Wellbore Strengthening - LCM or Casing
Wellbore Strengthening - LCM or Casing Hong (Max) Wang, PhD & PE
Sharp-Rock Technologies, Inc. Texas, USA Society of Petroleum Engineers Distinguished Lecturer Program www.spe.org/dl
1
Outline • Mechanisms and Methodologies • Advanced Solutions – Prevention – Remediation
• Summary • Demo • Discussions
2
Mud Loss Mechanisms • Closing Fractures
• Openings
3
Wedging for Higher Stress
4
Plugging to Hold Higher Pressure
5
Lost Circulation Methodologies
Prevention Closing Fractures (Wedging) Openings (Plugging)
Remediation
Stress Cage (M. Alberty)
Formation Closure Stress (F. Dupriest) Particulate LCM A New LCM (small) (large) 6
Loss Prevention – Stress Cage (Wedging) Wedging Particles in Mud Resilient Graphitic Carbon lost circulation material
Ground Marble lost circulation material
mud
7
Strengthening Process
Fractures open when mud pressure is above fracturing pressure Fracture growth arrested by wellbore strengthening fluid Fractures wedged by LCM Widened fractures mean higher hoop stress or stronger wellbore
8
Typical Challenge (A Real Case) Mud Weight for Cap Rock Shale Stability ≥ 2.10 gm/cm3 Frac Gradient for Depleted Reservoir ≈ 1.77 gm/cm3 Drilling Challenge from a Depleted Formation Pore Pressure and Fracture Gradient, gm/cm3 0
0.5
1
1.5
2
2.5
3
4000
Depth, meter
4500
5000
5500
6000 Pore Pressure
Fracture Gradient
Leak-off Test
9
Step 1: Fracture Width Calculation Minimum Data Requirement: – Stress/Pressure: • Current Wellbore Strength • Target Wellbore Strength
– Rock: • Young’s Modulus • Poisson’s Ratio
– Geometry: • Hole Size • Fracture Length
Calculated Fracture Width = 1800 micron (vertical well and SH = Sh) (Fracture Calculation - SPE 90493, 95895, 104947) 10
Step 2. Define a Particulate Solution
RGC = Resilient Graphitic Carbon
Particle Size Distribution
Cumulative particle percentage, %
Formulation
M aterials Amount D50, microns Base m ud (17.1 ppg), bbl 1.0 (Barite + clay) RGC-1, lb 40 1180 Ground M arble 1, lb 8 600 RGC-2, lb 8 425 Ground M arble 2, lb 8 325 RGC-3, lb 8 150 RGC-4, lb 8 80 100.0 80.0 60.0 40.0 20.0 0.0 10
100
1000
Particle size, micron
10000 11
Applications: Permeable Formations Preferred
1. Most Likely to Achieve Success: Strengthening Depleted Sandstone Formations 2. Most Unlikely to Achieve Success: Strengthening Shale Formations 3. Will Also Likely Achieve Success: Sealing Small Naturally Fractures 12
Issue: Drilled Cuttings Accumulation Solids Control vs. By-Pass Shale Shakers Solids Control: – Determine the amount of LCM lost over shale shakers. – Addition of LCM to counteract the LCM loss.
By-Pass: – Rheology impact – Erosion – Not good for drilling a long interval of a large hole section with water based mud
– Logistics and cost.
13
Loss Remediation (Plugging) High Fluid Loss Squeeze Pills – Rapid Filter Plug Forming High Fluid Loss
Impermeable to Mud
14
Loss Remediation (Plugging) Dolomite Vugs
Unknowns Rubble Pores Large Natural Fractures
15
Foam Wedges – “One Size Fits Many”
16
17
Plug Formation Assuring
18
Foam Wedge Extended High Fluid Loss Squeeze Slurry AADE-11-NTCE-25 2. conventional high fluid loss squeeze
1. foam wedges
Extended Squeeze Slurry Concept 3. a carrier fluid (water or oil)
High Fluid Loss
Technology built on the success of high fluid loss pills. 19
“Have it both ways” – Internal Plug Formation Assurance • Pump fast – All slurry goes through • Pump slow – Slots are plugged and holding pressure Plugging Tests 3 mm Slot (Tests) , BPM/in.2
3 mm 10 ft Fracture (Calc.), BPM
Flow though
0.22
3.2
Instantaneous plugging
0.04
0.6 20
Plugging Large and Small Openings Micron-Sized Particles Seal Different Gaps
Seal Multiple Openings
21
Squeeze to Customize - Squeeze for Higher Strength and a Longer Plug
70
12
60
10
50
8
40
6
30
4
20 10
2
0
0 150
0
50
100
Required Plug Length for 400 psi, inches
bp push-out tester
Instantaneous Shear Strength, psi
Squeeze Effects on Plugging
Squeeze Pressure Differential, psi Shear Strength
Plug Length
22
When Conventional High Fluid Loss Squeeze Pills Do Not Work Not Working
Working
23
Foam Wedge Extended High Fluid Loss Squeeze Pill Working
Working
24
Operation – Simple and Conventional • Northwest China – Mix with saturated salt water to 2.3 to 2.4 sg – No cement pumps – Balanced plug to place – Hesitation squeeze to needed ECD
25
Summary: Lost Circulation Methodologies • Wedging – Closing Fractures – Prevention – Stress Cage (M. Alberty) – Remediation – FCS (F. Dupriest)
• Plugging – Openings – Prevention (small) – Particulate LCM – Remediation (large) – Foam Wedge Extended High Fluid Loss Squeeze Pills 26
Demo
27
Contact Information Dr. Hong (Max) Wang Sharp-Rock Technologies, Inc. Houston, Texas 281-450-4944 [email protected]
