A top drive is a mechanical device on a

drilling rig A drilling rig is an integrated system that Drilling, drills wells, such as oil or water wells, or holes for piling and other construction purposes, into the earth's subsurface. Drilling rigs can be massive structures housing equipment used to ...

that provides clockwise torque to the

drill string A drill string on a drilling rig is a column, or string, of drill pipe that transmits drilling fluid (via the mud pumps) and torque (via the kelly drive or top drive) to the Well drilling#Drill bits in mechanical drilling, drill bit. The term ...

to drill a

borehole A borehole is a narrow shaft bored in the ground, either vertically or horizontally. A borehole may be constructed for many different purposes, including the extraction of water ( drilled water well and tube well), other liquids (such as petr ...

. It is an alternative to the

rotary table A rotary table is a precision work positioning device used in metalworking. It enables the operator to drill or cut work at exact intervals around a fixed (usually horizontal or vertical) axis. Some rotary tables allow the use of index plates ...

and

kelly drive A kelly drive is a type of well drilling device on an oil or gas drilling rig that employs a section of pipe with a polygonal (three-, four-, six-, or eight-sided) or Rotating spline, splined outer surface, which passes through the matching pol ...

. It is located at the swivel's place below the traveling block and moves vertically up and down the derrick.

Benefits

The top drive allows the drilling rig to drill the longer section of a stand of

drill pipe Drill pipe, is hollow, thin-walled, steel or aluminium alloy pipe (material), piping that is used on drilling rig (petroleum), drilling rigs. It is hollow to allow drilling fluid to be pumped down the hole through the bit and back up the annulus ...

in one operation. A rotary table type rig can only drill (single drill pipe) sections of drill pipe whereas a top drive can drill stands (double and triple drill pipe respectively, a triple being three joints of drillpipe screwed together), depending on the drilling rig size. Handling longer sections of drill pipe enables a drilling rig to make greater daily progress because up to can be drilled at a time, thus requiring fewer "connections" to add another of drill pipe. Another advantage of top drive systems is time efficiency. When the bit progresses under a kelly drive, the entire string must be withdrawn from the well bore for the length of the

kelly Kelly may refer to: Art and entertainment * ''Kelly'' (Kelly Price album), 2011 * ''Kelly'' (Andrea Faustini album) * ''Kelly'' (musical), by Mark Charlap, 1965 * "Kelly" (song), by Kelly Rowland, 2018 * ''Kelly'' (film), Canada, 1981 * ...

in order to add one more length of drill pipe. With a top drive, the draw works only has to pick up a new stand from the rack and make up two joints. Making fewer and quicker connections reduces the risk of a stuck string from annulus clogging while

drilling fluid In geotechnical engineering, drilling fluid, also known as drilling mud, is used to aid the drilling of boreholes into the earth. Used while drilling oil and natural gas wells and on exploration drilling rigs, drilling fluids are also use ...

is not being pumped.

Variations

Several different kinds of top drives exist, and are usually classified based on the "Safe Working Load" (SWL) of the equipment and the size and type of motor used to rotate the drillpipe. For offshore and heavy duty use, a 1000 short ton unit would be used, whereas a smaller land rig may only require a 500 short ton device. Various sizes of hydraulic motors, or AC or DC electric motors, are available.

Standards

The

American Petroleum Institute The American Petroleum Institute (API) is the largest U.S. trade association for the oil and natural gas industry. It claims to represent nearly 600 corporations involved in extraction of petroleum, production, oil refinery, refinement, pipeline ...

has set standards for top drives in a number of its publications including: * ''API 8A: Specification for Drilling and Production Hoisting Equipment'' (effective May 1998, withdrawn February 2013) * ''API 8B: Recommended Practice for Procedures for Inspections, Maintenance, Repair, and Remanufacture of Hoisting Equipment'' * ''API 8C: Specification for Drilling and Production Hoisting Equipment'' The

International Organization for Standardization The International Organization for Standardization (ISO ; ; ) is an independent, non-governmental, international standard development organization composed of representatives from the national standards organizations of member countries. M ...

publishes a standard relating to top drives in: * ''ISO 13535: Recommended Practice for Procedures for Inspections, Maintenance, Repair, and Remanufacture of Hoisting Equipment''

References

{{Petroleum-stub Oilfield terminology Drilling technology Petroleum engineering

Benefits

Variations

Standards

See also

References