Gas-, oil- and water-bearing Upper Jurassic formations (Malm) in the area of the Carpathian Foothills are built from carbonate reservoir rocks with vuggy-fracture porosity system (or fracture-vuggy), which absolute porosity is from a few to several percent. At the end of the twentieth century DST tests provided a lot of reliable reservoir information, on which the important decisions for geological research and exploration, can be taken. The credibility of these tests results depends largely on the technology used. The paper presents the results of three selected DST tests, differing in technology, particularly with attention to the usefulness of the obtained information in explorations for hydrocarbon deposits process.