Non-Darcy Skin factor
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Non-Darcy Skin factor
[highlight=red]Can the non-darcy component of Skin can reduce after acid stimulation?
I have read different views from different people.[/highlight]
I have read different views from different people.[/highlight]
- Bilal Amjad
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"Skin" is just a pressure drop due to non-ideal conditions. "Skin" is just a pressure drop due to non-ideal conditions. The "skin factor" is the dimensionless" pressure drop
Non-darcy skin is flow dependent - increases with increase in velocity of the fluid. However, after stimulation the increased magnitude in non-darcy skin is over come by decrease in other skin factors. I dont know the case when Non-darcy skin is negative.
Ref:
http://www.glossary.oilfield.slb.com/Di ... rcy%20flow
Non-darcy skin is flow dependent - increases with increase in velocity of the fluid. However, after stimulation the increased magnitude in non-darcy skin is over come by decrease in other skin factors. I dont know the case when Non-darcy skin is negative.
Ref:
http://www.glossary.oilfield.slb.com/Di ... rcy%20flow
Bilal Amjad
Reservoir Engineering Consultant
Reservoir Engineering Consultant
Non-darcy flow is usually manifested most clearly in gas reservoirs; on a test, it shows up as the abnormally high skin factor - which is assigned the term "apparent skin factor, s' ". From a modified Isochronal, we get the reconciled true skin value. It is this value that first decreases with a suitable stimulation job. But it does NOT mean that non-darcy flow will not prevail when you open up the choke - even after stimulation.
In high rate wells, in high perm sands, non-darcy flow will show up because of tubing restrictions for one - this will exert the back pressures that cause the D-corrected AOF plot to curve away from linearity.
In practical terms, non-darcy flow is just a frame of reference for how much you can produce, since beyond the inflexion point, opening the well up further only adds minimal incremental gas for quantum increases in drawdown (you will see this as the steep slope of the lower part of the deliverability plot)
In high rate wells, in high perm sands, non-darcy flow will show up because of tubing restrictions for one - this will exert the back pressures that cause the D-corrected AOF plot to curve away from linearity.
In practical terms, non-darcy flow is just a frame of reference for how much you can produce, since beyond the inflexion point, opening the well up further only adds minimal incremental gas for quantum increases in drawdown (you will see this as the steep slope of the lower part of the deliverability plot)
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