Abstract
There is a noticeable impact on a gas well's production rate when there is a build up of liquids downhole in the casing and the tubing of the well. The liquid may be in the form of formation water, condensed water or hydrocarbon condensate, but coupled with a fall in reservoir pressure the affect on production is the same. It causes the flow regime of the well to change, to an eventual point when the well ceases to produce. This is due to a hydrostatic lock, typically in the tubing, that the well pressure is unable to move.
To reduce the production decline and prevent premature well shut in chemical foamers can be used as a means of artificial lift. These are surfactant chemistries designed to modify physical properties of the liquids, such as surface tension, which aid unloading. The common chemistries used are discussed in this paper and a detailed explanation provided on how they are effective at deliquifying gas wells.
To develop this technology for commercial use it is important to have a process for evaluating performance. This begins in the laboratory using the unloading rig. This is a test method that provides information on the foam generated as well as indicate an unloading potential. Once a potential candidate has been identified in the lab then the process is undertaken to transfer the technology to the field. Identifying a suitable well to enable a field trial to be completed. Within the paper the test method is explained and the transfer process and results from the field presented.
