Acid Fracturing Etched Conductivity & Nierode-Kruk Calculator

Model differential etched fracture conductivity (md-ft) under closure stress in carbonate reservoirs using the industry-standard Nierode-Kruk empirical correlation.

Etch Geometry & Rock Mechanics

Dissolved Rock Equiv. Width w_de (in): w_de = (Acid vol × X) / Fracture Area

Effective Closure Stress σ_c (psi):

Rock Embedment Strength RES (psi): Hard limestone ~60k; chalk ~10k psi

Carbonate Rock Type:

Etched Fracture Conductivity

Conductivity Under Stress k_f·w:

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Zero-Stress Conductivity (k_f·w)_0:

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Stress Degradation Factor C_2:

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Conductivity Retention (%):

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Effective Flow Hydraulic Width:

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Long-Term Channel Stability:

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Frequently Asked Questions

Why does acid fracturing fail in soft chalks or deep formations?

Soft rocks (low RES) lack the mechanical hardness to support open channels under high closure stress (>5,000 psi). The etched pillars crush plastically into the opposing face within weeks, completely obliterating fracture permeability. Deep, hot, or soft formations require proppant fracturing.

How does alternating viscous pad and acid stages enhance conductivity?

Viscous fingering occurs when lower-viscosity acid displaces thick polymer gel, carving deep localized canyon-like channels instead of etching the entire wall evenly. This creates deeper, more stress-resilient flow grooves.