Reverse circulation jet pump and reaming stabilizer
View Patent ↗A jet pump reamer/stabilizer drilling assembly is used during the underbalanced or near-balanced drilling of an oil, gas, geothermal, or sequestration well or disposal reservoir to create a low pressure zone around the drill bit. The design of this jet pump drilling reamer/stabilizer assembly limits the flow of drilling/power fluid through the drill bit. The drilling fluid circulation behind the drill bit is a conventional flow down the drill pipe and back up through the annulus. The drilling fluid circulation around and up through the drill bit is reverse circulation.
1 . A system for drilling an oil, gas, geothermal, or sequestration well or waste disposal reservoir comprising;
a drill pipe;
a drilling fluid pumped down the drill pipe;
a bottom hole assembly attached to the drill pipe, the bottom hole assembly further comprising;
a jet pump housing containing a jet pump, the jet pump having a venturi system through which the drilling fluid pumped down the drill pipe is directed into an annulus between the wellbore and the drill pipe;
conduits in the jet pump housing through which some drilling fluid flows from within the jet pump housing via orifices into the wellbore around the drill bit, through the drill bit and venturi system and back to the surface;
a reamer/stabilizer surrounding the jet pump housing and
a rotary drill bit attached to the bottom hole assembly.
2 . The system of claim 1 wherein the volume of drilling fluid allowed to flow through the conduits and around the rotary drill bit is controlled by changing the diameter of the orifices.
3 . The system of claim 1 wherein the reamer/stabilizer is not fluted.
4 . The system of claim 1 wherein the small quantity of drilling fluid flowing through the orifices increases in velocity and acts as a pressure washer to clean drilling debris from the walls of the well bore immediately behind the drill bit.
5 . The system of claim 1 , wherein the drilling fluid is a light weight fluid.
6 . The System of claim 1 wherein the drill bit has nozzles reconfigured as suction ports.
7 . The system of claim 1 wherein the drill bit has ports removed to allow the upward flow of drilling fluid.