Reverse circulation drilling rig

Types of reverse circulation drilling rig

There are many types of reverse circulation drilling rigs available that serve different purposes and can be customized depending on the requirements of the project. The most popular types include:

• Pedestal reverse circulation drilling rig

  This rig is mounted on a sturdy base or pedestal and is usually positioned downhaul from a surface drilling location. It has features like a high-power reverse circulation system, a large-diameter drill, and a drill string for effective core recovery, making it a suitable choice for many different applications and rock formations.

• Portable reverse circulation drilling rig

  As the name suggests, this drilling rig is movable and is often used in remote locations. It is designed in a way that it can quickly be disassembled and reassembled or transported to its intended location. This makes it a suitable choice for various environmental monitoring, mineral exploration, and geotechnical investigation applications.

• Automatic control drilling rig

  Thanks to technological advancements, some reverse circulation drilling rigs have automatic control features. These types of drilling rigs allow for remote monitoring and operation. They have temperature and pressure sensors, data analysis, and digital transmission systems. Because of these features, reverse circulation drilling rigs with automatic control can improve drilling efficiency, precision, and safety.

Specification and Maintenance of Reverse Circulation Drilling Rigs

Some Reverse Circulation Drilling Rigs specifications are as following.

• Max Hole Diameter: The max hole diameter refers to the widest diameter of holes the drilling rig can create, typically represented in inches or millimeters. The reverse circulation drilling rig's maximum hole diameter ranges are typically between 3 to 24 in (i.e., 76 mm-610 mm).
• Max Hole Depth: The max hole depth refers to how deep the rig can drill reverse circulation holes. The depth range varies for different models and types of rigs. Generally, the reverse circulation drilling rig can reach a maximum hole depth of 3000 feet (i.e., 914 meters) or even deeper.
• Drilling Power: Drilling Power is the strongness of the motor power that drives the pump to push the drilling fluid and rock fragments up to the surface through the drilling pipes. Its unit is horsepower (HP) or kilowatts (KW). For some reverse circulation drilling rigs, the drilling power could be 200 HP, while, for others, it could be 400 HP or even more.
• Weight: The weight of a reverse circulation drilling rig varies depending on its model and configuration. Generally, the weight of the rig is between 13000 kg and 27000 kg. For example, one model's weight is 18000 kg, and another's is 25000 kg.
• Used Drilling Pipes: The reverse circulation drilling process needs to use drilling pipes to transport the drilling fluid and rock cuttings. Refrigerated drilling pipes are also used to stabilize the borehole. The commonly used drilling pipes are 4 inches to 12 inches in diameter (i.e., 100 to 300 mm).
• Power Source: A reverse circulation drilling rig can have various power sources, such as electric motors, diesel engines, hydraulic systems, etc.
• Rotation System: The rotation system of a reverse circulation drilling rig can be different types, such as conventional rotary table, top drive, or others.
• Drilling Speed: Its unit can be meters per hour or feet per hour. The drilling speed varies for different geological formations and drilling parameters. Generally, one reverse circulation drilling rig can have a drilling speed of 180 m/h in rock formation.

Maintenance

• Routine Inspection: Conduct a comprehensive inspection of the drilling rig at predictable intervals. Check the overall condition of the rig, looking for signs of damage, corrosion, or wear, and swiftly deal with problems found during the inspection.
• Lubrication Maintenance: Regularly lubricate each part that requires lubrication according to the prescribed maintenance schedule. This includes applying lubricants or oils to bearings, gears, chains, etc., to ensure smooth operation and reduce friction and abrasion.
• Replace Consumables: In the process of using the Reverse Circulation Drilling Rig, some consumable parts, such as drill bits, sealing rings, filters, etc., need to be replaced in time according to the usage and maintenance records to ensure the stability and reliability of the drilling operation.
• Equipment Cleaning: Clean the entire rig or its components of dirt, debris, or residues. This can be done using appropriate cleaning agents and methods, ensuring that the cleaned areas are free from impurities that may affect the equipment's performance.
• Drilling Fluid Management: For Reverse Circulation Drilling Rigs, maintaining the quality and properties of the drilling fluid is essential. Regularly monitor the parameters of the drilling fluid (such as viscosity, density, etc.), and conduct treatments or adjustments as necessary to ensure the proper functioning of the reverse circulation drilling.

Application scenarios of reverse circulation drilling rigs

RC drilling rigs are mainly used in the mining industry, but they also have several other applications.

