Will Wireline Formation Tests Replace Well Tests?

Abstract

Abstract Well testing in exploration and appraisal wells has become increasingly unpopular. Reasons include costs, safety and environmental impact. Well testing has also become rare in production wells because of the potential revenue loss during build-ups. Whether suitable alternatives can be found for sampling and reservoir parameter estimation is the subject of regular debate. Alternatives are wireline formation tests in exploration and appraisal, and continuous recording with permanent pressure gauge in production wells. The quality of pressure and rate transients measured during wireline formation tests has improved greatly in recent years. The transients obey the same laws of physics as those measured during a well test and can theoretically be interpreted in the same way. The scale of the measurements, however, is very different. The challenge is to understand what the wireline formation test interpretation results mean and how they can be upscaled to the information provided by a well test. The paper discusses these key issues with examples that illustrate the quality of the data and the analysis process. The interpretation methods are essentially the same as those used in well test analysis with the addition of the formation rate analysis plot, which is particularly useful in high permeability formations where other methods are limited by pressure gauge resolution.