Firing head and method of utilizing a firing head

A firing head assembly comprising:

• a tubular housing having a proximal end, a distal end and a tubular housing lumen extending between the proximal end and the distal end;
• a valve sleeve having a proximal end, a distal end and a valve sleeve axial lumen, the valve sleeve slidably disposed within the tubular housing lumen;
• a circulating valve slidably disposed within the valve sleeve axial lumen, the circulating valve having a piston end with a valve entrance and piston end circulating holes and a sealing end with sealing end circulating holes, a first section of the valve sleeve axial lumen sized to sealingly accommodate the piston end of the circulating valve and a second section of the valve sleeve axial lumen being of a reduced diameter to sealingly accommodate the sealing end of the circulating valve, a sealable section of the valve sleeve axial lumen is located between the second, reduced diameter section of the valve sleeve lumen and distal end of the valve sleeve;
• a biasing member configured to exert a force on the circulating valve toward the proximal end of valve sleeve;
• and
• an annulus defined by the piston end of the circulating valve, an inner wall of the valve sleeve, the second, reduced diameter section of the valve sleeve axial lumen and a circulating valve body portion connecting the piston end and the sealing end of the circulating valve, wherein;
• the piston end entrance is in fluid communication with the tubular housing lumen and the piston end circulating holes;
• the sealing end circulating holes are in fluid communication with the sealable lumen,
• the circulating valve occupies one of a circulating position or a non-circulating position in the valve sleeve, the circulating position being configured to allow fluid circulation between each of the tubular housing lumen, the piston end entrance, the piston end circulating holes, the annulus, the sealing end circulating holes and the sealable section of the valve sleeve axial lumen, and
• the non-circulating position is configured to prevent circulation between the annulus and sealing end circulating holes.

A method for activating a firing head assembly, the method comprising the steps of:

• disposing the firing head assembly adjacent a downhole tool, the firing head assembly comprising:
• a tubular housing having a first end, a second end and a lumen extending between the first end and the second end;
• a valve sleeve slidably disposed within the tubular housing lumen adjacent the first end of the tubular housing;
• a valve slidably disposed within the valve sleeve, the valve having a piston end exposed to the tubular housing lumen at the first end of the tubular housing;
• a lock mandrel having a head, a shaft, a distal end and a groove formed in the shaft adjacent the distal end;
• and
• a firing pin holder having an integral firing pin and a firing pin bolder latch;
• restraining axial movement of the valve sleeve in the tubular housing by one or more valve sleeve shear elements;
• restraining axial movement of the lock mandrel within the tubular housing by one or more lock mandrel shear elements;
• restraining the firing pin holder and firing pin from axial movement relative to the tubular housing by an engagement mechanism operably disposed between and contacting the lock mandrel and the firing pin holder latch;
• exerting a force on the valve in the absence of a drop ball;
• transmitting the force from the valve to the valve sleeve, resulting in failure of the valve sleeve shear element and releasing the valve sleeve to move axially;
• transmitting the force from the valve sleeve to the lock mandrel, resulting in failure of the lock mandrel shear element and releasing the lock mandrel to move axially;
• releasing the firing pin holder and firing pin by aligning the engagement mechanism and the lock mandrel groove.