Standard water well drilling rigs provide the most suitable option. These rigs are designed for shallow formations including clay and sand, feature compact dimensions, allow flexible positioning, operate with low energy consumption, and require no complicated systems for removing drill cuttings. The water drilling rigs deliver efficient drilling for domestic shallow wells is ensured.
A reverse circulation drilling rig provides better stability in loose formations. Reverse air or water flow enables rapid cuttings discharge and maintains a stable negative pressure inside the borehole, reducing disturbance to sand or gravel strata. When combined with mud-based wall protection, collapse risks are significantly lowered, whereas standard water well rigs exhibit higher collapse probability in these conditions.
A reverse circulation drilling rig is the recommended choice. Efficient debris removal prevents cuttings buildup at deep borehole bottoms, and high-power drive systems accommodate large-diameter drilling tools. This configuration supports deep drilling more efficiently than standard water well rigs.
The water well drilling rigs, including portable and compact vehicle-mounted models, are easier to deploy. These rigs require less than 10 m² of space, do not rely on large auxiliary equipment, and can be repositioned efficiently within limited areas. Reverse circulation drilling rigs generally require more operating space due to larger machine size and associated cuttings-removal systems.
For shallow wells under 200 m, standard water well drilling rigs provide the more economical option due to lower equipment procurement or rental cost and reduced energy consumption. For deep wells over 200 m or projects involving complex formations, reverse circulation drilling rigs offer a lower long-term cost by reducing collapse risks and minimizing rework.
A reverse circulation drilling rig provides higher vertical accuracy. Hydraulic leveling systems allow continuous control of drill-rod alignment, keeping borehole deviation typically within 0.5 percent. Standard water well rigs, particularly smaller percussion types, are more susceptible to deviation caused by formation forces.
A multifunctional reverse circulation drilling rig offers greater versatility. Certain RC models support interchangeable drilling tools, including bits designed for pile construction, enabling both water well drilling and small foundation pile work. Standard water well drilling rigs are more specialized and show reduced efficiency when used for pile applications.
The low air pressure series (working pressure 0.8-1.5 MPa) is recommended. Soft formations require lower impact energy for effective rock breaking. Low-pressure DTH hammers ensure sufficient penetration efficiency, reduced energy consumption, and slower tool wear. Medium- or high-pressure tools may cause excessive impact, increased cuttings pulverization, and higher risk of hole collapse, resulting in higher overall construction costs.
The large-diameter series is the preferred option. This series is engineered for large-diameter hole making and stable hole formation. Structural features include thicker tool walls for improved torsional strength and wider discharge channels to prevent cuttings blockage. Compatibility with high-torque output from pile-foundation drilling rigs ensures efficient, stable operation. Standard low- or medium-pressure tools may deform under load or suffer from inadequate cuttings discharge.
The medium air pressure series (working pressure 1.5-2.5 MPa) is suitable. Medium-pressure DTH tools deliver proper impact energy for medium-hard rock formations while matching the 1.8-2.2 MPa rig pressure range. Low-pressure tools provide insufficient impact, leading to slow penetration. High-pressure tools exceed the rig’s pressure capacity and cannot achieve normal performance.
Correct bit selection is essential.
- Limestone (dense, hard rock): Use spherical-button DTH bits, which provide high wear resistance and concentrated impact points for efficient rock breaking.
- Sand-gravel formations (loose formations with pebbles): Use flat-edge ballistic bits, which offer wider discharge grooves for rapid removal of gravel and reduced bit blockage.
Bit interfaces must match the selected DTH hammer connection standard, for example API REG threads, to ensure stable sealing and power transmission.
A medium air pressure DTH hammers paired with a composite-formation DTH bit such as a spherical-button can meet both layers’ requirements. Medium air pressure tools support efficient drilling in both sand layers and hard-rock layers. DTH bits with wear-resistant ballistic buttons and wide discharge grooves enhance cuttings removal in sand layers and improve rock penetration in hard rock.
When the lower hard-rock compressive strength exceeds 30 MPa, only the DTH hammer may be replaced with a high-pressure model while other components remain unchanged, reducing replacement cost.
The medium air pressure tools series is recommended, as the typical pressure range of 1.5-2.5 MPa matches most quarry drilling rigs.
The spherical-button DTH bit is suitable because quarry formations usually consist of hard rock requiring high wear resistance and strong impact concentration.
If later formation confirmation indicates soft formations such as tuff, low-pressure tools provide lower energy consumption. If the formation is extremely hard such as basalt, high-pressure tools may be applied. Medium-pressure tools function as a reliable universal choice that minimizes selection errors during early stages.
The rock drilling tools are compatible with handheld rock drills, drilling jumbos, surface rock drills, and rock drill and splitter commonly used in international engineering machinery.
Mining applications require high wear resistance and fracture toughness. Durable alloy spherical-button bits are commonly used, suitable for drilling hard rock and medium to large-diameter blast holes.
Tunnel drilling typically uses cross bits or small spherical-button bits paired with lightweight rock drills to improve maneuverability and excavation efficiency.
Surface mining blast-hole drilling commonly uses large-diameter spherical-button bits and extended threaded rods, paired with medium- or heavy-duty rock drills to ensure hole diameter and depth.
Small blasting operations typically use multi-sided rods and flat-edge ballistic button bits, suitable for handheld rock drills to quickly create shallow holes.