| 1 | Truck-mounted rotary mud rig | A rotating bit cuts the formation while drilling fluid circulates down the drill string and returns up the borehole, carrying cuttings. | About 100–500 m | About 100–450 mm | Water wells in unconsolidated ground and mixed formations. | Efficient drilling in many soil types; fluid can help support the borehole wall. | Requires a suitable fluid-handling system and space to manage drilling returns. Actual reach depends on formation, tooling and rig setup. |
| 2 | Truck-mounted down-the-hole (DTH) air rig | Compressed air powers a hammer near the bit, which repeatedly strikes the rock as the drill string rotates; air lifts rock fragments out of the hole. | About 100–400 m | About 100–300 mm | Hard-rock water wells where air drilling is suitable. | Fast penetration in competent rock and clear cuttings returns in suitable conditions. | Needs a high-capacity compressor. Air drilling may be unsuitable in some loose, water-sensitive or unstable formations without additional measures. |
| 3 | Crawler-mounted DTH rig | A crawler carrier positions the rig on site; the DTH hammer and compressed air perform the drilling in a similar way to a truck-mounted DTH system. | About 80–300 m | About 100–300 mm | Rough, sloping or access-limited sites that can accommodate a tracked machine. | Tracks can improve mobility on uneven ground, and the rig can be transported separately from road vehicles. | Check ground bearing capacity, transport arrangements and working-platform requirements before mobilization. |
| 4 | Trailer-mounted rotary rig | A towable rig turns a bit and uses drilling fluid or air, depending on its configuration, to remove cuttings from the borehole. | About 30–150 m | About 100–250 mm | Shallow to medium-depth domestic, agricultural and monitoring wells. | Can be less costly and easier to move than a large self-propelled rig. | Depth, bore size and drilling method vary substantially by equipment package; towing access and a suitable tow vehicle are necessary. |
| 5 | Compact skid-mounted rig | The rig is mounted on a skid or frame and uses rotary drilling or a small hammer system, with cuttings removed by fluid or air. | About 30–120 m | About 75–250 mm | Restricted-access sites, small farms and projects with limited space. | Compact footprint; can be moved by an appropriately rated vehicle or lifting equipment. | Often has less pullback, mast height and compressor capacity than larger rigs. Confirm that the setup meets the planned well design. |
| 6 | Reverse-circulation rig | Drilling fluid flows down the annular space and cuttings return inside a large-diameter drill pipe, typically with an air-lift system. | About 100–600 m | Often about 300–1,000 mm | Large-diameter production wells and projects requiring high-volume sample returns. | Can handle large boreholes and bring cuttings to the surface efficiently on suitable projects. | Requires specialized, larger equipment and substantial site and fluid-management planning; it is not necessary for many household wells. |
| 7 | Sonic drilling rig | A resonant head vibrates the drill string at high frequency while applying rotation and downward force; casing can advance with the bit to limit borehole collapse. | About 50–300 m | About 75–300 mm | Sampling-sensitive work, unconsolidated deposits and some environmental or groundwater investigations. | Can recover relatively continuous samples and reduce the need for drilling fluid in some conditions. | Specialized equipment and operating costs can be higher; performance depends on the formation and required bore diameter. |
| 8 | Cable-tool percussion rig | A heavy bit is repeatedly raised and dropped to break the formation; a bailer removes loosened material, and casing may be driven as drilling proceeds. | About 30–300 m | About 100–600 mm | Some shallow or medium-depth wells in formations where percussion drilling is practical. | Mechanically straightforward and does not rely on continuous high-pressure air circulation. | Generally slower than many rotary methods, particularly in hard rock; requires room for the equipment and handling of drilling tools. |
| 9 | Truck-mounted top-drive rotary rig | A top drive rotates the drill string from the mast while a mud or air circulation system transports cuttings out of the borehole. | About 100–500 m | About 100–450 mm | Contractors needing a versatile production rig for varied well projects. | Can make and break drill-string connections efficiently and can be configured for different rotary methods. | “Top drive” describes the rotation system, not a single drilling method. Check included pumps, compressor, mast capacity and tooling. |
| 10 | Combination rotary and DTH rig | The rig can use rotary drilling with fluid in softer or unstable layers and switch to an air-powered DTH hammer in suitable rock. | About 100–400 m | About 100–350 mm | Projects expected to cross both loose overburden and hard-rock formations. | Method flexibility can reduce the need to bring a second rig to a mixed-geology site. | Confirm that the rig includes compatible circulation equipment, compressor capacity and tools for the planned formations. |