Date of Award
Doctor of Philosophy in Electrical Engineering - (Ph.D.)
Electrical and Computer Engineering
Eliza Zoi-Heleni Michalopoulou
The performance of multichannel and single channel accelerometers used as uphole communication receivers is studied. Using measured channels from the drill string testbed, it is shown that one tri-axial accelerometer can provide nearly uncorrelated signals when compared to two single channel accelerometers. Having uncorrelated signals at the uphole receiver provides a diversity which in turn can lead to an increase in the communication system performance. The use of a strain sensor as a receiver in borehole communication is proposed. Using measured channels from the drill string testbed, the performance of a strain receiver with a single-accelerometer receiver is compared. The results show that the strain receiver has better performance than the single accelerometer receiver, and is further demonstrated that the strain channel impulse response has a better structure than a single-accelerometer channel impulse response. Furthermore, the multichannel reception using several receivers with the aim of improving communication system performance is studied. The combination of a strain sensor and a tri-axial accelerometer as a four-channel receiver is proposed. Given the complexity of studying the strain channel and the three acceleration channels analytically, experiments are conducted to obtain these channel impulse responses. The channel measurements show that these wireless channels are nearly uncorrelated and therefore can provide a diversity gain. This is further confirmed by the low bit error rates that this system provides. Comparison with single channel receivers shows the usefulness of the proposed system for wireless communication via drill strings.
Alenezi, Ali Hamdan, "Borehole communication via drill strings in oil wells" (2018). Dissertations. 1360.