One of the Productivity Diagnostics methods based on relation on correlation between time-weighted average pressure drawdown
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\overline {\delta p} (t) = \frac{1}{t} \int_0^t \left( p_{wf}(\tau) - p_e(\tau) \right) d\tau |
and and time-weighted average total sandface flowrate cumulatives
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| production/injection time |
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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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\overline {\delta p}(t) = J^{-1} \bar q_t(t) |
where
Due to integration procedure the t-weighted J-plot has a better tolerance to uncertainties in formation pressure and bottomhole pressure comparing to Unweighted J-plot and usually results in more accurate estimation of productivity index.
It is highly recommended to plot sandface flowrates rather than surface flowrates to achieve better linearity in correlation for stabilized reservoir In case pressure data is available for a fair interpolation it is recommended to plot sandface cumulatives rather than surface which provides better linearity with pressure integral for Steady-State flow.
Although it is equally applicable to producers and injectors, due to lack of BHP and formation pressure data availability for producers in most practical cases in the past the normalized Hall plot analysis was mostly applied for water injectors.
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\overline {\delta p} (t) = \frac{1}{t} \int_0^t \left( p_{wf}(\tau) - p_e(\tau) \right) d\tau = \frac{1}{t} \sum_k \left( p_{wf}(\tau_k) - p_e(\tau_k) \right) \delta \tau_k |
The main difference Normalized Hall Plot and traditional Hall Plot is that Normalized Hall Plot is using conventional properties along the axis: average pressure drawdown LaTeX Math Inline |
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body | --uriencoded--\overline %7B\delta p%7D |
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: and total sandface flowrate cumulatives :.
See Also
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Petroleum Industry / Upstream / Production / Subsurface Production / Field Study & Modelling / Production Analysis / Productivity Diagnostics
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