Wellbore stability 600 million to 1 billion dollars is the prevention of brittle failure or plastic deformation of the rock surrounding the wellbore due to mechanical stress or chemical imbalance.
Wellbore stability 600 million to 1 billion dollars is the prevention of brittle failure or plastic deformation of the rock surrounding the wellbore due to mechanical stress or chemical …Full description
A step-by-step guide to creating sparking dialogue from the writer of 17 films William C. Martell.
Descripción: Circuitos C. William Taipe H.
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A step-by-step guide to creating sparking dialogue from the writer of 17 films William C. Martell.
Advanced Wellbore Wellbore Stability Model Model (WELLSTAB-PLUS) Dr. William C. Maurer TP00-09
1
DEA-139 Phase I DEA Sponsor: Duration: Start Date: End Date: Participation Fee:
Marathon 2 Years May 1, 2000 April 30, 2002 $25,000/$35,000 $25,000/$35 ,000
Typical Occurrences of Wellbore Instability in Shales
soft, swelling shale brittle-plastic shale brittle shale naturally fractured shale strong rock unit
Wellbore Stability Problems High
Torque and Drag Bridging and Fill Stuck Pipe Directional Control Problem Slow Penetration Rates High Mud Costs Cementing Failures and High Cost Difficulty in Running and Interpreting Logs
Effect of Borehole Pressures
Effect of Mud Support Pressure on Rock Yielding High Support Pressure max
min
PW
Low Support Pressure max
PW
min
Rock Failure Mechanisms
BRITTLE
PLASTIC
Rock Yielding around Wellbores Laboratory Tests Rawlings et al, 1993
Isotropic Stresses
Anisotropic Stresses
Change In Near-Wellbore Stresses Caused by Drilling Before Drilling In-situ stress state
After Drilling Lower stress within wellbore
sV (overburden)
sHmin
Pw (hydrostatic)
sHmax
sHmin
sHmax
Stress Concentration around an Open Wellbore
z r
r Po
Hmin
z
r
Pw
Hmax
Strength vs Stress Identifying the Onset of Rock Yielding
s s e r t S r a e h Min SStress
sq´ sr´
Stable Stress State
sr´
Max Stress
sq´
Effective Compressive Stress
s s e r t S r a e h S
sq´ sr´
Unstable Stress State sr´
sq´
Effective Compressive Stress
Effect of Pore Fluid Saturation = z o
= z +p o f
Pf = Fluid Pressure
SOLID ROCK
POROUS ROCK
Effect of Near-Wellbore Pore Pressure Change on Effective Stresses
Yield
s s e r t S r a e h S
No Yield
Po increase r ´
r ´
´
Effective Compressive Stress
´
MEI Wellbore Stability Model: (mechanical model, does not include chemical effects)
Linear
elastic model (BP) Linear elastic model (Halliburton) Elastoplastic Model (Exxon) Pressure Dependent Young’s Modulus Model(Elf)
Wellbore Stability Model (WELLSTAB) Develop Enhanced Model (WELLSTAB-PLUS) Add time dependent feature to model Hold workshops Conduct field verification tests Write technical reports
Field Verification Goals Determine
model accuracy Improve mathematical algorithms Field calibrate model Make models more user-friendly Convert wellbore stability from an art into a science