The Effect of Partial Penetration on Pressure Build-Up in Oil Wells

Publisher Website
Google Scholar
Abstract
The classic theory of pressure build-up in shut-in oil wells as developed by Horner and van Everdingen is based on two-dimensional radial symmetry in the well-reservoir system. Such symmetry does not exist in the case of a well which partially penetrates the producing formation. As a result of this lack of symmetry the use of the classic theory in such cases become questionable. In this paper the mathematical theory has been extended to include the case of partially penetrating wells. Numerical solutions illustrating the application of the equations are presented. The effect of partial penetration on pressure build-up is shown by a comparison of synthetic pressure build-up curves derived from the numerical solution of the equation for partially penetrating wells for various degrees of penetration. It is shown that partial penetration is detectable from the characteristic shape of the pressure build-up curve and that formation productivity may be calculated from the pressure build-up data in a manner identical to that described by the classic theory. Introduction The use of pressure build-up data on shut-in oil wells is a well-established technique for the measurement of reservoir productivity. The work of Horner and van Everdingen is well known. Since the publication of their pioneering work, others have elaborated and extended the technique. These authors have dealt exclusively with the case of wells that completely penetrate the producing formation. Two-dimensional radial symmetry is achieved, thereby, and the problem is greatly simplified. This ideal situation is seldom encountered in practice. But, in spite of this, the technique is often employed anyway. The question, therefore, arises: how much confidence can be placed in the results of such calculations when the data are taken on wells that only partially penetrate the producing formation? It is the purpose of this work to answer this question. Only the single-phase fluid case will be considered.

This publication has 0 references indexed in Scilit: