Construction principle of reverse circulation drilling system (RCD) construction method

Reverse circulation, also known as gas lift reverse circulation drilling, is the simplest, most efficient and most reliable method of slagging for drilling large diameter and deep holes. The operation method is as follows:

The air compressor provides compressed gas to be injected into the drill pipe below the water level through the pipe of the drill pipe, slightly higher than the drill bit. The compressed gas expands and rises on the drill pipe, and the specific gravity of the fluid in the drill pipe is lower than that of the fluid in the hole. And the pressure difference in the hole. The fluid in the drill pipe is continuously discharged, and the sand and gravel in the hole enter the drill pipe through the suction inlet of the drill bit and then discharge to the ground through the discharge pipe. This is the operating principle of using gas lift to transport the sand and gravel at the bottom of the hole to the ground.

The pressure difference and sand output are related to the compressed gas injection volume, injection depth, and delivery depth. During operation, the compressed gas injection volume can be selected according to the actual situation to make full use of energy.