Experimental Results On the Drill String Design for Borehole Acoustic Communicatio

The use of acoustic waves to transmit information from sensors installed near the drilling head during the drilling process of oil wells is a promising technology. However, this method suffers from the high fading at certain bands due to the structure of the drill string, which consists of pipes connected by tool joints. This structure decreases the total bandwidth available for transmission up to 60 percent. This paper investigates the possibility of redesigning the drill string to increase the available bandwidth for information transmission. We have built a test- bed to study the drill-string acoustic channel experimentally. We adopted three pipe strings; each has a tool-joint with a different length. The results reveal that the channel frequency response of pipe string varies depending on the tool joint length. We also look at channel properties such as mean excess delay and Root Mean Square (RMS) delay spread, maximum excess delay, and coherence bandwidth for various pipe string configurations.