New Acoustic-Telemetry-Operated Tester Valve for Drill-Stem Testing Operation in Deepwater - Brazil PreSalt Case

Abstract

Drill Stem Tests (DSTs) in exploratory wells are important for production planning, for identifying the characteristics of oil and gas, and to assess the commercial viability of the entire reservoir. A new generation of downhole test tools has been developed to address the growing challenges of reservoir testing and evaluation in the deep and ultra-deep-water environments now being explored; these new tools maintain safety as paramount and strive for greater testing efficiency in the acquisition of the reservoir information being sought in nearly all evaluation and exploration wells today. There is a growing need to better understand each well in real time as it is being tested, not only concerning the reservoir itself, but also the downhole tool mechanics critical to the testing operation. This knowledge helps to reduce uncertainties of downhole conditions, and also, helps to ensure that operations are being carried out in a safe manner and as planned. With the improvements in operational efficiency, savings in rig time also can be gained.With the application of acoustic telemetry technology, the capability to acoustically communicate and control downhole tools in real time is achieved. Real-time data can be transmitted to and from the downhole tools, allowing on-demand control of well testing operations. The acquisition of real-time gauge data with the additional capability to actuate a new combination tester and circulating valve provides enhanced control of a DST and can provide the operator with ongoing feedback of tool position and status. This enhances the operators' ability to perform the well test with reduced uncertainties. Extending the real-time acoustic system to tool control provides the operator with additional capabilities. The operator can control downhole tools without using annulus pressure, which is not possible with the traditional DST tool systems operated with annulus pressure that restricts the number of different tools used for a DST due to casing pressure limitations. Acoustic-telemetry-controlled tools are not limited in function or number.This paper discusses a case history in a deepwater, pre-salt area in Brazil where a new acoustictelemetry-operated tester valve was used to successfully perform DST testing operations. This paper also discusses the new possibilities that this new tool can bring to well testing.While the main objectives of a DST are basically the same, this new tool enables downhole well-test tools to advance to a new generation of equipment that is designed to optimize time, streamline decision making, minimize environmental and operational risks; and ultimately, help maintain safety as a priority.