Drillstring Cal

Drillstring Calculations (1) Drillstring calculations Pipe Stretch Calculation Example Field Units e 30 P1 50000 P2 100000 W 19.5 dP 50000

in lbs lbs lb/ft lbs

Stretch due to differential pull lowest pull highest pull Weight of drill pipe tube per foot differential pull

L=

Using formula 1 L=

Length of free pipe

SI Units e P1 P2 W dP

30 50000 100000 30 25

mm kN kN kg/m kN

Rev 1.0 16 April 2001

735294 * 195 . * 30 ft = 8602.9 ft 50000

Stretch due to differential pull lowest pull highest pull Weight of drill pipe tube per foot differential pull

L=

Using formula 1

Length of free pipe

735294 *W * e ft dP

L=

26374 . *W * e m dP

26.374 * 30 * 200 m = 6329 m 25

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Drillstring Calculations (1) Torque and Pull Calculation Example Allowable simultaneous torque and pull on drillpipe tube. Field Units D d Ym SF A J P Q

5.000 4.365 135000 0.85 4.671 25.719 450000 30831

in in psi sq in in^4 lbs ft.lbs

OD of drill pipe ID of drill pipe Minimum yield stress Safety factor Cross sectional area of drill pipe tube Polar moment of inertia Tensile load Minimum torsional yield under tension

 0.096167 × [ PI ( D4 − d 4 )]       P2   32 2 Q( lbs) = × (Ym × SF ) −  2   D  A   Remember to check combined loading for the tool joint as well. SI UNITS D d Ym SF A J P Q

0.140 m 0.120 m 100000 pa 0.85 0.004 m^2 0.00001736 m^4 200 N 10 N.m

OD of drill pipe ID of drill pipe Minimum yield stress Safety factor Cross sectional area of drill pipe tube Polar moment of inertia Tensile load Minimum torsional yield under tension

PI   . × [ ( D4 − d 4 )] 1154     P2   2 32 Q( N ) = × (Ym × SF ) −  2   D  A   Remember to check combined loading for the tool joint as well.

Rev 1.0 16 April 2001

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Drillstring Calculations (1) Jarring Calculation Formulae 1 Formula for calculating the surface weight required to fire jar up (once it has been cocked). Apply a measured weight of at least Uj. Uj = UpWt − BHA .Wt .below. Jars − POF − Jar. up. tripforce POF = pump open force. 2 Formula for calculating the surface weight required to cock the jar to enable it to be fired up. Setdown to at least a measured weight of Uc (more may be required). Uc = UpWt − BHA .Wt .below. Jars − POF − Jar . fric 3 Formula for calculating the surface weight required to fire jar down (once it has been cocked). Set down to at least a measured weight of Dj. Dj = DnWt − BHA .Wt .below. Jars − POF − Jar. Dn. tripforce 4 Formula for calculating the surface weight required to cock the jar to enable it to be fired up. Apply a measured weight of at least Dc. Dc = DnWt − BHA .Wt .below. Jars − POF − Jar . fric Notes: 1: In a non-vertical well. BHA. Wt. Below jars = BHA Wt below jars x cos(Inclination) 2: Trip force = the force (tension or compression) at the jar that is being used to fire it. 3: Jar friction is usually about 5000lbs. It is ignored for the firing stroke.

Rev 1.0 16 April 2001

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