Preparing the well for completion
The well is now ready for completion and as stated in the introduction it is assumed that the well is to be completed immediately after the drilling operations are complete. At this stage, there are a number of alternative ways in which the operation may proceed. These routes are dependant on the way in which the well is to be perforated and cleaned up.
The well may be perforated with casing guns prior to the running of the tubing, it may be perforated with tubing conveyed perforating guns run on the tubing, or it may be perforated with through tubing perforators after the well has been completed. The advantages and disdvantages of each of these scenarios are discussed widely in textbooks relating to completion operations and will not be discussed here. It will be assumed that the casing is to be perforated with through tubing guns, after the completion has been installed.
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The production casing must be cleaned up and the drilling fluid displaced to brine after the drilling operation is complete and before any production tubing is run in the hole. A casing scraper is run on drillpipe, to the bottom of the production string, and a series of viscous pills, followed by brine, are circulated until the drilling fluid has been completely displaced to clean brine.
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