Treatment of Wellbore Storage Effects in the Analysis of Pressure Buildup and Drawdown Tests
1982; Linguagem: Inglês
10.2118/10784-ms
Autores Tópico(s)Oil and Gas Production Techniques
ResumoABSTRACT In this paper, we propose a new method for detecting the beginning of the useable portion of a Horner plot. The method is based on asymptotic solutions of the well-bore material balance in a form used in numerical simulators. They show that the Extent of Well-Bore Dominance, EWBD, which measure the effect of well-bore storage on pressure drawdown and buildup test results, is a function of well-bore storage capacity, the formation producing capacity (related to the productivity index), the bottom-hole pressure, and its time rate of change. EWBD always decreases to zero as the reservoir response assumes control of the bottom-hole pressure. This is true for any size well-bore, and is unaffected by the complicated flow history during the opening and closing of the valve. Here, the theoretical basis of EWBD is developed, followed by a description of its implementation in automated Horner analysis computer programs. Five examples are presented which demonstrate that the automated Horner analysis program can perform a classical Horner analysis rapidly, accurately, and reliably.
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