Design, Testing and Modeling of Axial Oscillation Tools Emmanuel Omojuwa, P.E.

Presenter Introduction Licensed Professional Engineer (P.E.) – OK State Board of Engineers Education BS Mechanical Engineering (University of Lagos, Nigeria) – 2007 MS Petroleum Engineering (University of Oklahoma, Norman) – 2011 Ph.D. Candidate, Petroleum Engineering (University of Oklahoma, Norman) Professional Experience Drilling Engineer, Sterling Oil Exploration, Lagos, Nigeria – 2007-2009 MWD/LWD Engineer, Schlumberger Oilfield Svcs, Youngsville, LA – 2011-2012 Well Placement Engineer, Schlumberger Oilfield Svcs, Midland, TX– 2012-2014 Drilling Analysis Engineer, Schlumberger Oilfield Svcs, Midland, TX – 2014-2015 Senior Product Engineer, JA Oilfield Mfg. Inc., Oklahoma City, OK – 2015-

Presentation Outline Introduction Design and Operation of Axial Oscillation Tools (AOTs) Testing of AOTs Modeling of AOTs in Drillstrings Model Validation and Parametric Study Conclusions and Recommendations

Introduction Slide Drilling in Mud Motor Applications: Horizontal and Extended-Reach Wells SWOB Flow Rate No RPM Inefficiencies Poor Weight Transfer High Stick Slip & MSE Unstable Toolface Control Low ROP Increased Drilling Cost High Frictional Force Gravity Hydraulic Loading Buckling Axial Oscillation Tool (AOT) Breaks Static Friction

Introduction Axial Oscillation-Supported Drillstrings (AOSD) One or more axial oscillation tool(s) (AOTs) in the drillstring Friction reduction technology for high-angle and extended reach wells Conclusions from experimental and field studies show that axial vibrations is most effective in reducing friction 70,000+ successful runs across six continents in conventional and unconventional formations Improved drilling efficiency: 200% increase in ROP and 50% reduction in WOB (NOV Website, 2019)

Design and Operation of AOTs Pulse height Pressure drop Total flow are (TFA) Rotor/Stator Configuration Pulse frequency Rotor speed Rotor/Stator Configuration

Design and Operation of AOTs Performance of Axial Oscillation-Supported Drillstrings AOTs Operating Parameters: Flow rate, frequency, fluid density, valve sizing, Pressure drop, AOT spring rate, pump open area (POA), type of drilling fluid, downhole temperature Drilling Parameters: Weight-on-bit (WOB) and RPM Friction: Coulomb friction damps oscillations (most dominant) Borehole Geometry: High friction in curve and lateral sections Drillstring characteristic: Stiffness, Length/Diameter ratio

Design and Operation of AOTs Methods Used to Evaluate the Effectiveness of AOTs Weight Transfer and ROP Improvement Stick-slip and Torsional Vibrations Toolface Control Mechanical Specific Energy (MSE) Drilling Dynamics (Axial Vibrations) Source: (Skyles et al., 2012)

Testing of AOTs

Testing of AOTs Input Data (6.5 in. AOT) 200 gpm 400 gpm Flow Rate vs. Frequency Relationship Soft Stack Stiff Stack

Testing of AOTs Design Optimization of the Orifice/Valves Using FEA Stress Analysis Velocity Profile Pressure Profile

Modeling of AOTs in Drillstrings Displacement Excitation Model Spring Rate ~ Key Input Coulomb Damping ~ Equivalent Viscous Damping Omojuwa, E., Ahmed, R., Acquaye, J. Practical Approach to Functional Testing and Analytical Modeling of Axial Oscillation-Supported Drillstrings. ASME. J. Energy Resour. Technol. 2019

Model Validation Martinez et al., 2013 Soft Stack at 200 gpm Tian et al., 2016 Stiff Stack at 200 gpm Stiff Stack at 400 gpm

Parametric Study Well Profile Drillstring Operating Parameters 8.5 in Bit 6.75 in. Motor 6.75 in. Float Sub 6.75 in. UBHO 2 x 6.625 in. NMDC 6.75 in. Flex Joint 6.75 in. Crossover Sub 81 x 5 in. Drillpipe 6.75 in. AOT 5 in. DP to Surface Flow rate (gpm) Frequency (Hz) Pressure Drop (psi) 250 9.5 280 300 11.4 380 350 13.3 540

Parametric Study 250 gpm, 9.5 Hz and 280 psi

Conclusions and Recommendations Model inputs use practical data without the use of arbitrary values (e.g. excitation force). Flow rate is the most fundamental parameter in the operations of AOTs. Spring rate improves the accuracy of the model. Embedding real time dynamic pressure transducers and strain gauges on AOTs and drillstring Effects of damping and friction can be delineated with vibrations data on AOT and drillstring Training of stakeholders on operating parameters of AOT and optimization strategies

Thank You