Injectivity Index

Injectivity index, abbreviated as II, is used to evaluate the performance of a well when injecting fluids, such as drilling mud or other injection fluids, into the reservoir.  It quantifies the ease with which a well can accept injected fluid and is a critical measure for understanding the efficiency of fluid injection operations.

 

Injectivity Index formula When referring to liquid volumes at stock tank conditions, use the units of Stock Tank Barrels (STB).
\( II \;=\;  q \;/\; p_{wf} - p  \)     (Geothermal Gradient) \( q \;=\;  II \; ( p_{wf} - p)  \) \( p_{wf} \;=\; ( q \;/\; II ) + p \) \( p \;=\;   p_{wf} - ( q \;/\; II ) \)
Symbol	English	Metric
\( II \) = injectivity index	\(bbl \;/\; day \;/\; psi\)	-
\( q \) = flow rate of injection well	\(bbl \;/\; day\)	-
\( p_{wf} \) = well flow pressure (psi)	\(lbf \;/\; in^2\)	-
\( p \) = reservoir pressure (psi)	\(lbf \;/\; in^2\)	-