Planning of Drilling Operations in Extreme Ocean Currents

DYNAMIC POSITIONING CONFERENCE October 11-12, 2016 OPERATIONS Planning of Drilling Operations in Extreme Ocean Currents Luca Pivano - Marine Cybernetics/DNV GL Kristopher Eide - Marine Cybernetics/DNV GL Øyvind Smogeli - Marine Cybernetics/DNV GL Per Frederiksen - Maersk Drilling Martin Poirer - Total Exploration and Production

MTS DP conference Houston 12 th Oct 2016 Planning Of Drilling Operations In Extreme Ocean Currents Experience From Time-domain Simulations and Full-scale Validation On Maersk Venturer Martin Poirier (TOTAL) and Luca Pivano (DNV GL)

INTRODUCTION Ongoing demand for energy + decreasing supplies of traditional fossil fuels Further offshore and deeper Toward more extreme environment Operators are facing new challenges! More operational constraints & risks Increasing operating costs Requirements for: Improving the operating philosophy Extending equipment limits Innovative tools for operation & preparation Planning of drilling operations in extreme ocean currents - DP conference Houston 12 th Oct 2016 2

CONTEXT Montevideo Raya-1 project 3404m water depth (world record) Harsh Weather (wind, waves, current) Remote operations No O&G business in Uruguay Last wells drilled offshore Uruguay in 1976 (shelf context) Raya-1 Challenges: Station keeping Rig motion Positioning strategy vs riser preservation Crew competency HSE Cost efficient solution Planning of drilling operations in extreme ocean currents - DP conference Houston 12 th Oct 2016 3

WELL PREPARATION MARINE ASPECTS PHASE 1 METOCEAN ANALYSIS Collection of Metocean data (hindcasts) Metocean acquisition Calibration & interpretation Environmental constraints (1yr,10yrs,100 yrs return periods ) PHASE 2 RIG SELECTION Design review Rig selected DP capability study (and/or mooring analysis) Rig motion analysis Preliminary riser study CPY requirements Planning of drilling operations in extreme ocean currents - DP conference Houston 12 th Oct 2016 4

PHASE 3 OPERABILITY STUDY Riser study Rig motion performances Operating limits WoW & NPT Targets Station keeping performances Time domain simulations PHASE 4 PREPARATION & OPTIMZATION Risk assessment Spud Training / crew preparation Trials / Tests Identification of additional support tools Operating philosophy Objectives (HSE, budget) Full scale validation WSOG Planning of drilling operations in extreme ocean currents - DP conference Houston 12 th Oct 2016 5

Full-scale trials with Maersk Venturer Samsung 96K design (V-class series drill ship) Advanced Thruster and Engine control Specially designed Power Managements System Fast blackout recovery and enhanced blackout prevention 6 x 5500 kw Azimuth Thrusters Description Symbol Unit Value Length over all L OA m 228 Length between perpendiculars L PP m 219 Breadth B m 42 Description Symbol Unit Value Draught T m 11 Mass displacement m tonnes 88218 Transverse metacenter height GMT m 3.9 6

Trial location South African coast Goals: Station-keeping performance in high current (Agulhas) Vessel motion with medium/high waves Vessel location with respect to current forecast for Day 1 Vessel location with respect to current forecast for Day 3 Vessel location with respect to current forecast for Day 2 Vessel location with respect to current forecast for Day 4 Measurements: DP control system logs (wind speed, GPS, Gyro, VRU, Thruster, Generators, etc.) Wave radar (H s, wave period, H max ) Wave direction measured by the crew ADCP: Current speed and direction once a day at 49 m Weather: 2.11 m/s current speed, 6 m Hs, 20 m/s wind speed 7

Summary of the trials 31 tests Station-keeping in DP at various heading Significant and sudden change of heading in DP Station-keeping in DP worst single thruster failure and worst case single failure Track-following in DP Simulated power blackout tests in addition with drift off tests 60 50 40 20 0 0 North Position [m] -50 North Position [m] -20-40 -100-60 -150-80 -100-200 -120-150 -100-50 0 50 100 150 East Position [m] -100-80 -60-40 -20 0 20 40 60 East Position [m] 9

