By Kiana Wilburg
Since 2015, much of the attention has been on the deep water exploration and subsequent discoveries by ExxonMobil. But the spotlight certainly has to be shared with the exploration potential Guyana’s shallow water now holds for prospective oil majors says Geologist, Anthony Paul.
During an interview with Kaieteur News, the Trinidadian said that his comment comes on the heels of recent oil discoveries made at the Jethro-1 and Joe-1 exploration wells on the Orinduik Block by Tullow Oil.
The Geologist explained that in a petroleum system, you need four things to find oil. He explained that one needs a source rock, which is rich in organic matter and has been buried deep in the earth, under the right conditions for it to have been heated under pressure for a long time to convert the organic matter into oil and/or natural gas.
Paul then said that a reservoir rock would be needed. He explained that this rock has pore spaces between the mineral grains that make up the body of the rock, into which spaces the oil goes, displacing water that would have been trapped when the rock was formed.
For the oil to move from the source rock to the reservoir rock, the Geologist said that there needs to be a “migration path,” such as a fault or a permeable rock, connecting the source and reservoir.
Paul added, “Then finally, you need a seal that traps the oil within the reservoir rock, preventing it from leaking out via another migration path. These elements have to be in place with the right relative timing for all conditions to be favourable. But what Tullow is finding is that the oil has found a migration path from the deeper parts of the Guyana basin, to the shallow parts, into the much younger Tertiary age reservoirs.”
Paul explained that Tertiary aged rocks are much younger than those of Cretaceous age. He highlighted that the reservoir rocks that ExxonMobil made most of its discoveries on are Cretaceous. Paul noted however that Exxon has also found Tertiary reservoirs, but all their discoveries for those have been in deep waters.
The Orinduik discoveries Paul noted, are of younger Tertiary age rocks and in shallower waters. The Geologist said that these discoveries have proven that there are migration pathways from the older Cretaceous source rocks to the younger Tertiary rocks and from deep water to shallower waters (Jethro and Joe). He said, “It therefore raises the question of whether there are other shallow water discoveries to be made.”
Further to this, the Trinidadian explained that shallow water exploration and oil production means cheaper costs. Citing drilling as an example, Paul noted that the rigs used for deep-water exploration are very expensive when compared to what is needed for shallow water. He said that deep-water rigs are very expensive since they are very specialised. Similarly, production systems are much cheaper, with the use of fixed platforms, rather than Floating Production, Storage and Offloading facilities (FPSOs) and associated, expensive sub-sea completion wells.
Further to this, the geologist said that a deep-water rig cannot be anchored on the sea floor, as such; it requires a very specialised, computer-controlled system of multiple thrusters, pushing in different directions, with variable force, to maintain position. He explained that this is the case with other vessels that are needed for deep-water projects such as Floating Production Storage and Operating (FPSO) vessels.
Paul said, “They have motors that are dynamically positioned and the thrust changes depending on the current and it is computer driven. So you can imagine that it is very expensive to keep it stationary but if you are in shallow water you can anchor these things to the ground with cables or by driving piles into the sea floor. It is much cheaper to do. So the beauty about shallow water is that it is cheaper to produce and the time for production is significantly reduced.”
In addition, since these are more common activities, Paul pointed out that more of the engineering, fabrication and operations support work can be provided from within Guyana and by Guyanese, thereby increasing the level of local content.
The Geologist added, “While shallow water exploration has the advantage of being cheaper to produce, deep water has the advantage of more productive reservoirs, which tend to be larger, cleaner and less broken up into small compartments, each of which holds more oil and can be produced with fewer wells. You get a higher yield per well.”
ORINDUIK JV PARTNERS
In January 2016, Eco signed a Petroleum Agreement and is party to a Petroleum Licence with the Government of Guyana and Tullow Oil for the Orinduik Block offshore Guyana.
Tullow Oil, as the Operator of the Block, paid past costs and carried Eco for the first 1000km2 of the 2550km2 3D Survey. Further, Tullow contributed an extensive 2D seismic data set and interpretation.
The Company’s 2550 km2 3D seismic survey was completed in September 2017, well within the initial four-year work commitment the Company made for the initial 1000km2.
In September 2017, Eco announced that its subsidiary, Eco Atlantic (Guyana) Inc. entered into an option agreement on its Orinduik Block with Total, a wholly owned subsidiary of Total S.A. Pursuant to the option.
Total paid an option fee of US$1 million to farm-in to the Orinduik Block. An additional payment of US$12,500,000 was made when Total exercised its option to earn 25 percent of Eco’s working interest in September 2018.
Following the exercise of the option by Total, the Block’s working interests became: Tullow – 60% (Operator), Total – 25% and Eco – 15%. In October 2018, the Government approved of the Total farm-in on the Orinduik Block, which has the potential for almost three billion barrels of oil equivalent.
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