Design and Experimental Research of a Fiber-Optic Communication Module for Well Logging

Fiber-optic transmission has been applied in oil and gas industry over the years. Compared with other methods applied in the industry, fiber-optic transmission has the advantages of low loss, long-distance, high-capacity and robust to the electromagnetic interference. The ability to provide reliable transmission systems in the harsh environments like high temperatures is the key driver for the continued use of fiber-optic communication for in-well applications. We design a fiber-optic communication system under high temperatures for well logging applications. It consists of high-temperature laser diode, high-temperature photodetector with photoelectric detection circuit, drive control circuit, and field-programmable gate array (FPGA) as the communication chip. This system ensures that data can be transmitted at a rate of 15 Mbps at temperatures up to 155°C. The FPGA board makes the system to control data transmission flexibly and enable the serial communication between the photoelectric module and the host computer. Additionally, the number of fibers used in fiber-optic communication in logging will be reduced to only a single fiber for transmitting and receiving. A series of experiments on the performance and effects of fiber-optic communication at different temperatures was carried out. Data transceiver tests and eye diagram tests are presented. The experimental results demonstrated that this fiber-optic communication system is capable of working steadily over a long period of time in harsh environments around 155°C to realize broadband and remote transmission of logging information. This system provides a way that allows optical information to transmit in a high-temperature environment. It can be applied to well logging and fiber-optic sensing (e.g., real-time environmental parameters transmission, fiber-optic well monitoring) for developing real-time, high-data-rate, bidirectional fiber-optic communication in the future.