| 摘要 |
A combined underreamer and calliper tool which permits simultaneous underreaming and measurement of the diameter of the borehole includes radially extendable cutter blocks 62 and a calliper means (58, fig 2a). The cutter blocks 62 can be extended to the bore diameter, the degree of extension being determined by position sensors on a pinion arrangement (84, fig 4) which extends the cutter blocks 62. Further measurements are taken by the calliper (58, fig 2a) and the measurements are compared and correlated. The measurements may be transmitted to the surface to a surface control and communication system. Also claimed is a cutter block 62 having at least one nozzle (112, fig 4) ; an underreamer having a helically arranged array of cutters (fig 11b); a trailing lock mechanism including a groove 98 (fig 4), a profiled collet finger (96, fig 4) and being actionable by fluid flow. |
