Reverse Circulation (RC) Drilling Technique

Reverse circulation (RC) drilling uses a dual-walled drill pipe (rod) with a solid drill bit to produce a hole in a formation and delivers rock chips (cuttings) to the surface for a subsequent analysis. The drilling mechanism is a pneumatic reciprocating piston (hammer) driving a tungsten-steel drill bit and a compressor to blow the cuttings, created by the drilling operation, to the surface. Reverse circulation is achieved by blowing air down the rods; the differential pressure creates air lift of the cuttings up the inner tube which is inside each rod. Normally the air exhausts through a centrifugal classifier so that the rock chips and dust will be captured in a sampler.

The most commonly used RC drill bits are 5-8 inches (12.7–20.32 cm) in diameter and have round metal “knobs” that protrude from the bit, which are required to drill through rock and shale. As the knobs wear down, drilling becomes slower and the rod string can potentially become bogged in the hole, therefore RC drill rigs must have a high pullback capacity and hydraulic power, otherwise trying to recover the rods may take hours and in some cases days.

While operating in remote sites or areas, Reverse Circulation drilling setup usually consists of several support vehicles, as well as the rig itself. The support vehicles hold the drilling rods (dual tube RC pipe), spare parts, diesel and water tanks, as well as any other tools and equipment required for resupplying and rig maintenance.

Most of the RC drill rigs have their own compressor to generate the air pressure needed to extract the cuttings. However, generally these compressors do not have the power for deeper drilling, due to lack of space on the rig itself for the larger, more powerful units. Alternatively, companies like Drilling Supply, are offering compressor free setup, which enables the driller to use a compressors with various power rated outputs to accommodate their particular project, while using the same RC Drilling Rig for all of them. As a consequence, even a broken air compressor will not cause disruption in the drilling operations. While a malfunctioning compressor is being repaired, a backup unit can be rapidly deployed to continue the drilling operation, saving the drilling contractor valuable time and money.

RC drilling routinely achieves depths of up to 500 metres. This depth is comparable to that of Diamond Core drilling, but unlike core drilling, RC drilling does not produce a solid core. The cuttings generated by the RC drill bit are generally delivered to the surface in the order in which they are produced but not always. Therefore, RC drilling is not as accurate as Core drilling. There is no way of knowing with a 100% certainty which depth the cuttings came from. Also there is a tendency for heavier minerals (e.g. gold) to fall to the bottom of the hole or be caught in elbows and curves in the drill pipe (Reverse Circulation Drill Pipe). As a result, assays from RC drilling may understate the amount of mineralization present in the formation; however this deficiency is largely offset by significantly reduced cost of drilling and rapid penetration rates.

For this reason, companies like Drilling Supply have developed a multipurpose hollow spindle rotary drive with variable/reversible hydraulic motor and automatic constant rotation power control. Drilling Supply can now offer drilling companies a capability to begin the drilling operation with Reverse Circulation drilling and once the mineralization warrants it and clean core samples are required, switch to Diamond Core drilling technique. This is done by using the same drill rig and simply changing from RC drilling tool set to Core drilling tools (coring rods and bit). This allows the driller to quickly and inexpensively achieve the mineralization depth and begin extracting quality cores for analysis.

Important water injection system UPGRADE on our Blasting, Exploration and Geothermal drilling rigs

Dear Customers,

In our constant pursuit of quality and reliability, DRILLING SUPPLY is pleased to announce, that after a meticulous study, we have decided to replace the existing Nippon Cat water pump on our Blasting, Exploration and Geothermal drilling rigs for WATER INJECTION unit Duplex piston pump model FMC A04 and WATER INJECTION unit Triplex piston pump model FMC A09.

During the past 3 years, we have been using the Nippon Cat water pumps on our Rock-Master rigs because of their relatively high-quality and affordable cost, but the drawback is that they require clean water, free of heavy particles such as sand and dirt, for proper operation. This means a lot of care and service in the remote areas with a limited filtered water supply.

As a result, after analyzing the drilling sites in Mongolia’s Gobi desert, Hermosillo Mexico and Palawan Philippines, we have decided to use water pumps which can function with unfiltered, dirty and muddy water, avoiding the pump’s deterioration and costly downtime and repairs.

