Denis Ariko

Denis Ariko

Petroleum Geologist

Directorate of Petroleum, Ministry of Energy and Mineral Development, Uganda

Denis Ariko is a Petroleum Geologist and the head of technical evaluation at the Petroleum, Exploration, Development and Production Department in the Ministry of Energy and Mineral Development, Uganda. He has 6 years of industry experience as a petroleum geologist undertaking tasks such as Geological and Geophysical data interpretation, well drilling monitoring and well data analysis, Reservoir characterization and modeling and Resources and Reserves Evaluation among others. Prior to joining the oil industry, Denis was involved in the mineral exploration sector in various parts of Uganda, Tanzania and South Africa for a period of 4 years. Denis has aN MSc in Petroleum Geoscience from Heriot Watt University, Scotland, UK and is a member of SPE and AAPG. He has also been involved in projects such as definition of the Stratigraphy of the Albertine Graben from the L. Edward sub-basin to the Rhino Camp sub-basin in Uganda from 2009 to 2012 with Dr. David Worsley and reservoir characterization to maximise recovery of the Ngege field in the Albertine graben, Uganda among others.


SESSION 11:  Evaluating Reservoir Connectivity between Ngiri and Kasamene Fields in the Albertine Graben

D. Ariko, T. Ddungu, H. MugiziR. Nuwagaba & A. Ayaa

A number of adjacent fields in the northern part of the Albertine graben in the Albert Nile delta are operated by different licensees. Data gathered over these fields as a result of appraisal activities demonstrates with reasonable certainty that some fields extend into adjacent licensee areas with a different operator. The Ngiri field which was discovered in September 2008 and located in the delta was found to extend into another license area for another operator adjacent to Kasamene field requiring a need for unitization between the different operators.

Furthermore, the studies by oil companies show that there is possible connectivity between reservoir intervals of these adjacent fields previously known to be compartmentalized. The operator’s data indicates that the Ngiri field is in pressure communication with the Kasamene field. The revised understanding may result in modification of development strategies and drilling of infill wells to warrant good reservoir management.

Due to the difference in interpretation between the companies and the technical teams of the government, additional work needed to be done to confirm connectivity or the lack of it between the Ngiri and Kasamene fields.

Consideration to acquire additional data including interference well testing across the fault can be made as this data would prove connectivity or lack of it. Acquisition of this data will need to be undertaken in accordance with the licensing provisions of the Petroleum Act.

A detailed evaluation to establish reservoir connectivity or compartmentalization between the two adjacent fields was carried out by the government integrating structural, stratigraphic, fluid property and pressure data as well as well test data interpretations of the various wells/fields to achieve a deeper, more comprehensive understanding of reservoir connectivity and/ or compartmentalization.

The methodology involved investigating sealing/non-sealing faults, channel margins, stratigraphic pinchouts, diagenetic boundaries among others which separate hydrocarbons and aquifers within a field or discovery. Connectivity as a result of sand juxtaposition was also investigated.

Seismic data was used for fault interpretation and top reservoir and/or topseal mapping, well data was used for well correlation (formation tops) and interpretation of depositional environment whereas pressure data was used to establish fluid contacts.

Overall, the results show that there is discontinuity between the adjacent fields. The fields are covered with 2D/3D seismic data and well data.
Seismic data shows the effect of faulting in the adjacent fields with relatively large throws which may infer discontinuity which is supported by the pressure data analysis. Although the correlation panel is inconclusive, it is noted that there is a variation in reservoir quality and thickness between Kasamene and Ngiri fields.