Research On Oil/water Two-phase Flow Conductance Imaging Technique In A Horizontal Well

Horizontal well is an important technology to improve the recovery ratio during the development of oil-gas field.Compared with vertical well,horizontal well technology can increase well production,recoverable reseaves and ultimate recovery ratio through the expansion of the reservoir drain area and the liquid inflow performance.Eventually,the economic efficiency of oil field could be improved.Horizontal well production profile logging could give fluid production of the productive interval of the horizontal well.However,due to the placement difficulty of the horizontal well logging instruments,the borehole fluid distribution and flow characteristics of complex factors,the development of the horizontal well production logging technology is severely delayed.The reliable measurement of downhole oil-water two-phase flow of water holdup has been a technical problem in horizontal well production logging.An array conductivity probe horizontal wells flow imaging logging system was designed and implemented in this paper.FPGA is the core device of the system,and the fuctions of signal acquisition,data storage,data codec,data transmission,and the host computer software are integrated together.The signal acquisition part uses 24 conductivity probes as the acquisition sensors of the oil and water signals.The 24 oil-water signal wires are directly connected to the FPGA I/O interface,and parallel acquisition method is used to increase the acquisition speed.To solve the problems such as interference rejection and the data attenuation in the high speed communication of long logging cable,the HDB3 codec circuit was designed based on FPGA.It could guarantee the speed and accuracy of downhole data transmission.The host coputer software is developed under the Visual Basic 6.0 environment,and the serial interface is used to communicate with the host computer.The host computer software could display the downhole oil-water status in three forms of dynamic map,waveform,and the value of the holdup.This system implemented monitoring of downhole oil-water states,and the measurement of the water retention rate.The array conductivity probe flow imaging prototype was designed and implemented,and the dynamic experiments in the vertical analog wells and level simulation well were carried out respectively.To vertical well,the plates of the oil bubble number between the flow and the water content was drawed.The comparative analysis was conducted between these two plates,and corresponding relation of the oil bubble number between the flow and the water content was obtained.To horizontal well,focus on oil-water stratification under different flow and water contents,the picture comparison and error analysis were carried out.Experimental results indicate that the real layered photos and the stratification results displayed in the host software are consistent.The system can be completed on the accurate monitoring of oil and water status of the horizontal wells.