Ejadawe: We are optimistic, we cannot give up on exploration
Elder Joe Ejadawe is the Managing Partner of Ejadawe & Partners (mineral and petroleum consultant), and a founding member and fellow of Nigeria Association of Petroleum Explorationists (NAPE). In this interview with ROSELINE OKERE, he spoke on advantages of prodpecting oil in new frontiers
Tell you what you feel about the Federal Government’s new zeal for exploration in the Chad Basin?
Before I answer your questions it is important to educate the general public with some basic ideas that enable all of us to become petroleum geologists. I have a pepper soup analogy for the general process of oil and gas formation as follows: In order to prepare pepper soup, the first thing we do is to collect the required ingredients (goat meat, the spices). For oil, we need to find the source rock i.e. rocks that contain organic materials that give rise to petroleum.
Once you get the ingredients then you have to put the ingredients in a pot and cook it. For petroleum, the source rock has to be cooked by burying it to a depth where the temperature is high enough (>100oC) for it to release the oil and gas. The rule of thumb is that the minimum depth is about 2000m.
While you are preparing the pepper soup, you proceed to prepare the table. For Petroleum, nature has to prepare the place where the oil will be stored and preserved. This place we call the trap, and it represents areas in the subsurface where the geometry of the rocks is convex upwards. This geometry consists of three elements – the reservoir rock which holds the oil and the seal rocks, which prevents the HC from escaping.
Once the pepper soup is ready, it has to be served on the table, while for petroleum; the generated hydrocarbon has to migrate from the source rock into the reservoir rock, in the trap. Note that the trap must exist before the migration, otherwise the oil will be lost.After feasting on the pepper soup we hope it nourishes us; the petroleum now has to be preserved for us to find it in the subsurface.
The Nigerian National Petroleum Corporation (NNPC) has tried exploring the Chad basin without much success. What do you think should be done in this new zeal for hydrocarbon in the basin?
Explorationists are eternal optimists and rarely give up on exploration in a sedimentary basin. However, the drilling of such a large number of consecutive failed wells is unusual and the first thing to do is to understand why the wells failed by doing a well- look back analysis. That work should be integrated into a play evaluation of the basin in order to establish if a fairway exists, which then constitutes the focus area for subsequent detailed investigation and possible drilling, where prospects can be defined. We must also establish the level of risk we are willing to take before we call it quits.
What do you think should be done to get optimal result from the new frontier, most especially, outside the Niger Delta?
Just as I have outlined above, the first thing for any basin is to do a regional evaluation in order to determine what part of the basin has the best chance of success. This will first determine if a petroleum system(s) exists and determine the risking for various parts of the basin.
How will crude oil find elsewhere help solve the issue of militancy in the Niger Delta?
This could be a blessing for Nigeria, as it will help to remove the focus from the Niger Delta and probably limit the incessant destruction that we currently encounter.
Apart from Chad basin, which other basins have prospect for oil and gas exploration?
The Dahomey basin is already successful, but there are parts of the basin that have not been explored. There is production from the Anambrs basin, but more data is required to have a better understanding of the prospectivity. Some minimal gas has been found in the Gongola basin, but a more regional evaluation is required to fully assess the potential. The Chad basin has so far yielded negative results, but one is not sure if the proper evaluation has been carried out.
Nigeria’s oil reserve is said to be depleting. What do you think the country should do to boost reserve and increase production?
If indeed there is decline in oil reserves it can only be because there is reduced investment in exploration. The potential for reserves growth in Nigeria is still pretty high with new frontiers in the Niger Delta and the Dahomey basin and possibly the inland basins. In addition, new technology and new concepts can easily be a game.
We are currently in a low oil price regime, in large part, caused by high success in increased discovery and exploitation of unconventional petroleum resources. The then prevailing high oil price created the environment for this gloom and, I fear, it has come to stay. For Nigeria, we need to look to the future with the realization that we missed our opportunity to take advantage of the boom years and need to adjust.
It now requires of us to bring out those ideas and innovations and integrate them with technology to drive exploration success. From this perspective, and with over 40 years experience in petroleum exploration, I cannot help but peek into what I see as the potential, if only to motivate all of us and especially the younger ones.
Nigeria’s reserves projection has remained at an unattainable 40 billion bbls for the past two or three decades. As explorers, we welcome the challenge of set targets, but we must understand that set targets are not self-fulfilling; appropriate measures must be put in place to facilitate success and, when we fail, we must endeavour to learn from our failure by carefully carrying out an after-action review (AAR).
Nigeria’s deep-water exploration seems to be reserved for the International Oil Companies. Why is this so?
The deep requires additional technical inputs in seismic imaging and overpressure control, as well as, better understanding of the depositional setting and trap configurations to actualise any potential reserves growth, which is in billions. Meanwhile, the new pool exploration will lead to small incremental reserves growth.
In the Deep-water, considerable creaming has taken place over the years and economics is a major determinant in exploration for new and smaller pools that can take advantage of existing facilities.
What about the inland basins and Nigeria’s determined efforts to increase reserves through these areas?
Discussion of exploration in the inland basins often seems to have political undertones, which, unfortunately, beclouds any objective assessment of the prospectivity. This objective assessment is crucial, and our professional integrity should assure this. Two broad Cretaceous plays (Upper and Lower Cretaceous) are defined in the Inland Basins and four basins stand out: The Benin Basin has yielded success in the Proximal shelf/Shelf Margin play domain, but little exploration has taken place in the deep-water turbidities domain, which may be more prospective.
In the Anambra basin, with only one marginal field, three characteristics dominate: dominant shale lithology, which limits typical reservoir development, but may favour source rock reservoirs, lack of structuration post Santonian with trapping configuration presumably dominated by stratigraphy, source rock over maturity and hence predominant gas occurrence and potential shale gas resource. However, spec seismic is required to aid understanding of the deep subsurface. In the Chad basin, the basic structural framework appears to have been defined and active studies are ongoing. However, geologic evolution suggests that, in comparison with successful analogue basins in the Sudan and the Chad, the basin was subject to extensive compressive deformation in the Santonian, followed by continuous uplift, and, as a result of the Turonian transgression, the key lacustrine source rock may not have been well developed. The risks associated with proper understanding of the petroleum system(s) need to be critically evaluated in assessing the potential for reserves growth. Excluding some marginal success in the Gongola basin in the Shell Kolmani River well, there is need for a proper play evaluation of all of the Benue Valley.
The NNPC Frontier Exploration Services (FES) should be a nimble team with responsibility to package the prospectivity assessment of these basins to attract investors, and to spearhead exploration evaluation outside Nigeria.As explorers, the future is not bleak, but new ideas and considerable investments will be required to realise the potential. We have plenty of work to do, and I believe we are up to the task.
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