When the first pipelines moved crude from wellhead to market in the early 1870s, it was difficult to balance the product in the line to the storage tanks at each end. If the receiving station was not ready for the crude, the sending station risked pumping too much product and might have overfilled the receiving station’s tanks. Communications were by telegraph in those days, but telegraph lines were usually run along railroads, not pipelines. Instead of telegraphing what was coming down the pipe so that the receiving station could get ready for the volume, the sending station would open and close a valve and pressures and volumes would be received at the other end. Morse code by pressure waves was used instead of the electrical current and electromagnetism of the Cooke and Wheatstone telegraph. This pulsing is thought to be the beginning of the measurement-while-drilling mud-pulse technology of today.
Several technological efficiencies have been achieved to increase the data rate of the mud-pulse technology, but they increased the data rate only marginally. Restricting the flow of mud inside the drillpipe through a poppet-and-orifice combination or modulating it through a siren would give longs and shorts like the dashes and dots of Morse code. Negative pulse technology added a small increase in efficiency. It used sharp pressure drops out the drillstring that provided a sharper signature at surface that was tied to time events and a few more bits could be compacted together. Electromagnetic systems send information to the surface with low-frequency electro-magnetic waves. The technology uses the flow of electricity to transmit bits. It has its applications but is dependent on the formation resistivity and depth. Wired drillpipe is a step-change solution for higher downhole data rates. If the cost can become competitive and the product is robust enough, data rates required to send high-definition images will be realized and the choice will exist to increase the data rate to 1 million times that of electromagnetic or mud-pulse telemetry.
Tubulars are evolving to become data transmitters of increasingly larger band-width. In both the drilling and completion phases, greater bandwidth is required to monitor the stimulation of a well and to drill a wellbore more efficiently. Evaluating position in the lateral while drilling, monitoring drilling efficiencies downhole, and monitoring stimulation efficiencies all require greater bandwidth. Conventional wire and even fiber-optic cable are being used in innovative ways, in harsh conditions, to solve these evaluation issues.
Recommended additional reading at OnePetro: www.onepetro.org.
SPE/IADC 163420 Drillstring-Mechanics Model for Surveillance, Root-Cause Analysis, and Mitigation of Torsional and Axial Vibrations by Deniz Ertas, ExxonMobil, et al.
SPE/IADC 163449 RFID—A Key Enabler in Drilling Automation by Mads Grinrod, Minerals Group, et al.
SPE 157388 New Test for Material Resistance Against Microbiologically Influenced Corrosion by Jeppe Jensen, DTI Oil & Gas, et al.