Engineering Success in Extended Reach Drilling...AV ≈ typically 200-300 ft/min Approximate Distance cuttings will travel before settling to low side… 200 ft/min A.V. & 1 ft/min

Engineering Success in

Extended Reach Drilling

Iain Hutchison

Merlin ERD Limited IADD Houston – 27 Feb 2014

www.MerlinERD.com All Rights Reserved

TODAYS TALK

Making Trouble-Free Hole

Risk, Consequence & Attitude

Key Considerations

• Common Problems

• Hole Cleaning

• Bladed DP

• Tripping & Back-reaming

Options to Reduce Risk

• Hole Condition Monitoring (Trends)

www.MerlinERD.com

Challenge Identified • Planned • Practiced/Trained • De-Risked

WHAT WE WANT

4

Rev 1

If we always do, what we’ve always done we’ll only get, what we always had

IMPROVEMENT

A Journey not a Destination

Industry Experience

Learn from others

• ≈80% of high angle hole problems are avoidable (industry stats)

– Human factors (insufficient planning & practices)

– Assumption that “10°” or “1,000ft” extra doesn’t make a difference.

• Common Problems:

– Inadequate clean-up

– O/pull Tripping

– Backream, pack-offs

– Hole condition worsens

– 1st cavings to surface

– Often in 12¼” hole….

• Swab / Surge

- Highest readings at start of pipe movement

High Angle Wells

Key Risks

Hole Cleaning

Must be Programmed, Implemented

& Monitored

Tripping Practices

ERD wells get stuck TRIPPING

Not Drilling

Back Reaming

Like Drilling Backwards (rpm? gpm?)

Hole Cleaning

Regimes vary with inclination

HIGH angle wells:

• Flow no longer directly opposes gravity.

• Short distance for cuttings to reach low

side & form a cuttings bed.

Downward Force

Gravity

Upward Force

(Buoyancy & Viscous

Drag)

Av > Slip Velocity

Net Result is Cutting Moves Up

LOW angle wells:

• Cuttings have long distance to fall.

• Mud Rheology slows settling.

• Flow will remove cuttings

Annular Velocity

(Flowrate)

Slip Velocity

(Gravity & Mud

Rheology) Resultant

Hole Cleaning

Low & High Angle Wellbores

Tubulars & Hole Size

12¼” Hole

& 9½” BHA

12¼” Hole

& 5” DP

8½” Hole

& 5” DP

Hole Cleaning

Challenges: Annular Space

Generic

Hole Cleaning Theory – Min Parameters

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In high angle wells, the pipe is

eccentric and the TJ will be in

contact with the wellbore wall

(all angles ≥ 1°).

The cuttings are tossed into

the flowing region but begin to

fall as soon as they get

here…Returning to the low

side of the hole within a few

stands

The annular velocity

is highest in the

centre & lower

towards the edges

Rotary < threshold = ineffective hole cleaning

Flowrate < threshold = ineffective hole cleaning

EFFECTIVE HOLE CLEANING = ROTARY AND FLOWRATE > THRESHOLD

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AV ≈ typically 200-300 ft/min

Approximate Distance cuttings will

travel before settling to low side…

200 ft/min A.V. & 1 ft/min Slip Velocity

≈ 2 Stands

Cuttings have to be moved into the high velocity flow above the DP to be transported

OOH. This is accomplished with drillstring rotation >> hole cleaning thresholds.

Bladed DP is more efficient at lifting cuttings and so hole cleaning is achieved at lower

drillstring rpms. Sufficient bladed DP must be run to lift the cuttings again once they

have fallen out of the high velocity flow region. This is typically 200 to 300 ft, which is

recommended spacing between joints of bladed DP.

If rpm > HC thresholds, bladed DP is not

Required

Spacing > 2 or 3 (90ft) stands of DP results in less effective hole cleaning at lower rpm.

HOLE CLEANING

Bladed DP

Risk Reduction

What Can We Do?

What Can We Do to Reduce Risks?

Risk Reduction

Drilling Data Requirements

Roadmap Data Required

• Drag (Hookload no rotation)

• PU/SO/ROB (rotation

• Torque

• Off btm

• Predicted & Actual

• Baseline

• Project Ahead

• REALTIME for Tripping

Risk Reduction

Drilling Parameter Trends

How Can Roadmaps Help?

• Prediction of Loads at TD

• Early Warning of Hole Problems

• Drilling

• Tripping

• Running Casing

Risk Reduction

Engineering Modelling - Drag

Hookload V depth

• Different Friction Factors

• Assumptions (MW, BHA, Traj)

Predicts Load at Section TD

• Still within equipent limits?

Highlights Changes During Drilling

• Hole Condition

Use on Trips

• Early Warning of Poor Hole

• Cuttings Beds

LOOKAHEAD

AVOID Rather than fix Problems

Risk Reduction

Hole Condition Monitoring (HCM)

Risk Reduction

HCM – Drag Superior to Torque

Risk Reduction

Tripping Trends

Mud Logging Data

• Greater uncertainty

Must have accurate data,

use dedicated resource

(ERD Advisor), until

systems updated.

Overpull

Greatest Risk in High Angle Wells

Avoid to Reduce

• Pack-off risk

• Tool failures

• Casing wear

If Required

• Apply parameters ≥ Drilling Hole Cleaning

• Continue to 30° inc & clean-up

BACK-REAMING

Drilling Backwards – Implications?

Risks

• Packing Off

Fatigue of Formation

Lost Circulation

• Stuck Pipe

• Casing Wear

• DP Fatigue

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Tough On Rig Equipment

Biggest Draw On Power

Back-Reaming

Drilling Backwards - Implications

Cuttings Must Be Moved Up Hole

Minimum Rotation to Move Cuttings Up Hole During Back Reaming

• 120+ RPM (hole > 8½”)

• Same As Drilling (Cuttings Behavior Doesn’t Change When the Bit Comes Off Bottom!)

Maximum Back Reaming Speed

• Slower Than Cuttings Move Up Hole…

• Cuttings Don’t Move the Same Speed as the Fluid

• Start With 5 ft / min (300 ft/hr)

Back-Reaming

Fundamentals

If Back Reaming

• Complete Full Clean Up Cycle Prior to:

Starting b/ream OOH

Tripping if inc > 30

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Equilibrium Bed Height is 1 – 2 Stands

Above BHA & Needs to be Reduced to a

Safe Tripping Height After Back Reaming

Back Reaming Equilibrium Height

Safe Tripping Height

Back-Reaming

Drilling Backwards - Preparation

TODAYS TALK

Making Trouble-Free Hole

Risk – we can control

Learn from others

Hole Cleaning to be fit for purpose

Tripping is key risk area

Trends can Provide Early Warning

Back-Reaming is a symptom not a solution

Avoid low bridges via Engineering, not luck!

www.MerlinERD.com

Merlin ERD Ltd

T: +44 1738 627922

W: www.MerlinERD.com

Questions?

Merlin Engineer at play!