This document provides an overview of rotary drilling systems and their components. It describes the key parts that make up the rotary table system including the kelly, kelly valves, rotary table, and top drive. It explains how these components work together to rotate the drill bit and transmit torque, weight, and drilling fluid downhole. The kelly transmits rotation from the rig to the drillstring while allowing it to move up and down. A top drive functions similarly but as a combined rotary table and kelly mounted on the rig.

1. Drilling Engineering 1 Course
3rd Ed. , 3rd Experience

2. 1.
The Rotary System
A.
Introduction
B.
Kelly, Kelly Valves, and Kelly Saver Sub
C.
Rotary Table and Components
D.
The topdrive

4. Introduction

The rotary system is the set of equipment necessary to promote the rotation of the bit.

The bit must be mechanically and hydraulically connected to the rig.

This connection is made by the drillstring.

The purpose of the drillstring is to transmit axial force, torque, and drilling fluid (hydraulic power) to the bit.
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5. Drillstring components

The basic drillstring is composed of the following components:

Swivel,

Kelly and accessories,

Rotary table and components,

Drillstring tubulars (drill pipe, drill collars, etc.),

BHA

Drill bit.
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6. The main components of rotating equipment

The main components are:

Rotary table

Kelly

Top Drive

equivalent to the Kelly and rotary table, i.e. either top drive or Kelly/rotary table

Swivel

Rotary hose

The rotary horse power requirement is usually between 1.5 to 2 times the rotary speed, depending on hole depth.

Hence for rotary speed of 200 rpm, the power requirement is about 400 HP.
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7. Swivel

The swivel

is suspended by the hook of the traveling block and

allows the drillstring to rotate as drilling fluid is pumped to within the drillstring.

supports the axial load of the drillstring.

Without the swivel,

drilling fluid could not be pumped downhole,

or the drillstring could not rotate.

A flexible hose connects to the gooseneck

which is hydraulically coupled to the top of the swivel stem by a stuffing box.

The stem shoulder

rest on a large thrust tapered roller bearing, which transmits the drillstring weight to the swivel body, and then to the bail.

The thread connector of the swivel

is cut left–hand so that it will not tend to disconnect when the drillstring is rotated by the kelly or by the top drive.
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8. cuts of a swivel showing the internal parts
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10. KELLY vs. TOP DRIVE

Strictly speaking the Kelly or top drive are not components of the drill string.

The Kelly is the rotating link between the rotary table and the drill string.

Its main functions are:

transmits rotation and weight-on-bit to the drillbit

Supports the weight of the drillstring

connects the swivel to the uppermost length of drillpipe; and

conveys the drilling fluid from the swivel into the drill string.
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11. kelly

Below and connected to the swivel is

a long four-sided (square) or triangular or

six-sided (hexagon, the most common) steel bar with a hole drilled through the middle for a fluid path called kelly.

The square or hexagonal section of the kelly

allows it to be gripped and turned by the kelly bushing and rotary table.

The Kelly comes

in lengths ranging from 40 to 54 ft (12 to 16.5 m)
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12. The purpose of the kelly

The purpose of the kelly is to transmit rotary motion and torque to the drillstring (and consequently to the drill bit),

while allowing the drillstring to be lowered or raised during rotation. Fall 14 H. AlamiNia Drilling Engineering 1 Course (3rd Ed.) 12
A square kelly and
a hexagonal kelly

13. kelly bushing

Torque is transmitted to the kelly by the kelly bushing. It

has an inside profile matching the kelly’s outside profile (either square or hexagonal),

but with slightly larger dimensions

so that the kelly can freely move up and down inside it.
Kelly bushings
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14. Applications of the kelly valves

The kelly valve consists of

a ball valve which allows free passage of drilling fluids without pressure loss.

This is a safety device

can be closed to prevent flow from inside the drillstring during critical operations like kick control.

