Drillstem Testing

Drillstem Testing (DST) is a valuable tool in the oil and natural gas extraction process. Drillstem Testing is a procedure to determine the productive capacity, pressure, permeability or extent of an oil or gas reservoir. Drill stem testing is essentially a flow test, which is performed on isolated formations of interest to determine the fluids present and the rate at which they can be produced. By employing parts such as a DST bottomhole assemblies (BHA) application tests can be done to determine the viability and commercial productivity of a well within an accelerated time line as well providing lower financial risk compared to conventional well testing methods.

Basic Drill Stem BHA consist of a packer or packers, which act as an expanding plug to be used to isolate sections of the well for the testing process, valves that may be opened or closed from the surface during the test, and recorders used to document pressure during the test. In addition to packers a downhole valve is used to open and close the formation to measure reservoir characteristics such as pressure and temperature which are charted on downhole recorders within the BHA.

Below are two types of BHA DST, Cased Hole which can be applied after the well has been cased, and Open Hole which may be preformed before casing.

Applications of drillstem testing:

Cased Hole

Performed after the well is cased, cased hole drillstem testing uses a retrievable production packer that is set above the zone of interest. The well is then flow tested through perforations in the casing. The two types of cased hole testing are pressure operated and mechanically operated. More details

Open Hole

Because it's performed before casing is run, open hole drillstem testing can be the most economical way to determine productive (see below) capacity, pressure, permeability or the extent of an oil or gas reservoir. The testing equip ment is run into the well and the zone of interest is isolated using inflate or compression-set packers, depending on your requirements and drilling conditions. More details

Alternate Procedures

Depending on testing objectives and scope of work DST may also be preformed in combination with various other exploration and completion process such as fluid loss control and well control, closed chamber tests, well stimulation, and a combination of DST and TCP.