RC vs Diamond Drilling: Pros and Cons

1. RC Drilling

RC (Reverse Circulation) drilling is a technique that employs a rotating hammer to break rock and transport the resulting cuttings to the surface via a hollow rod and compressor. This method is both faster and more cost-effective than diamond drilling, capable of reaching depths of up to 300 meters per day without the need for core barrels, drill bits, or water.

However, RC drilling has some drawbacks, such as producing contaminated samples due to the cuttings mixing with dust, water, or other materials in the rod or the cyclone; sample loss due to the cuttings being blown away by the wind or washed away by the rain; damage to the rock structure caused by the hammer creating fractures or altering the mineralogy of the rock; and a higher environmental impact from generating more noise, dust, and emissions than diamond drilling.

How Deep Is Reverse Circulation Drilling?

Reverse Circulation (RC) drilling is a quick drilling method used in mining exploration for evaluating chip samples and gathering preliminary geological data. Generally conducted prior to diamond core drilling programs, it is possible the drill to 500m depths utilizing RC drilling, with typical depths of 100 to 250m.

2. Diamond Drilling

Diamond drilling is a method that is generally slower and more expensive than RC drilling, achieving a maximum drilling rate of about 100 meters per day and requiring more equipment, fuel, and water. However, its advantages can make it a worthwhile investment. This method produces high-quality samples that maintain the original rock structure, texture, and mineralogy. It also yields more detailed information, as the core can be measured, logged, photographed, and tested for various parameters. Additionally, diamond drilling can reach greater depths, exceeding 2,000 meters depending on the geology and rig capacity. Furthermore, it tends to have a lower environmental impact compared to RC drilling, generating less noise, dust, and emissions.

3. Choosing the Right Method

Determining the superior drilling method is not straightforward, as it depends on various factors, including the purpose and scope of the exploration project, budget and time constraints, geology and terrain of the exploration site, as well as environmental and social regulations. Therefore, it's crucial to evaluate the pros and cons of RC and diamond drilling in the context of each project's unique goals and circumstances. By doing so, you can identify the most effective combination of methods to achieve your desired outcomes.

4. Challenge

While RC drilling is generally more cost-effective and faster than diamond core drilling, it is also more susceptible to deviation. Currently, controlling the natural deviation in RC drilling remains a challenge. To enhance the accuracy of drilling operations, it is essential to properly position the drill rig over each planned collar and conduct downhole navigation surveys to monitor deviation and record the actual drill hole position.

Due to the rapid penetration rates associated with RC drilling, drill crews tend to work quickly. Therefore, it is crucial for them to complete all rig setups and surveys efficiently and accurately to minimize any disruptions to drilling productivity and workflow. This need for speed and precision presents a significant challenge.