The Research And A Array Tool Design Of Water Holdup Measuring By Conductance Method

The water holdup is a very important monitoring parameter in oil field production. The online measurement of the water holdup of oil-water two phase flow in well can provide timely and accurate information for the formation resources evaluation and down-hole operation. But some conventional method for water holdup measuring can’t meet the demand of actual production at present in our country because the methods of the water injection and the highly-deviated well、the horizontal well technology is widely used in order to ensure high and stable yield of crude oil. The main reasons are as follows:first, the injecting water into well for oil causes the water content of down-hole fluid increased; second, the gravity cause the oil-water distribution difference on cross-sectional of the highly-deviated well or horizontal well, so that water holdup measuring method with single probe, which is suitable for vertical wells, can’t provide distribution information about water holdup on the cross-section of those well. Therefore, it is very important to research a new method for accurately measuring water holdup and develop the corresponding array logging tool to be used in the highly-deviated well or the horizontal well while the water content is high.This paper has studied the relevant information,introduced the research status at home and abroad of water holdup measuring by conductance method,compared the characteristics about different methods for water holdup measuring.According to the requirements of actual situation on China, this paper based on the principle of conductance method for water holdup measuring, discusses the basic method of water holdup measuring, carried out experimental studies with different excitation signal and different water holdup,provides the basis for the design of instrument. On this basis, demonstrates the design scheme of a array tool for water holdup measuring by conductance method.Focusing on the requirements of high-performance, use the latest levels of military or automotive integrated electronic devices, design the new excitation circuit and the module of orientation detection, and choose higher integrated A/D quantizer with the greater dynamic range, use the low voltage power supply as far as possible. Through the above scheme and measures, the instrument will be with higher integration, lower power consumption, better temperature performance, more precise data recording, more adaptable to the highly-deviated well or the horizontal well with high water content. After development, debugging and experiment, results show that, the instrument can meet expected design requirements.The main innovation of this paper lies in:first,the array-sensors which is designed for conductance method can solve the water holdup measurement problem of the space distribution of the highly-deviated well or the horizontal well;second,FPGA as the core control chip that can provide a lot of flexibility of hardware, so that the circuit is relatively simple and the stability of the hardware is improved;third,the use of the module of orientation detection can position sensors accurately,as a result,the images of water holdup become more authentic;fourth,it is more intuitive and convenient to real-time display the images of water holdup.In summary, the study of this paper solves several key problems of water holdup measuring at present, the result has important practical value to improve the performance of the instrument and engineering application.