Guided wave sensor for simple digital communication through an oil industry multi-wire cable

Abstract

This work presents the proprietary design and implementation of a lead zirconate titanate (PZT) sensor for simple digital transmission and reception of guided waves using a high-temperature and corrosion-resistant multiple-wire 1K22 MP-35N cable as a communication channel. These cables are commonly used in the hostile oil and gas borehole environments of the petroleum industry. The sensor design involves electrical/mechanical coupling, instrumentation and casing. The PZT guided wave transmitter instrumentation includes a microcontroller-based pulse position modulator, a signal booster, a PZT-5H crystal and a 9 V battery. The receiver sensor consists of a PZT-5H crystal, an amplifier and a real-time digital signal processing (RT DSP) and data acquisition module connected to a personal computer. Dispersion curves were obtained using Disperse software and a simplified model of the cable. Dynamic linear 3D finite element modelling of the sensor was performed to support the correct frequency selection. To evaluate the sensor design, the transmitter generated 60 kHz guided wave pulse position modulation (PPM) energy packages. Experimental tests were conducted in the laboratory using 1 m and 10 m cables. The results showed that, although there was significant dispersion and there were multiple mode excitations of the transmitted pulses, the system correctly identified 10-bit frames of guided wave PPM-encoded information.