| Separated layer water injection can adjust the water injection flow according to the productivity of each reservoir and improve the development effect of water drive oil field.It is an effective method to achieve high and stable production of oil field,and it is also a frontier topic at home and abroad.The existing water injection methods include general water injection and separated layer water injection with regular testing and adjustment.The water injection condition is unknown during the two test and adjustment periods of several months.In view of the above problems,a separated layer flow testing and adjustment method with implanted cable is proposed,which can monitor downhole water injection condition in real-time and online,and provide technical guarantee for high efficiency water injection in oil field.In this paper,on the premise of separated layer flow testing and adjustment of implanted cable,the downhole preset cable is docking with the ground controller to realize the bidirectional direct current carrier communication between the downhole test and the ground control.The real-time monitoring and control technology of the separated layer flow information of water injection wells are development,forming the implanted separated layer water flow adjustment and control system with relatively complete functions.The specific contents are as follows:(1)In order to optimize the demand for water injection,the theoretical model of adjustable nozzle of downhole water distributor is established.The flow coefficient of nozzle under different opening is obtained by FLUENT numerical simulation and the experimental test,and the suitable nozzle structure and opening are selected.(2)Circuit of downhole flow testing and adjustment is designed to measure parameters such as flow,temperature,pressure,nozzle opening and so on,uploading the test results to the ground through a single core cable.Which form a closed-loop test and adjustment system.(3)On the basis of simulation analysis and circuit research,the PWM regulation speed by DC motor is adopted to control the opening of the nozzle,also introducing the expert PID controller.Which make the flow regulation more rapid and stable,avoiding the interference of each layer.(4)For accurately measuring the water injection flow,a high-precision and high-reliability electromagnetic flowmeter suitable for the downhole environment of water injection well is developed.The relevant experiments are carried out and achieved good effects.(5)According to the requirements of ground command downloading and downhole data uploading,the impedance characteristics of high temperature and high pressure special single core cable are analyzed.The suitable coding mode and coupling system are selected to realize the high efficiency bidirectional transmission between the downhole and the ground.(6)For the sake of elimination the unreliability and failure factors of cable connection,considering the demands of high reliability and low cost of intelligent wells in the future,the self-generating technology is studied based on water injection flow as the motive force,and the prototype of water injection is tried.On the basis of the study of each components,the flow testing and adjustment experiments are carried out by using the water injection simulation platform built in the laboratory.The test results of two water injection layers testing and adjustment show that the implanted separated layer water flow testing and adjusting system can work normally and stably.The deviation between the measured value and the given value is about 1m~3/d each days,achieving higher adjustment accuracy.Moreover,the adjustment time is obviously shortened,the efficiency of adjustment and the displacement effects can be effectively improved.The technology realizes the intelligent and automatic of water injection adjustment with good application prospect for fine water injection in oil field. |
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