Paper Number 15116-MS
Title Pressure Transient Analysis for Wells With Horizontal Drainholes
Authors Clonts, M.D., ARCO Alaska Inc.; Ramey Jr., H.J., Stanford U.
Source SPE California Regional Meeting, 2-4 April 1986, Oakland, California
Copyright Copyright 1986, Society of Petroleum Engineers, Inc.
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Abstract
Drainholes have been drilled in several areas of the world and there is a need to understand these drainage systems for accurate well test analysis. This study presents an analytical solution for the transient pressure response of a uniform flux horizontal drainhole in an anisotropic reservoir of finite thickness. The solution also applies for a reservoir with multiple drainholes in a vertical array. The solution shows that there are two possible types of transient pressure behavior depending on the length of the drainhole relative to the height of the reservoir. If the drainhole is short, initial radial flow perpendicular to the drainhole axis is followed by a transition to a perpendicular to the drainhole axis is followed by a transition to a pseudo-radial flow period. If the drainhole length is long relative to pseudo-radial flow period. If the drainhole length is long relative to the reservoir height, the initial radial flow period ends rapidly and transient pressure behavior becomes identical to that of a uniform flux vertical fracture.
