In order to translate it pressure from downhole gauge to the Datum one needs to:
1 | Estimate gauge readings at formation top LaTeX Math Inline |
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body | --uriencoded--p_%7B\rm top%7D |
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| using the wellbore fluid density gradient |
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| p_{\rm top}(t) = p_{\rm gauge}(t) + g \cdot \int_{z_{\rm gauge}}^{z_{\rm top}} \rho_f(z) dz |
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2 | Recalculate the pressure at formation top to the Datum using regional hydrostatic pressure gradient |
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| p_{\rm dat}(t) = p_{\rm top}(t) + GP \cdot (z_{\rm dat} - z _{\rm top}) |
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where
When When wellbore fluid density is is fairly constant between the gauge location and formation top then one can simplify the Datum Pressure calculation to:
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anchor | 1ptop2 |
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alignment | left |
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p_{\rm dat}(t) = p_{\rm gauge}(t) + g \cdot \rho_f \cdot (z_{\rm top} - z_{\rm gauge}) + GP \cdot (z_{\rm dat} - z _{\rm top}) |
In flowing conditions the equations
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and LaTeX Math Block Reference |
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are both inaccurate as they do not account for pressure losses due to friction.The equation
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should be replaced with a proper solver for wellbore pressure profile.
See Also
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Petroleum Industry / Upstream / Subsurface E&P Disciplines / Pressure Testing & Production Analysis