Page 244 - Hydrocarbon Exploration and Production Second Edition

Well Dynamic Behaviour 231

represents a range of scenarios, aimed at determining the optimum development plan
(the one with the highest NPV, as defined in Chapter 14).
At the stage of field development planning, reservoir simulation would normally
be used to generate production profiles and well requirements for a number of
subsurface development options, for each of which different surface development
options would be evaluated and costs estimated.

10.2. Fluid Flow Near the Wellbore

The pressure drop around the wellbore of a vertical producing well is
described in the simplest case by the following profile of fluid pressure against radial
distance from the well (Figure 10.2).
The difference between the flowing wellbore pressure (P wf ) and the average
reservoir pressure ( ¯ P) is the pressure drawdown (DP DD )

ðpsiÞ or ðbarÞ
Pressure drawdown DP DD ¼ ¯ P P wf
The relationship between the flowrate (Q) towards the well and the pressure
drawdown is approximately linear for an undersaturated fluid (i.e. a fluid above the

Cross-section

well

r e r
r w P e

P P

Δ P DD

P wf

Plan View
Figure 10.2 Pressure distribution around the wellbore.