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There are cost advantages to reaming while drilling. The pilot hole offers good directional control while the enlarged hole from reaming creates the right conditions for running casing or completion equipment which relates to savings in time and cost. An underreamer is device designed to run in conjunction with a drill bit. It has cutters that can be expanded or contracted by mechanical or hydraulic means and used to enlarge or ream a borehole below the casing. Baker Hughes and Statoil jointly developed the industry's first on-command digital reamer as a single size prototype in 2007.
Demulsification is the breaking of a crude oil emulsion into oil and water phases. A fast rate of separation, a low value of residual water in the crude oil, and a low value of oil in the disposal water are obviously desirable. Produced oil generally has to meet company and pipeline specifications. For example, the oil shipped from wet-crude handling facilities must not contain more than 0.2% basic sediment and water (BS&W) and 10 pounds of salt per thousand barrels of crude oil. This standard depends on company and pipeline specifications. The salt is insoluble in oil and associated with residual water in the treated crude. Low BS&W and salt content is required to reduce corrosion and deposition of salts. The primary concern in refineries is to remove inorganic salts from the crude oil before they cause corrosion or other detrimental effects in refinery equipment. The salts are removed by washing or desalting the crude oil with relatively fresh water. Oilfield emulsions possess some kinetic stability. This stability arises from the formation of interfacial films that encapsulate the water droplets.
Demulsifier selection is still considered an art that improves with experience; however, there are methods now available to eliminate some of the uncertainties involved in demulsifier screening and selection. The properties of a good demulsifier were addressed previously. How to select the best demulsifier and to optimize its usage is addressed here. Demulsifier selection should be made with the emulsion-treatment system in mind. Some of the questions to be asked include the following.