SPE Distinguished Lecturer Program

The SPE Distinguished Lecturer Program is funded principally through a grant from the SPE Foundation.

The society gratefully acknowledges the companies that support this program by allowing their professionals to participate as lecturers.

Special thanks to the American Institute of Mining, Metallurgical, and Petroleum Engineers (AIME) for its contribution to the program.

Society of Petroleum Engineers Distinguished Lecturer Programwww.spe.org/dl

Improving Drilling Performance By Applying

Advanced Dynamics Models

Mark W. Dykstra, Ph.D.Shell Exploration and Production

Society of Petroleum Engineers Distinguished Lecturer Programwww.spe.org/dl

The Message• Drilling system vibration affects drilling efficiency• Uncontrolled vibrations can lead to poor hole quality

– Image logs difficult to interpret – Completions difficult to run– Formation damage

• Advanced dynamics models are helping us understand and mitigate vibrations

Reference: Santos, et al.“Consequences and Relevance of Drillstring Vibration on Wellbore Stability,” SPE/IADC 52820

Considering Engineering Simulation ?

Reference: ASME Journal

Types of Dynamics Models• Engineering Models • Research Models

Improved computational horsepower has made use of “research” models more practical

– Everyday use• BHA design

– Linear Finite Element Analysis• Beam elements• Simplified contact geometry• Idealized vibration inputs

– Estimates for planning and post-analysis

• Buckling load• Static and dynamic loads and

stresses• Natural frequencies and mode

shapes (critical speeds)

– More detailed analyses• Bit designs (PDC, RC)• BHA design• Bit/BHA system performance

– Nonlinear FEA• Beam elements• Complex contact geometry• Complex vibration inputs

– Refined load and stress estimates

• Transient dynamic loads and stresses

• Post-buckling analyses

Research Model Applications• PDC Bit Dynamic Stability

– Evaluated via laboratory testing• Constant speed (often 120 RPM)• Increment weight on bit (ROP)• Identify transition from “unstable” to “stable”

– Time consuming and costly– Needed a predictive model

Unstable 8.500-in. M434

Stable 8.750-in. M123

Bit Dynamics Model• Stability Prediction• Dynamic Load Evaluation

– 120 RPM, 3 ft/hr– Force vectors shown in yellow

and green

Unstable 8.500-in. M434

Reference: Hanson, Hansen“Dynamics Modeling of PDC Bits,” SPE/IADC 29401

If PDC Cutters Could Talk …

Verification of Stability Predictions• Laboratory Tests

– 27 designs, 5.875 to 17.500-in., various IADC classes

7.875-in. M4343 ft/hr, 120 RPM

0

2

4

6

8

10

12

0 2 4 6 8 10 12

Predicted Stable ROP Step

Mea

sure

d St

able

RO

P St

ep

Improving PDC Bit Stability• Laboratory Tests

– Hard limestone (co=15 kpsi), 120 RPM

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

0 3 6 9 12 18 24 36 48

Rate of Penetration (ft/hr)

Prob

abili

ty o

f Sta

bilit

y (%

)

Previous Generation (>50 bits)

Latest Generation (>25 bits)

Diamond Table Loss

Dynamic Load PredictionsCutter Power vs. Cutter Damage

7.875-in. M123

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.000%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Cutter Scaled Radial Position

Pow

er (B

TU/h

r)

Dia

mon

d Ta

ble

Loss

Smooth Rotation PowerAvg. Dynamic Power

Max. Dynamic Power

Bit Center Bit Gauge

Load Predictions Through Beds• Formation changes affect

load distribution

Soft→Hard(nose)

Hard→Soft(cone, shoulder)

HardSoft

HardSoft

HardSoft

Segmented core usedfor laboratory tests

Research Model Applications ...• Roller Cone Bit Design

– Elimination of off-center running tendencies

UnevenGauge Wear

ConeWear

Research Model Applications ...• BHA Dynamic Stability

– Unbalanced components feed whirl

• Mass imbalance in collars

• Eccentric rotor rotation

Whirl caused by mass imbalance

Eccentric rotor rotation

– Frictional interaction with wellbore triggers BHA whirl

• High average accelerations • Extreme impacts

– Needed a predictive model

490 ft 88 ft

Drillstring Dynamics Model• 8.500-in. Horizontal Hole

– Instrumented motor– MWD tool– LWD tool

• Operating Conditions– WOB = 22.4 klb– TOB = 4.6 klb-ft– ρM = 11.7 ppg

Reference: Heisig, Neubert“Lateral Drillstring Vibrations In Extended-Reach Wells,” IADC/SPE 59235

