Method and apparatus for initiating subterranean well perforating gun firing from bottom to top

The perforating gun for a subterranean well, comprising:

• an elongated carrier insertible in the well;
• a plurality of shaped charge containers transversely mounted in said carrier in vertically spaced relation, each said shaped charge container having a primer end and a discharge end;
• a firing mechanism including a primer charge disposed above said shaped charge containers;
• and a plural-component primer means extending between said primer charge and booster charge and disposed adjacent the primer ends of said shaped charge containers;
• said plural-component primer means including elongated adjacent elements respectively formed from low energy and high energy detonatable materials;
• said low energy material being ignitable by said primer charge and said high energy material being ignitable only by said booster charge;
• the detonation energy of said low energy material being inadequate to ignite said high energy material or to fire said shaped charges, and the detonation of the high energy material being adequate to fire said shaped charges;
• whereby actuation of said firing mechanism results in sequential firing of the shaped charges from the lowermost one upwardly to the uppermost one.

A perforating gun for subterranean well, comprising:

• an elongated carrier insertable in the well;
• a plurality of shaped charge containers transversely mounted on said carrier in vertically spaced relation, each said shaped charge container having a primer end and a discharge end;
• a firing mechanism including a primer charge disposed above said shaped charge containers;
• a booster charge disposed below said shaped charge containers;
• a detonation energy transmitting cord extending between said primer charge and said booster charge, and a detonatable primer cord extending from said booster charge upwardly adjacent the primer end of each said shaped charge container.

A perforating gun comprising:

• a plurality of substantially identical, axially stacked tubular sections;
• each said section mounting a plurality of shaped charge containers in vertically and angularly spaced relation;
• said containers having detonating ends disposed concentrically about the section axis;
• a primer cord extending axially through each section;
• a booster charge on the top and bottom ends of each primer cord, whereby the bottom booster charge of each primer cord is axially adjacent to the top booster charge of the primer cord in the next lower section;
• a length of detonation transmitting tubing extending through each said second in parallel relationship to the axis thereof;
• a charge mounted on the bottom end of each said length to ignite the top end of said length in the next lower section;
• and means for shielding said primer cord booster charges from the detonation of the adjacent one of said charges;
• except the lowermost primer booster charge, whereby detonation energy is transferred successively downwardly through said gun sections to said charge in the bottom of the lowermost section, thereby detonating said lowermost primer booster charge.

The method of detonating a plurality of vertically spaced shaped charges of a perforating gun for a subterranean well, comprising the steps of:

• (1) at the well surface connecting a booster charge below all of the shaped charged and a firing mechanism above all of the shaped charges;
• (2) connecting a detonation transmitting cord between the firing mechanism and the booster charge, said cord, when detonated, being incapable of detonating the shaped charges but capable of detonating the booster charge;
• (3) running a primer cord in close proximity to each of said shaped charges and into contact with said booster charge;
• said primer cord being detonatable by said booster charge and having sufficient energy to successively fire each of said shaped charges;
• and
• (4) lowering the perforating gun into the well to the desired location and actuating said firing mechanism, whereby said shaped charges are successively fired from the lowermost one upwardly.

The method of detonating a plurality of vertically spaced shaped charges of a perforating gun for a subterranean well, comprising the steps of:

• (1) at the well top surface connecting a booster charge below all of the shaped charges and a firing mechanism above all of the shaped charges;
• (2) running a primer cord in close proximity to each of said shaped charges and into contact with said booster charge;
• said primer cord being detonatable by said booster charge and having sufficient energy to successively fire each of said shaped charges;
• (3) positioning said gun at a location within said well;
• and
• (4) conveying a detonation energy downwardly from the firing mechanism to said booster charge to detonate same, thereby detonating the bottom of said primer cord and successively firing said shaped charges from the lowermost one upwardly.

The method of detonating a plurality of vertically spaced shaped charges disposed in a plurality of axially stacked sections of a perforating gun for a subterranean well, comprising the steps of:

• (1) prior to assembling each gun section, axially mounting a primer cord in the gun section with a booster charge secured to the top and bottom ends of the primer cord;
• (2) prior to assembly of the gun section, disposing a length of a detonation transmitting cord in parallel relationship to the primer cord in each gun section and securing a charge to the lower end of the detonation transmitting cord;
• (3) assembling the successive gun sections and enclosing the gap between the axially adjacent booster charges on the top and bottom ends of the primer cords in a protective shield;
• (4) lowering the assembled gun sections in the well;
• and
• (5) detonating the top end of the detonation transmitting cord in the uppermost gun section, whereby detonating energy is transmitting downwardly successively by the detonation transmitting cord length to detonate the charge and thereby detonate the lowermost booster charge to successively detonate the primer cords from the lowermost one upwardly through all the gun sections.