One trip perforating and gravel pack system

In an apparatus for use in a well bore and adapted to be run into the well casing on a tubular work string and in a single run-in of said string in said well accomplish perforation of the well casing adjacent a production zone and placement of a gravel pack in the casing adjacent the interior of the casing perforation, comprising, in combination:

• an axially elongated tubular liner assembly including a hollow screen element;
• a first packer secured to the lower end of said tubular liner assembly below said hollow screen, said first packer being initially settable in engagement with the casing bore at a position above the production zone;
• a tubular housing assembly secured in concentric depending relation to said first packer by a conduit, said tubular housing assembly defining a sealed, vertical axis, cylindrical chamber to house perforating charges, the top end wall of said chamber including a percussion operated detonator;
• a tubular carrier of polygon cross sectional configuration concentrically insertable in said chamber, said carrier having N faces where N is an even number in excess of four;
• means for positioning said carrier in concentric relationship to the cylindrical wall of said sealed cylindrical chamber;
• a plurality of shaped charge containers of generally cylindrical configuration and each having a peripheral flange adjacent the discharge end, each of the faces of said polygonal tubular carrier having a plurality of vertically spaced apertures respectively proportioned to snugly receive one of said shaped charge containers therein with said peripheral flanges respectively abutting the outer faces of said polygonal tubular carrier, there being N/2 apertures having their axes disposed in each of a plurality of vertically spaced horizontal planes, whereby the shaped charge containers are positioned in a plurality of vertically spaced, horizontal groups with the shaped charge containers in each horizontal group angularly displaced from the shaped charge containers in the vertically adjacent group;
• means responsive to said percussion operated detonator for concurrently discharging all said shaped charges contained in each said horizontal group;
• a second packer secured to the upper end of said tubular liner assembly;
• a work string supported setting tool releasably connected to said second packer, a hollow crossover mandrel assembly depending from said setting tool, said setting tool having pressure responsive means for expanding said second packer into sealing engagement with the well casing, said crossover mandrel assembly being insertable in said liner assembly;
• said first and second packers, said liner, said hollow crossover mandrel assembly and said conduit defining, in their run-in position, a continuous axial passage to permit dropping an activating means onto said percussion operated detonator to discharge same and perforate the casing by said shaped charges;
• said first packer being subsequently releasable from its set position, lowered below the casing perforations by the work string and resettable in said lowered position;
• a ball valve seat sleeve mounted in the bore of said hollow mandrel assembly;
• means for retaining said sleeve in an initial run-in position;
• said sleeve receiving a dropped ball in sealing relation after the perforating operation, thereby permitting build up of fluid pressure in the work string;
• said second packer being then expandable by said fluid pressure into sealing engagement with said casing above said perforations;
• said liner assembly and said hollow crossover mandrel assembly having flow passages and spaced sealing means selectively positionable upon movement of said ball valve seat means downwardly relative to said second packer from said initial run-in position to a second position for directing gravel carrying fluid flowing downwardly through the work string into the well bore between said first and second packers, thence through said screen into the bottom of said crossover mandrel assembly, and thence outwardly into the well casing annulus at a point above said second packer, thereby permitting the packing of gravel around said hollow screen;
• said ball vable seat sleeve being shiftable to said second position upon a further increase in fluid pressure in said work string.

A well casing perforating gun employing shaped explosive charges to perforate the well casing and adjacent formation, comprising an outer tubular housing assembly concentrically insertable in the well casing and defining a vertical axis sealed cylindrical chamber, a tubular carrier of polygonal cross sectional configuration insertable in said chamber, said carrier having N faces where N is an even number in excess of four, means for positioning said carrier in concentric relationship to the cylindrical wall of said sealed cylindrical chamber, a plurality of shaped charge containers of generally cylindrical external configuration and having a peripheral flange adjacent the discharge end, each of the faces of said polygonal tubular carrier having a plurality of vertically spaced apertures proportioned to snugly receive one of said shaped charge containers therein with said peripheral flange abutting the outer face of said carrier, said apertures being aligned to form horizontally aligned groups of vertically spaced apertures, there being N/2 shaped charge containers in each horizontal group, whereby the shaped charge containers may be positioned in a plurality of vertically spaced, horizontal groups with the shaped charge containers in each horizontal group angularly displaced from the shaped charge containers in the vertically adjacent group, and means for discharging all said shaped charges contained in each said horizontal group.

A combined method of perforating and gravel packing the production zone of a subterranean well with one trip of a work string comprising the steps of:

• (1) assembling on a tubular polygonal carrier a plurality of shaped charges with the charges arranged in vertically spaced, horizontal groups with the charges in one horizontal group being angularly displaced relative to the charges in the vertically adjacent horizontal group;
• (2) inserting the carrier with the charges assembled thereto within a vertical axis chamber defined by a tubular housing and sealing said chamber by means including a detonator at the upper end thereof;
• (3) assembling at the surface for attachment to the end of a tubular work string, a hollow liner assembly including a production screen, a first settable and releasable packer secured to the lower end of the hollow liner assembly, a hydraulically settable packer secured to the upper end of the hollow liner assembly, a pressure operated actuator releasably connected to the first packer, and a hollow crossover mandrel assembly connected to the actuator and insertable within the liner assembly and defining a horizontal annular valve seat intermediate the first and second packer;
• (4) connecting the tubular housing containing the spaced shaped charges in depending relationship to the first packer:
• (5) lowering the work string with the above listed assemblies thereon in the well until the spaced shaped charges are positioned adjacent to the desired production zone;
• (6) setting the first packer in a position immediately above the desired production formation with the spaced shaped charges adjacent the desired production zone:
• (7) dropping a detonating element through the hollow work string, the bore of the hollow mandrel assembly, and the first packer to energize the detonator, discharge the spaced shaped charges and perforate the casing;
• (8) releasing the first packer and lowering the work string to position the first packer below the perforated production zone, and then resetting said first packer;
• (9) inserting a valve element through the work string to sealingly seat on said annular valve seat in the hollow crossover mandrel assembly, thereby permitting fluid pressure to be built up within the work string:
• (10) increasing the fluid pressure in the work string to a level sufficient to cause the actuator to set the second packer;
• (11) increasing the fluid pressure in the work string to a level sufficient to cause the downward displacement of the valve element of said hollow crossover mandrel assembly and open a radial fluid passage from the bore of said hollow crossover mandrel to the bore of said liner assembly;
• and
• (12) introducing gravel carrying fluid through the work string to flow through passages defined by the hollow crossover mandrel and the hollow liner assembly downwardly along the casing annulus between said first and second packers, through the production screen, and upwardly through the crossover assembly to the casing annulus at a point above said second packer.