• Deep hole mining: RC drilling rigs are the preferred choice for deep hole mining. They can easily drill deep into the ground, even at great depths of over 1000 meters. Their ability to maintain precise control and manage high-volume air and mud flow makes them suitable for mining scenarios where extracting mineral resources located deep underground is required.
• Core recovery: RC drilling rigs have a unique dual-tube structure that allows for excellent core recovery. The inner tube collects rock samples while the reverse air flow in the outer tube holds the samples in place. This feature is crucial in geotechnical and mineral exploration because it ensures the integrity of rock samples.
• Geotechnical investigations: In geotechnical investigations, the structure and composition of the soil and rock formations at a construction site are examined. Reverse circulation drilling rigs can gather high-quality samples while also obtaining the in-situ data. They are thus very useful for soil- and rock-related quality analyses, as well as for building reliable foundations for engineering projects.
• Environmental monitoring: RC drilling rigs can be used to install groundwater monitoring wells. For instance, in landfill sites or hazardous waste storage areas, they can be used to determine pollution migration and monitor groundwater quality so as to protect the environment and public health.
• Well construction: Reverse circulation drilling (RC) is a commonly used technique for constructing water wells. RC drilling is capable of drilling deep vertical holes with good diameter control, and it can be used to construct large-diameter wells as well. Following these characteristics, RC drilling is suitable for exploring and developing groundwater resources, constructing production wells, and establishing monitoring wells.
• Directional drilling: RC drilling technology can be applied to directional drilling, which has the ability to make curved trajectories and hence drill holes in non-vertical orientations. RC directional drilling can be used when there is a need to avoid obstacles, go underneath existing structures, or reach particular target areas. One example of an application of RC directional drilling is the establishment of pipelines and the exploration of oil and gas fields.

How to Choose

It is essential to choose an appropriate reverse circulation drill for the task at hand in order to ensure economic drilling and operational effectiveness. The following factors are important to consider when purchasing a new reverse circulation drill:

• Drilling Requirement Analysis:

  It is essential to determine the factors influencing drilling operation before purchasing a reverse circulation drill. This includes the terrain of the location where drilling will take place, the level of rock hardness, the depth of the desired hole, and the drilling pattern that is required. A thorough requirement analysis should be performed in order to ensure that the final choice of drill is suited to both the geological conditions and the intended use.

• Technical Parameter Comparison:

  When looking for a reverse circulation drill, it is essential to compare the drill's technical parameters, such as its size and weight, power system, feeding system, rotation system, pressure and flow rate of the mud pump, and other relevant specifications. Make sure the drill meets the specific requirements of the intended use and has a solid, dependable performance.

• Manufacturer and After-sales Service:

  Choose a manufacturer with a proven industry reputation and reliable after-sales support. For critical reverse circulation drill operations, the availability of constant technical support and maintenance services is a significant advantage. When choosing, be sure to consider the provider's comprehensive after-sales service, including technical support, spare parts supply, and service network coverage, among other things.

• Cost-performance assessment:

  Finally, a thorough cost-performance assessment of the available reverse circulation drills is essential. This goes beyond just considering the purchase price but also examining the long-term operation and maintenance costs. The focus should be on balancing the initial outlay with ongoing expenditures for a drill that offers good value over the long term.

Q&A

Q1:What is the difference between a reverse circulation and an air-core drill?

A1: Reverse circulation drilling uses high-pressure air to circulate cuttings upward through the drill pipe. In contrast, air-core drilling relies on compressed air to push a lightweight hollow steelcollet bit through the ground,acting like a bit scooping up samples. RC drilling is typically used for hard rock exploration. In contrast, air-core drilling is more suitable for drilling through unconsolidated material or lightweight geological formations.

Q2:What are the benefits of using reverse circulation drilling?

A2:Reverse circulation drilling offers several benefits, including the ability to obtain high- quality rock samples, increased drilling speed compared to conventional techniques, and better borehole stability in challenging geological formations. Additionally, the close-system design of RC drilling helps minimize environmentalimpact by reducing the risk of cuttings contamination.

Q3:What are the limitations of reverse circulation drilling?

A3:Some limitations of reverse circulation drilling include the high cost of equipment and maintenance, the noise generated during the drilling process, and the potential for sample contamination if the sampling\;defects\;are not\;properly\;implemented.

Q4:Which industries or sectors commonly use reverse circulation drilling?

A4:Reverse circulation drilling is primarily used in the mining and mineral exploration industries. However, it may also be used in the environmental field, geotechnical investigations, and groundwater hydrology\;for\;specific\;applications\;or\;investigations\;requiring\;the\;technique.