Research and Application of Novel Bridge Concentric Zonal Water Injection Technology
Authors: Liu Yang , Wang Xudong , Song Zuchang , Gai Xubo , Lai Xueming , Hu Shifeng , Yang Haichao , Zhang Hongwei 
Published: March 2021

Bridge concentric zonal water injection technology adopts integrated structural design of water distributor and adjustable water nozzle. It has a high success rate of docking test instrument and water distributor when measuring and adjusting. It can realize measurement and adjustment of downhole water distributor. At the same time, downhole parameters of measurement and adjustment can be direct read from surface. However, there are some disadvantages of existing bridge concentric zonal water injection technology, such as downhole water distributor has large adjustment torque, water leakage in full-off state, low precision of zonal flow rate test. These problems make it difficult for bridge concentric zonal water injection technology to meet zonal water injection of high temperature, high pressure and high deviated deep wells.

This paper proposes a new bridge concentric zonal water injection technology, which has advantages of original concentric and eccentric zonal water injection technologies. The test instrument of this new technology is concentrically connected with downhole water distributor. Water inject rate can be adjusted with an eccentric valve. A gear transmission structure has been used in eccentric valve which can reduce torque by more than 70%. This can effectively improve the success rate of measurement and adjustment. In order to ensure that packers can be set more conveniently, a new T-type seal ring has been used in the water nozzle, which features no water leakage in full-off state. The downhole water distributor uses bridge channel to effectively eliminate interlayer interference. In addition, water nozzle adopts a herringbone opening structure design in order to improve the accuracy of measurement and adjustment. The integrated measurement and adjustment technology of downhole flowrate also can obtain flowrate, pressure, temperature and other parameters of any layer on line, which will significantly improve testing and adjustment efficiency. It can achieve packer sealing test on line through cable by using electrically controlled sealing test for packer technology. All packer sealing test operations can be completed in one trip. At the same time, this electrically controlled sealing test technology will improve efficiency and accuracy for packer sealing test.

Until now, this technology has been tested in 175 wells with maximum depth 3823m, maximum deviation 43.75°, maximum reservoir temperature 155°C, up to 4 injection layers. The maximum wellhead pressure during measurement is 33.8MPa and flow rate error is less than 5%. Besides, time consuming of sealing test, measurement and adjustment for one injection well is 4-5h.

Compared with existing technologies, this new technology has some advantages, such as high testing and adjustment successful rate, high efficiency, high precision and low cost etc. The research results can provide a reference for fine water injection development to enhance oil recovery in multi-layer reservoirs.