Experimental System Based On Array Conductivity Probes For Measurement Of Oil/water Two-phase Flow In A Horizontal Well

Horizontal well, which rapidly developed at the end of the 20th century in China, can improve oil well production and the efficiency of the development. Usually a horizontal well cost as 2.5 to 3.5 times as a vertical well with the same depth, but oil production of the former can increase 1.4 to 9.2 times, therefore the horizontal well technology has been treated seriously by oil industry generally. Drilling technology of horizontal well has become increasingly perfect mature, but due to difficulties of the logging equipment transportation, and the complicated flow patterns, production logging technology of horizontal wells developed slowly. Many oil fields have already successfully developed horizontal wells, which have achieved good economic benefits, but long-term development leads to instability of well production, and water-cut of some horizontal wells rise rapidly as soon as the well starting to produce water, which consequently make oil production decreased significantly. To solve these problems, geological researchers must understand the underground condition to determine its better reform plan, which made even more urgent requirements to production logging. At present in China, more and more researches on horizontal well technology have been carried out.It is a big technological challenge to precisely measure the water-cut (hold-up) of down-hole oil-water two-phase flow. A double-ring conductance sensor is full borehole, invasive structure that can be used to measure water holdup in horizontal well. This paper described instrument's structure consisted of poles, support arm, support shaft, and so on.Hardware system is critical, it's performance can largely affect instrument's accuracy. We designed the circuit based on FPGA technique .It has a lot of I/O ports and can be configure as different function module by programming. The control on ADC, analog switch and encoder is completed by FPGA.Prototype has been produced. Indoor experiment shows that the instrument is able to correctly distinguish oil and water in the location of pole. The instrument turned out to work steadily and reliably.