Owing to quay walls that are starting to collapse and their requiring replacement, drilling company Geomech Africa was contracted to conduct offshore drilling at various South African ports from the third quarter of 2022 through to the third quarter of 2023.

The company was contracted to drill offshore to conduct the necessary investigations for the design of new quay walls.

During the drilling programme, the crew faced several challenges, says Geomech Africa coastal director Barry Kruger.

These included transporting the 12 m South African Maritime Safety Authority-registered jacked-up barge from Johannesburg, in Gauteng, to the various ports on three superlink trucks, and then rebuilding the barge on a slipway.

“Shipping takes priority when moving around the ports; therefore, Geomech Africa needed to be in constant communication with port control to ensure the safety of the barge and commercial shipping,” he explains.

A professional surveyor was required to undertake exact surveys of the drill position in relation to the seabed.

Moreover, once the positions of the barge were agreed upon with the geologist, the barge was put into position and jacked out of the water, the depth of which reached up to 12 m.

Kruger adds that Geomech Africa often needed to jack through sediments to stabilise the barge, with the maximum depth of leg used being 18.5 m.

“The barge cannot move during the course of drilling a hole, which generally lasts between three and five days. Transporting the crew between land and the barge was challenging, owing to the tender boat bobbing up and down in the swell, making it harder to get onto the ladder of the barge.”

When moving between holes, Kruger notes that the wind conditions and open waters, or swells, had to be taken into account.

Larger swells generally enter the ports of open harbours and the Geomech Africa crew had to wait for the correct wind and wave conditions before moving the company’s barge, as it is not designed for swells.

“We were effectively drilling off a jacked-up platform 2 m above the water to take into account tides and wave action. Strict environmental controls were put in place, with regular audits to ensure there were no spillages.

“A successful drilling programme was carried out, valuable data provided to the client and a high safety standard followed with no incidents, within budget and completed on time, resulting in a satisfied client,” Kruger assures.

Meanwhile, Geomech Africa has also drilled on jack-up barges on Lake Malawi; the Zambezi river, in Zambia; the Nile river and Lake Albert, in Uganda; and Nacala in Mozambique.

The company is also working on a project on a lake in a remote mountainous area, with Kruger expecting accessibility limitations and cold weather to be some of the major challenges.