Meana Petro

Production & lift

Static gradient & bottom-hole pressure

Bottom-hole pressure from a wellhead reading — a liquid gradient for oil and water, and a stepwise gas-column integration for gas.

All tools

Inputs

Absolute, not gauge.

Results

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How it is calculated

  • Liquid: P_bh = P_wh + 0.4335·SG·TVD, with SG volume-weighted between oil and water.
  • Gas: dp/dh = 0.018748·γg·p/(z·T) integrated over twenty depth steps, with z from Dranchuk–Abou-Kassem re-evaluated at each step's mean pressure and temperature.
  • Sour gas gets the Wichert–Aziz correction to the pseudo-criticals before z is computed.
  • Temperature is taken as a linear gradient between the surface and bottom-hole values you give.

Standards it speaks

Where this stops being true

Both branches assume a single-phase, static column. A shut-in oil well with gas in the top of the tubing is neither, and the answer will be wrong by the height of the gas cap; a wet gas well with liquid holdup is wrong the other way. Where the number matters — a reservoir pressure for material balance, a datum correction for mapping — run a wireline gauge and use this only to check it.

The capability that automates this

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