Drillstring Design Training Course

1. Introduction to Drillstring Design

1.1 Drillstring Engineering Fundamentals

• Evolution of drillstring technology including (historical development, modern innovations).

• Functions of the drillstring including (weight transfer, torque transmission, circulation).

• Design considerations including (well type, trajectory, formation characteristics).

• Drillstring design workflow including (planning, component selection, analysis, verification).

• Introduction to API RP 7G and ISO 10407 standards for drillstring components.

1.2 Drillstring Components

• Drill pipe specifications including (sizes, grades, connections, properties).

• Heavy weight drill pipe applications including (transition management, stiffness enhancement).

• Drill collars and their functions including (weight application, stabilization, BHA stiffening).

• Specialty tools including (jars, accelerators, shock subs, vibration dampeners).

• Component inspection and classification including (DS-1 categories, acceptance criteria).

2. Mechanical Principles in Drillstring Design

2.1 Force Analysis

• Axial forces including (weight, buoyancy, pressure effects, friction).

• Torsional forces including (surface torque, downhole torque, rotational resistance).

• Bending stresses including (dogleg severity effects, contact forces, cyclic loading).

• Combined stress states including (Von Mises stress, principal stresses, safety factors).

• Stress concentration factors including (connections, tool joints, upsets, and shoulders).

2.2 Material Properties and Selection

• Steel grades and specifications including (E-75, X-95, G-105, S-135, V-150).

• Mechanical properties including (yield strength, tensile strength, ductility, hardness).

• Environmental considerations including (H₂S service, CO₂ environments, temperature effects).

• Fatigue characteristics including (S-N curves, endurance limits, cumulative damage).

• Material selection criteria including (well environment, loading conditions, and cost).

3. Drill Pipe Design and Selection

3.1 Drill Pipe Specifications

• Size selection including (hole size compatibility, hydraulics, stiffness requirements).

• Grade selection including (tension capacity, torsional capacity, environmental factors).

• Wall thickness options including (range 2, range 3, heavy wall pipe).

• Connection types including (API connections, premium connections, specialty designs).

• Hardbanding considerations including (wear prevention, casing compatibility, reapplication).

3.2 Drill Pipe Performance Limits

• Tension limit calculations including (body yield, connection strength, safety factors).

• Torsional limits including (make-up torque, yield torque, connection capacity).

• Internal pressure ratings including (burst pressure, collapse pressure, biaxial effects).

• Fatigue life assessment including (stress cycles, curvature effects, connection factors).

• Combined loading effects including (tension-torsion interaction, pressure effects).

4. Heavy Weight Drill Pipe and Drill Collars

4.1 Heavy Weight Drill Pipe Design

• Transitional stiffness benefits including (buckling prevention, vibration management).

• Mechanical properties including (weight per foot, OD/ID ratios, moment of inertia).

• Selection criteria including (hole size, BHA transition, directional requirements).

• Connection considerations including (strength, maintenance, inspection).

• Spiral configuration applications including (hole cleaning enhancement, torque reduction).

4.2 Drill Collar Selection

• Size and weight selection including (weight on bit requirements, stabilization needs).

• Slick vs. spiral configurations including (torque reduction, hole cleaning, wall contact).

• Connections including (regular, spiral, double shoulder, stress relief).

• Non-magnetic drill collars including (survey accuracy, formation evaluation).

• Specialty collars including (integral blade stabilizers, flex collars, vibration reduction).

5. Bottom Hole Assembly Design

5.1 BHA Fundamentals

• BHA functions including (directional control, weight application, stabilization).

• Assembly configuration including (packed hole, pendulum, fulcrum principles).

• Stabilizer placement including (rotary assemblies, steerable systems, point-the-bit).

• Force distribution including (side forces, contact points, bit loading).

• BHA selection criteria including (directional objectives, formation characteristics, hole size).

5.2 Directional BHA Design

• Rotary BHA design including (build, drop, hold assemblies).

• Steerable motor assemblies including (bent sub, bent housing configurations).

• Rotary steerable system considerations including (push-the-bit, point-the-bit designs).

• Hybrid assembly design including (combining rotary steerable with motors).

• Performance optimization including (ROP enhancement, directional control, vibration management).

6. Torque and Drag Analysis

6.1 Torque and Drag Fundamentals

• Friction models including (soft string, stiff string, finite element models).

• Friction factor determination including (field calibration, offset well comparison).

• Wellbore trajectory effects including (dogleg severity, tortuosity, micro-tortuosity).

• Wellbore conditions including (hole cleaning, tight hole, differential sticking).

• Lubricants and friction reducers including (effectiveness, application methods).

6.2 Torque and Drag Modeling

• Pick-up and slack-off weight prediction including (friction effects, buckling limits).

• Torque prediction including (drill string rotation, reaming, back-reaming).

• Soft string modeling including (assumptions, limitations, applications).

• Stiff string modeling including (contact forces, lateral displacement, bending stresses).

