Wellhead system and method for installing a wellhead system

1. A method for installing upon a conductor pipe, having an interior diameter, a conductor pipe upper end, and a conductor pipe lower end extending into a ground surface, a wellhead system for supporting at least one section of a casing in a borehole to be drilled onshore into the ground surface, comprising:

lowering a wellhead housing on top of the conductor pipe upper end and welding the wellhead housing to the conductor pipe upper end, the wellhead housing having a wellhead housing upper end, a wellhead housing lower end, a wellhead housing central interior bore extending between the wellhead housing upper end and the wellhead housing lower end, and the wellhead housing upper end having an annular flange member, the wellhead housing central interior bore having a diameter that is smaller than the interior diameter of the conductor pipe;

securing a blowout preventer, having a blowout preventer upper end and a blowout preventer lower end, to the annular flange member of the wellhead housing upper end; the blowout preventer having a blowout preventer central interior bore extending between the blowout preventer upper end and the blowout preventer lower end, and the blowout preventer central interior bore having a diameter which is less than the interior diameter of the conductor pipe;

drilling a first borehole, adjacent to and in a spaced relationship from, the conductor pipe, after the wellhead housing has been welded to the conductor pipe and conducting the drilling through the blowout preventer central interior bore and the wellhead housing central interior bore;

suspending a first section of casing from the wellhead housing into the first borehole;

drilling a second borehole adjacent to, and in a spaced relationship from, the first section of casing; and

suspending a second section of casing from the wellhead housing into the second borehole.

2. The method of claim 1 , wherein the diameter of the wellhead housing central interior bore and the diameter of the blowout preventer central interior bore are substantially the same; and the diameter of the blowout preventer central interior bore is substantially less than the interior diameter of the conductor pipe.

3. The method of claim 1 , including utilizing as the wellhead housing, a wellhead housing having an annular shoulder on an outer wall surface of the wellhead housing lower end, the outer wall surface being at the wellhead housing lower end, and securing the wellhead housing to the conductor pipe upper end by welding the annular shoulder of the wellhead housing to the conductor pipe upper end.

4. A wellhead system for supporting at least one section of a casing in an onshore borehole, for use with a conductor pipe having an interior diameter and a conductor pipe upper end, comprising:

a wellhead housing having a wellhead housing upper end, a wellhead housing lower end, and a wellhead housing central interior bore extending between the wellhead housing upper end and the wellhead housing lower end, the wellhead housing upper end having an annular flange member, the wellhead housing central interior bore having a diameter that is smaller than the interior diameter of the conductor pipe, and the wellhead housing has an annular shoulder on an outer wall surface of the wellhead housing lower end, the outer wall surface being at the wellhead housing lower end, and the annular shoulder is adapted to be welded on top of the conductor pipe upper end;

a blowout preventer, having a blowout preventer upper end, a blowout preventer lower end, and a blowout preventer central interior bore, extending between the blowout preventer upper end and the blowout preventer lower end, the blowout preventer central interior bore having a diameter which is less than the interior diameter of the conductor pipe, the blowout preventer lower end being associated with the annular flange member of the wellhead housing upper end; and

the wellhead housing central interior bore and the blowout preventer central interior bore are in fluid communication.

5. The wellhead system of claim 4 , wherein the diameter of the wellhead central interior bore and the diameter of the blowout preventer central interior bore are substantially the same.

6. The wellhead system of claim 4 , wherein the diameter of the blowout preventer central interior bore is substantially less than the interior diameter of the conductor pipe.

7. The wellhead system of claim 4 , including a section of casing suspended from the wellhead housing.

8. A method for installing upon a conductor pipe, having an interior diameter, a conductor pipe upper end, and a conductor pipe lower end extending into a ground surface, a wellhead system for supporting at least one section of a casing in a borehole drilled into the ground surface, comprising:

lowering a 13⅝ inch wellhead housing on top of the conductor pipe upper end and welding the wellhead housing to the conductor pipe upper end, the wellhead housing having a wellhead housing upper end, a wellhead housing lower end, a wellhead housing central interior bore extending between the wellhead housing upper end and the wellhead housing lower end, and the wellhead housing upper end having an annular flange member, the wellhead housing central interior bore having a diameter that is smaller than the interior diameter of the conductor pipe;

securing a 13⅝ inch bore blowout preventer, having a blowout preventer upper end and a blowout preventer lower end, to the annular flange member of the wellhead housing upper end;

the blowout preventer having a blowout preventer central interior bore extending between the blowout preventer upper end and the blowout preventer lower end, and the blowout preventer central interior bore having a diameter which is less than the interior diameter of the conductor pipe;

drilling a first borehole, within and adjacent to and in a spaced relationship from, the conductor pipe, after the wellhead housing has been welded to the conductor pipe and conducting the drilling through the blowout preventer central interior bore and the wellhead housing central interior bore;

suspending at least one first section of casing from the wellhead housing into the first borehole;

drilling a second borehole within and, adjacent to, and in a spaced relationship from, the first section of casing; and

suspending at least one second section of casing from the wellhead housing into the second borehole.

9. The method of claim 8 , wherein the diameter of the wellhead housing central interior bore and the diameter of the blowout preventer central interior bore are substantially the same; and the diameter of the blowout preventer central interior bore is substantially less than the interior diameter of the conductor pipe.

10. The method of claim 8 , including utilizing as the wellhead housing, a wellhead housing having an annular shoulder on an outer wall surface of the wellhead housing lower end, the outer wall surface being at the wellhead housing lower end, and securing the wellhead housing to the conductor pipe upper end by welding the annular shoulder of the wellhead housing to the conductor pipe upper end.

11. An onshore wellhead system for supporting at least one section of a casing in an onshore borehole, for use with an onshore conductor pipe having an interior diameter and a conductor pipe upper end, comprising:

a 13⅝ inch wellhead housing having a wellhead housing upper end, a wellhead housing lower end, and a wellhead housing central interior bore extending between the wellhead housing upper end and the wellhead housing lower end, the wellhead housing upper end having an annular flange member, the wellhead housing central interior bore having a diameter that is smaller than the interior diameter of the conductor pipe, and the wellhead housing has an annular shoulder on an outer wall surface of the wellhead housing lower end, the outer wall surface being at the wellhead housing lower end, and the annular shoulder is adapted to be welded on top of the conductor pipe upper end;

a 13⅝ inch bore blowout preventer, having a blowout preventer upper end, a blowout preventer lower end, and a blowout preventer central interior bore, extending between the blowout preventer upper end and the blowout preventer lower end, the blowout preventer central interior bore having a diameter which is less than the interior diameter of the conductor pipe, the blowout preventer lower end being secured to the annular flange member of the wellhead housing upper end; and

the wellhead housing central interior bore and the blowout preventer central interior bore are in fluid communication.

12. The wellhead system of claim 11 , wherein the diameter of the wellhead central interior bore and the diameter of the blowout preventer central interior bore are substantially the same.

13. The wellhead system of claim 11 , wherein the diameter of the blowout preventer central interior bore is substantially less than the interior diameter of the conductor pipe.

14. The wellhead system of claim 11 , including a section of casing suspended from the wellhead housing.