Despite of terminological similarity there is a big difference in the way WFP and Well Testing deal with formation pressure and flowrates which results in a difference in productivity index definition and corresponding analysis. This difference is summarized in the table below:
| WFP | Well Testing |
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| Formation pressure | | field-average pressure within the drainage area
| | average pressure value at boudary of the drainage area
|
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| Flow rate | | | | total flowrate at sandface | LaTeX Math Inline |
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| body | q_t = B_w \, q_W + \frac{B_o - R_s B_g}{1 - R_v R_s} \, q_O + \frac{B_g - R_v B_o}{1 - R_v R_s} \, q_G |
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| Prroducivity Index | | | LaTeX Math Inline |
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| body | J_W = \frac{q_W}{p_R - p_{wf}} |
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|
or , | LaTeX Math Inline |
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| body | J_O = \frac{q_O}{p_R - p_{wf}} |
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|
or , | LaTeX Math Inline |
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| body | J_G = \frac{q_G}{p_R - p_{wf}} |
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|
| | total multiphase proudcivity index | LaTeX Math Inline |
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| body | J_t = \frac{q_t}{p_e - p_{wf}} |
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