Pluspetrol took over as operator of the Block from 1 September 2009. In November 2009 ROC agreed to farmout 5% interest (6.25% paying interest) to Cuba Petroleo.
- In May 2011, ROC sold its remaining 10% interest in the Cabinda Onshore South Block. The sale is subject to relevant government approvals.
JV participants and interests
| |
Beneficial Interest |
Contributing Interest |
| Pluspetrol Angola Corporation (Operator) |
45.0% |
56.25% |
| Lacula Oil Company Limited (owned by ROC) |
10.0% |
12.50% |
| Force Petroleum de Angola, S.A. |
20.0% |
25.00% |
| Sonangol P&P |
20.0% |
- |
| Cuba Petroleo |
5.0% |
6.25% |
Note: assignment of 5% interest (6.25% paying interest) from Lacula Oil Company Limited to Cuba Petroleo subject to formal documentation and receipt of relevant approvals.