mark dykstra - stick slip presentation

Copyright of Shell Exploration & Production

Business Value of Stick-Slip Mitigation: Rejuvenation of Soft Torque Technology

Mark Dykstra

Rob Grauwmans

July 2010 1IADC Stick-Slip Mitigation Workshop

Shell Projects & TechnologyDrilling Efficiency Optimization


Overview

Effects of Stick-Slip on Drilling Cost

Mitigation of Stick-Slip using Soft Torque Rotary Systems

STRS description

Historic issues and recent improvements

Business Value: Case studies

Summary



Recap: The Science of Stick-Slip Conclusions

Torsional drillstring behavior includes torsional oscillations and stick-slip (periodic bit stalls)

Stick-slip is detrimental to drill bits and can be damaging to MWD tools

Stick-slip is relatively well understood, can be modeled, and can be recognized downhole and on surface

Stick-slip can be mitigated manually, automatically, and via downhole subs

Removing torsional oscillations increases the likelihood of MWD failure due to lateral vibrations


200 250

600

400

200

0

0

10

20

30

50

100

150

kN.m

kN

RPM

Reverse Rotation

Very High Bit RPM

Low WOB

Severe Torque Cycles

Stick-slippresent

Stick-slipNOT present


Economic Implications

High RPM accelerates wear

Reverse rotation and high RPM cause chipping and breakage

Blunt cutters drill poorly!


FootageTimeTripTimeDrillingRateRigCostBit

FootCost )(

Fewer bit runs

Longer bit runs

Faster bit runs Fewer trips

wfc TFvf

dtdH ,,

Wear rate RPM WOB Temperature

Abrasive Wear

Impact Damage

Glowka, D.: “Implications of Thermal Wear Phenomena for PDC Bit Design and Operation,” SPE 14222

Lower spread rate


Drilling Efficiency: New Versus Dull

The key to efficient drilling is to keep bits as sharp as possible, as long as possible

Both abrasive wear and impact damage must be controlled

Mitigating stick-slip is critical


J.V. Kenner, R. Waughman and T. Windham, “Alliance Yields New Understanding of Bit Wear - Drilling Performance Relationship,” ETCE98-4545, 1998 ASME Energy Sources Technology Conference & Exhibition

5

T1 Dull

New T1 Dull

New

Carthage Marble

Presenter

Presentation Notes

New vs. Dull: PDC Example The data shown in the right figures are for the light set PDC bit shown in the left photo drilling Carthage marble, which has a confined compressive strength of approximately 25 ksi. The solid black line represents the bit in new condition. As WOB increases the cutting mode transitions from grinding to shearing and the slope of the ROP versus WOB line increases as the MSE decreases. The peak efficiency at 20 klb is approximately 30%. Unlike the mill tooth bit in shale, The T1 dull condition required significantly more WOB – nearly twice as much -- for a given ROP in this hard rock. Accordingly, the MSE at a given WOB has also doubled. Further dulling would cause the slope of the ROP versus WOB to continue to decrease, as projected in the lighter dotted line.


Automatic Mitigation: Soft Torque Rotary Systems

Achieved by changing the drive controls

Could be software or electronics

Tuning is required: “Cf” and “Kf”


M

No STRS / STRS Off

M

STRS On

Added compliance

and damping Electric Motor

Drive Inertia

Pipe Stiffness

BHA Inertia


STRS Response

A few cycles in surface RPM

Rapid decay of torsional vibration amplitude

Larger “smooth drilling” envelope



STRS Past and Present

Initial Success

Analog STRS, analog drive controls

Eventual Issues

Interface between STRS and drive controls

QA and support

No existing installations met acceptance criteria

Recent Success

Fit for Purpose Solutions (10 rigs)

Clear commissioning protocols

RTOC monitoring

M

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 10

0.2

0.4

0.6

0.8

1x 10

-3

Mag

nitu

de [r

pm/N

m] Changbei Rig 2 | Sept. 2009 | ElectroProject STRS

MEASUREDMODEL

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1-180

-160

-140

-120

-100

Frequency [Hz]

Pha

se [d

eg]

MEASUREDMODEL



Rejuvenation Since 2009

Pinedale

Hans Deul

Roger Lewis

Changbei Rigs 1 & 2

Libya T202

GSF Monarch

SEDCO 711

Magnolia F34, F06

Libya EDC 56

SDA: SONGA VENUS

GABON RIG 59

BRAZIL STENA



Results: Noble Hans Deul


STRS turned on

NAM

Jackup, North Sea

Electroproject STRS

12 ¼” section

2450–5550 m

60º inclination

PDC bit

5 ½” DP


Hans Deul …

Eliminated stick-slip

Improved steerable system performance

Increased ROP by 10%July 2010 11IADC Stick-Slip Mitigation Workshop

STR

S O

FFS

TRS

ON

Detailed time zoom:Downhole stick-slip measurement:

Step change in stick-slip severity


Hans Deul Record Run

Well K15-FK-106, 12¼'' section drilled in 1 bit run from 1466 m to 5001m AHRT

Steering required at beginning (42º-55º) and end (55º-50º)

High WOB used in Rogenstein (30 MT vs. 22MT), lower RPM to reduce shocks due to whirl

STRS prevented onset of stick-slip at lower speed140 rpm

Average ROP = 30.2 m/hr

11.8 days ahead of base plan, 21.9 days ahead of AFE50/50

Saved millions of €July 2010 12IADC Stick-Slip Mitigation Workshop

Presenter

Presentation Notes

Additional points: First ever shoe to shoe run over this range of formations Rogenstein often drilled with impreg Keys for the success: give modern PDC bits and cutters good drilling conditions STRS keeps bit in shape PDC cutters survive hard/abrasive sands Rotary steerable BHA -> little (but some) BHA whirl


Results: Roger Lewis

Offshore Qatar

Batch drilling 8 ½” sections for >2 yr

Electroproject STRS installed for NP2-7, NP2-3 was previous best

42% ROP improvement since STRS

Keeping bits sharper, longer


No STRS With STRS0 100 200 300 400 500

11.5

12

12.5

13

13.5

14

MD

[100

0 *

ft]

ROP [ft/hr]

NP2-7 (With STRS)NP2-3


Results: Nabors F34

Northwest Louisiana

12 ¼” section, PDC, very hard rock (Hosston/Travis Peak)

Canrig STRS

Previous best performance with down hole motors

F34 drilled with rotary

STRS eliminates stick-slip

STRS + rotary matches performance with motor

Reduces spread rate


0 100 200

8300

8350

8400

8450

8500

8550

8600

ROP [ft / hr]

MD

[ft]

0 10 20

8300

8350

8400

8450

8500

8550

8600

TQ [k ft*lb]0 100 200

8300

8350

8400

8450

8500

8550

8600

SS [%]

Comparison Magnolia F34 vs. F20

0 50 100

8300

8350

8400

8450

8500

8550

8600

RPM0 50

8300

8350

8400

8450

8500

8550

8600

WOB [k*lbs]

F20. Motor. No STRS F34. ROTARY. CANRIG STRS


Summary

Stick-Slip is Expensive

Increased bit cost due to number of runs, repair/replacement charges

Increased hourly cost due to motor usage

Increased drilling time due to accelerated dulling (low ROP)

Increased trip time due to number of runs

Increased costs associated with downhole tool damage (MWD, LWD)

Mitigation of Stick-Slip using STRS Saves Money

STRS effective when properly implemented and commissioned

Proven ROP increases from 10-70%

Improved steerable system performance (reduced failures)

Reduced bit damage, longer bit runs

Savings from thousands to millions



Questions?


mark dykstra - stick slip presentation

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