Retrievable downhole cable antenna for an electromagnetic system

摘要

This invention provides an improved system and method for receiving electromagnetic (EM) signals from a wellbore in spite of EM unfriendly formations by placing a cable antenna in a wellbore, drilling another wellbore nearby, and using the cable antenna downhole in the wellbore to assist in receiving signal from the transmitter in the wellbore being drilled. The EM telemetry system can include a bottom hole assembly with an EM tool for transmitting a signal positioned in a first wellbore; EM equipment provided at or near the surface; and a cable antenna coupled to the EM analyzer positioned in a second wellbore. The cable antenna does not require other downhole antenna devices for receiving EM signals and therefore is independent of other antenna devices. The cable antenna can be retrieved after drilling is completed and moved to another drilling site.

主权项

1. An electromagnetic telemetry system comprising:
an electromagnetic tool deployed in a first wellbore and configured to transmit EM signals from the first wellbore; a cable deployed in a second wellbore and configured as an antenna to receive said electromagnetic signals from the electromagnetic tool independent of receiver devices attached to the cable antenna and couple the electromagnetic signals to an electromagnetic analyzer to analyze the electromagnetic signals; and a weight bar coupled to the cable antenna, the weight bar being non-conductive to the cable antenna.