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Formulas and Calculations for Drilling Operations

ISBN: 978-1-118-06312-5
406 pages
February 2011
Formulas and Calculations for Drilling Operations (1118063120) cover image


Presented in an easy-to-use format, Formulas and Calculations for Drilling Operations is a quick reference for day-to-day work out on the rig. It also serves as a handy study guide for drilling and well control certification courses. Virtually all the mathematics required on a drilling rig is here in one convenient source, including formulas for pressure gradient, specific gravity, pump, output, annular velocity, buoyancy factor, and many other topics.
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Table of Contents


1 Basic Calculations.

1.1 Capacities.

1.2 Displacement.

1.3 Buoyancy, Buoyed Weight, and Buoyancy Factor (BF).

1.4 Effective Weight.

1.5 Modulus of Elasticity.

1.6 Poisson's Ratio.

1.7 Minimum Yield Strength.

1.8 Ultimate Tensile Strength.

1.9 Fatigue Endurance Limit.

1.10 Twist.

1.11 Composite Materials.

1.12 Friction.

1.13 Gauge and Absolute Pressures.

1.14 Temperature.

1.15 Horsepower.

1.16 Flow Velocity.

2 Rig Equipment.

2.1 Overall Efficiency of Engines.

2.2 Energy Transfer.

2.3 Blocks and Drilling Line.

2.4 Derrick Load.

2.5 Ton-Miles (TM) Calculations.

2.6 Crown Block Capacity.

2.7 Line Pull Efficiency Factor.

2.8 Rotary Power.

2.9 Mud Pumps.

2.10 Energy Transfer.

2.11 Offshore Vessels.

3 Well Path Design.

3.1 Average Curvature – Average Dogleg Severity (DLS).

3.2 Vertical and Horizontal Curvatures.

3.3 Borehole Curvature.

3.4 Bending Angle.

3.5 Tool Face Angle.

3.6 Borehole Torsion.

3.7 Wellpath Length Calculations.

3.8 Types of Designs.

3.9 Tool Face Angle Change.

3.10 Horizontal Displacement.

3.11 Tortuosity.

3.12 Well Profile Energy.

3.13 Magnetic Reference and Interference.

3.14 Wellbore Trajectory Uncertainty.

4 Fluids.

4.1 Equivalent Mud Weight.

4.2 Mud Weighting.

4.3 Common Weighting Materials.

4.4 Diluting Mud.

4.5 Base Fluid – Water-Oil Ratios.

4.6 Fluid Loss.

4.7 Acidity–Alkalinity.

4.8 Marsh Funnel.

4.9 Mud Rheology.

4.10 Plastic Viscosity, Yield Point and Zero-Sec-Gel.

5 Hydraulics.

5.1 Equivalent Mud Weight.

5.2 Equivalent Circulating Density.

5.3 Hydraulics: Basic Calculations.

5.4 Bit Hydraulics.

5.5 Bingham Plastic Model.

5.6 Power Law Model.

5.7 Gel Breaking Pressure.

5.8 Hole Cleaning – Cuttings Transport.

5.9 Transport Velocity.

6 Tubular Mechanics.

6.1 Drill Collar Length.

6.2 Bending Stress Ratio (BSR).

6.3 Pipe Wall Thickness.

6.4 Resonant Frequency.

6.5 Tensions.

6.6 Drag Force.

6.7 Side Force Calculation.

6.8 Torque and Makeup Torque.

6.9 Buckling.

6.10 Maximum Permissible Dogleg.

6.11 Length Change Calculations.

6.12 Stresses.

6.13 Fatigue Ratio.

6.14 Bending Stress Magnification Factor.

6.15 Slip Crushing.

6.16 Cumulative Fatigue Calculation.

7 Drilling Tools.

7.1 Stretch Calculations.

7.2 Backoff Calculations.

7.3 Overpull/Slack-Off Calculations.

7.4 Motor Calculations.

7.5 Stabilizer Calculations.

7.6 Percussion Hammer.

7.7 Positive Displacement Motor (PDM).

7.8 Rotor Nozzle Sizing.

7.9 Downhole Turbine.

7.10 Jar Calculations.

7.11 Specific Energy.

8 Pore Pressure and Fracture Gradient.

8.1 Formation Pressure.

8.2 Leak-off Pressure.

9 Well Control.

9.1 Kill Mud Weight.

9.2 The Length and Density of the Kick.

9.3 Hydrostatic Pressure Due to the Gas Column.

9.4 Leak-off Pressure.

9.5 Maximum Allowable Annular Surface Pressure (MAASP).

9.6 Accumulators.

9.7 Driller's Method Operational Procedure.

9.8 Kill Methods.

9.9 The Riser Margin.

10 Drilling Problems.

10.1 Stuck Point Calculations.

10.2 Differential Sticking Force.

10.3 Spotting Fluid Requirements.

10.4 Loss Circulation.

10.5 Increased ECD Due to Cuttings.

10.6 Mud Weight Increase Due to Cuttings.

10.7 Hole Cleaning – Slip Velocity Calculations.

10.8 Transport Velocity and Transport Ratio.

10.9 Keyseating.

11 Cementing.

11.1 Cement Slurry Requirements.

11.2 Yield of Cement.

11.3 Slurry Density.

11.4 Hydrostatic Pressure Reduction.

11.5 Contact Time.

11.6 Gas Migration Potential.

11.7 Cement Plug.

12 Well Cost.

12.1 Drilling Costs.

12.2 Future Value (FV).

12.3 Expected Value (EV).

12.4 Price Elasticity.

Appendix: Useful Conversion Factors.



About the Author.

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Author Information

DR. ROBELLO SAMUEL is a chief technical advisor in the drilling division of Halliburton and has been with the company since 1998. With dozens of articles and several books to his credit, including Downhole Drilling Tools, Drilling Engineering, and Advanced Drilling Engineering, he is also an adjunct professor in the petroleum program at the University of Houston. Dr. Samuel is also on the board of Journal of Petroleum Science and Engineering, and he holds degrees from the University of Madurai (BS and MS) and Tulsa University (MS and Ph.D.).
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