Skin & Damage Analysis
Calculate the impact of skin factor on well performance. Determine pressure drop due to skin, flow efficiency, equivalent wellbore radius, and damage ratio.
Reservoir & Well Parameters
ΔP_skin = 141.2 qμBo S / (kh) | rw' = rw * e^(-S) | FE = ln(re/rw) / [ln(re/rw) + S]
ΔP Skin
--
psi
Flow Efficiency
--
fraction
Equiv. Wellbore Radius
--
ft
Damage Ratio
--
Ideal Rate (S=0)
--
STB/d
Actual Pwf
--
psia
Condition
--
How this was calculated
Pressure drop due to skin: ΔP_skin = 141.2 * q * μ * Bo * S / (k * h). This is the additional pressure drop caused by near-wellbore damage or improvement.
Flow Efficiency: FE = ln(re/rw) / [ln(re/rw) + S]. Ratio of actual productivity to ideal (undamaged) productivity. FE > 1 indicates stimulation.
Equivalent Wellbore Radius: rw' = rw * exp(-S). The effective radius that gives the same drawdown without skin.
Damage Ratio: DR = 1/FE. Values > 1 indicate damage, < 1 indicate stimulation.
Skin interpretation: S > 0: damaged; S = 0: ideal; S < 0: stimulated (fractured).
Related Tool
Formation Damage Estimator
Estimate formation damage from drilling and completion operations.
Open Tool →High skin damaging your well's production? We can help with well testing analysis and stimulation planning.
Book a free strategy call →Understanding Skin Factor and Formation Damage
The skin factor is a dimensionless parameter that quantifies the departure of a well's actual productivity from its ideal (undamaged) value. A positive skin indicates formation damage in the near-wellbore region, which increases the pressure drop required to flow fluids from the reservoir to the wellbore. A negative skin indicates stimulation, typically from hydraulic fracturing or acidizing, which enhances productivity beyond the ideal case.
Formation damage can result from drilling fluid invasion, fines migration, clay swelling, scale deposition, or other mechanisms that reduce permeability near the wellbore. The pressure drop due to skin (ΔP_skin) is directly proportional to the skin factor and flow rate, meaning that the economic impact of damage increases with production rate. Flow efficiency (FE) provides a direct measure of how much of the well's potential is being realized. An FE of 0.5 means only half the expected production is achieved. This calculator helps quantify the impact of skin on well performance. All calculations run in your browser. Built by Groundwork Analytics.