Production tests are usually taken to be the gold standard by which to appraise the reservoir. The ability to flow the zone after it has been cased and perforated provides the best approximation to what actual reservoir performance will be. The complete interval is perforated, usually with the same completion technique that the reservoir will be developed with. Large volumes of fluid can be flowed which ensures representative samples are acquired and also allows for deep depth of investigation during the pressure transient analysis of the build-up. However, such a wealth of information does not come easily. In certain environments a full production test can takes weeks and cost many millions of dollars. And in addition to the cost is the reduced drilling efficiency – in environments with limited drilling seasons the time taken to perform a production test will reduce the number of wells that can be drilled in a season.

An alternative to the above approach is the wireline formation tester (WFT). The pump-out WFT has been in use for over twenty years. Although these tools can never hope to fully replace the production test, a judicious combination of WFT and DST data can answer many of the pertinent issues for reservoir evaluation and in some cases address the requirements of state or financial regulatory bodies.

In this paper we present a reservoir analysis based on data acquired with a conventional DST and compare this to an analysis with data acquired using a wireline formation tester. The strengths, weaknesses and applications of each are discussed.

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