The invention discloses a downhole pressurizing water
injection device. The downhole pressurizing water
injection device comprises a water injection
pipe, a water injection rod column, a driving device, a
piston type pressurizing device, a
wellhead connector and a
water supply device, wherein the water injection
pipe is arranged inside a well, the lower end of the water injection
pipe communicateswith an oil layer, the
piston type pressurizing device is fixedly connected to the inner wall of the water injection pipe and the connecting portion is sealed, the bottom end of the water injection rod column is fixedly connected with a
piston of the piston type pressurizing device, the
wellhead connector is arranged at a
wellhead, the top end of the water injection pipe is connected with the wellhead connector in a sealed mode, the top end of the water injection rod column upwards penetrates out of the wellhead connector and then is connected with the driving device, the driving device and the
water supply device are both arranged on the ground of the wellhead, and the
water supply device communicates with the water injection pipe. The invention further provides a downhole pressurizing water injection method adopting the above downhole pressurizing water
injection device. According to the downhole pressurizing water injection device and method, a ground pressurizing device is not needed, more safety is achieved, and
technical support is provided for water injection failure and remote well single well tank water injection caused by the fact that a mechanical production well is converted into a water
injection well and the wellhead pressure of the water
injection well is high.