CONSTRUCTION OF AN

AUTONOMOUS LABORATORY

SCALE-DRILLING RIG FOR

TESTING AND CONTROL OF

DRILLING SYSTEMS

Authors: Erik Andreas Løken (UiS) & Suranga

C.H. Geekiyanage (UiS)

Co-Authors: Dan Sui (UiS) & Robert Ewald (IRIS)

OUTLINE

• Introduction

• Rig structure (system design, components, sensors)

• Data acquisition & data quality improvement

• Control system design (WOB regulation, fault detection)

• Rig performance optimization

• Conclusion

• Future work

1.

INTRODUCTION

• Team

• Drillbotics™ 2017

competition

• Fully autonomous

laboratory-scale rig

2.

RIG STRUCTURESYSTEM DESIGN

3.

RIG STRUCTURE

• Power transmission

• Hoisting

• Circulation

• Drill string, BHA & bit

SYSTEM DESIGN

Rock

Actuator

hoisting

system

Multi-

filtration

system

Dual-Pump

setup

Leak

valve

Pressure

valve

Return line

Swivel

Top Drive

Drill pipe

BHA

PDC bit

4.

RIG STRUCTURE

• Hollow-shaft brushless top

drive (0 – 3500 RPM)

• 2.86 Nm rated torque (8.59

Nm instantaneous torque)

• Direct torque transfer to drill

string assembly

• Low vibration-signature

• Programmable auto-braking

POWER TRANSMISSION

5.

RIG STRUCTURE

• Three actuators w/ stepper

motors and brakes

• 500 N WOB capacity (hook

load = 168 N)

• Variable speed adjustment

for different drilling stages

HOISTING SYSTEM

6.

Actuator #1

Actuator #3Actuator #2

Z-axis

X-axis

Fy

Fz

Fx

Top Drive

RIG STRUCTURE

• Pmax = 4.1 bara

• Q = 11.5 l/min (min. velocity

range of 0.5 – 0.7 m/s for

cuttings transportation)

• Attached w/ swivel (1000 RPM

capacity)

• Filtration deposit system

CIRCULATION SYSTEM

7.

RIG STRUCTURE

• Interchangable string

(DP), BHA & bit

• Aluminum pipe

(WT = 0.889mm)

• Stainless steel BHA

w/ three stabilizers

• PDC bit with raked

cutters

DRILL STRING, BHA & BIT

8.

DATA ACQUISITION

• Three triaxial load cells (LC),

0-100N range (Fx, Fy, Fz)

• RPM and torque (TTD) in top

drive sensors

• Ferromagnetic torque sensor

(T)

• Pressure transmitter (P)

• Reference height sensor (H)

SENSOR INTEGRATION

Rock

LC LC

LC

P

T

RPM

&TTD

∆ h

H

9.

DATA ACQUISITION

• Torque Sensor sample rate

<< 17 ms at 1000 RPM

• Arduino DUE loop-time for

other sensors

• Data logging:

uploaded every

100ms

DATA LOGGING & SAMPLING

10.

DATA QUALITY IMPROVEMENT

• T, RPM, P, Fx/Fy, ∆h –

low-pass (LP) filtered

• ∑Fz (WOB) – median,

moving avg. & LP

filters

• Frequency-analysis

for cut-off frequency

FILTERING OF DATA

11.

CONTROL SYSTEMHIERARCHICAL TWO-LAYER STRUCTURE

STRATEGIC DECISION CONTROLLER + VISUALIZATION

HOISTING SYSTEM

CONTROLLER

3 TRIAXIAL LOADCELLS & HEIGHT

SENSOR

ROTATIONAL SYSTEM

CONTROLLER

2 TORQUE SENSORS + RPM FEEDBACK

CIRCULATION SYSTEM

CONTROLLER

PRESSURE SENSOR

Main computer

Arduino DUE (3x)

Sensor distribution

Arduino DUE

programmed as finite-

state machines (FSMs)

Non-

deterministic

control loopNormal Drilling

Fault Detection

12.

CONTROL SYSTEM

• Complete closed-loop PID-

controller for WOB

• Phases (1. calibration, 2.

pilot hole drilling, 3. normal

drilling, 4. optimization, 5.

completion)

• Incremental increase of

RPM and WOB setpoint

(sweep algorithm)

NORMAL DRILLING STATE

RPM

WOBmax

max

Input

13.

