Drill Stem Test Design Optimization Improves Quality of Reservoir Data and Time Requirements for Deep and Ultra Deep Water Well Testing

摘要

Energy requirements are continuing to rise, and because the oil and gas industry has been one of the largest contributors to the fulfillment of energy needs worldwide, it is imperative that the technology needed to explore new arenas that can expand oil and gas production be available. Since exploration for new reserves has had to move into more complex environments that include deep and ultra-deep water reservoirs more difficult to access, all involved in exploration must also address the new challenges for deepwater. For operators, attempting to produce these areas represents huge investments for development of the new deeper reserves; for service companies, attempting to service these new developments means that new technologies must be available to ensure that sufficient high-quality data is gathered in exploratory wells to justify subsequent production. This requires that updates to technology be ongoing. Drill-Stem Testing (DST) provides one of the most important reservoir evaluation methods for the incorporation of new hydrocarbon reserves, because DST allows dynamic reservoir characterization and can assess potential production as well as the proposed production plan. When target reservoirs produce heavy oil, gas, and condensate, DST in deep and ultra-deep water requires prolonged periods of exposure to low temperatures and heat loss, which may not only affect viscosity for oil but also result in hydrate formation in gas presence; in order to control all these variables, the DST design must focus on gathering reservoir quality data that also consider safety and risk mitigation. To achieve the above objectives, a new methodology that focuses on DST test design in deep and ultra-deep water has been developed that considers new workflow criteria. It includes: 1. Analysis of hydrate formation 2. Injection design of viscosity-reducing systems 3. Realtime data acquisition 4. Operative decision making. This paper presents details of this state-of-the-art method that enables reliable DST testing to be conducted in deep and ultra-deep water and that can increase the quality of the reservoir data as well as reduce testing time and operational risk.