Oil Inflow Performance for a Two-Phase Reservoir

Vogel (1968) introduced an empirical relationship for q_o based on a number of history-matching simulations. The relationship, normalized for the absolute open flow potential, q_o,max is

where, for pseudosteady state,

where k_o is the effective permeability to oil that might be estimated from a pressure buildup test. Therefore,

The convenience of the Vogel correlation is that it allows the use of the properties of only oil in a two-phase system.

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Example 3-5. Calculation of Inflow Performance Using Vogel’s Correlation

Develop an IPR curve for the well described in Appendix B. The drainage radius is 1490 ft and the skin effect is zero.

Solution

Equation (3-55) for  psi becomes

The flow-rate prediction with Equation (3-55) is simple. For example, if p_wf = 3000 psi, from Equation (3-56), q_o = 2427 STB/d.

Figure 3-6 is a plot of the IPR curve for this well. Note that the shape of the curve is no longer a straight line as for the single-phase oil in Chapter 2.

Figure 3-6. Inflow performance curve for a two-phase well.

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