Well testing operations are an essential component in reservoir characterization process. In deepwater environments where rig costs are high, operating safely and cost efficiently is important. As a result, many operators are constantly searching for more efficient and cost effective ways to test their reservoirs. The use of newly developed tools and technologies is necessary to deal with the challenges of efficiency and effectiveness while at the same time, safely optimizing the operational sequences, improving decision making with real-time information and reducing rig costs, without sacrificing data quality.
Designed specifically for testing operations, the single trip downhole tools with real-time bottomhole data enabled by wireless acoustic telemetry address those challenges. This technology eliminates unnecessary trips compared with a conventional drillstem test (DST) in deepwater environments. Furthermore, real-time bottomhole data aid processes such as test design optimization and real-time well test interpretation and help to ensure that data are sufficient for the purpose of reservoir characterization prior to ending the test.
This paper summarizes the benefits of using the new generation of downhole reservoir testing tools. Maersk Oil Angola was the first operator to use these tools in West Africa. The well testing operation was performed in a single trip, saving 3 days of rig time compared with the time required for a traditional DST with a permanent packer. Data acquired during the test were transmitted to secure servers, and were available in real-time for remotely located decision makers. The improved communication and collaboration between offshore and office, resulted in a short decision-making time cycle. The team performed pressure transient analysis on downhole data during the well test, turning the raw data into knowledge. This helped to confirm that sufficient data had been acquired for reservoir characterization; thus, the test duration was shortened by 28 hours while still meeting all test objectives. In summary, the operator was able to perform a safe and cost-effective well test operation in a deepwater environment.