Study of rock drillability in oil reservoir conditionssbgimr-bvigrm.be/wp-content/uploads/2017/03/TFE_Cornet_Mathieu.pdf · Faculté Polytechnique Tests in atmospheric conditions,

Faculté Polytechnique

Tests in atmospheric conditions, evolution with confinement, numerical simulation

Study of rock drillability in oil reservoir conditions

Mathieu CORNET June 2012

Under the direction of Pr. Dr. Ir. J-P Tshibangu K

Université de Mons

Problem

Final year dissertation | Mathieu CORNET 2

Economic issues in oil drilling

Maximizing drilling rates

Optimizing drilling tools

Knowledge of rock cutting mechanism

Modeling the cutting process under confinement

Université de Mons

• Understanding of rock cutting

→ Mechanism of chip formation

→ Evolution of cutting force

Theoretical study of phenomenological models

Laboratory tests in atmospheric conditions (single cutter test device currently out of service)

Development of a numerical model with FLAC2D

in atmospheric conditions

extension to underground conditions

→ Comparison of models

Objectives

3 Final year dissertation | Mathieu CORNET

Université de Mons

Cutting : an overview


• Drill bit • PDC cutter • Cutting angle:

15° • Depth of cut:

0.1 to 1 mm • Cutting width:

10 mm • Chamfer surface

area

(So

urc

e : S

chlu

mb

erge

r) (S

ou

rce

: Pel

fren

e)

Université de Mons

Phenomenological models


Merchant (1944)

Plasticity law Shear

→Plastic materials

Evans & Murrel (1965)

Crack propagation under tensile stress

→ Brittle materials (Coal)

Nishimatsu (1972)

Macrocracks propagation Shear

→ Brittle materials

Université de Mons

• Phenomenological models

• Only positive cutting angle (mining)

Comparison of cutting models (1)


0

100

200

300

400

500

600

700

800

900

1000

0 0,2 0,4 0,6 0,8 1 1,2

PD

C c

utt

ing

forc

e (

N)

Depth of cut (mm)

Merchant Evans & Murrel Nishimatsu

Université de Mons

a) Crushing and formation of micro-chips

b) Increase of chip size

c) Formation of a macro-chip

Cutting cycle


Increase of the cutting force with the chip size Valid for brittle materials

↔Plastic materials: chips and cutting force = continuous

(So

urc

e : R

ich

ard

)

Université de Mons

• Moca limestone

Rock selection and characterization


• Density : 2.4

• Young’s modulus : 17 900 MPa

• Poisson’s ratio : 0.33

• Compressive strength : 44 MPa

• Tensile strength: 4.5 MPa

• Internal frcition angle: 40°

• Cohesion : 15 MPa

Slightly abrasive Well known

Université de Mons

• RSD tests « Rock Strength Device »

• Cutting results 0.1 mm : friction dominated

0.9 mm : brittle

• Cutting forces Mean forces

Mean of force peaks : representative of formation of large sizes chips

Laboratory tests


100

150

200

250

300

350

400

450

500

550

600

650

700

750

800

850

900

0 0,005 0,01 0,015 0,02 0,025 0,03 0,035 0,04 0,045

Forc

es

(N)

Avancement axial (m)

Evolution des forces horizontale et verticale pour deux profondeurs de passe 0.1 et 0.9 mm.

force horizontale 0.1 mm

force verticale 0.1 mm

force horizontale 0.9 mm

force verticale 0.9 mm

0

200

400

600

800

1000

1200

1400

0 0,5 1 1,5 2

Fo

rce

s e

t p

ics

de

fo

rce

s (

N)

Profondeur de passe (mm)

Forces moyennes

Pics de forces moyens

(So

urc

e :

Legr

ain

, 19

99

)

Université de Mons 10 Final year dissertation | Mathieu CORNET

0

100

200

300

400

500

600

700

800

900

1000

0 0,2 0,4 0,6 0,8 1 1,2

Forc

e d

e c

ou

pe

(N

)

Profondeur de passe (mm)

Merchant

Evans & Murrel

Nishimatsu

RSD 2012

RSD 1999*

RSD 1999**

• Experimental model : horizontal force • 2012 : mean values

• 1999 (Legrain H.) : mean values *; mean peak values **

Comparison of cutting models (2)

