文档介绍：FormationFormation DamageDamage
What is formation damage ?
•Impairment of the reservoir permeability
by any process / system, resulting in
decreased production / injection of the
well is termed as formation damage.
–Fast production / injection decline of
affected well
–Reduced near well bore permeability
Damage characterization
•To characterize formation damage & its
identification we should know:
–Type of damage
–Location of damage
–Extent of damage
–Its effect on well productivity / injectivity
Damage quantification
•Skin value is used to quantify formation
damage
•Then what is skin
S= (k/ks-1) ln rs/rw
Objective of removal of damage
• Enhance
hydrocarbon
Bypassing damaged zone production
• Increase
recoverable
reserves
Prefrac: Radial flow pattern • Develop
uneconomical/
Post frac : Area greatly
increased marginal reserves
6
Introduction
Wellbore Area Linear Flow
Pay Zone
damage Area
How Stimulation Improves Productivity
• Stimulate to increase the production rate
– Treated length effectively increases r'w
– Can connect to existing fracs
– But can also connect to water/gas zones
• Stim. past damage to restore production
– Treated length just longer than damaged length
• Increase Pwf for a given production rate
– Enables flow to pipeline pression
Importance of Permeability
Figure -1 - Approximate Fracture Half-length Desired for Different Perms.
Elkins, .: ‘Western Tight Sands Major Research Requirements’,
Proceedings First International Gas Research Conference, Chicago, 1980
Note: This chart is be illustrative only
It may contain assumptions that
prevent applications to other wells
Fracture Half-Length (100 ft)
In-situ Gas Perm (md)
Formation Damage mechanism
•Natural damage
–Due to the production of reservoir fluid
•Induced damages
–Due to external operations on the well