28
Sharp-Rock Technologies, Inc. Texas, USA Society of Petroleum Engineers Distinguished Lecturer Program www.spe.org/dl
1
Outline • Mechanisms and Methodologies • Advanced Solutions – Prevention – Remediation
• Summary • Demo • Discussions
2
Mud Loss Mechanisms • Closing Fractures
• Openings
3
Wedging for Higher Stress
4
Plugging to Hold Higher Pressure
5
Lost Circulation Methodologies
Prevention Closing Fractures (Wedging) Openings (Plugging)
Remediation
Stress Cage (M. Alberty)
Formation Closure Stress (F. Dupriest) Particulate LCM A New LCM (small) (large) 6
Loss Prevention – Stress Cage (Wedging) Wedging Particles in Mud Resilient Graphitic Carbon lost circulation material
Ground Marble lost circulation material
mud
7
Strengthening Process
Fractures open when mud pressure is above fracturing pressure Fracture growth arrested by wellbore strengthening fluid Fractures wedged by LCM Widened fractures mean higher hoop stress or stronger wellbore
8
Typical Challenge (A Real Case) Mud Weight for Cap Rock Shale Stability ≥ 2.10 gm/cm3 Frac Gradient for Depleted Reservoir ≈ 1.77 gm/cm3 Drilling Challenge from a Depleted Formation Pore Pressure and Fracture Gradient, gm/cm3 0
0.5
1
1.5
2
2.5
3
4000
Depth, meter
4500
5000
5500
6000 Pore Pressure
Fracture Gradient
Leak-off Test
9
Step 1: Fracture Width Calculation Minimum Data Requirement: – Stress/Pressure: • Current Wellbore Strength • Target Wellbore Strength
– Rock: • Young’s Modulus • Poisson’s Ratio
– Geometry: • Hole Size • Fracture Length
Calculated Fracture Width = 1800 micron (vertical well and SH = Sh) (Fracture Calculation - SPE 90493, 95895, 104947) 10
Step 2. Define a Particulate Solution
RGC = Resilient Graphitic Carbon
Particle Size Distribution
Cumulative particle percentage, %
Formulation
M aterials Amount D50, microns Base m ud (17.1 ppg), bbl 1.0 (Barite + clay) RGC-1, lb 40 1180 Ground M arble 1, lb 8 600 RGC-2, lb 8 425 Ground M arble 2, lb 8 325 RGC-3, lb 8 150 RGC-4, lb 8 80 100.0 80.0 60.0 40.0 20.0 0.0 10
100
1000
Particle size, micron
10000 11
Applications: Permeable Formations Preferred
1. Most Likely to Achieve Success: Strengthening Depleted Sandstone Formations 2. Most Unlikely to Achieve Success: Strengthening Shale Formations 3. Will Also Likely Achieve Success: Sealing Small Naturally Fractures 12
Issue: Drilled Cuttings Accumulation Solids Control vs. By-Pass Shale Shakers Solids Control: – Determine the amount of LCM lost over shale shakers. – Addition of LCM to counteract the LCM loss.
By-Pass: – Rheology impact – Erosion – Not good for drilling a long interval of a large hole section with water based mud
– Logistics and cost.
13
Loss Remediation (Plugging) High Fluid Loss Squeeze Pills – Rapid Filter Plug Forming High Fluid Loss
Impermeable to Mud
14
Loss Remediation (Plugging) Dolomite Vugs
Unknowns Rubble Pores Large Natural Fractures
15
Foam Wedges – “One Size Fits Many”
16
17
Plug Formation Assuring
18
Foam Wedge Extended High Fluid Loss Squeeze Slurry AADE-11-NTCE-25 2. conventional high fluid loss squeeze
1. foam wedges
Extended Squeeze Slurry Concept 3. a carrier fluid (water or oil)
High Fluid Loss
Technology built on the success of high fluid loss pills. 19
“Have it both ways” – Internal Plug Formation Assurance • Pump fast – All slurry goes through • Pump slow – Slots are plugged and holding pressure Plugging Tests 3 mm Slot (Tests) , BPM/in.2
3 mm 10 ft Fracture (Calc.), BPM
Flow though
0.22
3.2
Instantaneous plugging
0.04
0.6 20
Plugging Large and Small Openings Micron-Sized Particles Seal Different Gaps
Seal Multiple Openings
21
Squeeze to Customize - Squeeze for Higher Strength and a Longer Plug
70
12
60
10
50
8
40
6
30
4
20 10
2
0
0 150
0
50
100
Required Plug Length for 400 psi, inches
bp push-out tester
Instantaneous Shear Strength, psi
Squeeze Effects on Plugging
Squeeze Pressure Differential, psi Shear Strength
Plug Length
22
When Conventional High Fluid Loss Squeeze Pills Do Not Work Not Working
Working
23
Foam Wedge Extended High Fluid Loss Squeeze Pill Working
Working
24
Operation – Simple and Conventional • Northwest China – Mix with saturated salt water to 2.3 to 2.4 sg – No cement pumps – Balanced plug to place – Hesitation squeeze to needed ECD
25
Summary: Lost Circulation Methodologies • Wedging – Closing Fractures – Prevention – Stress Cage (M. Alberty) – Remediation – FCS (F. Dupriest)
• Plugging – Openings – Prevention (small) – Particulate LCM – Remediation (large) – Foam Wedge Extended High Fluid Loss Squeeze Pills 26
Demo
27
Contact Information Dr. Hong (Max) Wang Sharp-Rock Technologies, Inc. Houston, Texas 281-450-4944 [email protected]
28
