Inflate testing is the most time- and cost-effective method that can be used to isolate multiple formations since multiple zones can be analysed during a single RIH. Open hole inflate testing utilises a pair of interval-spaced packers to isolate the formation of interest. The packers are inflated by means of a down hole pump using annular fluid which is set to a predetermined pressure to inflate the packers. This type of testing is adaptable to a wide range of conditions.
A conventional drill stem test uses a compression set packer 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 flow into the tool and rise to the surface. The formation is flowed for a specified time period, after which a shut-in valve is rotated to the closed position for a specified shut-in period. This method is a very reliable form of testing and is more commonly utilised upon penetration. This ensures that the exploration well is tested as soon as a possible target has been discovered and evaluation is required immediately to eliminate formation damage that may obstruct testing results.