A new concentric zonal water injection technique for highly-deviated wells

Abstract

Existing eccentric zonal water injection techniques cannot meet the requirements of separated layer water injection, testing and adjustment in highly-deviated wells, because of their low fishing success rate of down-hole nozzles, low efficiency of connection between instruments and nozzles, and low precision of zonal flow rate test. A new concentric zonal water injection technique is proposed for highly-deviated wells. This technique adopts concentric testing and adjustment, i.e., the test instrument is concentrically connected with the down-hole regulator, with high success rate of connection. The down-hole regulator uses bridge-type channel to effectively eliminate inter-layer interference and thereby improving testing and adjustment efficiency. Water flow rate is adjusted with an eccentric valve, which features small loss in full-off state, small adjustment torque and easier water adjustment. This technique is functional for both collected flow test and non-collected flow test, so it is workable for low flow rate test. It can achieve packer seal test on line by cable, the status of seal balls can be monitored and all seal test operations can be completed in one trip. This technique can obtain flow rate, pressure, temperature and other parameters of any layer on line and automatic testing and adjustment of injection allocation rate, without fishing, significantly improving testing and adjustment efficiency. Until now, this technique has been tested in 11 wells (maximum well deviation of 55°), with tested flow rate error of less than 5%, and three-layer seal check and adjustment time of less than one day. Compared with the existing techniques, this new technique has advantages such as high testing and adjustment efficiency, high precision and low cost. Key words: highly-deviated well, concentric zonal water injection, cable test and adjustment, cable seal test, automatic water allocation, testing and adjustment efficiency