Drill-stem testing (DST) has been used for many years in the oilfield to establish reliable reservoir characterization. The DST data are used to provide estimated production, fluid analysis, and to help design the final completion and production facilities.

More recently, discoveries in abnormal pressure gradients and deep formations have not only pushed the capabilities of traditional equipment and procedures, but also increased the safety hazards inherent to DST operations. At surface, high pressures, the presence of H2S, and toxic well fluids increase the difficulty in deployment of real-time data acquisition and sampling equipment via wireline. Downhole, the high hydrostatic pressures normally found in deep environments can hinder the operation of the downhole tools. Often, to achieve high hydrostatic pressures, the operator is forced to use drilling muds which may have very low pressure transmissibility and solids problems that interfere with annulus-pressure/pulse-response tools.

The need to improve the quality of information gathered during DSTs in hostile environments has driven a major oilfield engineering company to research concepts that could improve capabilities of traditional DST systems.

This research led to the development of a novel telemetry system that uses acoustic bi-directional acoustic transmission through the tubing string. This system, compact and easy to deploy into the well, provides real-time data-acquisition flexibility in various depths in the string, enabling the constant monitoring of the wellbore conditions throughout the DST. It’s design, applications, and ability to simplify job procedures, reduce risks, and improve quality of information when linked to data acquisition and tool operation, will be the focus of this paper.

This new system provides greater efficiency in acquiring data in deeper, high-pressure DST environments than are currently possible with the standard methods.

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