CONTROL SYSTEM

• Coordinator implemented

• Detects axial vibrations,

stick slip, lateral vibrations,

pack-off (OP), leak, key-

seating & overpull

• Problems simulated in

laboratory

• Example: stick-slip

management

FAULT DETECITON & INCIDENT MANAGEMENT

Stick slip detected (T increase, RPM

decrease)

Pick-up off-bottom (10mm) Increase

RPM by 10%, reduce WOB 10-

15%. Retag bottom

YesDrilling

commences

If still stick slip at RPM/WOB-thresholds, pick-up off-bottom. Set very low WOB & very high RPM.

Continue slow drilling before sweep can commence

Stick slip?

No

14.

CONTROL SYSTEMFAULT DETECTION & INCIDENT MANAGEMENT

• Stick slip & lateral

vibrations get detected

• System attempts to correct

the faults and reduce

vibrations

15.

CONTROL SYSTEMHUMAN MACHINE INTERFACE

16.

RIG PERFORMANCEROP CALCULATION

• ROP calculated (∆ℎ

∆𝑡)

• Instantaneous- and

average-ROP

calculated using

arrays of 15 s & 180 s

• Effect of DP deflection

will be implemented

(depth-based

measurement)

1st second < 1 2 3 … 14 15>

2nd second < 2 3 4 … 15 16 >

3rd second < 3 4 5 … 16 17>…

Etc. 𝑠𝑢𝑚 ∆ℎ𝑒𝑖𝑔ℎ𝑡𝑎𝑟𝑟𝑎𝑦

# 𝑜𝑓 𝑑𝑎𝑡𝑎𝑝𝑜𝑖𝑛𝑡𝑎𝑟𝑟𝑎𝑦∗ 60 = 𝑅𝑂𝑃 [

𝑚𝑚

𝑚𝑖𝑛]

Replace oldest value with newest every second

17.

RIG PERFORMANCERESULTS, NORMAL DRILLING

0 2 4 6 8 10 12 14400

600

800

RP

M

time(min)

0 2 4 6 8 10 12 140

5

10

RO

P(m

m/m

in)

time(min)

0 2 4 6 8 10 12 140

0.5

Torq

ue o

f bit(N

m)

Time(min)

0 2 4 6 8 10 12 140123

WO

B(k

g)

Time(min)

0 2 4 6 8 10 12 14 16 18 20200400600800

RP

M

time(min)

0 2 4 6 8 10 12 14 16 18 200

1

2

RO

P(m

m/m

in)

time(min)

0 2 4 6 8 10 12 14 16 18 200

0.5T

orq

ue o

f bit(N

m)

Time(min)

0 2 4 6 8 10 12 14 16 18 200

2

4

WO

B(k

g)

Time(min)

Weak formation (cement) Hard-drilling formation (floor tiles)

18.

RIG PERFORMANCENEW FORMATION DETECTION

0 2 4 6 8 10 12 140

100

200

300

MS

E(M

Pa)

Time(min)

0 2 4 6 8 10 12 140

20

40

60

UC

S(M

Pa)

Time(min)

0 2 4 6 8 10 12 14 16 18 200

500

1000

MS

E(M

Pa)

Time(min)

0 2 4 6 8 10 12 14 16 18 200

100

200

300

UC

S(M

Pa)

Time(min)

Weak formation (cement) Hard-drilling formation (floor tiles)

𝑀𝑆𝐸 =4 𝜏𝑏𝑖𝑡 𝑅𝑃𝑀

𝜋 𝑑𝑏𝑖𝑡2 ROP

+4 𝑊𝑂𝐵

𝜋 𝑑𝑏𝑖𝑡2

𝑈𝐶𝑆 = 0.35 ∗ 𝑀𝑆𝐸19.

CONCLUSION

• Understanding, evaluating

and investigating current

solutions available

• Experiments for developing

models, control system

algorithms etc.

• Prototyping of BHA /

sensors / components / bits

ADVANTAGES CHALLENGES

• Not necessarily scalable to

industry

• Some components (i.e.

actuators for hoisting) only

work well on lab-rig

• Limited sensors &

processing power

20.

FUTURE WORK

• Drill string dynamics model

development

• Machine-learning fault detection

• Kalman filtering for WOB and ROP

estimation

• Gauss-Seidel Constraint

Control for ROP-optimization

• New BHA design w/ real-time

downhole measurements

• Mud design & cuttings transportation21.

QUESTIONS?

22.