Inner pressure type temperature compensation high-temperature high-pressure optical fiber grating sensor

Abstract

The invention relates to an intrinsic pressure type temperature compensation high-temperature high-pressure fiber grating sensor. A shell is provided with an inlet port in the radial direction, a left end of the shell is provided with a left coupling head of a left capillarity steel pipe, and a right end thereof is provided with a right coupling head of a right capillarity steel pipe, an elastic base is arranged in the shell and positioned at the side of the inlet port, the edge of the elastic base is provided with axial holes, an optical fiber is provided with a pressure sensing fiber grating and a temperature sensing fiber grating, and penetrates the left capillarity steel pipe to be arranged at the outer side of the elastic base, and the other end of the optical fiber extends out of the shell through the right capillarity steel pipe. By laboratory tests and high-temperature high-pressure oil well actual examination on the producing scene, the sensor of the invention has the pressure detection range of 0 to 100MPa, the temperature detection range of minus 30 to plus 350 DEG C, the pressure sensitivity coefficient of 14pm / MPa, the temperature sensitivity coefficient of 12pm / DEG C, the pressure absolute precision of plus or minus 0.2MPa and the temperature absolute precision of plus or minus 0.5 DEG C, and can be promoted and applied under the oil well.

Description

technical field [0001] The invention belongs to the technical field of optical fiber sensors, and in particular relates to an optical fiber grating sensor for simultaneously distinguishing and measuring high temperature and high pressure. Background technique [0002] The fiber grating sensor can detect many physical quantities such as pressure, temperature, stress, displacement, strain, flow velocity, flow rate, viscosity, etc., because of its simple structure, small size, light weight, corrosion resistance, strong anti-electromagnetic interference ability, and easy realization of wave Since it came out in the 1970s, it has received widespread attention at home and abroad. At present, it is devoting itself to the development and application research of fiber grating sensors. [0003] Zhao Yong of Tsinghua University and others once proposed to use the cantilever beam structure placed in the free elastic cylindrical pressure transducer to realize the fiber grating sensor for...

AI Technical Summary

Problems solved by technology

Traditional methods mostly use electrical measurement methods, which are easily limited by conditions such as downhole high-temperature environment and electromagnetic interference. At present, the use of fiber bragg gratings to replace electrical measurement methods has attracted much attention at home and abroad, but so far, it has been used in heavy oil injection in China. A fiber grating sensor suitable for detecting temperature and pressure in a high temperature and high pressure well with a wide range has not been reported yet.

[0005] The existing fiber grating temperature sensor can only detect the maximum temperature of 250 ℃, and cannot adapt to the temperature detection above 300 ℃ under the oil well. The detection pressure of the fiber grating pressure sensor is low. The hysteresis loop of the input characteristic curve causes large hysteresis errors and nonlinear errors

The existing optical fiber grating temperature and pressure sensor that distinguishes between temperature and pressure at the same time, due to the cross-sensitivity interaction of temperature and pressure, the sensitivity of this fiber optic temperature and pressure sensor is low, the detection error is large, and the detection range is small

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