Drag bits with predictable inclination tendencies and behavior
AssigneeSmith International, Inc.
InventorsGraham Mensa-Wilmot, John H. Simmons
Life of this patent
Estimating the term…
Abstract
A drill bit with dropping tendencies includes an active region, a passive region, a biased mass distribution, an uneven torque generation, and an imbalance force vector directed toward the middle of the active region. Cutting elements in the active region of the drill bit may be more aggressive than those in the passive region through manipulation of, e.g., backrake angle, blade length, cutter sizes, blade angles and bit profile. The imbalance force vector may be achieved by manipulation of bit geometric parameters such as cutter radial position, angular position, longitudinal position, and rake angle.
Claims36
A drill bit with dropping tendencies for drilling a borehole, comprising:
- a bit body having a longitudinal axis and a bit face having an active zone and a passive zone;
- a first plurality of cutters on said face in said active zone;
- a second plurality of cutters on said face in said passive zone, said first plurality of cutters being more aggressive than said second plurality of cutters, wherein an imbalance force vector exists on said drill bit during said drilling from said first plurality of cutters and said second plurality of cutters, said imbalance force vector being directed toward the approximate middle of said active region of said drill bit.
A drill bit having dropping tendencies, comprising:
- a drill bit body having a drill bit diameter;
- a first blade of a first length located on said drill bit supporting body and a first plurality of cutters;
- a second blade of a second length and supporting a second plurality of cutters;
- wherein said first length is greater than said second length, said first plurality of cutters is dominant to said second plurality of cutters, and wherein said drill bit has a force imbalance force vector while drilling, said force imbalance force vector being directed in a direction more proximate said first blade than said second blade.
A method to design a drill bit with dropping tendencies, comprising:
- a) defining an active zone on said drill bit that covers a first angular portion of said drill bit, includes a first set of cutters, and cuts formation with a first aggressiveness;
- b) defining a passive zone on said drill bit that covers a second angular portion of said drill bit, includes a second set of cutters, and cuts formation with a second aggressiveness;
- c) calculating an imbalance force vector that is the total vector from at least said first set of cutters and said second set of cutters, said imbalance force vector being directed generally toward the axial center of said active region.
Dependencies are inferred from the claim text.