Net pressure p_{\rm net} is the excess pressure over the frac pressure p_c required to open the fractures:
| (1) | p_{\rm net} = p_{\rm BHP} - p_c |
where
p_{\rm BHP} | botom-hole pressure during the frac treatment |
p_c | the closure pressure which is approximately minimum horizontal stress |
The physical meaning of the Net pressure is that it is the energy required for propagating fracture and creating its width during the frac job.
See Also
Petroleum Industry / Upstream / Well / Well-Reservoir Contact (WRC) / Hydraulic Fracture