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But when field-average formation pressure is above bubble-point
(which means that most parts of the drainage area are saturated oil) the
PI can be farily approximated by some analytical correlations.
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| Expand |
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| title | Terminological Difference between DM, WFP and WT on formation pressure. flow rate and productivity index definitions |
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| Despite of terminological similarity there is a big difference in the way Dynamic Modelling, Well Flow Performance 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:
| Formation pressure | Flow rate | Prroducivity Index |
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| DM | | field-average pressure within the 9-cell area | | phase flowrate at sandface: | LaTeX Math Inline |
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| body | \{ q_w, \, q_o, \, q_g \} |
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(each fluid phase separately) | | phase productivity index:
| LaTeX Math Inline |
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| body | J_ w = \frac{q_q}{p_R - p_{wf}} |
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, | LaTeX Math Inline |
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| body | J_o = \frac{q_o}{p_R - p_{wf}} |
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, | LaTeX Math Inline |
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| body | J_o = \frac{q_o}{p_R - p_{wf}} |
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| WFP | | field-average pressure within the drainage area | | surface liquid rate (each fluid component separately) | | fluid component productivity index: | LaTeX Math Inline |
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| body | J_W = \frac{q_W}{p_R - p_{wf}} |
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, | LaTeX Math Inline |
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| body | J_O = \frac{q_O}{p_R - p_{wf}} |
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, | LaTeX Math Inline |
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| body | J_G = \frac{q_G}{p_R - p_{wf}} |
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| WT | | average pressure value at the boudary of drainage area | | total flowrate at sandface: | LaTeX Math Inline |
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| body | q_t = B_w \, q_W + B_o \, q_O + B_g \, ( q_G - R_s q_O) |
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– for Black Oil| 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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– for Volatile Oilor pseudo-components of Compositional Model | | total multiphase productivity index: | LaTeX Math Inline |
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| body | J_t = \frac{q_t}{p_e - p_{wf}} |
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VLP – Vertical Lift Performance
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