Patent ID: 8739902

Claim:
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.