Study On The Measurement Of Steam Dryness In Heavy Oil Thermal Recovery By Matrix Conductance Method

In the underground oil reservoir,in addition to the light crude oil which is easy to be exploited,there are many heavy oil which can not be directly exploited.Steam dryness is an important parameter to measure the quality of wet saturated steam in heavy oil thermal recovery process,which has an important impact on the efficiency of heavy oil thermal recovery.At present,the measurement of the dryness of the oil field steam is still based on the test method,the measurement process is tedious and the result is lag.Therefore,for the purpose of on-line monitoring of steam dryness,this paper proposes a new measurement method of wet saturated steam dryness in steam injection pipeline matrix conductance method.The measurement principle and structure of matrix conductance method are analyzed in detail.Based on the principle of matrix conductance method and the thermodynamic formula,the algorithm model of matrix conductance method for measuring the dryness of high temperature and high pressure wet saturated steam is derived,Based on the ANSYS Fluent software,the fluid model of the measurement area in the pipeline with matrix conductance method is simulated and analyzed.Compared with other throttling steam dryness measurement methods,this paper analyzes the pressure and speed changes in the measurement area,and verifies the feasibility of matrix conductance measurement of steam dryness from the perspective of fluid impact.Based on ANSYS Maxwell software,the electric field simulation analysis of matrix electric wire mesh is carried out.Refer to the working condition to determine the material of the conductance wire.Establish a single-phase model to analyze the distribution law of electric field between wire mesh;establish a two-phase model to analyze the electric field change caused by the difference of medium size and position;control variables to establish a multi group model to analyze the electric field distribution difference between matrix conductance wire mesh with different diameter and layer spacing.The simulation results can provide reference for the design of primary measurement elements.The data acquisition system is designed for 32×32 matrix wire mesh.The system is mainly composed of FPGA,multiplexer,operational amplifier,sample/hold circuit and A/D converter.Based on the results of electric field simulation and algorithm model,this paper analyzes the cause and range of measurement error,and compares the influence of linear interpolation and cubic spline interpolation on measurement error range.The position distribution of the measurement points that produce the measurement error is analyzed to provide the optimization direction for the subsequent improvement of the measurement accuracy.