Study on an Intermittent Power Generation Technology for Water Injection Wells

Abstract Currently, smart layered water injection technology is mostly powered by batteries or cables. Batteries have limited power and cables are complicated to install and easily damaged, neither of which can meet the power needs of downhole tools. This paper proposes a downhole power generation technology for water injection wells, using the kinetic energy of the injected water as the energy source and a small-diameter turbine generator to generate electricity. The device adopts an eccentric design, which does not take up the center channel and does not affect the normal production process of the intelligent layered water injection process. In the process of water injection, the water nozzle can be used to select the flow channel according to the demand for electricity so as to control the start and stop of the generator, realizing intermittent controllable power generation and improving the service life of the generator. A prototype was manufactured and a hydro generator test platform was constructed. The prototype was connected to the test process, and the circulating flow was pumped in by a variable frequency pump to simulate the downhole water injection environment, and the power generation performance of the prototype was tested under different flow rates. The test results show that the prototype works stably under the flow rate of 20-40m3/d, the output power increases with the flow rate, and the maximum output power is 12.4W, which meets the downhole power supply demand of intelligent water injection wells. In addition, the prototype has completed 720 hours of continuous experiment under 24m3/d flow rate with stable output voltage and current. This technology is expected to provide a new idea for solving the problem of long-term power supply for downhole electric control tools of water injection wells, effectively reduce the circuit maintenance cost of downhole electric control tools, and improve the long-term monitoring and automatic control level of water injection wells.