Complete environmental waste management

Offshore Processing, Cameroon

"TWMA’s Technical Services and Engineering teams worked together to deliver a custom engineered, environmentally sound solution in West Africa in under 8 weeks.

TWMA's Engineering department were able to design, fabricate and ship equipment to successfully fulfi the clients requirements, while our experienced Technical Services project team engineered a solution to overcome space restrictions and footprint challenges while delivering the project on time.

TWMA continues to deliver integrated drilling waste management services to this operator."

Neil Thomson

Group General Manager

Customer Challenge

An International Oil Company working in Cameroon, West Africa was to undertake a three well drilling campaign within an environmentally sensitive estuary region offshore Douala. 

The area scheduled for drilling was marine sensitive and used daily by fisherman to provide for local villages along this coastline. The well designs were for three HPHT wells to be drilled to depths approx. 3500-4000m through unstable geology. 

Non-Aqueous Drilling Fluid (NADF) was the preferred methodology based on the well design. The asset was a small jack-up rig with limited availability to locate 3rd party equipment, coupled with deck loading restrictions, presenting an engineering challenge for TWMA. 

The contract was awarded in January 2013 with a project delivery date to Cameroon of just 8 weeks later. TWMA’s Technical Services and Engineering departments were tasked with meeting this tight deadline to deliver a custom engineered, environmentally sound solution.


Scope of Work

Install the TWMA EfficientC™ system to contain and transport drill cuttings and associated drilling waste from the rig shakers via the screw conveyor system to the TWMA Cuttings Storage & Transfer (CST) units then transfer by pump to the TWMA TCC RotoMill® for continuous processing.  

Monitor the flow of drill cuttings from the shaker house via the transfer system. Provide the client discharge sampling data on recovered materials to demonstrate meeting our commitment to quality.


TWMA Solution

TWMA recommended the use of our EfficientC™ and TCC RotoMill® system to transport and process Non-Aqueos Drilling Fluid (NADF) based drill cuttings on board the rig.  

Our commitment was to return the base oil back to the active system for reuse, and disperse the recovered water and rock solids back to sea within agreed levels by the Operator and environmental department of the Cameroon government. The agreed consent levels of oil on rock solids content of less than 1%, in this case achieving an average of 0.036 and Oil in Water content of less than 30ppm, in this case achieving an average of 15.40ppm.  

By using the TWMA EfficientC™ and TCC RotoMill® systems we eliminated the need to transport approximately 1,500 MT onshore for processing and ultimately to landfill. We removed the need for supply vessels and other operational costs associated with transporting the material onshore, while eliminating the inherent safety risks and environmental impacts involved with the manual labour in both the offshore and onshore operations  through utilising this ‘at source’ treatment.


TWMA Approach

The TWMA Technical Services and Engineering departments were tasked with delivering a custom engineered solution to meet the confined footprint presented this jack-up rig in less than 8 weeks.


Phase 1 - Custom Design to meet strict requirements

TWMA Technical Services conducted a survey of the rig for the full integration of the EfficientC™ and TCC RotoMill® system using their technical expertise to determine layout of the equipment, making the best use of the available space and liaising with Engineering to ensure the solution would be designed to meet the strict requirements. 

TWMA were able to fast track the production of detailed models and drawings. The TWMA team then flew to Houston to work in partnership with the Operator’s rig contractor to further speed up the process to obtain approval on the design and installation for the project.

Operational space requirements of the rig, and health and safety issues with the area around the units presented a particular challenge. The custom designed EfficientC™ package included a 150ft Screw Conveyor. The Screw Conveyor was challenging in itself due to the unusual length, limited footprint and numerous deck obstacles it had to be designed around, while ensuring full and safe access to the area.  TWMA successfully engineered a suitable solution and received sign-off on final designs all within 4 weeks.


Phase 2 - Fabrication and Maintenance of required equipment

TWMA designed, fabricated and delivered all the required equipment for the EfficientC™ package, and the TCC RotoMill®. TWMA’s Tullos Aberdeen facility were able to expedite the process fabricating all required equipment for the asset within 2 weeks while Vacuum System, Hopper and Cuttings Storage & Transfer Units were prepared for dispatch.  TWMA’s Peterhead Process Support facility prepareda TWMA TCC RotoMill to meet the required shipment dates.


Phase 3 - Installation and Delivery

Installation drawings with work-pack, manifest for all equipment, load-out containers including all piping and pre-fabricated screw conveyor supports; and all materials required for the installation such as electrical, workshop, stores and installation containers including a fully commissioned TCC RotoMill® and EfficientC™ package were produced and ready just 8 weeks after the contract was awarded.


Project Results 

Hole Section





Processed Amount (Mt)





Run Time (hrs)





Avg. Tonnage per hr.





Avg. Sg of NADF





Recovered Oil (m3)





Recovered Water (m3)





Recovered Powder (Mt)





Avg Oil on Water (ppm)





Avg. Oil on Solids (%)





*TWMA were also tasked with handling Slops generated from pit cleaning activities. These were processed with the drill cuttings from the final 6" section.


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