Well testing has been cited as one way to ensure that the investment of a company’s time and capital has been justified and is sustainable in the future. With accurate test data, acquired through an appropriately designed testing program, the critical information necessary to characterize a reservoir and establish well deliverability is presented. Centrica and Schlumberger recognized the biggest risk to achieving the test objectives was inconclusive data. Even if tests were designed with the best intentions, only evaluating actual reservoir dynamics while testing could provide the necessary confidence in the results. Thus, a concurrent well testing campaign was designed for the Grove gas field project in the UK with the objectives of cleaning up all the wells and determining the reservoir deliverability, as well as its extent.