Laboratory Verification

Reference: Aldred, W.D. and Sheppard, M.C“Drillstring Vibrations: A New Generation Mechanism and Control Strategies,” SPE 24582

Verification of Bending Predictions

• Controlled Field Tests– 12.250-in. hole, RC-STB-MWD-STB-DC– Limestone drilling

3000

1500

0

-1500

-3000330 332 334 336 338 340

Dow

nhol

e B

endi

ng(lb

-ft)

50 52 54 56 58 60Time (s)

Sim

ulat

ed B

endi

ng(lb

-ft)

3000

1500

0

-1500

-3000

Research Model Applications ...• Bit-Drillstring System

Performance– Effect of BHA vibration

on bit loading

Research Model Applications ...• Bit-Drillstring System Performance

– The effect of BHA vibration on bit loading– Operating parameters for sub-optimal BHAs

Cutter Force Distribution7.875-in. IADC 627

0

500

1,000

1,500

2,000

2,500

Aver

age

Forc

e (lb

)45 RPM, Lab Rig45 RPM, Slick BHA90 RPM, Slick BHA

Financial Impact: Improved Bits• UK North Sea Application

– Hard and abrasive zones• Poor PDC life in offsets

– Needed to improve in 12.250-in. section

9443 Tor

10667 Flounder

12133 Herring

12629 Plenus/Hidra

12902 Cromer Knoll

13262 Kimmeridge

13591 Brae 113755 Brae 2&3

Fm. Tops Lithology Series

408609

Bit Type Depth Out(ft)

Drilled(ft)

Hr. Avg. ROP(ft/hr)

Cost/ft(US$/ft)

Standard 1.1 13,535 49 11.7 4.1 2,274

New 609 13,930 395 30.1 13.2 467

New 408 14,437 507 42.2 12.0 476

New 608 14,820 383 38.3 10.0 686

Standard 1.2 15,013 193 32.1 6.0 897

Standard 2.1 15,128 115 14.3 8.0 1,049

0

100

200

300

400

HP2 HP1

Drilling Hours

12.250-in. Section Performance• Focus Well

– New designsdrilled furtherand faster

• Versus Offset– Section drilled in half the time

• Savings– US $663 per foot– US $816,282 for section

Financial Impact: BHA Refinement• Norwegian North Sea Application

– 6,000-10,000 ft horizontals in reservoir– Geosteering to stay above O/W contact – Soft sands, some calcite cemented zones– Could not steer PDC bits on motors– RS systems potentially offered step change

• Early Challenges– Bit performance– RS system durability

• Multidisciplinary Focused Study– Advanced models used for both bit

and RS system refinement

Reference: Fiksdal, Rayton, Djerfi“Application of Rotary Steerable System/PDC Bits … ,” SPE/IADC 29401

Premature Fatigue Cracks

9.500-in. Hole Section Performance

• Improved Drilling Efficiency– Improved bit performance– Improved RS BHAs– Savings approach US$1MM per well based on drilling time

Description Before Study After Study

Average interval length 8,856 ft 8,856 ftCalcite stringers 7% 7%Number of runs 8.5 5Run length 1,273 ft 2,102 ftBit runs 10.4

(6.7 RC, 3.7 PDC)4.6

(0.9 RC, 3.7 PDC)ROP 35.1 ft/hr 67.2 ft/hrBHA component failures 3.5 1.9

Failure Distribution< 25 circulating hours 25% 14%25 - 75 hr 18% 14%> 75 hr 57% 72%

Summary• Advanced dynamics models are useful for planning

– Bit design optimization– BHA design optimization

• Advanced dynamics models are useful while drilling– Lessons learned provide insights into improved operating

parameters• Advanced dynamics models are useful for post-analysis

– Evaluation of downhole vibration measurements– Failure analysis of drilling system components

• Advanced dynamics models improve performance– PDC bit efficiency and durability– RC bit efficiency and durability– LWD tool durability– Hole quality

The Next Challenge

Reference: Dupriest and Koederitz“Maximizing Drill Rates with Real-Time Surveillance of Mechanical Specific Energy,” SPE/IADC 92194

Potential Performance

Performance is enhancedby redesigning to extendthe founder point

Region II: Efficient Drilling

Region I: Inadequate Depth of Cut

Weight On Bit

Rat

e of

Pen

etra

tion

(Or T

orqu

e)

Region III: Founder• Bit Balling• Bottom Hole Balling• Vibrations

Questions?

Society of Petroleum Engineers Distinguished Lecturer Programwww.spe.org/dl