Nolte-Smith Net Pressure & Fracture Diagnostics Calculator

Interpret real-time log-log net pressure slopes (Mode I to Mode IV) during pumping to diagnose unrestricted propagation, height growth, or impending screenout.

Net Pressure & Slope Evolution

Initial Net Pressure P_net,1 (psi):

Current Net Pressure P_net,2 (psi):

Initial Time t_1 (min):

Current Time t_2 (min):

Minimum In-Situ Horizontal Stress σ_min (psi):

Bottomhole Treating Pressure BHTP (psi):

Diagnostic Interpretation & Mode

Log-Log Slope b = Δlog(P_net) / Δlog(t):

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Nolte-Smith Diagnostic Mode:

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Calculated Instant Net Pressure:

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Total Net Pressure Growth ΔP_net:

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Fracture Propagation State:

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Recommended Field Action:

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Frequently Asked Questions

How is net pressure determined in the field if downhole gauges are absent?

Net pressure is calculated from surface treating pressure (STP): BHTP = STP + Phyd - dPpipe - dPperf. Net pressure is then: Pnet = BHTP - ISIP (where ISIP represents closure stress σ_min).

Is a unit slope (b = 1.0) always bad?

In conventional fracturing, unit slope signals an unwanted premature screenout that risks sanding off the casing. However, in soft, high-permeability sandstones (Frac-Pack completions), a planned Tip Screenout (TSO) is deliberately engineered to inflate fracture width to over 1 inch for maximum flow capacity.