Chuong 8 kicks and well control

Dynamic Kick Control[Kill well “on the fly”] For use in controlling shallow gas kicks  No competent casing seat  No surface casing - only conductor  Use diverter not BOP’s  Do not

Well Drilling Engineering

Kicks & Well Control

Dr DO QUANG KHANH

Kicks and Well Control Methods

 The Anatomy of a KICK

 Kicks - Definition

 Kick Detection

 Kick Control

 (a) Dynamic Kick Control

 (b) Other Kick Control Methods

* Driller’s Method

Applied Drilling Engineering, Ch.4

HW#:

Causes of Kicks

Causes of Kicks

Causes of Kicks

What is a kick?

 An unscheduled

entry of formation fluid(s) into the wellbore

Why does a kick occur?

 The pressure inside the

wellbore is lower than the formation pore pressure (in a permeable formation)

p < p

 Mud density is too low

 Fluid level is too low - trips or lost circ.

 Swabbing on trips

 Circulation stopped - ECD too low

) p p

( W  F

What ?

What happens if a kick is not

controlled?

Typical Kick Sequence

1 Kick indication

2 Kick detection - (confirmation)

3 Kick containment - (stop kick influx)

4 Removal of kick from wellbore

Kick Detection and Control

1 Circulate Kick out of hole

2 Circulate Old Mud out of hole

Kick Detection

Some of the preliminary events that may

be associated with a well-control

problem, not necessarily in the order of

occurrence, are:

1 Pit gain;

2 Increase in flow of mud from the well

3 Drilling break (sudden increase in

Kick Detection

5 Shows of gas, oil, or salt water

6 Well flows after mud pump

has been shut down

7 Increase in hook load

8 Incorrect fill-up on trips

4 Decrease in circulating pressure;

Dynamic Kick Control

[Kill well “on the fly”]

For use in controlling shallow gas kicks

 No competent casing seat

 No surface casing - only conductor

 Use diverter (not BOP’s)

 Do not shut well in!

Dynamic Kick Control

1 Keep pumping Increase rate!

(higher ECD)

2 Increase mud density

0.3 #/gal per circulation

3 Check for flow after each

complete circulation

4 If still flowing, repeat 2-4



Dynamic Kick Control

Other ways that shallow gas kicks

may be stopped:

1 The well may breach with the

wellbore essentially collapsing

2 The reservoir may deplete to the

point where flow stops

Conventional Kick Control

{Surface Casing and BOP Stack are in place} Shut in well for pressure readings.

(a) Remove kick fluid from wellbore;

(b) Replace old mud with kill weight mud

Use choke to keep BHP constant

Conventional Kick Control

1 DRILLER’S METHOD

** TWO complete circulations **

 Circulate kick out of hole

using old mud

 Circulate old mud out of hole

Conventional Kick Control

2 WAIT AND WEIGHT METHOD

(Engineer’s Method)

** ONE complete circulation **

 Circulate kick out of hole

using kill weight mud

Driller’s Method - Constant Geometry

Information required:

Well Data:

Depth = 10,000 ft

Hole size = 12.415 in (constant)

Drill Pipe = 4 1/2” O.D., 16.60 #/ft

Surface Csg.: 4,000 ft of 13 3/8” O.D 68 #/ft

Driller’s Method - Constant Geometry

Kick Data:

Original mud weight = 10.0 #/gal

Shut-in annulus press = 600 psi

Shut-in drill pipe press = 500 psi

Kick size = 30 bbl (pit gain)

Additional Information required:

= 0.13006 bbl/ft

Successful Well Control

1. At no time during the process of

removing the kick fluid from the wellbore will the pressure exceed the pressure capability of

 the formation

 the casing

 the wellhead equipment

Successful Well Control

2. When the process is complete the wellbore

is completely filled with a fluid of sufficient density (kill mud) to control the formation pressure

Under these conditions the well will not flow

when the BOP’s are opened

From the initial shut-in data we can

calculate:

 Bottom hole pressure

 Casing seat pressure

 Height of kick

 Density of kick fluid

NOTE:

The bottom hole

pressure is kept

constant while the kick

fluid is circulated out of

the hole!

In this case

Circulate Kick Out of Hole

Constant Annular Geometry

Driller’s Method.

Conditions When

Top of Kick Fluid

Reaches the Surface

Top of Kick at Surface

As the kick fluid moves up the annulus, it expands If the expansion follows the gas law, then

[bottom]

]

surface [

RT n

Z

V

P RT

n Z

V

P

B B

B

B B

0 0

0

0

Top of Kick at Surface

Ignoring changes due to compressibility

factor (Z) and temperature, we get:

Since cross-sectional area = constant

h P

h P

e i

h v

P h

v P

V P

V P

B B

0 0

B B

B 0

0 0

B B

0 0







Top of Kick at Surface

We are now dealing two unknowns, P0 and

h0 We have one equation, and need a

Top of Kick at Surface

2

684 ,

684

* 4 480

480 P

0 684684

P 480 P

231

* 5700

* 52

0 P

P 480

2 0

0

2

0

2 0 0

Well Control Worksheet

Example:

When circulating at a Kill Rate of 40 strokes per

minute, the circulating pressure = 1,200 psi

The capacity of the drillstring = 2,000 strokes

Mud Weight = 13.5 lb/gal

Well Depth = 14,000 ft

Aggie Drilling Research PRESSURE CONTROL WORKSHEET

Division of PETE Dept., TAMU DATE:

College Station, TX 77843-3116 TIME WELL CLOSED IN:

1 PRE-RECORDED INFORMATION

System Pressure Loss @ 40 stks = 1,200

psi

STROKES - Surface to Bit = 2,000 stks

TIME - Surface to Bit - 2,000 stks / 40 stks/min = 50

min

2 MEASURE

Shut-in Drill Pipe Pressure (SIDPP) = 800

psi

Shut-in Casing Pressure (SICP) = 1,100 psi

Pit Volume Increase (Kick Size) = 40 bbl

3 CALCULATE INITIAL CIRCULATING PRESSURE (ICP)

ICP = System Pressure Loss + SIDPP = 1,200 + 800 = 2,000

psi

4 CALCULATE KILL MUD DENSITY (New MW)

Mud Weight Increase = SIDPP / (0.052 * Depth) = 800/(0.052*14,000) = 1.10 lb/gal

Kill Mud Density (New MW) = Old MW + MW Increase = 13.5 + 1.10 = 14.6 lb/gal

1,298 2,000

800

1,100

0 psi 800

1 3 4

Engineer’s Method