Well-Testing Planning in Deepwater Wells in High-Pressure, High-Temperature Environments – The Brazil Experience

Abstract

Abstract High-pressure/high-temperature (HP/HT) deepwater areas continue to challenge performance of well testing, especially when considering wells defined as "deepwater." This definition is applied to wells that are at least 15,000 feet deep. Also, these wells are considered HP/HT when they have bottomhole pressures of approximately 10,000 psi and bottomhole temperatures in excess of 300°F. Several wells under these extreme environmental conditions have recently been tested in Brazil, and these attempts have confirmed the importance of the proper preliminary analysis of test parameters according to the specifications of the prospect, the requirements at surface, and the possible impact of testing at bottomhole conditions. Typical variables such as high hydrostatic pressures and high temperatures are usually considered, but it is also important to assess the types of operations involved in performing the tests that could increase the value of the different physical variables in such a way that the tool string could be damaged. Often, combined variables can surpass the design characteristics of the test tools, and if this occurs, the test data or even the well could be lost. Thus, it is critical that design specifications of the necessary equipment and operational limitations be considered with a detailed analysis of operations and alternatives in a HAZID/HAZOP. This paper will focus on the steps that must be followed to enable successful well-testing evaluations in HP/HT environmental conditions. With the planning suggested, it is possible to minimize the risks that can negatively impact testing operations. The planning, design criteria and tools required to perform successful well-testing evaluation in severe well conditions will be discussed in detail. The steps discussed here for designing deepwater well-tests can provide a safety envelope for equipment and help ensure that the operations will be successfully performed.