Impulse Testing

Summary This paper proposes a new method for evaluating hydrocarbon wells. The formation is subjected to a rate impulse created by briefly flowing the well or injecting into the formation. The pressure response to an ideal rate impulse (i.e., to an instantaneous source of strength unity) is given by the derivative of the pressure response to a conventional step-rate change. This general solution is used in developing an interpretation method based on recently published type curves of the derivative of pressure. Impulse™ testing is particularly useful for wells that do not flow to the surface and for wells where extended flow may not be desirable (because of sand problems, for example). Applied in conjunction with underbalanced perforating, this method provides a low-cost evaluation of the reservoir and wellbore condition. Several field examples are presented to illustrate the analysis technique.