Interference testing is widely used in the petroleum industry to obtain reservoir descriptions vital to the evaluation of proposed tertiary recovery projects. A new analytical method that provides an accurate reservoir description and requires only early time data was developed for this purpose. This method worked very well when applied to data from the literature and was successfully applied in the design, monitoring and analysis of interference tests conducted in a mid-continent field.

The conventional method of interference test analysis involves the application of a complex exponential integral function fit of the data to "type curves" either by least squares on a computer or by transparent overlays. In the new technique, the early interference data from each well are fit with a straight line. The slope of the straight line is then used to compare the degree of interwell communication. A practicing engineer with a pocket calculator can successfully use this method to design, monitor and analyze interference tests.

The method is particularly useful in reservoirs of wide spacing where the interference testing period can be inordinately long even when a highly sensitive pressure gauge is used. With judicious application of this technique, the test duration can be minimized considerably thereby reducing testing costs and delayed production.

The method is rigorously developed and a field example is given.

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