Study of rock drillability in oil reservoir...
Transcript of Study of rock drillability in oil reservoir...
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
4 Final year dissertation | Mathieu CORNET
• 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
5 Final year dissertation | Mathieu CORNET
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)
6 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
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
7 Final year dissertation | Mathieu CORNET
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
8 Final year dissertation | Mathieu CORNET
• 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
9 Final year dissertation | Mathieu CORNET
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
11 Final year dissertation | Mathieu CORNET
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
12 Final year dissertation | Mathieu CORNET
• 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
13 Final year dissertation | Mathieu CORNET
Université de Mons
Modeling with a cutter
14 Final year dissertation | Mathieu CORNET
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
15 Final year dissertation | Mathieu CORNET
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
16 Final year dissertation | Mathieu CORNET
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
17 Final year dissertation | Mathieu CORNET
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
Université de Mons 18 Final year dissertation | Mathieu CORNET
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
19 Final year dissertation | Mathieu CORNET
Confining pressure = depth x rock density Mud pressure = depth x mud density
Université de Mons
Modeling under confinement
20 Final year dissertation | Mathieu CORNET
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
21 Final year dissertation | Mathieu CORNET
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
22 Final year dissertation | Mathieu CORNET