Well Interference Test in the Chingshui Geothermal Field

Abstract

The initial assessment of geothermal reservoirs usually has two main objectives. One is determination of the deliverability rate from the reservoir, and the other is estimation of the reserves, or the economically producible amount of steam in the system. Many geothermal reservoirs are complicated by the fact that neither the porosity-thickness product nor producible area are known, either early in the life or after extended production. The mjost reliable means of determining the deliverability is usually a pressure transient test. Pressure transient tests can be conducted in a reasonably short period of time, and early in the life of a geothermal development. However, estimation of steam reserves usually requires an extended period of production with observation of mean reservoir pressure' at various stages of production. Material and energy balance performance matching with a detectable decline in pressure following production is the minimum information for performance matching. Thus it is necessary to produce a reservoir for an extended period of time before performance matching can be accomplished with reasonable precision.

The dilemma is that short-time pr ure testing frequently provides inaccurate information on deliverability (permeability thickness or transmissivity), while long-term production testing is required to establish reserves. sure transient test than can be accomplished in a reasonable period of time, and yet provide important information concerning apparent reserves early in the life of a geothermal development. The main purpose of this study is to illustrate the interpretation of interference tests. Fortunately, an interference test is a type of pressure transient test than can be accomplished in a reasonable period of time, and yet provide important information concerning apparent reserves early in the life of a geothermal development. The main purpose of this study is to illustrate the interpretation of interference tests.