Cementing

Heavy Oil Cementing Jose David Vela Principal Technical Prof. Fluid Systems Quito, Ecuador

November 29, 2006

Good Cementing from first time Avoid annular communication trough well life & reduce expensive workovers

GOOD RESULTS

Cement Challenges on Thermal Recovery Projects

Cement Challenges on Thermal Recovery Projects

High Temperatures Preventing Strength Retrogression

First High Temperature Cements 

Portland Cement > 230 F •Strength Retrogression •Increase in Permeability •Industry Adapted Portland Plus 35% to 40% Silica Flour

Properties are virtually retained

“G” + 35 % SSA-1

Reduced CS and increased porosity & permeability

Neat “G”

Effective Mud Displacement to Prevent Casing Buckling & Shearing

Casing Buckling & Shearing 

Residual Mud Pockets can cause casing Buckling



How to Improve? • Best Cementing Practices • Reduce washouts

Casing Buckling & Shearing



Casing Caliper Buckling Measurements



Need good bond and flexible cement properties



Solution: Thermatek

Insulating the Wellbore

Insulating the Wellbore 

Benefits

• • • • •

Lower the Steam to Oil Ratio Less Energy Used More Economic Production Marginal Fields now Economical More Environmentally Friendly

Conduction, Convection & Radiation HT

Insulating the Wellbore

Q

r1 r2

Heat Transfer Rate 2 Pi L kef (T1 – T2) Q= ln(r2 / r1)

Thermal Conductivity of Cements kef (W/mK)

Neat Cement

0.9

MicroSphere

0.5

ZoneSeal (Foam)

0.2

Q ≈ kef As

kef 

Q

Cyclic Loading in the Wellbore

Well Events After Primary Cementing • Cement Hydration & hydration volume reduction

• Completions & pressure decrease inside the casing

• Pressure Testing & pressure increase inside the casing

• Hydraulic Fracturing & pressure increase

• Production & pressure/temperature increase inside tubulars

Modes of Cement Failure 

De-bonding

@ rock-cement interface De-bonded

@ cement-casing interface

Rock Cement

Casing

Casing

Cement De-bonded De-bonded

Rock

Modes of Cement Failure 

 Deformation

Cracks Rock

Cement

Rock Cement

Casing

Casing

Design and Testing

Lab Test Damaged Cement Sheath

Resilient Sheath – No Damage

Lab Testing

Material Strength and Deformation

Stress

1

Brittle

2 Ductile

1

Strain

2

Typical Young’s Modulus Steel 3.0* 107 psi

Aluminum

“neat cement”

1.0* 107 psi

1.5*10 psi 6

“modified” cement 0.2*106 psi

Typical Young’s Modulus Nitrogen

Steel 3.0* 107 psi

Aluminum

“neat cement”

1.0* 107 psi

1.5*10 psi 6

“modified” cement 0.2*106 psi

Typical Young’s Modulus Nitrogen

Steel 3.0* 107 psi

Aluminum

“neat cement”

1.0* 107 psi

1.5*10 psi 6

“modified” cement 0.2*106 psi

Typical Young’s Modulus Nitrogen

Steel 3.0* 107 psi

Aluminum

“neat cement”

1.0* 107 psi

1.5*10 psi 6

“modified” cement 0.2*106 psi

Typical Young’s Modulus Nitrogen

Steel 3.0* 107 psi

Aluminum

“neat cement”

1.0* 107 psi

1.5*10 psi 6

“modified” cement 0.2*106 psi

Engineering Analysis

Analysis Damaged Cement Sheath

Resilient Sheath – No Damage

Lab Test

Analysis Cement

formation

casing

WellLife® Analysis

Data Needed for FEA Analysis Rock properties • Casing properties • Cement slurry and sheath properties •

• • • • •

Young’s Modulus Poisson Ratio Compressive Yield Parameters Tensile strength Effective volume change from cement hydration

• Operation details • Completion • Stimulation • Production

Rock Casing Cement

Cyclic Loading 

Stress in the material should be below a certain value so that it can withstand a large number of cycles

Cyclic Loading Stress in the material should be below a certain value so that it can withstand a large number of cycles

Ultimate Strength (failed)

Stress



Number of Cycles

Cyclic Loading Stress in the material should be below a certain value so that it can withstand a large number of cycles

x

Ultimate Strength (failed)

Stress



Number of Cycles

Cyclic Loading Stress in the material should be below a certain value so that it can withstand a large number of cycles

x Stress



Ultimate Strength (failed)

x

Number of Cycles

Cyclic Loading Stress in the material should be below a certain value so that it can withstand a large number of cycles

x Stress



Ultimate Strength (failed)

x x

Number of Cycles

Cyclic Loading Stress in the material should be below a certain value so that it can withstand a large number of cycles

x Stress



Ultimate Strength (failed)

x x

Number of Cycles

x

Cyclic Loading Stress in the material should be below a certain value so that it can withstand a large number of cycles

x Stress



Ultimate Strength (failed)

x x

Number of Cycles

x

x

Cyclic Loading Stress in the material should be below a certain value so that it can withstand a large number of cycles

x Stress



Ultimate Strength (failed)

x x

Endurance Limit

Number of Cycles

x

x