Drill stem testing is an oil and gas exploration procedure to...

Drill stem testing is an oil and gas exploration procedure to isolate, stimulate and flow a downhole formation to determine the fluids present and the rate at which they can be produced. The main objective of a DST is to evaluate the commercial viability of a zones economic potential by identifying productive capacity, pressure, permeability or extent of an oil or gas reservoir. These tests can be performed in both open and cased hole environments and provide exploration teams with valuable information about the nature of the reservoir. Drill stem testing involves deploying a series of tools known as a test bottomhole assembly (BHA). A basic drill stem test 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.