Matrix Acidizing Maximum Injection Rate & Paccaloni Calculator

Determine the maximum safe surface and bottomhole injection rate (bpm) to avoid exceeding formation parting pressure per the Paccaloni matrix acidizing method.

Reservoir & Wellbore Parameters

True Vertical Depth TVD (ft):

Fracture Gradient FG (psi/ft):

Reservoir Pressure P_res (psi):

Net Pay Thickness h (ft):

Formation Permeability k (mD):

Initial Total Skin Factor S:

Acid Viscosity μ_acid (cP):

Acid Density (ppg):

Maximum Safe Injection Parameters

Max Safe Injection Rate Q_max:

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Max Allowable BHTP P_frac:

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Max Surface Treating Pressure (STP):

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Acid Hydrostatic Head P_hyd:

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Allowable Differential ΔP_max:

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Post-Acid Skin (S=0) Rate Q_clean:

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Frequently Asked Questions

What happens if you accidentally exceed fracture pressure during matrix acidizing?

The well enters "acid fracturing" mode. A fracture opens out-of-zone, diverting acid away from the damaged matrix interval and potentially breaching bottom-water contacts, ruining well economics.

Why does the allowable injection rate increase as matrix acidizing progresses?

Because near-wellbore skin S decreases from positive (choked) to near zero or negative (stimulated). With less hydraulic skin restriction across the damaged zone, more fluid can enter the reservoir at the same maximum allowable pressure.