Drill bits
AssigneeWeatherford/Lamb, Inc.
InventorGiancarlo T. Pia
Life of this patent
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Abstract
An expandable drill bit (10) comprises a body (14) for mounting on a support string and two roller cutters (12, 13) mounted on the body (14). The cutters (12, 13) are movable between a smaller diameter first configuration and a larger diameter second configuration. In one embodiment the bit (10) is adapted to drill with the cutters (12, 13) in both the first and second configurations.
Claims52
An expandable drill bit comprising:
- a body for mounting on a support string;
- and
- at least two roller cutters mounted on the body, the cutters being movable between a smaller diameter first configuration and a larger diameter second configuration and the bit being adapted to drill with the cutters in both the first and second configurations.
The drill bit of any of the preceding claims, wherein faces of the cutters for contact with the rock during drilling always describe a complete swept circle as the bit is rotated.
The drill bit of any of the preceding claims, wherein the cutters are in the form of cones.
The drill bit of any of the preceding claims, wherein each cutter is rotatable about its main axis.
The drill bit of any of the preceding claims, wherein the cutter length is at least 50% of the body diameter.
The drill bit of any of the preceding claims, wherein the cutters are arranged to allow intermeshing of cutting structures on each cutter.
The drill bit of any of the preceding claims, wherein the cutters are rotatable about respective non-radial axes.
The drill bit of any of the preceding claims, wherein each cutter axis lies in a plane which is non-perpendicular to the main body axis.
The drill bit of any of the preceding claims, wherein the cutters are mounted on arms pivotally mounted to the body.
The drill bit of any of the preceding claims, wherein the cutters are supported at both ends.
The drill bit of any of the preceding claims, wherein the cutters are provided with bearings at both ends.
The drill bit of any of the preceding claims, further comprising means for actuating the cutters between the first and second configurations.
The drill bit of any of the preceding claims, wherein the actuating means comprises means for retaining the cutters in the second configuration.
The drill bit of any of the preceding claims, wherein the cutters are configured to permit back reaming when the cutters are in the second configuration.
The drill bit of any of the preceding claims, wherein the bit defines a lubricant reservoir for supplying lubricant to bearings and other moving parts provided in the bit.
The drill bit of any of the preceding claims, wherein the body defines jetting nozzles.
The drill bit of any of the preceding claims, wherein the body defines fluid outlets configurable to be selectively opened or closed, depending on the configuration of the cutters, and wherein, in use, the blade configuration may be determined from surface by monitoring the resulting fluid back pressure.
An expandable drill bit comprising:
- a body for mounting on a support string;
- and
- at least two roller cutters mounted on the body, the cutters being movable between a smaller diameter first configuration and a larger diameter second configuration.
A drilling method comprising the steps:
- providing an expandable drill bit comprising a body and at least two roller cutters mounted on the body, the cutters initially being in a smaller diameter first configuration;
- mounting the drill bit on a drill support and running the drill bit into a bore of a first diameter;
- moving the cutters to a larger diameter second configuration;
- and
- drilling the bore with the cutters in the second configuration and with the bit defining a cutting diameter greater than said first diameter.
A drill bit comprising:
- a body for mounting on a support string;
- and
- at least two roller cutters mounted on the body wherein inner ends of the cutters overlap.
Dependencies are inferred from the claim text.