An Integrated Approach to Maximizing Recovery and Improving Gas Management for the Kizomba A Project

Edson R. Dos Santos, David Courtnage, E-Chien Foo, and Alvaro Alves
Exxonmobil, Houston, TX

The Lower Miocene 1516 reservoir in the Hungo field is the largest reservoir system in the Kizomba A project in Angola Block 15. To increase recovery from this reservoir and position the Kizomba A project to more efficiently store gas until availability of a regional gas export solution, a highly-integrated study was conducted to optimize the overall depletion plan. The integrated approach consisted of fully utilizing reservoir data from 7 well penetrations, downhole pressure data, RCI pressure data, high-resolution 3D and 4D seismic data, and production data. Integration of all the data sources led to an improved geologic characterization of the reservoir, specifically concentrating sands in a low net-to-gross interval to improve vertical communication. The improved geologic model, when incorporated into a reservoir simulation model, matched performance and pressure data that earlier geologic characterizations could not. Further, the improved model matched water movement and gas evolution as inferred from the 4D seismic response. The history-matched simulation model was utilized to evaluate three depletion strategies: (1) a waterflood, (2) water-alternating-gas injection, and (3) simultaneous downdip water injection and crestal gas injection, or combination drive. The simulation modeling showed that the combination drive mechanism maximized ultimate recovery and near-term production rates, while also offering a more efficient way for the Kizomba A project to store gas until availability of the regional export solution.

AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery