Downhole Reservoir Testing (DST)

Reliable and Proven Drill Stem Test

Since 1979 we’ve performed over 7,000 drillstem tests and have helped clients accurately characterize their reservoirs. Whether the goal is determining reservoir pressure, permeability, skin, or productivity, our downhole technologies deliver the right answers.
downhole reservoir testing

What is a Drill Stem Test (DST)?

The isolation of an interval of interest (part of a reservoir formation or multiple formations) using one or more packers to produce reservoir fluid through a temporary production tubing or drill pipe (work string).

A Downhole Valve can be installed in the work string to control the production with Pressure Gauges recording the interval pressure or transmitting pressure readings wirelessly to surface (Wireless Surface Readout).

Shutting in the production downhole with gauges near or within the interval (sandface) results in a faster pressure response due to a minimized wellbore storage volume compared to shutting in at surface (Surface Well Testing). 

The reservoir fluid is typically flowed to surface through a Surface Well Testing Package capable of separating the produced multi-phase flow and measuring the production rate of each phase (Oil, water, gas, condensate, solids).

Alternatively, Closed Chamber testing involves opening the Downhole Valve and flowing the reservoir fluid into the tubing/drill pipe volume with the wellhead closed.  The flow rate is calculated from the rate of pressure increase measured at surface and downhole.

Downhole Reservoir Testing schematic
downhole reservoir testing
Downhole Reservoir Testing graphic
typicam derivative curve with different cases
The recorded pressure data and subsequent data analysis (Pressure Transient Analysis) provides important reservoir characterization parameters:

Drill Stem Tests can be conducted during or shortly after the drilling of a well (Open Hole DST) or after casing has been run (Cased Hole DST).

Open Hole Inflate
Testing System

Open hole inflate tests utilize a pair of interval spaced packers which are inflated using annular fluid to isolate the formation of interest. This type of testing is adaptable to a wide range of conditions. Inflate testing is the most…

Cased Hole
Testing System

In a cased hole drillstem test, where a closed system is desirable due to a high pressure, high temperature environment, this set of tools can be run and activated using pressure. The Cased Hole Pressure Operated tools can be run…

Conventional drillstem tests use compression set packers set above the formation, with tail pipe below the packers to the bottom of the hole. Placing weight on the tool string opens the hydraulic valve allowing the formation to…

Closed Chamber
Testing System

Closed chamber testing enables the calculation of inflow fluid volume as a function of time by monitoring surface pressure. It also allows the measurement of the smallest flow rates with pinpoint accuracy, with flow rate and…

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