7/26/2019 TORQUE, DRAG AND BUCKLING.pdf

1/8

TORQUE, DRAG AND BUCK

IN HORIZONTAL WELL DRILL S

7/26/2019 TORQUE, DRAG AND BUCKLING.pdf

2/8

TORQUE AND DRAG

In a directional well, the friction between the drillstring and the wall

well produces drag and torque. Drag is produced when the drills

moving and torque is produced when the drillstring is rotating.

Knowledge of torque and drag will enable the selection of an optim

profile and optimum size and weight of the drillstring and its compone

In horizontal wells, it is usual to run the heavy-weight Drillpipe (HWD

the curved section of the wellbore to counteract the forces caused by

and drag.

7/26/2019 TORQUE, DRAG AND BUCKLING.pdf

3/8

TORQUE EQUATIONS

Horizontal Section

Th =OD x Wm x L

72

Dimana, OD = outside diameter of tool joint (in)

Wm = bouyant weight of pipe (lb/ft)

L = length of hole or pipe section (ft)

Straight Section of Hole

T =OD x Wm x L x f x sin

24

Dimana f adalah friction factor dan adalah sudut

inklinasi sumur

Build up Section

For WOB < (0.33 x Wm x R)

Th =OD x Wm x R

72

For WOB > (0.33 x Wm x R)

Th =OD x Wm x R

72+

OD46

(WO

Dimana

R = Build up radius (ft)

7/26/2019 TORQUE, DRAG AND BUCKLING.pdf

4/8

DRAG EQUATIONS WHILE TRIPPING)

Horizontal Section

Dh = 0.33 x Wm x L

Dimana Dh = drag force in horizontal section (lb)

Straight Section of Hole

D = Wm x L x f x sin

Dimana f adalah friction factor dan adalah sudut

inklinasi sumur

Build up Section

First calculate Fo,

Fo = 0.33 Wm L, or Fo = Dh

For Fo < 0.85 Wm R, then u

Db =Wm x R

3

For Fo > 0.85 Wm R, then u

Db = 0.69 Fo0.25 Wm R

Dimana

Fo adalah axial force dan Db a

build up section

7/26/2019 TORQUE, DRAG AND BUCKLING.pdf

5/8

DRAG EQUATIONS WHILE DRILLING)

Horizontal Section

Dh = 0.33 x Wm x L

Dimana Dh = drag force in horizontal section (lb)

Straight Section of Hole

D = Wm x L x f x sin

Dimana f adalah friction factor dan adalah sudut

inklinasi sumur

Build up Section

First calculate Fo,

Fo = Dh + WOB

For Fo < 0.25 Wm R, then u

Db = 0.4 Wm R

For Fo > 0.25 Wm R, then u

Db = 0.25 Wm R + 0.69 Fo

Dimana

Fo adalah axial force dan Db a

build up section

7/26/2019 TORQUE, DRAG AND BUCKLING.pdf

6/8

BUCKLING

Buckling of drillpipe occurs when the applied compressive force exceeds the pipe

buckling load. The critical buckling force is the minimum compressive force which resupipe buckling. The critical buckling force is given by:

Fc = 550 5.5

0.5

I =As16

(+)

As = 0.7854 ( )

Where:

Fc = Critical buckling force, lb

I = Moment of inertia of pipe, in4

As = cross sectional area of pipe, in2

OD = outside diameter pipe bodID = inside diameter pipe body,

W = weight of pipe in air, lb/ft

MW = mud density, ppg

Dh = hole diameter, in

Dtj = diameter of tool Joint, in

= hole angle, degrees

7/26/2019 TORQUE, DRAG AND BUCKLING.pdf

7/8

TORQUE AND DRAG CALCULATION EXAMPLE

Suatu pemboran menggunakan HWDP dengan OD 5pada bagian lengkulateral. Panjang bagian lateral sekitar 1500 ft dan jari-jari kelengkunga

sumur 1042 ft. Diketahui berat HWDP di udara 50 lb/ft dan OD tool j

Berat lumpur yang digunakan 9.2 ppg dengan densitas baja 65.5 ppg.

a. Tentukan torsi total saat WOB sama dengan nol (rotating off bottom)b. Tentukan torsi total pada saat WOB sebesar 30,000 lbs

c. Tentukan drag pada saat tripping

d. Tentukan drag pada saat drilling

7/26/2019 TORQUE, DRAG AND BUCKLING.pdf

8/8

CRITICAL BUCKLING FORCE CALCULATION

Tentukan beban buckling kritis pada drill pipe 5 (ID 4.276, 22.6 lb/f

lubang dengan diameter 12.25dan inkinasi akhir sebesar 80. Densitas

12.5 ppg dan diameter tool joint pipa 6.25.