Apparatus and method for driving casing or conductor pipe

1. An apparatus for driving an open-ended conductor pipe into the ground comprising in combination:

an open-ended conductor pipe capable of being driven into the ground,

a drill string,

a means for pumping fluid through the drill string,

a means for supporting the conductor pipe on the drill string,

a reciprocable impact driving means supportable by the drill string within the conductor pipe,

a means for reciprocating the reciprocable impact driving means using fluid pumped through the drill string,

an anvil capable of transferring the percussive force of the reciprocable impact driving means to the conductor pipe; and

a means for jetting fluid into the lower portion of the conductor pipe.

2. An apparatus as claimed in claim 1 , further comprising shock absorbing means for reducing the percussive force transmitted between the conductor pipe and the drill string.

3. An apparatus as claimed in claim 1 , wherein the conductor pipe has an internal shoulder engageable with the anvil.

4. An apparatus as claimed in claim 1 , wherein the means for jetting fluid into the lower portion of the conductor pipe comprises a tubular element in fluid communication with either or both of the drill string and the reciprocal impact driving means; the tubular element having openings through which relatively high pressure fluid can pass into the lower portion of the conductor pipe.

5. An apparatus as claimed in claim 1 , wherein means are provided for breaking up the soil disturbed by the means for jetting fluid.

6. An apparatus as claimed in claim 1 , wherein the conductor pipe comprises two or more lengths of pipe, each successive length being of a smaller diameter than the preceding pipe.

7. An apparatus as claimed in claim 6 , wherein the conductor pipes are of different wall thickness.

8. A method for driving open-ended conductor pipe into the ground comprising:

assembling at the lower end of a drill string means for supporting an open-ended conductor pipe on the drill string, a reciprocable impact driving means, means for reciprocating the reciprocable impact driving means using fluid pumped through the drill string, an anvil capable of transferring the percussive force of the reciprocable impact driving means to the conductor pipe and means for jetting fluid,

positioning the assembly within a conductor pipe such that the assembly and conductor pipe are supportable by the drill string and the means for jetting fluid is at the lower end of the conductor pipe,

positioning the lower end of the conductor pipe on the ground into which it is to be driven,

actuating the reciprocable impact driving means to impact the anvil and drive the conductor pipe into the ground,

simultaneously or sequentially jetting fluid into the lower part of the conductor pipe such that it flows upwardly carrying with it particles that have been forced into the conductor pipe the fluid and particles being removed from the upper part of the conductor pipe.

9. A method as claimed in claim 8 , wherein the particles removed from the upper part of the conductor pipe overflow the conductor pipe and settle around the outside of the conductor pipe.

10. A method as claimed in claim 8 , wherein a first surface conductor pipe is driven into the ground and subsequently a second conductor pipe of smaller diameter is lowered through the first conductor pipe and the second is then driven into the ground below the first conductor pipe.

11. A downhole assembly comprising, attached at the lower end of a drill string means for supporting an open-ended conductor pipe on the drill string, a reciprocable impact driving means, means for reciprocating the reciprocable impact driving means using fluid pumped through the drill string, an anvil capable of transferring the percussive force of the reciprocable impact driving means to the conductor pipe and means for jetting fluid.