https://www.engineeringnews.co.za

Drilling project completed off Nacala coastline

26th April 2013

  

Font size: - +

Drilling and testing services company Geomechanics successfully completed an offshore drilling project 2 km off northern Mozambique’s Nacala coastline in August last year. The site investigations were carried out in Nacala Bay for a proposed new offshore coal jetty linked to the onshore coal terminal.

The project entailed drilling to bedrock, conducting standard penetration tests and removing thin-wall tube samples undisturbed from the seabed.

The drilling and testing are all in a normal day’s work for the Geomechanics crew but the fact that it all had to take place from a 12 m × 12 m platform, up to 8 m above sea level, 2 km offshore, and in water ranging from 15 m to 25 m deep added a whole host of dimensions to the planning and execution of the job. Many tasks that would be simple on land become logistically complex, from getting the rig into position to ensuring the safety and comfort of the crew during their shift.

“To maintain the integrity of the drill hole and recover the highest percentage of core and samples, the drilling was carried out using drill muds compatible with seawater. From an environmental point of view it was also very important to operate in such a manner that there would be no spillage of any drill muds or any potential hazardous substances into the sea. “Therefore, all waste as well as used drill muds had to be removed from the platform regularly and disposed of at desig- nated land-based locations,” says Geomechanics marketing manager Caroline Kruger.

“The Delta P100 rig could only be loaded from the dockside onto the floating platform at high tide using a 25 t crane. Once on the platform, the rig and all the equipment had to be securely tied before the tugboat could tow the platform to its drilling position. “There, the hydraulic legs were lowered onto the seabed raising the platform above sea level. Only then could the drilling and testing begin,” she adds.

Delivery of the resulting core and test samples had to be scheduled to coincide with high tide to simplify the loading and offloading of the transfer boat at the dockside.

Moving between drill positions entailed lowering the platform back onto the sea and towing it to its next position.

“This project ran 24 hours a day and seven days a week. All staff, their food, the drilling and testing equipment, and anything else needed for the next 8 hours had to be transferred by boat from the shore to the platform for shift changes at 06:00, 14:00 and 22:00. Each shift change required loading and offloading of equipment and people, and a full safety and hand-over briefing. Manag- ing these shift changes in the dark presented its own set of chal- lenges. In addition, safety challenges related to working in a confined space above water and the differences between this and a regular land-based job become more evident,” concludes Kruger.

Edited by Tracy Hancock
Creamer Media Contributing Editor

Comments

Showroom

Willard
Willard

Rooted in the hearts of South Africans, combining technology and a quest for perfection to bring you a battery of peerless standing. Willard...

VISIT SHOWROOM 
Weir Minerals Africa and Middle East
Weir Minerals Africa and Middle East

Weir Minerals Europe, Middle East and Africa is a global supplier of excellent minerals solutions, including pumps, valves, hydrocyclones,...

VISIT SHOWROOM 

Latest Multimedia

sponsored by

Option 1 (equivalent of R125 a month):

Receive a weekly copy of Creamer Media's Engineering News & Mining Weekly magazine
(print copy for those in South Africa and e-magazine for those outside of South Africa)
Receive daily email newsletters
Access to full search results
Access archive of magazine back copies
Access to Projects in Progress
Access to ONE Research Report of your choice in PDF format

Option 2 (equivalent of R375 a month):

All benefits from Option 1
PLUS
Access to Creamer Media's Research Channel Africa for ALL Research Reports, in PDF format, on various industrial and mining sectors including Electricity; Water; Energy Transition; Hydrogen; Roads, Rail and Ports; Coal; Gold; Platinum; Battery Metals; etc.

Already a subscriber?

Forgotten your password?

MAGAZINE & ONLINE

SUBSCRIBE

RESEARCH CHANNEL AFRICA

SUBSCRIBE

CORPORATE PACKAGES

CLICK FOR A QUOTATION







sq:0.276 0.338s - 178pq - 2rq
Subscribe Now