Research On Structure Optimization Of Array Optical Fiber Probe Sensor In Oil Well

The gas fraction dynamic measurement in oil-gas-water three-phase flow is veryimportant to improving production logging technology. With the emergence anddevelopment of fiber optic probe technology, optical fiber sensor employed in measuringmultiphase flow parameters such as gas fraction is presented. The optimization of a singleoptical fiber probe and optical fiber probe array structure is studied principally in thispaper, and the process that optical fiber probe pierces the bubble is simulated and analyzed.Array optical fiber probe sensor for measuring gas fraction of three-phase flow accuratelyis developed.Firstly, to improve sensitivity and recognition ability of gas and liquid of the opticalfiber probe sensor, the single optical fiber probe sensitive tip was optimized. Thecorrespondence relationship between optical fiber probe tip geometry and the collectedpower is analyzed. This paper presents two performance indicators for optimizing opticalfiber probe structure, and performs angle optimization of optical fiber probe sensitive tip.The optimized optical fiber probe reduces the interference to flow and enhancesmeasurement performance under the premise of ensuring the more returned power. Afterunderstanding the whole process of piercing bubble, the research on responsecharacteristics of piercing bubble based on ZEMAX simulation provides the necessarytheoretical basis for in-depth understanding of optical fiber probe sensor piercingmechanism and follow-up signal processing.Secondly, aiming at one-side of single probe and hindering fluid of too many probes,array optical fiber probe sensor is presented. Fluid operation of different oil-gas-waterratio is simulated by computational fluid dynamics software FLUENT, gas points areextracted for various operating conditions via MATLAB computing, and the gas fractiondistribution characteristics of radial and axial under different conditions are obtained.Using the accuracy of measuring the gas fraction and the fluid block level as an indicatorof the degree, optical fiber probe array structure is optimized on radial position and angleposition. Finally, the array optical fiber probe sensor is developed based on above optimization,and a simulation experimental platform is built for containing gas fraction. The gasfraction information in oil-gas-water three-phase flow is measured under differentconditions by array optical fiber probe sensor. The signal acquisition and processing areperformed under various gas flows in oil-gas-water three-phase flow, and gas fractionsobtained is compared with the actual value.