Tension/collar/reamer assemblies and methods

A drill string for drilling an earth formation, the drill string comprising:

• a plurality of drilling assemblies, the drilling assemblies comprising:
• an outer tubular;
• a wash pipe axially mounted within said outer tubular;
• a high-density weight section between said wash pipe and said outer tubular and movable during downhole operation in an axial direction with respect to said outer tubular;
• wherein said plurality of drilling assemblies are axially connected in the drill string;
• wherein said wash pipes in the drill string provide a substantially continuous bore through the drill string.

A drilling assembly for use in a drill string for drilling an earth formation, the drill string comprising:

• an outer tubular;
• an inner tubular mounted within said outer tubular, said inner tubular comprising two separate parts, an inner upper part and an inner lower part;
• and
• a high-density weight section between said inner tubular and said outer tubular and being mounted to permit axial relative movement between said high-density weight section and said outer tubular during downhole operation.

A drill string for drilling an earth formation, the drill string being operable to provide a drilling weight, the drill string comprising:

• a plurality of drilling assemblies, the drilling assemblies comprising:
• an outer tubular;
• a high-density weight section within said outer tubular and movable in an axial direction with respect to said outer tubular;
• a force transfer member mounted for axial movement within said outer tubular;
• wherein said high-density weight section comprises a material with specific gravity greater than 10;
• a drill bit;
• wherein said plurality of drilling assemblies are axially connected in the drill string with said drill bit connected at the bottom of the drill string;
• wherein said force transfer members are operable to transfer a force through said outer tubulars to said drill bit to provide at least a portion of the drilling weight on said drill bit.

A method for drilling a straight wellbore for oil, gas and the like in an earth formation, the method comprising the steps of:

• a) providing a drilling rig;
• b) providing a drill bit;
• c) providing a plurality of drilling assemblies comprising:
• 1) an outer tubular;
• 2) a high-density weight section within said outer tubular and movable in an axial direction with respect to said outer tubular, said weight section comprising a material with specific gravity greater than 10;
• 3) a weight transmission element extending axially through said outer tubular;
• d) assembling a drill string comprising the drill bit and a number of drilling assemblies such that the weight of the high-density weight sections of the number of drilling assemblies are substantially transferred to said drill bit to provide at least a portion of a drilling weight on said drill bit.

A drilling assembly for use in a drill string for drilling an earth formation, the drilling assembly comprising:

• an outer tubular comprising an upper part connected to a middle part and a lower part connected to said middle part;
• a high-density weight section mounted within said outer tubular such that said upper part and said lower part may each be removed from said middle part without removal of said high-density weight section from said middle part of said outer tubular;
• and
• wherein the average weight per unit volume of the drilling assembly is greater than 0.283 pounds per cubic inch.

A method for placing in tension a downhole assembly utilized in a bottom hole assembly of a drill pipe string for drilling oil and gas wells, said method comprising:

• providing a plurality of tubulars comprising a plurality of associated connections, said plurality of tubulars being connectable together to form said downhole assembly;
• providing a plurality of slidable force transfer member within at least some of said plurality of tubulars such that said plurality of force transfer members are operable for transferring a sufficient axial compressive force through said connections to hold one or more of said plurality of tubulars in axial tension;
• and
• producing at least a portion of said sufficient axial compressive force utilizing thermal expansion within said tubulars.

A tension inducing sub for use with a drilling assembly, said drilling assembly comprising a plurality of tubulars and a plurality of force transfer elements slidably within said threaded tubulars operable to transfer a axial compressive force through said tubulars, said tension inducing sub comprising:

• a tubular housing;
• a connection for said tubular housing for connecting to said other of tubulars to form the drilling assembly;
• and
• a force transfer element slidable in said tubular housing, at least one high density weight element applying weight to said slidable force transfer element for transferring said axial compressive force through said connection to a force transfer element in an adjacent tubular wherein said force transfer elements apply compressive force to apply axial tension to said outer tubulars.