Self-orienting perforating gun

Abstract

A self-orienting perforating gun includes an outer housing having a throughbore, a charge carrier positioned in the throughbore of the outer housing, a hub secured directly or indirectly to the outer housing, a bearing secured to each carrier end of the charge carrier wherein the bearing overlies the hub to provide a rotatable relationship between the hub and the charge carrier about a rotational axis within the outer housing, and an eccentric weight coupled to the charge carrier applying an off-axis orienting force to the charge carrier for urging the charge carrier to rotate about the rotational axis toward a predefined orientation relative to the direction of gravity.

What is claimed is: 
     
         1 . A self-orienting perforating gun for creating one or more perforations through casing in a wellbore formed in a subterranean earthen formation, the perforating gun comprising:
 an outer housing having a central throughbore;   a charge carrier positioned in the throughbore of the outer housing wherein the charge carrier comprises an elongate body and one or more charge receptacles;   a hub coupled to a longitudinal end of the outer housing and at least partially received in the throughbore of the outer housing;   a bearing coupled to a longitudinal end of the charge carrier to provide a rotatable relationship between the hub and the charge carrier about a rotational axis within the outer housing to provide a load path extending from the charge carrier, through the bearing, and to the hub; and   an eccentric weight coupled to the charge carrier applying an off-axis orienting force to the charge carrier for urging the charge carrier to rotate about the rotational axis toward a predefined orientation relative to the direction of gravity.   
     
     
         2 . The perforating gun according to  claim 1 , further comprising a tandem sub comprising the hub, wherein the tandem sub is threadably coupled to the longitudinal end of the outer housing. 
     
     
         3 . The perforating gun according to  claim 1 , further comprising a tandem sub that comprises a sub body coupled to the outer housing and the hub that is coupled to the bearing and projects longitudinally at a longitudinal end of the sub body. 
     
     
         4 . The perforating gun according to  claim 3 , wherein the hub is threadably coupled to the sub body. 
     
     
         5 . The perforating gun according to  claim 3 , wherein a maximum outer diameter of the sub body is greater than a maximum outer diameter of the hub. 
     
     
         6 . The perforating gun according to  claim 1 , wherein a minimum inner diameter of the bearing is greater than a minimum outer diameter of the hub. 
     
     
         7 . The perforating gun according to  claim 6 , wherein a maximum outer diameter of the hub is greater than a maximum outer diameter of the bearing. 
     
     
         8 . The perforating gun according to  claim 1 , wherein the bearing comprises a plurality of roller elements circumferentially spaced around the hub. 
     
     
         9 . The perforating gun according to  claim 8 , wherein the plurality of roller elements axially overlap the hub. 
     
     
         10 . The perforating gun according to  claim 1 , wherein the charge carrier comprises an endplate coupled to a longitudinal end of the body of the charge carrier, and wherein the bearing is secured to the endplate. 
     
     
         11 . The perforating gun according to  claim 1 , wherein the eccentric weight is positioned at least partially exterior the body of the charge carrier. 
     
     
         12 . The perforating gun according to  claim 1 , wherein the hub is entirely received in the throughbore of the outer housing. 
     
     
         13 . The perforating gun according to  claim 1 , wherein an outer surface of the hub is in sliding contact with an inner surface of the outer housing. 
     
     
         14 . A self-orienting perforating gun for creating one or more perforations through casing in a wellbore formed in a subterranean earthen formation, the perforating gun comprising:
 an outer housing having a throughbore extending between longitudinally opposed housing ends thereof;   a charge carrier positioned in the throughbore of the outer housing and comprising an elongate body with a pair of longitudinally opposed carrier ends thereof, one or more charge receptacles positioned between the opposed carrier ends;   a bearing assembly attached to each of the longitudinally opposed carrier ends; and   a switch in electrical communication with an electrical signal path that extends into the charge carrier from a first of the carrier ends and includes an electrically conductive primary ground path extending back from the switch to the first carrier end.   
     
     
         15 . The perforating gun according to  claim 14 , further comprising an electrically conductive secondary ground path in addition to the primary ground path where an electrical signal may pass parallel to the primary ground path. 
     
     
         16 . The perforating gun according to  claim 14 , wherein the ground path includes a ground brush arranged in continuous contact with a hub. 
     
     
         17 . The perforating gun according to  claim 16 , wherein an interface is formed along which the ground brush contacts and slides along the hub whereby the interface has an orientation transverse to a central axis of the perforating gun. 
     
     
         18 . The perforating gun according to  claim 16 , wherein an interface is formed along which the ground brush contacts and slides along the hub whereby the interface has an orientation disposed at a non-zero angle to a central axis of the perforating gun. 
     
     
         19 . The perforating gun according to  claim 14 , wherein the ground path comprises a ground brush having a radially inner end arranged in continuous contact with a longitudinally extending surface. 
     
     
         20 . A self-orienting perforating gun for creating one or more perforations through casing in a wellbore formed in a subterranean earthen formation, the perforating gun comprising:
 an outer housing having a throughbore extending between longitudinally opposed housing ends thereof;   a charge carrier positioned in the throughbore of the outer housing and comprising an elongate body with a pair of longitudinally opposed carrier ends thereof and wherein the charge carrier comprises one or more charge receptacles positioned between the opposed carrier ends and configured to receive one or more explosive charges, and wherein the charge carrier defines an axis of rotation about which the charge carrier is permitted to rotate within the throughbore of the outer housing; and   an electric pin connector supported by the outer housing along the axis of rotation having a length and a width in which the length is at least four times the width, the electric pin connector comprising frangible sections along the length thereof having a reduced bending strength relative to other sections of the electric pin connector.