FIELD: oil and gas production industry.
SUBSTANCE: apackage of inventions is related to oil and gas industry, i.e. to drilling systems. Device includes drill string, run in hole; at that annulus is provided between string and wellbore wall and string includes longitudinal port for drill mud with outlet located in the bottom part of the string, the pump for drill mud injection to annulus through longitudinal port, drill mud discharge pipe connected by fluid medium with annulus, drill mud backpressure system connected by fluid medium with drill mud discharge pipe. Backpressure system includes bypass pipe and three-way valve installed between pump and longitudinal port. The pump is connected by fluid medium with drill mud discharge pipe via three-way valve and bypass pipe that bypasses, at least, a part of the mud longitudinal port. In accordance with the second invention object the backpressure system includes the first and the second flow limitation control devices.
EFFECT: increase of annulus pressure control efficiency and reliability.
8 cl, 3 dwg
