As TotalEnergies continues drilling the Macaw-1 well in Suriname’s Block 64, attention is shifting to the Demerara Shelf and what the activity there might mean for future exploration.
According to Henk Kombrink, Editor-in-Chief of GEO ExPro, oil companies are now more interested in shallower waters than the deeper offshore zones that previously drew focus. “There is a drive to discover more resources nearby,” Kombrink said, “rather than focusing on deep water, as was done in recent years, the shallows of the Demerara High have come on the radar, again.”
Several companies are positioning themselves for this shift. “Shell is planning on drilling the Araku Deep-1 in Block 65,” Kombrink stated. “Chevron may have identified another hydrocarbon migration pathway heading south from the kitchen in the north – they will target the Korikori prospect in Block 5.”
In petroleum geology, ‘kitchen’ refers to an area deep underground where heat and pressure have generated oil and gas, which can then migrate to other locations.
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Kombrink noted that earlier wells in the area are helping explorers interpret the region. “It is the information derived from these wells that can subsequently be used as material to learn a bit more about what the French are targeting with Macaw-1.”
He referenced Tullow’s Goliathberg-Voltzberg North-1 (GVN-1) well, drilled in 2021. “Both wells are situated on the Demerara High,” Kombrink said.
“It is thought that the Tullow well was planned in such a way that it tapped into a Canje source rock preserved in a local and small mini-basin.” A mini-basin is a smaller geological depression where oil might gather under specific conditions.
He added that, given that the well was dry, this might indicate that the source rock maturity was insufficient. Another issue may have been ineffective migration.
Kombrink said, “Even if the source rock from the local Canje pool would have been in the oil window, hydrocarbon migration would probably have taken place in a radial manner, lacking structural focus.” Radial migration suggests oil may have dispersed in different directions instead of moving along a well-defined path into a reservoir.
This could explain why nearby reservoirs weren’t filled with oil. Underfilling reservoirs surrounding the mini-basin, Kombrink noted, could be the result.
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Macaw-1 may have better luck due to its distance from the source rock. Kombrink explained, “It is of the same order of magnitude as the distance the oil travelled to the Tambaredjo and Calcutta fields.” These fields are Suriname’s only known commercial oil producers so far.
“It looks like there is no mini-basin at the location of the TotalEnergies well,” Kombrink added, suggesting that the company may be relying on a model where oil traveled from a known source rock to the west. “A Lower Cretaceous Canje source rock model that migrated from the kitchen in the west.”
This is the same model that led to the Golden Lane discoveries, although Kombrink cautioned that success has been limited. “The distance is long and so far no commercial discoveries were made on the Suriname offshore shelf apart from the Tambaredjo and Calcutta heavy oil fields.”
Still, he pointed out, the oil found in those fields proves one thing. “Long-distance migration does work.”
Whether Macaw-1 is positioned in the best spot remains to be seen. Kombrink recalled a 1977 well drilled by ExxonMobil. “Demerara-A2-1 drilled by ExxonMobil in 1977 seems to be in that very spot, where migration pathways from the kitchen in the west meet,” he said. “It’s interesting that this was already understood in the 1970s, using much more rudimentary seismic data.”
There may also be another factor at play with Macaw-1. “Another possibility is that Macaw-1 targets a deeper source rock in Jurassic carbonates,” Kombrink stated. These older rock layers could hold oil, especially if they’re mixed with sediments that generated hydrocarbons in the past.
Some reports mention the possibility of oil coming from rocks formed in ancient lakes, but Kombrink is skeptical. “The evidence for that seems a little flaky,” he said.
Still, the industry is watching Macaw-1 closely. “Whatever the play model that TotalEnergies favours,” Kombrink said, “a discovery at Macaw will be a very encouraging sign for Suriname in general and the Demerara High in particular.”
