Reverse circulation drill pipe,also known as double-wall drill pipe,is a kind of drilling tool used for reverse circulation drilling,which is composed of inner and outer layers of drill pipe (called inner pipe and outer pipe).An annular gap is for between that inner pipe and the out pipe,and the circulating medium flows to the bottom of the hole from the annular gap of thedouble-wall drill rod during drill.
The central hole of the inner pipe is used to take out the circulating medium and bring the core sample back to the surface.Each double-wall drill pipe is connected by the screw thread of the outer pipe to ensure the transmission of torque and pressure.The inner pipe is usually connected by plugging,which generally only plays the role of circulating the circulating medium. The plugging is equipped with a sealing device.Reverse circulation drilling can effectively prevent the collapse of the well wall and improve the drilling efficiency.
Reverse Circulation drill rod (also called dual-wall drill pipe) comprises an outer and inner pipe with a sealing system (usually 0 Rings) to keep the drill string pressurized. As RC drill rods are subjected to high wear in the drilling process Prodrill use only the high quality hardened alloy steel for the both rods and tool joints.