FIELD: well drilling.
SUBSTANCE: claimed group of inventions relates to the drilling oil and gas wells with downhole drilling motors, namely to a mud-lubricated bearing section and a bearing assembly for a drilling motor and a method for returning drilling mud to the central channel of the spindle in a mud-lubricated bearing section. A mud-lubricated bearing section for a drilling motor comprises a casing, a spindle, at least one mud-lubricated bearing, a piston, an intermediate annular space between the outer surface of the spindle and the inner surface of the casing, a flow path for the first fluid, a bottom seal, a chamber between the outer surface spindle and the inner surface of the casing and between the piston and the lower seal. At least one mud-lubricated bearing is located in the central bore of the casing and around the outer surface of the spindle above the fluid port in the spindle. At least one mud-lubricated bearing comprises a mud-lubricated radial bearing and an axial bearing. The piston is mounted with the possibility of sliding in the central channel of the casing and around the outer surface of the spindle below the fluid port in the spindle. The piston contains an internal piston seal interacting with the outer surface of the spindle, and an external piston seal interacting with the inner surface of the casing. The flow path for the first fluid passes through at least one mud-lubricated bearing, through the intermediate annulus, through at least one fluid port in the spindle, and into the central bore of the spindle. The chamber between the outer surface of the spindle and the inner surface of the casing and between the piston and the lower seal is configured to contain the second fluid. A method for returning drilling fluid to a centre bore of a spindle in a mud-lubricated bearing section includes filling a chamber with a second fluid that is grease or oil, supplying a first fluid through a mud-lubricated bearing, an intermediate annulus, a fluid port in the spindle, and into the port for the fluid in the spindle. In this case, the piston directs the first fluid into the intermediate annular space in the central channel of the spindle through the fluid hole in the spindle.
EFFECT: increased efficiency of drilling oil and gas wells with downhole drilling engines.
19 cl, 6 dwg
