2009 drlg challenges in directional gulf

8/13/2019 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

2009 drlg challenges in directional gulf

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