Well testing in exploration and appraisal wells has become increasingly unpopular. Reasons include costs, safety, and environmental effects. Well testing also has become rare in production wells because of the potential revenue loss during the buildup tests. Alternatives for sampling and reservoir-parameter estimation include wireline formation tests in exploration and appraisal wells and continuous recording with permanent pressure gauges in production wells. Essentially, the interpretation methods are the same as those used in well-test analysis with the addition of the formation-rate analysis, which is particularly useful in high-permeability formations in which other methods are limited by pressure-gauge resolution.