| CPC E21B 7/04 (2013.01) [E21B 4/003 (2013.01); E21B 4/02 (2013.01)] | 20 Claims |
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10. A method of drilling a wellbore, the method comprising:
flowing drilling fluid within the wellbore to operate a mud motor to rotate a driveshaft to rotate a drill bit to drill the wellbore;
rotatably supporting the driveshaft using a bearing assembly comprising a radial bearing comprising an internal radial gap;
diverting at least portion of the drilling fluid from a bore of the driveshaft into a bypass fluid flow path through the bearing assembly;
controlling a pressure of the drilling fluid in the driveshaft downstream of the bypass fluid flow path by restricting flow of the drilling fluid into the bypass fluid flow path using an annular flow restrictor;
wherein restricting flow into the bypass fluid flow path further comprises the annular flow restrictor creating a restrictor clearance between an inner sleeve rotatable with the driveshaft relative to a restrictor housing and an outer sleeve rotationally stationary with respect to the restrictor housing; and
dynamically radially supporting the outer sleeve and allowing the outer sleeve to move eccentrically relative to the restrictor housing such that a radial load absorbed by the annular flow restrictor from eccentric movement of the driveshaft is below a selected threshold.
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