AMC’s top tips to prevent incidents around the drill rod pipe

Drillers missing a finger or two have always been a common occurrence in our industry. 90% of these unfortunate incidents take place around the drill rod pipe, due to just a few common processes:

• during rod insertion or extraction
• retrieval or displacement of the inner tube
• when applying drill rod and thread grease directly to the stands while the rods are in the foot clamp / gripper-box, while being held stagnant through the rotational head / drill chuck or by the hoisting cable.

When drill rods are not handled effectively then drillers are at risk from; crushing, repetitive strain and manual handling injuries. Accidents like these cause pain for the victim and potential lifelong injury’s, with lost time also heavily impacting operations that may already be under pressure.

Drill rod grease is still one of the traditional and most cost-effective solutions to reduce severe rod vibration and high downhole torque conditions that can create undesirable problems and reduced Rate of Penetration (ROP). The most common problems are:

• breakages in the rod line that will follow with a the retrieval of the broken pipe
• general wear-and-tear and reduced rod life
• hole deviation
• weakened thread joints
• additional stress and higher workload requirements for the drill rig mechanics, hydraulic components and main engine
• separated casing to cause problems down the hole.

A lot of drilling contractors and resource companies come to us questioning the value of using lubricants and rod greases. However these products are vital to the reduction of rod tripping and can be the necessary safeguard against major manual handling issues, particularly as most of these accidents occur at depth.

AMC’s aim is to eliminate or reduce the overall use of drill rod grease, incidental risks, loss in production time and wear on downhole drill equipment. The company’s approach is to focus on overall improvement in safety and productivity, with high quality drilling fluids, better workflows and technology innovations such as the AMC BOS™ can provide better hole stability and water return without disrupting operational flow.

Our approach for better, safer greasing

One shortfall of modern day exploration rig designs is the ability to apply any form of grease through an automated system. An automated thread greasing system has had a long history in operations on production drilling machines drastically reducing manual handling as well as the presence of hands around the rotational and clamping mechanism of a drilling rig.

Regardless of this, the use of greases in the exploration drilling industry is a must, especially in dry hole conditions caused by downhole loss of fluid return and angled / wedged holes. In some regions, there are very few standard operational procedures or methods of application when applying grease.

AMC has a few key guidelines to follow:

1. Most of the time the drillers over grease the rod surface, causing the excess grease to collect around the drill collar or in the ground pits forming a floating mattress of grease on the water surface. The company suggests the following guideline for the required amount of grease per rod diameter.
   
   For dry hole conditions use:
   
   NQ Rods 1-3 kg per 100m
   HQ Rods 2-4 kg per 100m
   PQ Rods 3-5 kg per 100m
   
   More information is in each of our Product Data Sheets.
2. If your operational design allows for the rods to be stored or stacked on a rod rack of rod sloop, the recommendation is to grease the pipe whilst being in this horizontal position
3. Try to apply the required rod grease to only half of the total circumference for the rod line. This practise will ensure that the total rod surface is not covered with grease. If the full rod surface is covered, downhole problems like high displacement pressure will be experienced as the drilling fluid will struggle to make their way up the annulus past the grease. Also limit mud use for the first one to two runs to prevent the stripping of grease
4. AMC’s latest innovation, the AMC BOS™ can also be an effective and preventative measure against borehole torque, making a positive impact on ROP, on-site safety and component life. Regular injections of AMC BOS FIX™ to the bottom of the drill string and up the annulus continually seals natural fractures and fissures, to stabilise the borehole, reduce downhole losses and occurrence of lost circulation.

What rod grease to use?

AMC has a range of economic, long-term adhering and environmentally acceptable greases to reduce friction and assist in extreme downhole environments, such as high pressure and temperature conditions.

Designed in Africa for our clients, AMC GORILLA GRIP™ is a specially formulated, tenacious, barium-based grease recommended for use on diamond drill rods to reduce vibration and friction between the rod and casing or rock strata. This product is designed for performance in a variety of harsh conditions, including bad water conditions, high pressure and high temperatures. It’s superior adhesion characteristics make it easy to apply to the rod under virtually any condition with minimal wastage.

Many operators prefer to use a liquid rod grease, where there is no requirement to pull the rods to grease. AMC LIQUID ROD GREASE™ has the ability to adhere to the formation and the steel rods to dramatically improve lubrication and reduce rotational pressure and torque. This product is non-toxic, environmentally acceptable and easy to apply.

The company is continuously improving their product line and testing their capabilities. Browse our website for the full list of lubricants and greases available in your region.

The new, proactive method against torque

To manage and reduce borehole torque, traditionally a driller will manually apply rod grease to the drill string at intervals (requiring regular rod trips causing time loss, component wear and increased manual handling) or to introduce a liquid rod grease (which is generally more expensive as a product but reduces rig down time). Using grease is vital, but borehole torque is largely affected by downhole conditions, which can vary at any time. Down the borehole you can’t always predict when or how things will go wrong, so we developed our Borehole Optimisation System (AMC BOS™), a system that anticipates fluid loss, high torque and unstable zones, even in high pressure, high temperature, wet or dry environments.

The AMC BOS™ creates a thin, robust lubristic membrane to target and control excessive torque and reduce rod vibration or chatter. Unlike traditional reactive methods (such as liquid rod greases or casing), the AMC BOS™ is a preventative measure which can significantly improve diamond drilling productivity, at rig safety, reduce environmental impact and lower overall operational costs. The unit takes less than 5 minutes to set up or refill, which can be done at any time during the drill shift, without interruption.

Waroonga Underground Mine & New Holland Underground Mine Case Study

A recent trial of the AMC BOS™ and new AMC BREAKOUT THREAD GREASE™ at Waroonga Underground Mine & New Holland Underground Mine in Western Australia showed significant results in reducing downhole torque and minimising rod handling.

AMC BREAKOUT THREAD GREASE™ was run where excessive rod torque had been encountered and subsequently rods were stalled. When breaking out the rod string, no hammers were required to decouple nor were additional Stilson’s required. All threads showed residual levels of AMC BREAKOUT THREAD GREASE™. The product was easy to apply and held on the threads well.

Targeted shots of AMC BOS FIX™ reduced downhole problems and stabilised water pressures while drilling. No indications of the previous pressurisation and hydraulic lock issues were seen after the introduction of the AMC BOS™. The entire formation became much more stable than the drill crews had previously encountered.

For more information

More information about the AMC BOS™ and our greases and lubricants can be found at our website www.amcmud.com.