Downhole instruments for well operations

摘要

Pressure and temperature signals are transmitted between a predetermined point in a wellbore and the earth's surface by an electromagnetic wave transmitter disposed in the well and connected to a bow-spring centralizer forming one contactor of a dipole and a mandrel or hanger connected to a landing nipple of a tubing string in the well whereby the other conductive path forming the other end of the dipole may be formed by a packer or similar mechanism in conductive engagement with the tubing string and the well casing. The hanger may be a lock mandrel or a suitable conventional downhole tool hanger. The electromagnetic wave transmitter may be deployed in the well and engaged with the casing by spaced-apart magnets to establish the conductive path and the dipole distance. The transmitter may also be deployed on and connected to coilable tubing which has an insulative coating on the exterior surface for a predetermined length to prevent short-circuiting the conductive path by engagement of the coilable tubing with the casing wall, for example.