Parameter estimation is one of the two principal functions of well test interpretation. Accurate parameter estimation depends on several factors, including correct reservoir model selection, sufficient test data within the flow regime(s) of interest, and accurate input data. The focus of this paper is the effects of errors in input data such as net pay, porosity, viscosity, formation volume factor, flow rate, and compressibility on the results of well test interpretation.

We consider two of the most commonly used reservoir models – a vertical well with wellbore storage and skin, and a finite-conductivity hydraulically fractured well. For the vertical well case, we allow for the presence of one or more boundaries, and for homogeneous or dual porosity behavior.

Many, if not all, of the observations offered in this paper are part of the working knowledge of the full-time well test analyst. However, these observations have not been systematically catalogued and discussed in the literature. The purpose of this paper is to provide just such a systematic catalog and discussion.

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