Fiber bragg grating temperature and pressure sensor for oil and gas well

Temperature and pressure are very important parameters in oil and gas well exploitation. The downhole environment is harsh so it is difficult for traditional electronic sensors to achieve long-term and stable monitoring of downhole parameters. In this paper, a fiber Bragg grating temperature and pressure sensor based on a carbon-fiber sensitized tube is proposed. The sensor is composed of a hollow tubular structure woven of carbon fibers as a skeleton. The composite carbon fiber tubes are cured by high-temperature resistant epoxy resin as an elastomer, and the high-temperature resistant fiber Bragg grating is embedded on the surface as a sensing element to realize the simultaneous measurement of downhole temperature and pressure. The experimental results show that the sensor can work stably in environments of 0 similar to 150 degrees C and 0 similar to 80 MPa, and the maximum pressure sensitivity can reach -50.02 pm/MPa. The sensor has a good linear response. By adding a reference grating as a temperature compensation grating, the cross-sensitivity problem in the process of the simultaneous measurement of temperature and pressure is solved, and the accuracy requirements in the process of underground mining are met. This technique provides an experimental basis for the design of high-temperature and high-pressure optical fiber sensors in oil and gas wells.