Testing Tool Conveyed by Coiled Tubing Enables Multiple Tasks in One Run
Authors: Carpenter Chris 
Published: June 2020

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 199853, “Development and Testing of an Electrical Drillstem Testing Tool Conveyed by Coiled Tubing With a Real-Time Control and Acquisition System,” by Michael Affleck, SPE, Aramco, and Monika Bakke Malmin and Per Egil Almas, Target Intervention, et al., prepared for the 2020 SPE/ICoTA Well Intervention Conference and Exhibition, The Woodlands, Texas, 24-25 March. The paper has not been peer reviewed.

Some well-testing operations are executed by performing multiple runs in hole using slickline and coiled tubing (CT). A technology has been developed that combines many of these operations, including contingency stimulation activities, into one run. The complete paper introduces the major system components and reviews challenges associated with design, manufacture, and testing.

Developing and Qualification Testing of the Tool

Before engaging in the tool- development process, the following major operation-al requirements were identified and confirmed:

Reduce the number of different services required and their associated rigup and rigdown times by maximizing the work scope performed with CT

Increase timely access to high-quality data for rapid onsite decision making during well testing by converting from memory-based gauges and time-activated downhole shut-in tools to real-time control and data transmission to surface

Maximize operational efficiency during well testing by having real-time data transmission to surface

Introduce on-demand, selective stimulation capability while the tool and CT remain downhole

Allow multiple testing periods during one trip in hole when required at different depths

Increase the effectiveness of transferring the well from underbalanced to overbalanced status or vice versa by changing out fluids in the well or pumping nitrogen through the CT

Reduce overall risk of stuck pipe or stuck tools during well testing by always having circulation available above the packer module

Following multiple design iterations, two complete prototype tools were manufactured and module-level function testing was performed. In parallel, software development and testing of the graphical user interface commenced. Significant effort was applied to ensure that module testing was conducted in realistic downhole scenarios. Dedicated testing equipment was designed and manufactured. Design, manufacture, and module testing was performed in Algard, Norway.

Primary components and specifications of the tool are provided in de-tail in the complete paper. Fig. 1 shows the tool [known as the e-drillstem test (e-DST) tool], while Table 1 provides specifications.

Following qualification testing but before the first field application, a system-integrity test was performed with the CT service company. Special attention was paid to verifying all interfaces between the downhole tool and the supplier of CT equipment and processes. The verification of operating the new tool through the full length of cable (inside the CT) was tested thoroughly. Significant calibration was expected, required, and performed because the monoconductor cable is used for data communication in addition to tool power supply.