Analysis of well test pressure data from a restricted entry well in a layered reservoir
The procedures presented here can only be applied to data obtained subsequent to the time when wellbore storage effects have become negligible. However, if both pressure and sandface rate are measured, Duhamel's principle can be applied to obtain equivalent constant sandface rate data; that is, to remove wellbore storage effects. By using an analytical solution to an associated steady-state problem, the correlating parameters for the pseudoskin factor due to restricted entry are identified. This analytical expression yields accurate results for ranges of parameters normally of practical interest. The form of the analytical expression for the pseudoskin factor suggests procedures for correlating pressure data and leads to new type curves for analyzing pressure data from a restricted-entry well. By using these type curves in combination with semilog analysis, a complete analysis often can be obtained. This includes an estimate of the true skin factor and an estimate of the effective vertical permeability. The analysis procedures can be applied to both drawdown and buildup data. However, for buildup data, it is shown that it is preferable to use equivalent shut-in time in the analysis. The emphasis is on analyzing data corresponding to the infinite-acting period, but the effect of producing time on up data is discussed. Moreover, new type curves are also presented for analyzing pressure data influenced by the outer reservoir boundary. For restricted-entry wells, it is known that Hawkin's equation does not apply if the radial extent of the skin zone is large. Two new correlations for correcting Hawkin's formula are presented.
- Research Organization:
- Tulsa Univ., OK (USA)
- OSTI ID:
- 7256229
- Country of Publication:
- United States
- Language:
- English
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