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 pressureFlow ratePrroducivity Index
DM

field-average pressure within the 9-cell area

phase flowrate at sandface:

(each fluid phase separately)

phase productivity index:


, ,

WFP

field-average pressure within the drainage area 

p_e = \frac{1}{A_e} \iint_{A_e} p(x,y,z) dS


surface component flowrate

(each fluid component separately)

and sometimes liquid flowrate

fluid component productivity index:

, ,

and sometimes liquid productivity index:

WT

average pressure value at the boudary of drainage area 

p_e = \frac{1}{L_e} \int_0^{L_e} p(x,y,z) dl

where is the boundary of drainage area

total flowrate at sandface:

– for Black Oil

– for Volatile Oil

or pseudo-components of Compositional Model

total multiphase productivity index: