Nodal analysis is a modelling tool used by drilling, subsurface, and well test engineers to help achieve an optimum well design in terms of perforations, tubing size, and fluid and underbalance design, as well as to provide some of the key data inputs for the design of surface facilities.
Nodal analysis models both the inflow performance of reservoir fluid into the wellbore (IPR) and the outflow performance of reservoir fluid through the tubing (VLP).
Both the Inflow Performance Relationship and the Vertical Lift Performance Relationship relate the wellbore flowing pressure to the surface production rate. While the IPR represents what the reservoir can deliver to the bottom hole, the VLP represents what the well can deliver to the surface.
The intersection of the IPR with the VLP, called the operating point, yields the well deliverability, an expression of what a well will actually produce for a given operating condition (Pr, PI, WC, GOR, THP, Tubing size…).