Blasting and Geothermal rigs such as the Rock-Master RM615-DTH, Geo-Trac GT635 & Geo-Max GM835 will feature the WATER INJECTION unit Duplex piston pump model FMC A04.
(34 L / min.  <> 9 gall. /min. at 550psig, 500rpm)

Exploration and Coring rig units like Explo-Trac ET635 & DP635 will feature the WATER INJECTION unit Triplex piston pump model FMC A09.
(109 L /min. <> 28.7 gall. /min. at 700psig, 890rpm)

Furthermore, all our water tanks are now made of high quality stainless steel, which reduces repairs and maintenance and makes the water tank much more long-lasting.

These increased operational capabilities come at a price. The new pumps are more expensive then the Nippon Cat units. Regardless, our decisions are always geared towards the benefit and satisfaction of our clients, and even though the additional expenditure will amortize rather quickly due to the reduced service costs and the much increased efficiency of the drill rig. DRILLING SUPPLY will absorb the additional costs for the implementation of this upgrade.

GT635 Geothermal Drill Rig live in action

Video 1 :

The GT635, Tracked Geothermal Drill Rig was especially designed and manufactured for the geothermal drilling, water well drilling and construction markets; and is geared to offer the drilling companies and contractors the most efficient , reliable and safe drilling environment.

Geothermal Drilling for Green Energy

Geothermal Heat Pumps (Ground-Source Heat Pumps) are electrically powered heating and cooling systems which transfer heat to and from the earth via a refrigeration process. Geothermal Heat Pumps have been in operation for over 40 years and operate on the same principle as your household refrigerator or air conditioner.

At depths below 30 feet (10 meters), ground temperature stays a constant 42 – 55 deg F. (6-12° C) year-round. During the winter season, a geothermal system absorbs the heat from the earth, amplifies it and transfers it into your home. During the summer, the system absorbs the heat from indoors and releases it back underground. On most models of Geothermal Heat Pumps domestic hot water is produced any time the heat pump operates.

Studies by the US Department of Energy and Natural Resources Canada ranked new generation geothermal heat pumps above all other heating and cooling systems in their ability to conserve energy and reduce CO2 emissions.

When compared to an electrically heated home, geothermal heat pumps consume less than 1/3 the amount of electrical energy to heat the structure, which is close to 66% reduction in energy consumption. Consequently the electric utility company generates only 1/3 the emissions it normally would.

Geothermal Heat pumps are available for both commercial and residential heating and cooling systems in a variety of output capacities, which can accommodate any building design.

What can a home or business owner expect from a Geothermal (Ground Source) Heat Pump?

The drilling equipment used can play an enormous role in the final price tag of the entire geothermal system. An experienced drilling contractor, with the right drilling rig can execute all the necessary drilling and piping within a few hours, but even the most experienced driller with inferior drilling equipment will require days to complete the same project, increasing the costs exponentially. We have been manufacturing drilling equipments since 1988 with 270 units in operation around the world. We conceive, design and manufacture our own drilling equipment, constantly setting a performance standard within the drilling industry. Our main objective is to satisfy our customers’ needs in drilling performance, safely, reliability and cost reduction. We achieve this by custom engineering our rigs specifically as the geothermal drill units.

The GT/GWT Series geothermal drilling rigs, versatile, safe and reliable are proving to be ideally suited for the ever-growing demands of the rapidly emerging ground source heat pump (GSHP) geothermal industry.

The powerful single or double rotary head and the machine’s 35,000 lb (15,000 kg) pullback strength mean that the GT/GWT series geothermal drilling rigs can drill very rapidly up to 1200 ft (400m) to enable the quick installation of the geothermal systems’ closed GSHP loop. Also, the GT/GWT series rigs, being considerably smaller than a typical drilling unit, are ideal for accessing difficult terrains and constricted space sites.

Please visit our website www.drillingsupply.info for more information regarding our geothermal drill rigs machines and more. Feel free to fill out the Contact Form and a member of our team will be happy to assist you.

Geothermal Energy – Saving the environment, while saving you money.