High-speed triple string drilling system
AssigneeDura Drilling, Inc.
InventorRobert E. Able
Life of this patent
Estimating the term…
Abstract
A drilling system for boring into ground includes a bottom hole assembly having a rotatable casing shoe, an independently rotatable driveshaft disposed within the casing shoe, and a bearing housing interdisposed between the driveshaft and the casing shoe to control a distance between a centerline of the driveshaft and a centerline of the casing shoe. The driveshaft includes a bit disposed at a distal end thereof, extending beyond the casing shoe distal end. The driveshaft centerline and the casing shoe centerline are substantially parallel and radially offset.
Claims30
A drilling system for boring into ground, the drilling system comprising a bottom hole assembly comprising:
- a rotatable casing shoe comprising a distal end;
- an independently rotatable driveshaft disposed within the casing shoe, the driveshaft comprising a bit disposed at a distal end thereof extending beyond the casing shoe distal end;
- a bearing housing interdisposed between the driveshaft and the casing shoe to control a distance between a centerline of the driveshaft and a centerline of the casing shoe, wherein the driveshaft centerline and the casing shoe centerline are substantially parallel and radially offset;
- and
- a drill string assembly coupled to the bottom hole assembly, the drill string assembly comprising:
- an outer drill string coupled to the casing shoe;
- an inner drill string disposed within the outer drill string and coupled to the driveshaft, the inner drill string forming an interior passage;
- and
- an intermediate drill string interdisposed between the outer drill string and the inner drill string, the intermediate drill string coupled to the bearing housing.
A method for boring into ground, the method comprising the steps of:
- orbiting and advancing into the ground a high speed rotating bit mounted to a driveshaft to form a bore having a nominal diameter;
- following the bit with a casing shoe independently rotating at lower speed and having a diameter substantially equivalent to the nominal diameter;
- and
- controlling a distance between a centerline of the driveshaft and a centerline of the casing shoe with a bearing housing interdisposed between the driveshaft and the casing shoe, such that the driveshaft centerline and the casing shoe centerline are substantially parallel and radially offset, wherein
- (i) an outer drill string is coupled to the casing shoe;
- (ii) an inner drill string is disposed within the outer drill string and coupled to the driveshaft, the inner drill string forming an interior passage;
- and
- (iii) an intermediate drill string is interdisposed between the outer drill string and the inner drill string, the intermediate drill string is coupled to the bearing housing.
Dependencies are inferred from the claim text.