• Operational windows including (hook load limits, surface torque limits, downhole limits).

7. Buckling Analysis

7.1 Buckling Mechanics

• Sinusoidal buckling including (onset conditions, helical transition, critical force).

• Helical buckling including (lock-up potential, contact forces, friction amplification).

• Lateral displacement including (clearance utilization, wall contact, wear mechanics).

• Stability factors including (stiffness, weight, buoyancy, hole size).

• Critical force calculations including (Lubinski's equations, modified models).

7.2 Buckling Prevention and Management

• Compressive load management including (weight transfer, friction reduction).

• BHA stiffness optimization including (collar placement, stabilizer position).

• Hole cleaning effects including (cuttings bed reduction, fluid rheology).

• Operational best practices including (rotation while slacking off, reciprocation).

• Critical parameters monitoring including (surface weight, torque, differential pressure).

8. Vibration Analysis and Mitigation

8.1 Drilling Vibration Fundamentals

• Axial vibration including (bit bounce, stick-slip, longitudinal resonance).

• Lateral vibration including (whirl, BHA resonance, stabilizer positioning).

• Torsional vibration including (stick-slip, torsional resonance, bit-rock interaction).

• Coupled vibrations including (mode conversion, complex patterns, harmonics).

• Vibration detection including (surface measurements, downhole sensors, indirect indicators).

8.2 Vibration Management

• BHA design for vibration mitigation including (mass distribution, stiffness control).

• Anti-vibration tools including (shock subs, dampening tools, resonance breakers).

• Operational parameters including (WOB, RPM, hydraulics, drilling practices).

• Drilling dynamics modeling including (frequency analysis, mode shapes, critical speeds).

• Monitoring and response strategies including (real-time detection, mitigation protocols).

9. Hydraulics Optimization

9.1 Hydraulics Fundamentals

• Flow rate determination including (hole cleaning, motor requirements, optimal bit hydraulics).

• Pressure loss calculations including (pipe friction, annular friction, tool restrictions).

• Equivalent circulating density including (annular friction pressure, static head, surge/swab).

• Hole cleaning factors including (particle transport, fluid velocity, rheology).

• Hydraulic optimization including (bit hydraulic horsepower, impact force, jet velocity).

9.2 Advanced Hydraulics Design

• Drill pipe hydraulics including (ID selection, pressure losses, turbulent flow).

• BHA hydraulics including (motor differential pressure, MWD requirements, LWD cooling).

• Bit hydraulics including (TFA calculation, nozzle selection, optimization methods).

• Specialty considerations including (managed pressure drilling, underbalanced, foam).

• Hydraulics modeling including (steady state, transient models, temperature effects).

10. Fatigue and Failure Prevention

10.1 Fatigue Mechanics

• Fatigue process fundamentals including (crack initiation, propagation, final failure).

• Stress concentration including (geometrical discontinuities, notch effects, connections).

• Cyclic stress analysis including (rotating bending, dogleg severity, surface rotation).

• Cumulative damage including (Miner's rule, inspection intervals, retirement criteria).

• Environmental factors including (corrosion fatigue, hydrogen embrittlement, temperature).

10.2 Failure Prevention Strategies

• Design modifications including (connection selection, material upgrade, component sizing).

• Operational practices including (dogleg severity control, RPM management, WOB control).

• Inspection protocols including (frequency determination, techniques, acceptance criteria).

• Monitoring systems including (real-time torque, vibration, trajectory control).

• Contingency planning including (fishing preparation, failure response, recovery methods).

11. Special Applications

11.1 Extended Reach Drilling

• Torque and drag management including (friction reduction, rotary steerable applications).

• Drill pipe selection including (premium connections, high-torque capacity, wear resistance).

• Buckling prevention including (compression limits, pipe selection, trajectory planning).

• Running practices including (float techniques, rotation while running, centralization).

• Specialized tools including (torque reduction subs, non-rotating drill pipe protectors).

11.2 HPHT Applications

• Material selection including (yield strength deration, environmental limits).

• Connection considerations including (pressure ratings, temperature effects, sealing).

• Fatigue management including (temperature effects on S-N curves, inspection frequency).

• Thermal effects including (expansion, contraction, stress distribution).

• Special equipment including (HPHT rated components, specialty metals, and connections).

12. HSE in Drillstring Design and Operations

• Risk assessment including (failure mode analysis, consequence evaluation).

• Handling and running procedures including (safe lifting, connection make-up).

• Well control considerations including (string integrity, pressure ratings, barrier verification).

• Environmental protection including (failure prevention, spill mitigation).

• Emergency response planning including (contingency procedures, recovery options).

13. Case Studies & Group Discussions

• Regional case studies from Middle East operations including (deep wells, extended reach wells).

• Failure analysis examples including (root cause determination, prevention strategies).

• Optimization success stories including (performance enhancement, problem avoidance).

• Decision-making exercises including (component selection, design verification).

• The importance of proper training in successful drillstring design and operations.