Université de Mons

• FLAC2D (Fast Lagrangian Analysis of Continua) : Finite differences method

+ Ideal for non linear problems

+ Spatial coordinates updated at each calculation step (large strain mode)

• Model behavior of the rock : elastoplastic with Mohr-Coulomb criterion

Numerical simulation


ρ (kg/m³) E (MPa) ν Rc (MPa) Rt (MPa) φ(°) C (MPa)

Moca 2 400 16 000 0.33 57 4.5 40 15

PDC Cutter 15 800 650 000 0.25

Université de Mons

The mesh


• X for fixing the lateral edge • Y for fixing the bottom edge • 160 columns and 80 rows, with a concentration at the cutting interface • Horizontal velocity at the cutting interface : 10-8 m/s

→ Impossible to achieve balance

Université de Mons

Hypothesis : failure occurs when the reaction force is maximum at the interface

Evolution of the state of plasticity

Chip formation


Université de Mons

Modeling with a cutter


Without cutter : Fc = 1200 N

With cutter : Fc = 1300 N

• Interest : Rigidity of the cutter Friction at the interface

• Mechanical properties of the

cutter • Friction coefficients at the

interface

→ Slight increase of the cutting force and the volume of the chip

Université de Mons

Parametrical study


y = 3381,6x + 60736 R² = 0,9442

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5 10 15 20 25 30 35

Forc

e d

e c

ou

pe

(N

)

Cohésion (MPa)

y = 2,847x + 70470 R² = 0,9717

0

20000

40000

60000

80000

100000

120000

140000

160000

180000

0 5000 10000 15000 20000 25000 30000 35000

Forc

e d

e c

ou

pe

(N

)

Module de Young (MPa)

• Young’s modulus

• Cohesion

Université de Mons

Parametrical study


ϕ= 30° ϕ= 40° ϕ= 50°

• Rock internal friction angle φ

Evolution towards a more brittle behavior

Increase of the cutting force

• Tensile strength No change

Université de Mons

Changing the depth of cut


0

20000

40000

60000

80000

100000

120000

140000

0 0,2 0,4 0,6 0,8 1 1,2

Forc

e d

e c

ou

pe

(N

)

Profondeur de passe (mm) 0.2 mm 0.4 mm 0.6 mm 0.8 mm 1 mm

Increase of size of chip with the depth of cut Friction behavior dominant at low depth of cut


0

200

400

600

800

1000

1200

1400

0 0,2 0,4 0,6 0,8 1 1,2

Cu

ttin

g fo

rce

(N

)

Depth of cut(mm)

Merchant

Evans & Murrel

Nishimatsu

RSD 2012

RSD 1999*

RSD 1999**

FLAC2D

• Numerical model FLAC2D

Comparaison of cutting models (3)

Université de Mons

Modeling under confinement


Confining pressure = depth x rock density Mud pressure = depth x mud density

Université de Mons

Modeling under confinement


7000

27000

47000

67000

87000

107000

127000

147000

167000

187000

207000

0 10 20 30 40 50 60 70 80

Forc

e d

e c

ou

pe

(N

)

Confinement (MPa)

The cutting force increases with confinement but the rate of increase decreases with the confinement.

Université de Mons

Cutting is a complex process with a multitude of possible configurations (geometries, materials, operating conditions, etc.)

Difficult to provide a general formulation

Interest for numerical modeling

PDC cutter : The main cutting mechanism is SHEAR

Evolution towards a dominant friction behavior with decreasing depth of cut

Increase of cutting force with confinement until stabilization

Comparison of models : Nishimatsu, experimental and numerical are comparable FOR THIS

ROCK

Conclusions


Université de Mons

Changing the behavior model of the rock

Establishing relations : properties (rock + cutter), depth of cut, confinement

Uploading factors : temperature, normal force, wear of the cutter, action of the mud, etc.

3D modeling: edge effects, cutter geometry

+ Comparison with cutting device equipped with a three-dimensional force sensor

Discrete element method (PFC2D ou 3D) : heterogeneity of

the rock

Perspectives



Thank you for your attention

Documents

Study of rock drillability in oil reservoir conditionssbgimr-bvigrm.be/wp-content/uploads/2017/03/TFE_Cornet_Mathieu.pdf · Faculté Polytechnique Tests in atmospheric conditions,