(1)COPYRIGHT 1990 MITCHELL ENGINEERING, PO BOX 1492. GOLDEN, CO, 80402, USA (303) 273 3744

** Bottom Hole Assembly Design and Usage**

GRADE YIELD

**Jar Triggering Load**

D 60,000

E 75,000

**6,000**

ft Length of Pipe G 105,000

**5**

in Pipe OD N 80,000

**4.276**

in Pipe ID S 135,000

**S**

API Grade of Pipe (D,E,G,N,S,X) X 95,000

**21**

ppf W eight of Pipe

**20**

% % W ear of Pipe

**135,000**

psi API Unit Yield Strength of the Pipe

**90**

ft Length of Collars

**136.3**

ppf W eight of Drill Collars

**7.75**

in Collar OD

**448,604**

lbs W orking Tensile Strength

**3**

in Collar ID

**112,919**

lbs Bouyed W eight of the String Above the Jars

**12**

ppg Mud W eight

**335,685**

lbs Maximum Triggering Load

**15**

in^2 Seal Area of Jar

**15,000**

lbs Pump Extending Force

**1,000**

psi Assistance Pressure for Jars

**448,604**

lbs Maximum Load W ITHOUT Hydraulic Assistance

**433,604**

lbs Maximum Load W ITH Hydraulic Assistance

**Mechanical Properties of the B.H.A.**

**Air Weight and Bouyed Weight of the B.H.A.**

**8**

in Collar OD or Side Length,S

**3**

in Collar ID

**N**

Is(Are) the Collar(s) Square ?

**146.9**

ppf W eight per Foot of Drill Collars

**26.5**

ft Length of Collars

**3,891.5**

lbs W eight of Drill Collars

**16**

ppg Mud W eight - Outside

**110.9**

ppf Bouyed W eight per Foot of Drill Collars

**16**

ppg Mud W eight - Inside

**2,940.1**

lbs Bouyed W eight of Drill Collars

(2)**3.00E+07**

psi Modulus of Elasticity

**197.1**

in^4 Resistance to Axial Bending

**394.2**

in^4 Resistance to Torsion

**0.275589877**

in Sag (Resistance to Sag)

**0.635577836**

° Droop (Resistance to Droop)

**Tapered B.H.A.**

**6**

in Pipe OD

**4.276**

in Pipe ID

**8**

in Collar OD

**3**

in Collar ID

15.74 in³ Section Modulus of Pipe

49.27 in³ Section Modulus of Collars

3.13 Section Modulus Ratio of Collars to Pipe

**YES**

SHOULD CONNECTION BE MADE ??

**Wall Forces**

**Wall Force in Doglegs**

**5**

in Pipe OD

**4.276**

in Pipe ID

**21**

ppf W eight of Pipe

**30**

ft Length of a Joint of Pipe

**8**

in Collar OD

**3**

in Collar ID

**500**

ft Length of Collars

**146.9**

ppf W eight of Collars

**14,000**

ft Drilling Depth

**203,261**

lbs Tension in the Drillpipe

**11**

ppg Mud W eight

### TENSION

**1.85**

°/100' Dogleg Severity

**1968.9**

lbs W all Force

**2,000**

ft Depth of Dogleg

**2,500**

ft Depth of Interest

**YES**

IS W EAR ACCEPTABLE ??

**50,000**

lbs W eight on Bit

(3)**50**

° Slant Angle

**9.9**

ppf Bouyed W eight of Pipe

**17**

ppg Mud W ieght - Outside

**7.6**

ppf W all Force per Foot

**8.4**

ppg Mud W eight - Inside

**228.1**

lbs W all Force per Joint of Pipe

**Centrifugal Force**

**91**

R.P.M. Rotary Speed

**163.9**

ppf W all Force per Foot

**17.5**

in Hole Diameter

**Torsional Damping - The Fly Wheel Effect**

**Collars Currently In The Hole**

**8**

in Collar OD or Side Length,S

**3**

in Collar ID

**N**

Are the Collars Square ?

**400**

ft Length of Collars

**394.2**

in^4 Resistance to Torsion (Polar Moment of Inertia)

**40**

R.P.M. Current Rotary Speed

**79.8**

Dampening Variable [DV]

**Collars To Be Added To The Hole**

**11**

in Collar OD or Side Length,S

**3**

in Collar ID

**N**

Are the Collars Square ?

**180**

ft Length of Collars 1,429.4 in^4 Resistance to Torsion (Polar Moment of Inertia)

**3**

R.P.M. New Rotary Speed 9.8 Dampening Variable [DV]

**89.5**

Total Dampening

**Torque Of A Spinning B.H.A.**

**9.5**

in Collar OD or Side Length,S [Of Collars In Hole]

**2.75**

in Collar ID [Of Collars In Hole]

**N**

Are the Collars Square ?

**300**

ft Length of Collars

**360**

R.P.M. Current Rotary Speed

**794.0**

in^4 Resistance to Torsion (Polar Moment of Inertia)

**227,250**

lbs-ft Torque Transmitted To The Bit

(4)**Torsional Bucking Of A B.H.A. And Drillpipe**

**5**

in Pipe OD

**4.276**

in Pipe ID

**10,000**

ft Length of Pipe

**21**

ppf W eight of Pipe

**8**

in Collar OD or Side Length,S

**3**

in Collar ID

**N**

Are the Collars Square ?

