A North Sea Application of Slug Testing for Quick Reservoir Analysis

Abstract

ABSTRACT The application of slug testing in the Valhall Field, a North Sea reservoir, is presented. Specific field examples are given which show this pressure transient testing method to be a quick and reliable way to determine reservoir flow capacity and wellbore skin factor. Some of these examples show confirmation of a channel behind pipe that was indicated by a cement bond log. A review of the theoretical basis of the method is also given. Although this method has found wide application in ground water hydrology, it has been used on a very limited basis in the petroleum industry. As applied here, the test is conducted on an isolated zone at the time of perforating underbalanced with the well filled with diesel. The primary advantage of this test is the extremely short time required to collect sufficient data for analysis, even when permeability is relatively low or skin factor is high. The test also eliminates problems associated with wellbore storage. Therefore, both required rig time and the production deferred due to data collection are minimized. This advantage is especially important in costly offshore applications and should lead to use of the technique in many other fields worldwide.