In the industry, I am always trying to keep up to date with new techniques, equipment and methods and being able to write for GDI means I can help others in the industry consider ways of improving techniques, sharing photos and past experiences while also opening the door to a new opportunity to learn.

Having worked in the drilling industry for around 15 years, I find that modern technology and changes in practice regularly present themselves, which has left me wondering if could I improve our mud treatment here at Drilcorp?

I think many will agree that dealing with wastewater from drilling applications always causes a problem, especially when working in areas where space is an issue and timing and programming of waste removal is impossible.

A new system

Fortunately, I recently found a new mud treatment system which I thought would be perfect for working in London on a project for geothermal closed loops. It had recently undergone a field trial and I was impressed with the outcome.

The system I discovered comes in a range of sizes to suit every application, from large projects with pump rates up to 1,000L per minute and higher to the small mobile unit featured I'm concentrating on here, which makes it suitable for water well, tunnelling, HDD and the ever-popular Geobore S coring systems.

The system in question is from AMC Europe and it has been designed to treat the drilling fluids and slurry through a process of a shale shaker and a centrifuge before producing a clean drilling fluid for re-use.

This process is very effective for a closed-loop system and negates the need for large surface pits and volumes needed for a total circulation while drilling. A reduction in water consumption and a reduction in drilling fluids have all been seen on projects where it has been used, too, thus reducing costs.

The compact system we at Drilcorp used can fit on a road towable trailer and can be supplied with its own power source. However, the system can also be as big as an articulated truck depending on the application it is needed for.

The system we used had a fluid capacity of 3m³ which meant it was great for open-hole drilling of up to 200m with an 8in diameter and also perfect for Geobore S.

Solid removal

Solid removal is always a challenge and conventional shaker systems are limited in what they can do, only removing the larger particles down to sands. Typically, 20 microns is the average. With conventional systems, there is always the risk of pumping a solid that is still present in the fluid around the system. This can have negative effects on the borehole stability and increase the wear and tear on mechanical parts, including pumps and seals. The AMC SRU (Solids Recycling System) can remove particles down to a micron size of 4-6, and complete removal is achievable with flocculation.

Keeping weight under control is a major part of the process while installing loops, being able to remove weight quickly and easily is something that we were keen to have at our fingertips. The unit can process up to 6m³ per hour something that gravity settle tanks would take days to achieve.

The mud treatment system was easily manoeuvrable into tight spaces and once set up and filled with fluid it proved extremely efficient and straight forward to operate.

 

The shaker system placed the larger drill cuttings directly into a skip while the centrifuge was set to remove fines down to a size of five microns. The combined cuttings were dry enough to allow disposal straight into a normal soil skip.

I will continue to work closely with the provider of this great system to develop it further as I feel this is the future of drilling. Our first trial was a success saving our client costs on water and waste disposal (tankers and gully suckers) as well as a considerable amount of downtime for cleaning and refilling of tanks.

The new system also allowed Geotechnical Exploration Services a lot more room on-site to operate. I will use this system again as I am keen to see how it performs in different applications such as Geobore S. Without question, this system will also extend the life span of drilling pumps, water swivels and drill bits, costs that we all find hard to recover in the current busy very competitive market.

Summary of works waste disposal and program

Scott Burt provides a brief outline of how the two phases of the project were completed; the first with a conventional set-up and the second using the AMC SRU package.

Phase one of the London geothermal project undertaken by Drilcorp was 200m of 8in diameter borehole with double 40mm loop installation. It was completed with 25m3 drilling tanks (Russian Dolls) telehandler and grab bucket attachment. Three lots of 18m3 of water were delivered to site and three 18m3 gully suckers were used for waste removal, along with one eight-yard skip. This was a 15-day programme and ran three days over.

Phase two saw exactly the same borehole design (200m, 8in diameter borehole with double 40mm loop) installation. However, it was completed with 3m3 mud treatment system, with the water source a standard outside tap. Two 8m3 gully suckers were used as well as two eight-yard skips. This was a 15-day programme and was completed in 12 days.

 

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