WFP – Well Performance Analysis analysis is a comparative analysis between:
and
It is based on correlation between surface flowrate and bottomhole pressure as a function of tubing-head pressure and formation pressure and current reservoir saturation.
Most reservoir engineers exploit material balance thinking which is based on long-term well-by-well surface flowrate targets (whether producers or injectors).
In practice, the flowrate targets are closely related to bottomhole pressure and associated limitations and require a specialised analysis to set up the optimal lifting (completion, pump, chocke) parameters.
This is primary domain of Well Flow Performance (WFP) analysis.
Well Flow Performance (WFP) is performed on stabilised wellbore and reservoir flow and does not cover transient behaviour which is one of the primary subjects of Well Testing domain.
The conventional WFP – Well Performance Analysis is perfomed as the cross-plot with two model curves:
The intersection of IPR and VFP curves represent the stabilized flow (see Fig. 1)
Fig. 1. The stablised flow rate is represented as junction point of IPR and VLP curves. | Fig. 2. The dead well scenario. |
Given a tubing head pressure the WFP Junction Point will be dynamic in time depending on current formation pressure (see Fig. 2) and formation saturation (see Fig. 3).
Fig. 2. A sample case of stablised flow rate as function of formation pressure. | Fig. 3. A sample case of stablised flow rate as function of formation water saturation and corresponding production water-cut. |
Fig. 4. A bunch of IPRs at different formation pressures and VLPs at different THPs. |
The above workflow is very simplistic and assumes single-layer formation with no cross-flow complications.
In practise, the Well Flow Performance (WFP) analysis is often very tentative and production technologists spend some time experimenting with well regimes on well-by-well basis.
Joe Dunn Clegg, Petroleum Engineering Handbook, Vol. IV – Production Operations Engineering, SPE, 2007
Michael Golan, Curtis H. Whitson, Well Performance, Tapir Edition, 1996
William Lyons, Working Guide to Petroleum and Natural Gas production Engineering, Elsevier Inc., First Edition, 2010
Shlumberge, Well Performance Manual