The story of the Ekofisk field, the first commercial and petroleum producing field in Norway, tells of the uncertainty in determining the prospectivity of petroleum basins and life cycle of an oil and gas field.
The discovery of Ekofisk in 1969 stimulated exploration on the Norwegian Continental Shelf (NCS) in the North Sea, during a period when many wildcat exploration companies were abandoning the NCS after drilling over 200 unsuccessful wildcat wells.
The successful oil exploration, development and production efforts in the North Sea is partly credited to the discovery of Ekofisk. This field has been in production for over 45 years, and this is attributed to investment in research and application of new technologies for enhanced oil recovery, among other reasons.
The current estimated lifetime of the field was certainly not the expectation in 1969 when the discovery was made, and when production figures plummeted in the early 1980s, with only an initial 20% recovery rate expected.
There was a turn of events when enhanced oil recovery techniques and application of new technologies led to not only a rise in production, but also an increase in reserves of the field.
The current recoverable factor is close to 50% and the field is now expected to continue producing till 2050 with an estimated 6 billion barrels of in place resources.
Uganda’s current resource base is 6.5 billion barrels of oil in place with 1.4 billion barrels of recoverable resources/reserves. This is far below the resources of countries like Saudi Arabia, Venezuela, Canada with hundreds of billions of reserves or the likes of Nigeria, Libya, Qatar, Russia with tens of billions of reserves.
However, Uganda’s resources are still significant and ranked within the same range as countries such as Australia, Chad and United Kingdom and therefore can make a significant contribution to fast-tracking economic growth and development.
It is important to appreciate the fact that the current resource level is from exploration of close to 40% of the Albertine Graben (AG), Uganda’s most prospective sedimentary basin.
The Albertine Graben is one of the four sedimentary basins with potential for petroleum accumulation. The discovered resources in the Albertine Graben are also spread across 17 fields that have been fully appraised and are being prepared for production.
None of these fields compares in size to Norway’s Ekofisk, but all the same provides important lessons on resource potential of the Albertine Graben.
At a peak production rate of 200,000 barrels per day, Uganda’s current resources can last for about 20 - 25 years. However, although exploration has been undertaken in about 40% of the AG, the licensed area in the AG is less than 15%.
This means that 80% of Uganda’s most prospective basin is still unlicensed. This is in addition to three other sedimentary basins in the country, whose potential is now under investigation. These are lake Kyoga Basin, Moroto-Kadam basin and Hoima Basin.
There is also potential for increasing the recoverability of the current fields, whose production licenses have been issued. As companies undertake development activities and begin to produce the fields, a lot more data is collected, analysed and interpreted which contributes to a better understanding of the reservoirs.
In addition, production technology evolves and investment in research normally leads to better oil recovery technics to improve production rates and timelines. It is also important that the resources are produced gradually in an efficient manner and at an economic rate that will also provide a sustained benefit to the country.
Therefore, Uganda has potential for additional resources because of the unlicensed and unexplored areas in the Albertine Graben, the virgin sedimentary basins in the country and the impact of new technology, parameters which indicate the additional resource potential of Uganda.
The presence of additional resources can only be ascertained after exploration and appraisal work has been undertaken in the unlicensed areas, and after the start production for the fields whose production licenses have been issued.
However, the infrastructure to support production has been planned basing on the current resource levels but with potential for expansion in case additional resources are discovered and hence the life cycle of the oil and gas resources extends beyond the anticipated 20 - 25 years.
SOURCE: Petroleum Authority of Uganda