Summary of the trials 31 tests Station-keeping in DP at various heading Significant and sudden change of heading in DP Station-keeping in DP worst single thruster failure and worst case single failure Track-following in DP Simulated power blackout tests in addition with drift off tests Intact worst single thruster failure worst case single failure 10

Station-keeping results 8 6 4 2 North (m) 0 Waves, Hs 4.0m Wind, 18.1m/s Current, 1.1m/s -2-4 -6-8 -8-6 -4-2 0 2 4 6 8 East (m) Weather: 1.13 m/s current speed, Hs 4 m, 18 m/s wind speed 13

Station-keeping results 5 Scenario 21 4 3 2 1 Wind, 16.4m/s North (m) 0 Waves, Hs 3.4m Current, 1.1m/s -1-2 -3-4 Trial 21-5 -5-4 -3-2 -1 0 1 2 3 4 5 East (m) N W E Current S Weather: 1.13 m/s current speed, Hs 3.2 m, 16.4 m/s wind speed 14

Station-keeping results 5 Scenario 24 4 3 2 1 North (m) 0 Wind, 17.4m/s Waves, Hs 4.8m Current, 1.1m/s -1-2 -3-4 Trial 24-5 -5-4 -3-2 -1 0 1 2 3 4 5 East (m) N W E Current S Weather: 1.13 m/s current speed, Hs 4.5 m, 17.4 m/s wind speed 15

Heave, Roll and Pitch Max heave: Max roll: Max pitch: 5 m (top-trough) 2.5 degrees 2 degrees 16

Heave, Roll and Pitch Max heave: Max roll: Max pitch: 5 m (top-trough) 2.5 degrees 2 degrees 17

Heave, Roll and Pitch Max heave: Max roll: Max pitch: 5 m (top-trough) 2.5 degrees 2 degrees 18

Station-keeping results Robustness of station-keeping with heading away from optimal heading up to 35/40 degrees with high current Vessel heading against current or waves? Maersk and Total pleased with the vessel performance, both regarding station-keeping and vessel motion Trial 11 N Trial 21 N Trial 24 N W E W E Current W E Current S S S 19

Time-domain simulations with DynCap Full-motion simulator Dynamic environmental loads Pos-refs and sensors Vessel motion Propeller dynamics and losses Power system dynamics Position Refs and sensors DP control system Propeller dynamics DP control system dynamics Dynamic environmental loads Power system dynamics Thrust losses 21

Station-keeping comparison 22

Heave, roll and pitch Heave difference was max 60 cm for 95% of the simulations Roll and pitch differences was always less than 1 degree 23

Thruster failure tests Transient analysis Trial 5: - Loss of THR 1-1.95 m/s current speed - Hs 2.85 m - 9.4 m/s wind speed Trial 6: - Loss of THR 1 and 4-1.95 m/s current speed - Hs 2.66 m - 13.8 m/s wind speed 24

Uncertainty in the results Simulator model uncertainty Environmental conditions uncertainty Current velocity and direction measured once a day Wave direction observed by the crew Lengths of the simulations when comparing maxima (5 wave random seeds) DP control system tuning and gains Simulator vs actual vessel DP control system steady-state before a test started 25

Conclusion 4 days of trials performed in harsh weather Maersk Venturer performed very well in station-keeping, both in positioning and vessel motion With the weather during the test there was no a clear gain on having the vessel heading toward the current or towards the waves The vessel responded very well upon thruster failure tests Experience was gained during the heading change trials DynCap time-domain simulations performed for comparison Simulation results showed satisfactory agreement for both positioning and vessel motion Such tool could be used for operational planning (WSOG) 26

Planning Of Drilling Operations In Extreme Ocean Currents Experience From Time-domain Simulations And Full-scale Validation On Maersk Venturer Thanks! Luca Pivano Luca.pivano@dnvgl.com www.dnvgl.com Martin Poirier Martin.poirier@total.com www.total.com SAFER, SMARTER, GREENER 2 7