Fluid drilling system with drill string and retro jets

A self-advancing drilling system, comprising:

• a drilling apparatus having at least one rotatable fluid cutting nozzle;
• an advancing device positioned to provide forward movement of the drilling apparatus, the advancing device including at least one retro nozzle positioned to provide a forward thrust to the at least one rotatable fluid cutting nozzle, the advancing device further comprising at least one side reaming nozzle;
• a protective cage disposed about the rotatable fluid cutting nozzle to at least restrict contact between the at least one rotatable fluid cutting nozzle and a wall of the bore hole as the at least one rotatable fluid cutting nozzle spins, the protective cage having a step behind a location where a fluid jet issuing from the at least one side reaming nozzle impinges the wall of the bore hole;
• a retractable, flexible conduit coupled to the drilling apparatus;
• and
• a feed and retraction device coupled to the flexible conduit to feed and retract the drilling apparatus.

A method for drilling a bore hole in an underground formation, comprising:

• supplying high-pressure fluid to a drilling head in the bore hole through a retractable, flexible, axially unsupported conduit coupled to the drilling head;
• expelling the high-pressure fluid from the drilling head to cut into the formation and increase a length of the bore hole;
• advancing the drilling head through the bore hole from a first position to a second position by directing a propulsive force from the drilling head;
• and
• moving the conduit through the bore hole as the drilling head advances from the first position to the second position;
• and
• steering the drilling head by directing at least one jet of fluid through at least one jet nozzle at an angle to an axis aligned with the length of the bore hole.

A method for drilling in a subterranean seam, comprising:

• drilling a first bore hole from the surface into the subterranean seam;
• forming a cavity in the first bore hole adjacent to the seam;
• passing a whipstock into the first bore hole and into the cavity;
• positioning a drilling head in a selected orientation in the cavity with the whipstock;
• and
• cutting a second bore from the cavity into and along the seam by:
• supplying high-pressure fluid to the drilling head in the second bore hole through a retractable, flexible, axially unsupported conduit coupled to the drilling head;
• expelling the high-pressure fluid from the drilling head to cut into the seam and increase a length of the second bore hole;
• advancing the drilling head through the second bore hole from a first position to a second position by directing a propulsive force from the drilling head;
• and
• moving the conduit through the second bore hole as the drilling head advances from the first position to the second position.

A method for drilling a bore hole in an underground formation, comprising:

• disposing in the bore hole a drilling apparatus having at least one rotatable fluid cutting nozzle;
• advancing the drilling apparatus through the bore hole by directing fluid through at least one retro nozzle to provide a forward thrust to the drilling apparatus;
• engaging a forward facing step of protective cage disposed about the rotatable fluid cutting nozzle with a protrusion on a wall of the bore hole as the nozzle spins;
• directing fluid from a side reaming nozzle of the drilling apparatus to engage the protrusion forward of the forward facing step and remove the protrusion and;
• supplying fluid to the drilling apparatus through a retractable, flexible conduit coupled to the drilling apparatus.

A retractable bore drilling apparatus for forming a bore hole in an underground formation, the apparatus comprising:

• a self-advancing drilling head having at least one high pressure fluid cutting nozzle configured to increase a length of the bore hole;
• an advancing device provided on the drilling head to provide forward movement of the drilling head from a first position in the bore hole to a second position in the bore hole;
• a retractable, flexible conduit coupled to the drilling head and coupleable to a source of high-pressure fluid, the conduit being axially moveable through the bore hole as the drilling head moves from the first position to the second position;
• and
• a steering device operatively coupled to the drilling head and configured to direct the drilling head in a forward direction, wherein the steering device includes at least one jet nozzle configured to direct a jet of fluid in a selected direction, and wherein the steering device further includes a deflecting member, the deflecting member being movable into and out of a jet of fluid passing through the at least one jet nozzle to deflect the stream, the deflecting member including a ring rotatable relative to the at least one jet nozzle between a first location with a portion of the ring engaged with the jet of fluid and a second location with the portion disengaged from the jet of fluid.