1 4 kick tolerance

Network of Excellence in TrainingKick Tolerance... Kick Tolerance– At the end of this lecture YOU will be able to: concept of the casing design process, lithological column, predicted po

Network of Excellence in Training

Kick Tolerance

Kick Tolerance

– Lecture Objectives, – Definition,

– Gas Behaviour, – Before Circulation, – Gas at Half Way up the Hole, – Gas at Surface,

– Gas Volume at Casing, – Gas Volume at TD, – Example,

– Drilling Kick Tolerance.

Kick Tolerance

– At the end of this lecture YOU will be able to:

concept of the casing design process,

lithological column, predicted pore pressures and fracture gradients, are given

Kick Tolerance

– It is defined as the maximum kick size which can be

circulated out without fracturing the previous casing shoe,

– It can also be defined as the maximum allowable pore

pressure at next TD or maximum mud weight that can be

without fracturing the previous casing shoe

Kick Tolerance

– Gas is highly compressible It’s volume depends on both

pressure and temperature.

– Boyles Law:

Kick Tolerance

• Gas behaviour;

– Imagine two tubes full of mud One tube is open to the

atmosphere and one is closed,

0

Open

0

Closed

Kick Tolerance

• Gas behaviour;

of mud One is open to the atmosphere and one is closed,

Gas pressure = 5000 psi.

In a real well, the hole will

be fractured when gas is at surface.

BHP = 5000 + 5000 = 10000 psi.

Kick Tolerance

• Gas behaviour;

– Hence gas expansion must be allowed to reduce wellbore

pressure This is the basis of well kill methods,

– Gas expansion is carried out in a controlled manner by

manipulating the choke at surface.

Gas

TD

Kick Tolerance

Px = Pf - Pg - (TD - H - CSD ) ρ m * 0.052

(ppg)

– Ca = capacity between pipe and hole.

– FG(fracture gradient) and its the max pressure at shoe.

G - ) ρm 052

0 (

Pf) 0.052

* CSD

* (FG CSD)

(TD ρm

*

0.052 H

*

− +

−

=

• Gas Volume at Casing Shoe;

– P1 = Fracture pressure at shoe, (psi),

– P 2 = Formation pressure at next TD, (psi),

– The value of V2 is the circulation kick tolerance in bbls.

5” drillpipe from surface to TD

Ca = 0.0459 bbl/ft

* 17000

* (14 0.052)

* 4500 1

* (16 14500)

7000 1

-( 5 4 1

* 0.052 H

.

*

=

Kick Tolerance

– The following minimum kick tolerance must be

maintained for routine drilling operations:

Kick Tolerance

concept of the casing design process,

lithological column, predicted pore pressures and fracture gradients, are given

Network of Excellence in Training

Kick Tolerance

End of Lecture