2009 Drlg Challenges in Directional Gulf
Transcript of 2009 Drlg Challenges in Directional Gulf
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Introduction Salt drilling almost mandatory in deepwater GoM
Drilling the tertiary trend wi ll require more salt drilling
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Introduction GoM salt fairly well understood
First sub-salt discovery in 1990 Salt is unique due to its ability to creep
Multiple drivers for directional drilling in salt DW sub-salt developments coming online
Trajectory limitations due to completion/step-out
Geology issues
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Directional Well Planning Where to kick-off
KO above & hold angle through salt
KO and build in salt
Managing formation tendencies Consider salt trend vs. maximum build rate of BHA
Difficult to manage in tight anti-collision si tuations
Managing drilling mechanics Increasing vibrations with inclination
Geomechanical issues Creep
Hole quality can impact on long term life of well
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Riserless Drilling & Salt Entry
Riserless Drilling
Limited mud volume BHA must maximize salt ROP
Directional Control
Salt footage may drive decisions
SALT
Salt Entry Risks of wellbore stability and/or losses
Control drilling parameters prior to entry
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Challenges in Drilling & Exiting Salt Shocks & Vibration Issues
Bit selection & pre-drill vibration
modeling Real-time diagnosis & intervention
Inclusions High uncertainty regarding pressure,
stability, loss circulation risk Shocks from dri lling non-homogenous
formation
Tar
Avoid it!
Salt Exit Strategy What mud weight to use?
Go slow control drilling parameters
Develop local exit strategy
SALT
Base of salt
SALT
Base of salt
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Enabling Technologies Deepwater Rigs
Increased torque, hydraulics, &pick-up required
Directional Drilling
Components
Rotary steerable systems Improved bits & under-reamers
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Enabling Technologies
Sub-salt Imaging & LWD 3D pre-stacked depth images
Gamma ray at bit, sonic &
seismic while drilling
Real-time Monitoring
Maximize data available to
optimize drilling
Remote support for leveragingexpertise
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Case Study #1 Objectives & Challenges
Kick-off and drill & under-ream salt in 18.25-in x 20-in
hole
Nudge the well to mitigate collision risks
Steering against salt tendency
Results & lessons Learned Drilled to TD in one run w minimal shocks
Casing successfully run to bottom
Successfully managed anti-collision risks & preserved
ability to drill other slots
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Case Study #2 Objectives & Challenges
Kick-off and dril l & under-ream salt in 14.75-in x
16.5-in hole
Drill 11000-ft in one run
Severe shocks & vibrations in offset wells
Results & lessons Learned Drilled to TD in one run w minimal shocks
Casing successfully run to bottom
Optimized bit design
Use of Eccentric stabilizer to aid in shockmitigation above the reamer
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Lessons Learned Rotary steerable best option
Can be optimized in combination w high toque motor
More common on older rig applications More common on big PDC bit sizes
Optimize PDC bit design
Include geomechanical considerations in trajectory design
Account for salt tendency in planned build rates
Control drilling parameters on entry and exit
Real-time monitoring of shock & vibrations
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Conclusion Increasing trend of directional drilling in salt will continue
Sub-salt horizontals?
Understand & plan within current limits Equipment
Rig Formation
Technology will continue to develop as limits are pushed
Collaboration required between operators, drilling contractors andservice providers