Shaped charge and method of modifying a shaped charge

1. A shaped charge liner for use with a separate and non-unitary charge case, the shaped charge liner comprising:

a cylindrically shaped lip member that is configured to engage the charge case, one end of the lip member defining a planar face having a diameter and an opposite end of the lip member defining a bottom face, a star shaped concavity extending between the planar and bottom faces of the lip member; and

a projecting section defined by side walls projecting from the planar face of the lip member to define an apex end at a location that is spaced furthest from the planar face in a direction along a main liner axis that passes through the apex end and the lip member, the side walls having both inner surfaces and outer surfaces, wherein a maximum width of the outer surfaces at an end of the projecting section opposite the apex end extends in a direction perpendicular to the main liner axis and is less than the diameter of the planar face of the lip member such that flat surfaces are defined on the planar face of the lip member between all portions of the end of the projecting section and an outer perimeter of the lip member, the projecting section being rotationally symmetric about the main liner axis such that the projecting section has discrete rotational symmetry about the main liner axis, a cross section of the projecting section in a plane perpendicular to the main liner axis defining a four or five pointed star shape of both the inner surfaces and the outer surfaces of the side walls of the projecting section;

wherein all of the inner surfaces and all of the outer surfaces of the side walls of the projecting section are flat, planar surfaces.

2. The liner as claimed in claim 1 , wherein the planar face of the lip member is circular.

3. The liner as claimed in claim 1 , wherein the concavity of the lip member is contiguous with a star shaped aperture of the projecting section so as to form a single contiguous star shaped opening.

4. The liner as claimed in claim 3 , wherein a width of the concavity of the lip member is wider than a width of the aperture of the projecting section in the direction perpendicular to the main liner axis.

5. The liner as claimed in claim 3 , wherein the concavity of the lip member has a smaller volume than the aperture of the projecting section.

6. The liner as claimed in claim 1 , wherein the liner is formed from a wrought metal.

7. The liner as claimed in claim 6 , wherein the liner is formed from a pressed metal powder, and the metal powder includes tungsten powder.

8. The liner as claimed in claim 6 , wherein the apex end of the projecting section defines an internal apex angle, and the angle is substantially 50 degrees or substantially 60 degrees.

9. The liner as claimed in claim 6 , wherein the projecting section is hollow.

10. The liner as claimed in claim 6 , wherein the liner is a reactive liner.

11. A perforator for perforating an oil/gas well and forming a hole in surrounding rock comprising a liner according to claim 6 , a charge case within which the liner is received and a quantity of high explosive positioned between the liner and the charge case.

12. The perforator as claimed in claim 11 , wherein the charge case is open at one end and wherein the open end of the charge case is rotationally symmetric.

13. The perforator as claimed in claim 11 , wherein the charge case is open at one end and wherein the open end is circularly symmetric.

14. A perforator gun comprising one or more perforators according to claim 11 .

15. A method of completing an oil or gas well comprising the step of providing a perforator according to claim 11 .

16. The liner as claimed in claim 6 , wherein the charge case defines a lower end, and the lip member engages a region of the charge case adjacent the lower end.