Wenan Zhao

Research of Optical Fiber Fluid Flow Monitoring System Based on Flow-Induced Pipe Vibration

In the oil field development and production, fluid flow is an extremely important parameter which determines the transmission characteristics of the oil production, real-time monitoring of fluid flow parameter provides a scientific basis for oil and gas optimization exploration and increase of reservoir recovery. A method for interrogating fiber optic sensors using flow-induced pipe vibration is proposed, and fluid flow is measured non-intrusively, the study is conducted on vibration induced by turbulent flow when fluid flow through pipe. The frequency characteristics of the pipes vibration signals is found,then the fixed relationship between standard deviation of pipe walls vibration induced by fully developed turbulence and mean flow rate is determined.

Optical fiber pressure sensor based on F-P cavity in the oil and gas well

To meet the need of the measurement in high temperature and high pressure in oil and gas well, an optical fiber pressure sensor based on extrinsic Fabry Perot (F-P) cavity is developed. The sensor is fabricated by hydrogen and oxygen flame thermal bonding in high temperature technique, and the change of the senors cavity length is compensated in temperature changing with cascading fiber bragg grating, and the sensor has characteristics of large dynamic range, high resolution, high repeatability, long term operation stability and high temperature resistance. The pressure measuring range is 0~69MPa, the repeatability is 0.01% FS,the hysteresis is less than 0.01% FS, the long term stability is less than 0.02MPa/y, and the sensor can satisfy the requirement of the measurement in the oil and gas well. Practical application proved that the relative deviation of the pressure measurement value is less than 0.01% compared with the traditional electronic pressure sensor.

Design of fiber optic F-P cavity pressure sensor based on corrugated diaphragm

To meet the need of the measurement in high temperature and high pressure in oil and gas well, an optical fiber extrinsic Fabry Perot(F-P) cavity pressure sensor based on corrugated diaphragm is developed. The measured medium is isolated from the fiber F-P cavity by corrugated diaphragm which can transmit pressure simultaneously. The probe of the sensor is fabricated by hydrogen and oxygen flame thermal bonding in high temperature technique, and the change of the senor’s cavity length is compensated in temperature changing with cascading fiber bragg grating, and the sensor has characteristics of large dynamic range, high resolution, high repeatability, long term operation stability and high temperature resistance. The pressure measuring range is 0~69MPa, the repeatability is 0.01% F·S, the hysteresis is less than 0.01% F·S, the long term stability is less than 0.02MPa/y, and the sensor can satisfy the requirement of the measurement in the oil and gas well.

Fiber optic pressure and temperature monitoring system for downhole application

A Pressure and temperature (P&T) monitoring system based on fiber Bragg grating (FBG) and extrinsic Fabry-Perot interferometer (EFPI) for downhole application is designed and tested. The system is electronically passive, with no electronics downhole, and can monitor downhole pressure and temperature continuously without breaking in production of oil well. It is demonstrated in experimental well test that the system measurement error is less than 1 °C for temperature and 0.03 MPa for pressure. The system is installed in a production well and monitor the downhole P&T for a year at the temperature of 140°C and the highest pressure of 50 MPa.

Design for a new fiber optic interferometer of water cut meter in oil well logging

With the continual advancement of oil field development, water cut is an extremely important parameter which determines the transmission characteristics of the oil production and provides a scientific basis for oil and gas optimization exploration and increase of reservoir recovery. A new water cut meter based on fiber optic interferometer is proposed, sound pressure signal on the pipe is generated when the acoustic wave is propagated in a mixture of the pipe, the fiber optic sensors wrapped closely around the outside wall of pipe is capable of sensing sound pressure signal, the use of phase-carrier technology aloud sound velocity is solved out through the method of Phase Generated Carrier(PGC)and sound pressure spectrum, then water cut can be solved according to the relationship between sound velocity and water cut.

Research on optical fiber flow test method with non-intrusive

In the field of oil well logging, real-time monitoring of fluid flow parameter provides a scientific basis for oil and gas optimization exploration and increase of reservoir recovery, so the non-intrusive flow test method based on turbulent vibration is proposed. The specific length of sensor fiber wound tightly around the outer wall of the pipe is connected with the optical fiber gratings at both ends, the sensor fiber and the optical fiber gratings compose the flow sensing unit. The dynamic pressure is generated by the turbulence when fluid flows through the pipe, and the dynamic pressure results in the light phase shift of the sensor fiber. The phase information is demodulated by fiber optic interferometer technology, time division multiplexing technology and Phase Generated Carrier modulation and demodulation techniques. The quadratic curve relationship between phase change and flow rate is found by experimental data analysis, and the experiment confirms the feasibility of optical fiber flow test method with non-intrusive and implements the realtime monitoring of flow.

Introduction of new optical fiber monitoring system of fluid flow with nonintrusion

In the oil field development and production, fluid flow is an extremely important parameter which determines the transmission characteristics of the oil production, real-time monitoring of fluid flow parameter provides a scientific basis for oil and gas optimization exploration and increase of reservoir recovery. A method for interrogating fiber optic sensors non-intrusively sensing fluid flow is proposed, those sensors are positioned between pairs of low reflectivity fiber Bragg gratings, the fiber optic sensors wrapped closely around the outside wall of pipe are used to sense the internal information of fluid flow, new optical fiber monitoring system of fluid flow bases on optical signals. When optical signals are transported in optical fibers, phase is changed due to the effects of the fluid flow , the size of which can be determined by measuring the relative changes of the phase. So the optical fiber monitoring system of fluid flow making use of modulation and demodulation techniques of phase generated carrier accurately determines the size of fluid flow with non-intrusion.