It also

isolates the drillstring from the surface equipment and allows disconnecting the kelly during critical operations.
A kelly valve
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15. The Kelly cocks (the kelly valves)

The Kelly is usually provided

with two safety valves, one at the top and one at the bottom,

called upper and lower Kelly cocks, respectively.

The upper kelly valve

has left–hand threads

The lower Kelly cock

is always manual
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16. kelly saver sub

A kelly saver sub is simply a short length pipe with has male threads on one end and female on the other.

It is screwed onto the bottom of the lower kelly valve or top drive and onto the rest of the drillstring.

When the hole must be deepened, and pipe added to the drillstring,

the threads are unscrewed between the kelly saver sub and the rest of the drillstring, as opposed to between the kelly valve or top drive and the saver sub. Fall 14 H. AlamiNia Drilling Engineering 1 Course (3rd Ed.) 16

17. kelly saver sub (Cont.)

This means that the connection between the kelly or top drive and the saver sub rarely is used, and suffers minimal wear and tear,

whereas the lower connection is used in almost all cases and suffers the most wear and tear.

The saver sub is expendable and does not represent a major investment.

However, the kelly or top drive component threads are spared by use of a saver sub, and those components represent a significant capital cost and considerable downtime when replaced.

It is important that

both lower kelly valve and kelly saver sub be of the same diameter of the drill pipe tool-joints to allow stripping into the hole during control operations.
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19. master bushing and master casing bushing

The kelly bushing fits in the master bushing,

which, in turn, attach to the rotary table.

It connects to the master bushing either by pins of by a squared link.

The master bushing transmit torque and rotation from the rotary table to the kelly bushing.

A master casing bushing is used to handle casings.
Master bushings, and casing bushing
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20. Kelly bushing and master bushing

Figure shows a kelly bushing, master bushing, and rotary table assembly.
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21. Drillpipe slip (detail when set in the master bushing)

The master bushing (and also the master casing bushing) has a tapered internal hole.

The purpose of the tapered hole is to receive the pipe slips.

During pipe connection or drillstring trip operations, this tapered hole receives either the drill pipe slips, or the drill collar slips, or the casing slips, which grips the tubular and frees the hook from its weight.

Because of the slick shape of most drill collars,

a safety clamp is always used above the drill collar slips (mandatory!)

If the drill collars slides in the slips, the safety clamp works as a stop to force the slips to grip the drill collar.
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22. DC slips, safety collar, casing slips and A rotary table

A drill collar slips (a), a safety collar (b), and a casing slips (c) are shown in the Figure.

The rotary table receives power from the power system

(either mechanical or electric.)

A gearbox allows several combinations of torque and speed.
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23. Kelly set
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25. The top drive outlook

The top drive is basically a combined rotary table and Kelly.

The top drive

consists of a DC drive motor that connects directly to the drillstring without the need or a rotary table.

The top drive

is mounted on the rig’s swivel, the swivel attaches to the travelling block and supports the drillstring weight. Fall 14 H. AlamiNia Drilling Engineering 1 Course (3rd Ed.) 25

26. The elevator and elevator links of a topdrive

The top drive has

a pipe handler consisting of a torque wrench and a conventional elevator to assist in pipe handling during connection and round trip operations.

The elevator and elevator links

are supported on a shoulder located on the extended swivel stem.
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27. Different positions of a topdrive
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28. Advantages of topdrive

The top drive functions is the same way as the Kelly.

However, it has many advantages over the Kelly system including

circulating while back reaming,

circulating while running in hole

or pulling out of hole in stands.

The Kelly system can only do this in singles; i.e. 30 ft.
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29. 1.(CDF) Jorge H.B. Sampaio Jr. “Drilling Engineering Fundamentals.” Master of Petroleum Engineering. Curtin University of Technology, 2007.
Chapter 2
2.(WEC) Rabia, Hussain. Well Engineering & Construction. Entrac Consulting Limited, 2002.
Chapter 16 and 10