Optical reflective device for a well

摘要

When a tool locator 104, e.g. a casing collar locator, is not in the presence of a tool, an obstacle 114 does not block a light path between a mirror 116 and a fibre optic line 112. However, upon detecting a casing collar, the reflected light 122 is reduced in intensity by moving the obstacle 114 so as to block the light path between the mirror and fibre optic line. In this way the position of tool is accurately telemetered to the surface via the fibre optic line. In another embodiment the mirror is attached to a spinner to measure flow rate or speed of a tool.