Miniature Robotic Drilling Rig for

Research, Technology Development

and EducationStudents:

Astrid Lescoeur, Martin Olsen, Mayuran Vasantharajan

and Runa Linn Egeland

Supervisors:

Sigve Hovda and Alexey Pavlov

Affiliation:

Department of Geoscience and Petroleum

Norwegian University of Science and Technology

The Team

STUDENTS

• Astrid Lescoeur

• Martin Olsen

• Mayuran Vasantharajan

• Runa Linn Egeland

SUPERVISORS

• Alexey Pavlov, Professor

• Tor Berge Gjersvik, Professor

• John-Morten Godhavn, Professor

• Sigve Hovda, Professor

• Noralf Vedvik, Technical Support

(mechanical)

• Steffen W. Moen, Technical Support

(electrical)

OBJECTIVE

«Design a drilling rig and

related equipment to

autonomously drill a vertical

well as quickly as possible

while maintaining borehole

quality and integrity of the

drilling rig and drillstring»

Work Process

Fall 2016

• Design of the drilling rig

• Finding sponsors

• Report and application for the

competition

Spring 2017

• Building the drilling machine

• Automation design

• Software development

• Testing the drilling machine

• Participating in the competition

What does it look like?

Hardware Limitations

• Drillstring is made of aluminum with

OD=0.625’’ and ID=0.305’’

• Maximum combined length of stabilizers is

8.9 cm

• Riser is limited to 10 cm

• Conclusion: vibrations will be a major issue that can be

adressed by the control system and the structural design

Hardware Components

HOISTING SYSTEM

• Ball screw driven by an AC-

motor with linear roller guides

• Provides vertical movement

and weight on bit

TOP DRIVE SYSTEM

• Provides rotational force to the

drill string

• Electrical swivel to avoid

twirling sensor cables

c

Hardware Components

CIRCULATION SYSTEM

• Piston pump provides circulation, cuttings

transportation and desired pressures

• Swivel designed to withstand pressures up

to 50 bar

Hardware Components

STABILIZING ELEMENTS AT

SURFACE

• Drill deck bushing

• Riser at formation top and

landing module

Hardware ComponentsSENSORS

• Downhole Sensors:

Temperature

• Surface Sensors:

Load cell and pressure transducer

• Integrated Drive Sensors:

• Hoisting system: position and torque

• Top drive system: RPM and torque

c

Hardware ComponentsMOBILITY

• Foldable rig

• Structure dimensions

• Casters with foot-activated

lift- mechanism

VERSATILITY

• Can tolerate rock sample

height up to 85cm and width

and length up to 60cm

• Adjustable top drive motor

position

Safety SystemHARDWARE

• Emergency shutdown of the system

– Manual stop button cuts the power supply

to the motors and pump

• Hoisting system

– Limit switch added to each of the

extremities to avoid running off the rails

• Electrical system:

– All electrical components stored inside

waterproof cabinet to avoid shorting and

electrical hazards

Safety SystemHARDWARE

• Safety related to drill pipe failure:

– Plexiglass set up around the rig structure, isolating drilling

zone from personnel and avoiding water spillage

CONTROL SYSTEM

• Safety limits are implemented in the drives to avoid failure

and hazardous situations

• The safety limits have the highest priority in the control system

Key Areas of DesignGEOMETRICAL STIFFNESS

OF THE DRILL PIPE

• Nozzle was added in the

BHA

• This increases the internal

pressure which increases the

tension in the pipe wall

• Differential pressure of 46.9

bar over the constriction

220.5 N acting downwards

Key Areas of DesignCONTROL SYSTEM

• Control inputs:

– Hoisting speed

– Top drive speed

• Measured parameters:

– WOB

– Torque (hoisting)

– Torque (drill string)

– RPM (drill string)

– Downhole:

• Temperature

• Bit position

– ROP (from position)

– MSE

Simulink

Design

Criteria

PRIORITIES

1. Integrity of the rig

2. Borehole quality

3. ROP maximization

4. Energy efficiency

5. Keep it simple – fit for purpose

Pre-Study

ASPHALT MARBLE SLATE SOAPSTONE

• Multiple experiments carried out on various rocks

Key Findings

AT RPM = 1000

• Higher WOB provides higher ROP and the same, or higher efficiency (from MSE calculations)

• Comment: RPM = 1000 for all plots below

Key Findings

Key FindingsOPTIMIZATION STRATEGY

• Push system to the limits by increasing WOB

WEAKEST LINK OF THE DESIGN

• Connection between BHA and drill string

• Excessive drill string torques and torque peaks

Max drill string torque limit set to 4 Nm in the control system drive

• Control drill string torque to a set-point below safety limit (2.4 Nm is chosen) to avoid excessive peaking of drill string torque.

• Torque is controlled through WOB (increasing/decreasing)

Design

Criteria

PRIORITIES

1. Integrity of the rig

2. Borehole quality

3. ROP maximization

4. Energy efficiency

5. Keep it simple – fit for purpose

Strategy

1. Drill down at safe values (400 RPM) before the

surface stabilizing element is in place

2. Set RPM = 1000

Control Tds to a set-point

Key Areas of DesignCONTROL SYSTEM

• Hoisting system

– Hoisting motor in speed control mode with max torque limit

– Controllers implemented in Simulink: WOB control mode and

Drillstring Torque control mode

– Nonlinear gains ensure fast reduction of the WOB if the

Drillstring Torque peaks over the set-point Tds

sp

TdsM

(Top Drive)

Non-linear

gain

PID

WOB M

(Load Cell)

Non-linear

gain

PID

⍵hSPWOBsp

Key Areas of DesignCONTROL SYSTEM

• Top drive

– Top drive motor is in speed control mode with max torque

safety limit

• Necessary filtering is applied to signals to avoid noise issues

Test DayROCK FORMATION

• Dimensions of box: 153x305x610 mm

• Unknown rock formations

SET-UP

• A one inch pilot hole was manually drilled the day before

• Top drive and hoisting motor were running autonomously

• Water based circulation system was run manually (not pressurized)

• Baker Hughes drill bit was used

• BHA was manufactured in the workshop

Test DayRESULTS

• Two twist-offs occurred due to weight imbalance between the BHA and the pipe

• The rock was drilled through in approximately 1 hour

Lessons LearnedMECHANICAL

• The structure was designed assuming that the aluminum pipe

as the weakest link. Testing phase showed that the BHA/pipe

connection was the weakest link.

• Critical resonances were in the design phase only studied for

the drill pipe, not for the whole structure

• Bit bouncing was not expected through literature study in

design phase, but showed up being a severe bottleneck

CONTROL SYSTEM/SIGNALS

• Discovered the importance of tuning PID-controllers, filtering

signals and setting proper safety limits

• The control system was designed from zero control system

experience. If we look back, we would probably do things

differently

GENERAL

• Teamwork and communication is critical to enhance productivity

and efficiency

• The importance of project and time management when bringing

a project from design to final product

• Hands-on experience: areas of learning gained through the

competition not covered in the university course material

• Insight into other engineering disciplines

QUESTIONS?