How to....drill stem test..from drill ship buddy To do a drill stem test they run a set of perforating guns (many small shaped charges) below a packer. Both are run on drillpipe or tubing string (test string). When the guns are at the correct depth, verified by logging tools, they displace the test string to a light fluid, probably diesel oil and then expand the packer to seal off the annulus. They then connect the “surface tree” to the top of the test string. Then the blowout preventer is closed around the test string which seals off the annulus from above. Then they fire the guns most likely using pressure within the test string. The reservoir fluid flows up the test string, through the surface tree to the “separator”. It separates gas, oil and water. The gas and oil are burned in large burners on a boom which is swung out and away from the oil rig. Water is dumped overboard. The oil and gas are metered to determine flow rates and samples are taken.
After all of this they “shut-in” the well and monitor build up of pressure to get a feel for the size of the reservoir.
From here they likely pump the test string contents back into the well using about 50 bbls of “HEC” which plugs the pores in the reservoir to that fluids will not come out when the packer is released.
Open the blowout preventer, release the packer, rig down the surface tree.
From here they may abandon or suspend the zone just tested with about 30m of cement and then pull up hole to test another zone or abandon/suspend the well.[