A group of methods assessing the productivity index (J) of a well.
The direct methods (called J-plots) assume that both drain-area formation pressure and bottomhole pressure data is available, at least in select time moments:
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Comprehensive comparison of various J-plots is provided at Productivity Plots = J-plots can be found here.
In case the drain-area formation pressure is not available the value of Productivity Index can be estimated from:
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