ReconAfrica’s daring move in the Kavango Basin
by Wonder Guchu September 6, 2024 in Oil & Gas
ReconAfrica has come a long way, and the company’s path needed economic faith.
It also needed a lot of money and strength to fight off spirited campaigns to stop the company from exploring the vast Kavango Basin.
Before ReconAfrica’s journey into the Kavango Basin, the East African Karoo tectonics studies indicated rift-like structures stretching from the East African Rift to the Namibian Coast.
In 2014, ReconAfrica enlisted the services of Earthfield Technology to produce depth-to-basement inversion and high-resolution aeromagnetic data.
Using this data, ReconAfrica applied for PEL 73, which covers 25,341 km2.
Today, ReconAfrica is drilling a fourth well, the Naingopo, while preparing to spud a fifth one, Prospect P, in the Owambo Fold Belt.
Last week, the company said the Naingopo
exploration well had drilled beyond 2,400 metres or 7,875 feet, with surface casing set at 350 metres and a first casing string set at 1,200 metres.
The well is targeted to be drilled to a depth of approximately 3,800 metres or 12,500 feet and is expected to encounter four primary reservoir intervals containing oil and natural gas.
The company will soon undertake the next set of logging and coring activities and setting the second casing string, targeted at approximately 2,600 metres or 8,530 feet.
“The well has been tracking drilling depth and well cost estimates, and it is on schedule and planned with the primary objectives beneath our current drilling depth,” ReconAfrica said in its quarterly financial report.
It added that if successful, the well would be a significant play-opening discovery, providing access to multiple drill-ready prospects.
ReconAfrica is also progressing with constructing the access road for the second Damara Fold Belt exploration well, Prospect P on PEL 73.
Based on the Netherland, Sewell & Associates, Inc. report, Prospect P targets 309 million barrels of unrisked prospective light/medium oil resources, or 1.6 trillion cubic feet of prospective natural gas resources, on a 100% working interest basis.
The well aims to drill to a depth of approximately 3,800 metres or 12,500 feet and is expected to encounter four primary reservoir intervals targeting oil and natural gas.
The well would be a significant play-opening discovery, providing access to multiple drill-ready prospects.
Daring feat
Writing for GeoExpro in 2023, ReconAfrica geologists Ansgar Wanke and Jim Granath said the company’s frontier exploration program in the Kavango area, east of the Owambo-Etosha Basin in Namibia, continued to yield surprises and encouragement.
The geologists said exploring an untouched basin for hydrocarbons is rare in the twenty-first century, considering that the closest legacy well to ReconAfrica’s block is well over 200 km away, in the Owambo-Etosha basin.
According to the geologists, the deepest water wells in the Kavango Basin ended in the uppermost Karoo unit, the Jurassic Etjo Sandstone.
Wanke and Granath pointed out that the aeromagnetic data suggested extensional features that could harbour a complete Karoo sequence of rocks occupying grabens associated with the Africa-wide belt.
They further said this became the ‘Kavango Sedimentary Basin’ to distinguish it from the long-recognised Owambo-Etosha Basin to the west.
ReconAfrica subsequently commissioned a Karoo paleogeographic study for southern Africa that outlined how all these basins might tie together in a model of Karoo depositional systems.
These studies conceptualised ReconAfrica’s play in the Namibian license and neighbouring PEL 1 in Botswana.
The Kawe well
ReconAfrica’s first stratigraphic test well, Kawe, was planned for drilling in 2020, but COVID-19 stood in the way.
Even then, ReconAfrica overcame the COVID-19-induced disruptions by bringing its acquired rig, Jarvie-1, from Houston, USA, to the Kavango region to start drilling, which began in January 2021.
Wanke and Granath said Kawe’s location for the first well (Kawe) was chosen on an intermediate high within the deep part of the basin based on aeromagnetic-derived depth-to-basement maps.
They added that Kawe was designed to reveal the stratigraphy’s nature and dimensions below what was known from the water wells and to establish whether a petroleum system was present.
“No other data nearby gave any definitive indication of the age of any basin fill that might be present,” the geologists said.
They said the Etjo Formation could be on top of a more extensive Karoo section as in the neighbouring Waterberg Basin, or it could just form a thin veneer resting on the Precambrian Mulden Group, which is the case to the west in the Owambo-Etosha Basin proper.
However, after drilling about 740 metres, hydrocarbon shows were reported from about 740 m below the surface as the drill bit entered the Lower Permian Karoo sandstones and shales.
Wanke and Granath said light hydrocarbon fluid indicators were more potent than associated gases, and hydrocarbon shows continued into the pre-Karoo stratigraphy.
They noted that flow tests and downhole fluid sampling tools were off-location as the well was permitted and planned only as a stratigraphic test.
They, however, used wireline logs, closely spaced cutting samples, and over 180 rotary sidewall cores to provide a wealth of information to better understand the newly discovered rift basin with an associated petroleum system.
The Kawe was drilled to a final depth of 2,294 meters (7,526 feet). Over three zones, over 250 meters (820 feet) of conventionally migrated light oil, natural gas, and natural gas liquids were encountered.
The Mbambi well
ReconAfrica drilled the second well, Mbambi, in 2021. The well intersected only 630 metres of Mesozoic-Cenozoic basin fill resting on deformed pre-Karoo carbonate and evaporite lithologies.
Mbambi also encountered vital gas and fluid indicators over long intervals.
