Expandable reamers move from marginal to integrated componentsWhile reamers have been in use for more than a century, reliability issues have kept them out of the spotlight… until now.
Hole openers are not new to the industry. In the early days of rotary drilling, bits lost gauge as they traveled downhole. To allow for the setting of casing, this tapered effect had to be dealt with. In its origin, a reamer, or a hole opener as they were referred to then, was run to ensure adequate hole size throughout the well bore. As early as the 1930s, stationary reamers were used to open up pilot holes drilled for sidetracks and whipstocks.
Standard hole openers exist in fixed sizes and feature carbide metal teeth insert cutters with sizes ranging from 6-in. up to 26-in., typically with three or four cutters. As technology advanced, the addition of motors, MWD tools, and rotary steerable systems to the drillstring now called for an integrated system. The need for expandable reamers came into play. Today, reamers are designed to pass through a restriction and open up beneath it to expand the hole for the next series of casing to be run, providing sufficient room between the casing and the formation for the cementing to take place. By the mid-1990s, expandable reamers were becoming a viable type of tool. “This is really when the under-reamer came into its own,” said Les Shale, business development manager – Hole Enlargement, Baker Hughes.
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