Swivel

Matanović Davorin, profesor

Faculty of mining, geology and petroleum engineering, Zagreb

Swivel is a device joining two parts so that one or both can pivot freely.

The rotary drilling swivel, attached directly to the kelly cock, and hence the kelly, allows the drill stem to rotate.

It also has two other functions:

it supports the drill stem, and

it acts as a pressure-sealed passageway for the drilling mud that is pumped into the drill stem.

It consists of two main parts:

(1) non-rotating –cast steel body withload carrying bails, pins and roller bearings, and

(2) rotating –"T" mandrel and wash pipe.

Non-rotating part consists of:

(1) body,

(2) bail,

(3) bonnet,

(4) gooseneck.

Rotating parts are:

(5) stem with “T” beam

(6) main bearing

Upper bonnet base is:

(7) upper thrust bearing.

To center the bonnet in the housing radial lower and upper bearings are mounted (8) i (9).

Sealing is provided through:

fitting in wash pipe packing,

upper fitting for oil seal, and

lower oil seals.

Standpipe and rotary hose

A standpipe conducts drilling fluid from the mud lines coming from the mud pump to the rotary hose.

It includes a gate valve and a pressure gauge, with built-in dampening means for preventing excessive movement.

SWIVEL

ROTARY

HOSE

STAND PIPE

The rotary hose is attached to the standpipe with a special fitting and makes the connection to the gooseneck of the swivel.

It enables the vertical movement of the swivel while circulating mud.

Typical dimensions when manipulation height is 27 m are:

UPPER

WORKING

POSITION

ROTARY HOSE

16,76 m (55ft)

CLEARANCES

0,3048 m (1ft)WORKING

AREA

LOWER

WORKING

POSITION 2,44

m (8ft)

HOOK

MOVEMENT-

24,4 m (80 ft)

STANDPIPE

14,6 m (48 ft)

Z

R

15o

15o

Standpipe length is 14,6 m (48 ft), and rotary hose length is 16,8 m (55 ft).

That enables about 24,4 m (80 ft) vertical movementof the swivel and kelly.

Such length is necessary to allow make up the connection of drill pipe in “mouse" hole, when kelly length is 13,71 m (45 ft) and drill pipe length is 9,144 m (30 ft), with enough reserve to prevent excessive standpipe bending.

Standpipe height is determined from:

Hs=Lr/2+Z

where:

Hs– vertical standpipe height, m

Lr– rotary hose travelling length, m

Z – height from the working area to the gooseneck connection when i lower working position, m

Rotary hose must be flexible and watertight even for high pressures.

It is constructed as:

THREAD

COVER

OUTER SKELETON

(CANVAS)

SKELETON LAYERS

SECONDARY SKELETON

WIRELINE

STRENGTHENING

PRIMARY SKELETON

CANVAS STRENGTHENING

PIPE

The length of the rotary hose is determined from:

LH

=Lr/2+p⋅R

s+S

Where:

LH – length of rotary hose, m

Rs – minimal bending radii, m

(for 50,8 mm pipe radii– 0,91 m;

for 88,9 mm pipe radii– 1,37 m)

S – pipe shortening due the inside pressure – 0,3 m for all pipe dimensions