**400**

ft Length of Collars

**100**

R.P.M. Current Rotary Speed

**0**

lbs Axial Load On Pipe (- = Compression)

**-40,000**

lbs Axial Load On Collars (- = Compression)

**14.3**

in^4 Resistance to Axial Bending (Pipe)

**28.5**

in^4 Resistance to Torsion (Pipe)

**146.9**

ppf W eight per Foot of Drill Collars

**58,740.0**

lbs W eight of Drill Collars

**197.1**

in^4 Resistance to Axial Bending (Collars)

**394.2**

in^4 Resistance to Torsion (Collars)

**1,867.8**

lbs-ft Buckling Torque of the Pipe

### UNDEFINED

lbs-ft Buckling Torque of the Collars

**-0.293397869**

lbs Value of Axial Load on Pipe for Zero B.T.

**-2,532.8**

lbs Value of Axial Load on Collars for Zero B.T.

**4,231.2**

lbs-ft Torque Placed On Drillpipe By Collars

**Buckling By Rotational Drag**

**^^^^^Uses Pipe And Collar Data From Example Above ^^^^^**

**440**

Volts Voltage Across Motor

**150**

Amps Amperes Consumed

**92**

% Electrical Efficiency

**95**

% Mechanical Efficiency of Rotary System

**80**

R.P.M. Drill Pipe Rotational Speed

(5)**75**

% % of Rotational Drag Created by B.H.A.

**5,076.2**

lbs-ft Drillpipe Torque by Rotary System

**3,807.1**

lbs-ft Torque Created By B.H.A.

(6)**Critical Buckling Loads**

**5**

in Pipe OD

**3**

in Pipe ID

**0**

ppg Mud W eight

**1**

st Order of Buckling (1,2)

**80.13**

f (Order Coefficient for Buckling)

**1.000**

Bouyancy Factor

**4,153.4**

lbs Critical Buckling Load

**Weight on Drill Bit In Vertical And Inclined Holes**

**36**

in Hole Diameter

**146.9**

ppf W eight per Foot of Drill Collars

**5**

in Pipe OD

**13,217**

lbs W eight of Drill Collars

**4.276**

in Pipe ID

**0.827**

Bouyancy Factor

**21**

ppf W eight of Pipe

**121.5**

ppf Bouyed W eight per Foot of Drill Collars

**9,000**

ft Length of Pipe

**10,934**

lbs Bouyed W eight of Drill Collars

**8**

in Collar OD or Side Length,S

**1,093**

lbs Bouyed W eight of Stabilizers

**3**

in Collar ID

**10,416**

lbs Available W eight from Collars & Stabilizers

**N**

Is(Are) the Collar(s) Square ?

**8,253**

lbs Available W eight from the Drillpipe

**90**

ft Length of Collars

**18,669**

lbs Total W eight Available

**3**

Number of Stabilizers (Same Size as Collars)

**3**

ft Length of Each Stabilizer

**11.3**

ppg Mud W eight - Outside

**11.3**

ppg Mud W eight - Inside

**30**

° Hole Inclination

**Critical Rotary Speeds Of B.H.A.**

**8**

in Collar OD or Side Length,S

**146.9**

ppf W eight per Foot of Drill Collars

**3**

in Collar ID

**73,425**

lbs W eight of Drill Collars

**N**

Is(Are) the Collar(s) Square ?

**2.31**

Hz Longitudinal Frequency

(7)**500**

ft Length of Collars

**46.2**

R.P.M. Critical Longitudinal Rotary Speed

**50**

R.P.M. Rotary Speed

**5.33**

Hz Torsional Frequency

**1**

Order of Harmonic (1,3,5...)

**106.5**

R.P.M. Critical Torsional Rotary Speed

**Y**

Is The Bit A Tri-Cone ?

**2.5**

Hz Frequency Of Bit

**Y**

Is There A Shock Sub On The B.H.A. ?

**40,000**

lbs/in Enter Spring Constant For Shock Sub

**Critical Rotary Speeds Of The Drillpipe**

**5**

in Pipe OD

**4.276**

in Pipe ID

**21**

ppf W eight of Pipe

**7,500**

ft Length of Pipe

**30**

ft Langth Between Tool Joints

**241.6**

R.P.M. Critical Nodal Rotary Speed

**34.4**

R.P.M. Critical Longitudinal Rotary Speed

**Fatigue Of Drillpipe**

GRADE YIELD
D 60,000
E 75,000

**5**

in Pipe OD G 105,000

**4.276**

in Pipe ID N 80,000

**21**

ppf W eight of Pipe S 135,000

**14,000**

ft Length of Pipe X 95,000

**S**

API Grade of Pipe (D,E,G,N,S,X)

**30**

ft Distance Between Joints

**135,000**

psi API Unit Yield Strength of the Pipe

**8**

in Collar OD or Side Length,S

**5.275**

in² Cross Sectional Area Of Drillpipe

**3**

in Collar ID

**146.9**

ppf W eight per Foot of Drill Collars

**N**

Is(Are) the Collar(s) Square ?

**0.827**

Bouyancy Factor

**300**

ft Length of Collars

**333,723**

lbs W eight Of String Below Dogleg

**42**

ft Length of Tools In Hole

**276,097**

lbs Bouyed W eight Of String Below Dogleg

**30000000**

psi Modulus Of Elastisity

**52,345**

psi Bouyant Tensile Stress In The Drillpipe [Teff]

(8)**11.3**

ppg Mud W eight - Outside

**14.269**

in^4 Cross-Sectional Moment Of Inertia Of Drillpipe

**11.3**

ppg Mud W eight - Inside

**0.0254**

K

**5**

°/100' Dogleg Severity

**12,780**

psi Maximum Permissible Bending Stress [Grade E & S]

**500**

ft Depth Of Dogleg

**2.56**

°/100' Maximum Permissible Dogleg Severity [Fatigue]

**2,000**

lbs Maximum Lateral Tooljoint Force

**1.38**

°/100' Maximum Permissible Dogleg Severity [W ear]