Slimhole DST String

Reservoir test in small-casing wells

The slimhole drillstem testing (DST) string is designed for holes down to 41/2-in casing, enabling you to conduct well testing and gather data in small casing sizes that were previously untestable. The HPHT testing string has similar features to the standard PCT pressure-controlled tester valve string and provides high operational flexibility and capability using 3 1/8-in × 11/8-in slim-diameter tools.

Enable DST system redundancy

The multicycle circulating valve with lock (MCVL) is reclosable. In addition to reversing out to kill the well at the end of the test, it can be used to spot treat fluids and change out the cushion if necessary. The MCVL is tubing-pressure operated and provides system redundancy, as a single-shot reversing valve (SHRV) is run as a secondary reversing valve and is annulus-pressure operated.

Provide a rugged and reliable seal above the producing zone

The retrievable FlexPac high-performance service packer with holddown tool provides a rugged and reliable seal above the producing zone and string support and prevents pumping the string uphole because of hydraulic forces. Two or more slip joints (SLPJs) are run, as needed, to compensate for any string movement between the two fixed points at the packer and surface resulting from temperature changes during the job.

Schlumberger engineers customize the string design for optimal deployment to ensure that the necessary data is collected and risks are mitigated.