Drilling advances ///

Many oilfield folks think coiled tubing is used only for well servicing work. However, Coiled Tubing Drilling (CTD) has been around for some time, and it is gaining daily in popularity, especially in certain critical applications. The first US patent for CTD was issued in 1951 to G. D. Priestman, et al. The device included many of the features one finds today, including a drive system with opposing wheels that grip the pipe (motorized pipe benders and pipe straighteners), a reel with an electric motor driver, and a bottomhole assembly with a downhole motor above the bit. In the 1960s, R. H. Cullen Research perfected armored, wire-wrapped flexible pipe that could be spooled with minimal effort. It was used to drill several wells up to 4,500 ft by 1969 before the project was suspended. In the early 1970s, small-diameter coiled tubing was used for specialized remediation work in West Texas.

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