The second stratigraphic test well, the 6-1 in Mbambi, Namibia, was drilled to a final depth of 2,780 meters (9,121 feet). The casing was set to total depth.
A preliminary total of 350 meters (1,148 feet) of oil and natural gas shows were encountered over seven potential zones.
Wanke and Granath said after the two wells, an initial loose network of about 500 kilometres of 2D seismic data was acquired across most of the northern part of the block.
This Phase 1 seismic campaign established the initial inventory of leads, third-party prospective resource estimates, and a framework for the second phase of seismic acquisition.
The Makandina well
In late 2022, ReconAfrica drilled the third and first seismically defined well, the Makandina.
The drilling of the Makandina followed the completion of another 761 km of 2D seismic acquisition.
Makandina encountered hydrocarbon gas liquids, specifically ethane, butane, and propane, as well as smaller quantities of heavier hydrocarbons.
Hydrocarbon gases were recorded between 838 metres and 1807 metres and between 1990 metres and 2058 metres.
ReconAfrica said that although geologically, it was a successful well, economic accumulations of hydrocarbons were not encountered, very likely due to the absence of a trap or a four-way dip closure.
After this slight setback, ReconAfrica extended its seismic acquisition program to acquire over 2,600 km in late 2022 and the first half of 2023.
With acquisition limited to 2D seismic on existing roads, tracks, and fence lines, an enhanced Full Tensor Gravimetry (eFTG) survey has been permitted to complement the seismic data.
This high-resolution gravity information is expected to improve the interpolation between 2D seismic lines.
Wisdom 5-1 Well
Unfazed by Makandina’s results, ReconAfrica announced it would move to the next well, the Wisdom
5-1.
The well was expected to principally test stacked plays in a different part of the Karoo Rift Basin lying over the eastern most edge of the Owambo-Etosha basin.
On June 28, 2022, ReconAfrica engaged a leading airborne geophysical survey provider to conduct an eFTG survey over an area of nearly 2,200 square kilometres (540,000 acres) in ReconAfrica’s 25,000 square kilometres (6.3 million acres) PEL 73 exploration license in northeastern Namibia.
ReconArica announced that it delayed the target commencement date for drilling this well until late February 2023.
ReconAfrica communications manager Ndapewoshali Shapwanale said the Wisdom well was not drilled because the well was supposed to add more data to the portfolio.
Shapwanale said the company had to decide whether to proceed with the drilling or use the available data from the Kawe and Mbambi wells.
According to Shapwanale, the Enhanced Full Tensor Gravity was also completed before the drilling at the Wisdom prospect had started.
Wanke and Granath gave an example of a seismic line across the Karoo Rift Basin, which shows the graben structure and growth faults typical of an extensional basin.
In addition, seismic data had shown that the rift straddles the frontal fold and thrust belt of the late Precambrian-Cambrian Damara Orogenic Belt.
The geologists said the term ‘Karoo Rift Basin’ is now the preferred terminology within ReconAfrica to describe this rift overlying older rocks.
Then came the Damara Fold Belt
On April 3, 2023, ReconAfrica said a phase two 2-D seismic program had confirmed a significant new play type in the southern and western parts of PEL 73.
This new fold belt province, the Damara Fold Belt, initially identified the southwest of the Karoo Rift Basin, consists of a prominent and imaged series of anticlinal structures known as Whaleback anticlines.
The Damara orogenic belt stretches from the coast eastwards across the country to eventually disappear as it trends under the same Cenozoic Kalahari cover that hides the Karoo Rift Basin.
The seismic data revealed that the width of the Damara-age frontal fold belt is more significant than was suspected and that the fold assemblages undergo a central northward deflection to become north-northwest trending in the license area.
Wanke and Granath said this change in orientation from the west-east oriented structures in Otavi Mountainland is the only frontal fold belt exposure supported by Future Market Insights analysis of the bedding data sets from the three wells.
They said the pre-Karoo had been an exploration target further west in the Owambo-Etosha basin; so far, only five stratigraphic/exploration wells have been drilled between 1964 and 1986.
Monitor Exploration is planning its exploration program in the eastern portion of the Owambo-Etosha basin, west of ReconAfrica’s license acreage.
ReconAfrica conducted a Vibroseis seismic parameter test to establish the best vibrator sweep parameters and number of vibrators in a fleet and to investigate field data processed results for future seismic projects on PEL 73.
Six runs of a six-kilometre line with different vibrator and sweep configurations were completed to reshoot a 23-kilometre line previously shot with an Accelerated Weight Drop source.
The initial field data processing results from the 6 km line identified the best vibrator and sweep configuration for the 23 km test line. After shooting the 23 km line, the results were processed to a brute stack and compared to the previous Accelerated Weight Drop processed data, showing marked improvement in data quality.
Individual Vibroseis and Accelerated Weight Drop shot records were also analysed, and similar improvements were observed.
ReconAfrica CEO Brian Reinsborough said the Naingopo exploration well drilling is on time and budget.
Reinsborough also said the seismic velocities are running faster than modelled, hence, reservoirs are coming in deeper than predicted, with all primary reservoir targets below the current drilling depth.
“We continue progressing with the road construction work before getting the well pad ready for the Kambundu (Prospect P) exploration well, which is targeted to start drilling in the fourth quarter,” he said.
https://theextractormagazine.com/2024/09/06/reconafricas-daring-move-in-the-kavango-basin/
..
.
News 
Market Data 
Discover 
AI
