One of the Productivity Index diagnostics methods based on plotting pressure integral
| LaTeX Math Inline |
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| body | --uriencoded--G(t) = \int_0%5et \left( p_%7Bwf%7D(\tau) - p_e(\tau) \right) d\tau |
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vs
cumulatives | LaTeX Math Inline |
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| body | --uriencoded--Q_t(t) = \int_0%5et q_t(\tau) d\tau |
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where
| production/injection time |
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| LaTeX Math Inline |
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| body | --uriencoded--p_%7Bwf%7D |
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| bottomhole pressure as function of time |
It shows unit slope on log-log plot for stabilized reservoir flow:
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In case pressure data is available for a fair interpolation it is recommended to plot subsurface sandface cumulatives rather than than surface which which provides better linearity with pressure integral for Steady-State flow.
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