Digital Transmission of Well Logs by Radio and Telephone

A new telemetry system enables remote point recording of electrical welllogs. Simultaneously with logging operations on offshore Louisiana wells, filmrecords are being produced in a New Orleans office more than 100 miles away. The system, using microwave as a data link, was installed to reduce costlyshut-down time caused by delays in transporting logs to the office, and toextend well coverage by key personnel. At the well site, simultaneously with the recording of an optical log, aportable quantizer converts log data to digital signals suitable fortransmission over microwave and/or telephone facilities. At the receiving endthe transmitted data are decoded into analog signals and recorded on film in astandard optical recorder. The film recording at the receiver is synchronizedwith the offshore logging operation and the log is available at the office assoon as at the well. An alternate procedure is to record the digital output on magnetic tape forsubsequent transmission. This procedure is used when microwave facilities arenot immediately available on the well platform. The tape may then be taken tothe nearest microwave station or telephone for transmission. The system is applicable to the transmission of most types of electricalwell logs. Induction-electrical surveys and Sonic logs have been successfullytransmitted. Introduction A new era in logging is opened by the recently developed DART system fortransmitting well logs by radio and/or telephone lines. Using a designprototype of this new system, well logs are now recorded simultaneously atoffshore platforms and at a New Orleans office over 100 miles away. In thisparticular application, a microwave system supplies the necessary link betweenwell site and receiving office. However, the equipment has worked equally wellover telephone lines, and has been tested using FM radio facilities. The rapid conveyance of logs from well site to a decision-making level hasalways been important - particularly on offshore wells where rig costs arehigh. In such operations, airplanes and speedboats are often used to deliverlogs so that time lost waiting on orders can be reduced to a minimum. In manyinstances, key personnel go to the well site. However, with the DART system, logs are available in the office at the sametime as at the remote well. Thus, a team of experts in the office can monitorlogging operations, study the logs and issue instructions - all with a minimumof lost time. Records and files on adjacent wells that might be too bulky totake to a location are readily available in the office. Furthermore, with thelogs transmitted to the office, a team of experts can, in effect, be availableon several offshore locations in a single day. The DART system thus offersappreciable savings of time - savings not only of expensive rig time, but alsothe time of key personnel who make important decisions.