Rotary Drill Rigs – Their Structure And Function

Rotary drilling is one among the most used and effective drilling techniques. It was used in the 1900s in the oil industry in some European oil-producing nations. A major breakthrough in rotary drilling happened in 1901, when a steam-driven rig was used along with mud instead of water. Rotary drill rigs make use of a sharp, rotating drill bit to penetrate into the hard rocks in the Earth’s crust.



The idea of rotary drilling dates back to 3000 B.C. Leonardo Da Vinci had developed a rotary drill design in the 1500s. Although rotary drill techniques were patented in the year 1833, the techniques found applications in petroleum drilling only in 1901.

Rotary drill rigs used in oil wells use tri-cone roller, fixed-cutter diamond, carbide embedded, or diamond-impregnated drill bits. The use of sizable machinery enables penetration of several kilometres. The hollow drill pipes have drilling muds infused with bentonite and barite, which cool, lubricate and clean up the drilling bit. The drilling and extraction of oil and gas can be hazardous for the environment as the ignition of the entrained gas may cause fires and the oil leakage can pollute land and groundwater. Rotary drilling techniques can be used in onshore as well as offshore drilling.

The rotary drill rigs comprise four component groups – the prime movers, rotating equipment, hoisting equipment, and circulating equipment. All these components are equally essential for the rotary drilling process.

Prime Movers: In rotary drilling rigs, the prime movers are equipments that offer power to the whole rig. Traditionally, rotary rigs were powered by steam. After the second World War, gas was used to power rotary drills and eventually diesel engines were used. Some rotary drill rigs make use of electricity from power lines. Rotary rigs usually need 1,000 to over 3,000 horse power. The prime movers provide the energy to power the other three components.

Rotating Equipment: The rotating equipment helps rotate the drill bit thus digging deeper into the ground. This equipment has many parts, which transfer power to the drill bit from the prime mover.

Hoisting Equipment: The hoisting equipment has the tools for raising and lowering other equipment going in and out of the well. Derrick is the tall tower-like part that pops vertically out of the well hole. It supports drilling lines and pulleys and its height is an indication of the well’s depth.

Circulating System: The circulating system of rotary drill rigs helps in controlling the pressure inside the well, lubricating and cooling the drill bit, coating the well’s walls with a mud type-cake and removing cuttings and debris. The system has a drilling fluid, which is circulated into the well hole during the drilling process. A typical drilling fluid used is ‘mud’, which contain clay, weighting materials, chemicals, oil, water, or gases.

Hutte of the Casagrande group manufactures drill rigs and accessories for more than 30 years now and offers solutions for modern-day drilling demands. Their product range includes upto 30 ton weighing drill rigs, customized machinery and excavator attachments. Soilmec is another global leader in providing drilling equipment.