Abstract: A system can include multiple explosive assemblies, each assembly comprising an outer housing, an explosive component rotatable relative to the housing, and a selective firing module which causes detonation of the component in response to a predetermined signal. A method can include assembling multiple explosive assemblies at a location remote from a well, installing a selective firing module, an electrical detonator and an explosive component in a connector, and connecting the connector to an outer housing, and then transporting the assemblies from the remote location to the well. A well perforating method can include assembling multiple perforating guns, each gun comprising a gun body, a perforating charge, and a selective firing module which causes detonation of the charge in response to a predetermined signal. The guns are installed in a wellbore, with the charge of each gun rotating relative to the respective gun body.

Abstract: A system can include multiple explosive assemblies, each assembly comprising an outer housing, an explosive component rotatable relative to the housing, and a selective firing module which causes detonation of the component in response to a predetermined signal. A method can include assembling multiple explosive assemblies at a location remote from a well, installing a selective firing module, an electrical detonator and an explosive component in a connector, and connecting the connector to an outer housing, and then transporting the assemblies from the remote location to the well. A well perforating method can include assembling multiple perforating guns, each gun comprising a gun body, a perforating charge, and a selective firing module which causes detonation of the charge in response to a predetermined signal. The guns are installed in a wellbore, with the charge of each gun rotating relative to the respective gun body.

Abstract: A method and apparatus are presented for actuating a differential pressure firing head to actuate a perforating gun at a downhole location in a subterranean wellbore adjacent a formation. An exemplary method includes positioning the perforating gun and the differential pressure firing head at a downhole location on a tubing string and then communicating an applied fluid pressure to a wellbore annulus, a first chamber which communicates the applied fluid pressure to a low-pressure side of the firing head assembly, and a second fluid chamber which communicates the applied fluid pressure to a high-pressure side of the firing head assembly. The applied fluid pressure is then trapped within the second fluid chamber. When the applied pressure in the annulus is subsequently removed, a pressure differential is created across the firing head by the low pressure in the first chamber and the trapped applied pressure in the second chamber.

Abstract: A method and apparatus are presented for actuating a differential pressure firing head to actuate a perforating gun at a downhole location in a subterranean wellbore adjacent a formation. An exemplary method includes positioning the perforating gun and the differential pressure firing head at a downhole location on a tubing string and then communicating an applied fluid pressure to a wellbore annulus, a first chamber which communicates the applied fluid pressure to a low-pressure side of the firing head assembly, and a second fluid chamber which communicates the applied fluid pressure to a high-pressure side of the firing head assembly. The applied fluid pressure is then trapped within the second fluid chamber. When the applied pressure in the annulus is subsequently removed, a pressure differential is created across the firing head by the low pressure in the first chamber and the trapped applied pressure in the second chamber.

Abstract: A system can include multiple explosive assemblies, each assembly comprising an outer housing, an explosive component rotatable relative to the housing, and a selective firing module which causes detonation of the component in response to a predetermined signal. A method can include assembling multiple explosive assemblies at a location remote from a well, installing a selective firing module, an electrical detonator and an explosive component in a connector, and connecting the connector to an outer housing, and then transporting the assemblies from the remote location to the well. A well perforating method can include assembling multiple perforating guns, each gun comprising a gun body, a perforating charge, and a selective firing module which causes detonation of the charge in response to a predetermined signal. The guns are installed in a wellbore, with the charge of each gun rotating relative to the respective gun body.

Abstract: Pressure cycle operated apparatus and methods. A method of actuating a firing head includes the steps of: reciprocably displacing an actuator piston of the firing head, the displacing step including the piston being alternately pressure balanced and unbalanced; and igniting a combustible material in response to the piston displacing step. A method of generating electricity includes: reciprocably displacing a piston, the displacing step including the piston being alternately pressure balanced and unbalanced; and generating electricity in response to the piston displacing step. A firing head includes an actuator piston separating at least two chambers; a check valve which permits one-way flow between the chambers; a flow restrictor which restricts flow between the chambers; a biasing device which biases the piston toward one of the chambers; and a firing pin releasing device which releases a firing pin in response to displacement of the piston.

Abstract: Pressure cycle operated apparatus and methods. A method of actuating a firing head includes the steps of: reciprocably displacing an actuator piston of the firing head, the displacing step including the piston being alternately pressure balanced and unbalanced; and igniting a combustible material in response to the piston displacing step. A method of generating electricity includes: reciprocably displacing a piston, the displacing step including the piston being alternately pressure balanced and unbalanced; and generating electricity in response to the piston displacing step. A firing head includes an actuator piston separating at least two chambers; a check valve which permits one-way flow between the chambers; a flow restrictor which restricts flow between the chambers; a biasing device which biases the piston toward one of the chambers; and a firing pin releasing device which releases a firing pin in response to displacement of the piston.

Abstract: Pressure cycle operated apparatus and methods. A method of actuating a firing head includes the steps of: reciprocably displacing an actuator piston of the firing head, the displacing step including the piston being alternately pressure balanced and unbalanced; and igniting a combustible material in response to the piston displacing step. A method of generating electricity includes: reciprocably displacing a piston, the displacing step including the piston being alternately pressure balanced and unbalanced; and generating electricity in response to the piston displacing step. A firing head includes an actuator piston separating at least two chambers; a check valve which permits one-way flow between the chambers; a flow restrictor which restricts flow between the chambers; a biasing device which biases the piston toward one of the chambers; and a firing pin releasing device which releases a firing pin in response to displacement of the piston.

Abstract: Pressure cycle operated apparatus and methods. A method of actuating a firing head includes the steps of: reciprocably displacing an actuator piston of the firing head, the displacing step including the piston being alternately pressure balanced and unbalanced; and igniting a combustible material in response to the piston displacing step. A method of generating electricity includes: reciprocably displacing a piston, the displacing step including the piston being alternately pressure balanced and unbalanced; and generating electricity in response to the piston displacing step. A firing head includes an actuator piston separating at least two chambers; a check valve which permits one-way flow between the chambers; a flow restrictor which restricts flow between the chambers; a biasing device which biases the piston toward one of the chambers; and a firing pin releasing device which releases a firing pin in response to displacement of the piston.