DIRECTIONAL DRILLING

This is a popular technique which is widely used in the UK for the installation of pressure pipes (water, rising mains, gas, oil and cement pipelines), electricity and communications cables. Directional drilling involves the installation of a pilot rod into virgin ground, which is steered from above ground using a tracking device. The head of the pilot rod is eccentrically loaded, so that rotational steering can take place. Once the pilot rods have reached their destination point, the product pipe is attached to the front pilot rod. The product pipe is usually coiled, or welded sticks of pipe. The rig then pulls back the rods, thus pulling back the new pipe, along the line of the pilot rods.

Directional drilling offers the following benefits:

• Pipes can be of any material which can be jointed into a continuous length, including steel, polyethylene and PVC
• Pipe diameters can range from 50mm to 1000mm
• Pipe lengths of over 1000 metres can be achieved
• Mud recycling and biodegradable drilling fluids reduce waste to landfill
• Accuracies +/- 100mm can be achieved
• Suitable for a variety of ground conditions including clay, sands, chalks, ballasts and gravels

Mud Recycling
One of the disadvantages of directional drilling is that large amounts of slurry are produced and have to be tankered away from the drilling site. The waste material has to go to a landfill site incurring significant costs for transport and landfill tax.

To solve this problem, Perco has invested in a mud recycling unit which works alongside the drilling rig throughout the drilling process. The MCM-2000 Drill Fluid Cleaning System recycles mud by separating solids from drilling fluids.

• Solids can be reused onsite or taken to conventional landfill sites for disposal
• Drill fluids are cleaned and can be reused again and again throughout the drilling process

The benefits of mud recycling are:

• Reduced disposal costs
• Lower landfill costs
• Lower transportation costs

• Reduced environmental impact
• Less pollution from reduced vehicle journeys
• Less material to landfill
• Solids not classified as hazardous waste

Biodegradable Drilling Fluids
Perco is now trialling the latest developments in biodegradable drilling fluids as part of its environmental policy. Biodegradable drilling fluids provide the following benefits:

• The liquid phase can be sent for water treatment
• The solids can be disposed of in conventional landfill sites
• They can be used in conjunction with conventional mud recycling plant