Abstract: A perforation tool assembly is provided. The perforation tool assembly comprises an energy train, a first perforation gun, and a second perforation gun. The energy train comprises a moderator to reduce the speed of propagation of a detonation in a direction parallel to the axis of the perforation tool assembly. The first perforation gun comprises a plurality of explosive charges coupled to a first portion of the energy train. The second perforation gun comprises a plurality of explosive charges coupled to a second portion of the energy train, wherein the second portion of the energy train is coupled to the first portion of the energy train.

Abstract: A method of mitigating perforating effects produced by well perforating can include causing a shock model to predict perforating effects for a proposed perforating string, optimizing a compliance curve of at least one proposed coupler, thereby mitigating the perforating effects for the proposed perforating string, and providing at least one actual coupler having substantially the same compliance curve as the proposed coupler. A well system can comprise a perforating string including at least one perforating gun and multiple couplers, each of the couplers having a compliance curve, and at least two of the compliance curves being different from each other. A method of mitigating perforating effects produced by well perforating can include interconnecting multiple couplers spaced apart in a perforating string, each of the couplers having a compliance curve, and selecting the compliance curves based on predictions by a shock model of shock generated by the perforating string.

Abstract: A shock de-coupler for use with a perforating string can include perforating string connectors at opposite ends of the de-coupler, a longitudinal axis extending between the connectors, and a biasing device which resists displacement of one connector relative to the other connector in both opposite directions along the longitudinal axis, whereby the first connector is biased toward a predetermined position relative to the second connector. A perforating string can include a shock de-coupler interconnected longitudinally between components of the perforating string, with the shock de-coupler variably resisting displacement of one component away from a predetermined position relative to the other component in each longitudinal direction, and in which a compliance of the shock de-coupler substantially decreases in response to displacement of the first component a predetermined distance away from the predetermined position relative to the second component.

Abstract: A bending shock de-coupler for use with a perforating string can include perforating string connectors at opposite ends of the de-coupler. A bending compliance of the de-coupler may substantially increase between the connectors. A well system can include a perforating string including at least one perforating gun and multiple bending shock de-couplers, each of the de-couplers having a bending compliance, and at least two of the bending compliances being different from each other. A perforating string can include a bending shock de-coupler interconnected longitudinally between two components of the perforating string. A bending compliance of the bending shock de-coupler may substantially decrease in response to angular displacement of one of the components a predetermined amount relative to the other component.

Abstract: A shock de-coupler for use with a perforating string can include perforating string connectors at opposite ends of the de-coupler, a longitudinal axis extending between the connectors, and a biasing device which resists displacement of one connector relative to the other connector in both opposite directions along the longitudinal axis, whereby the first connector is biased toward a predetermined position relative to the second connector. A perforating string can include a shock de-coupler interconnected longitudinally between components of the perforating string, with the shock de-coupler variably resisting displacement of one component away from a predetermined position relative to the other component in each longitudinal direction, and in which a compliance of the shock de-coupler substantially decreases in response to displacement of the first component a predetermined distance away from the predetermined position relative to the second component.

Abstract: A method of mitigating perforating effects produced by well perforating can include causing a shock model to predict perforating effects for a proposed perforating string, optimizing a compliance curve of at least one proposed coupler, thereby mitigating the perforating effects for the proposed perforating string, and providing at least one actual coupler having substantially the same compliance curve as the proposed coupler. A well system can comprise a perforating string including at least one perforating gun and multiple couplers, each of the couplers having a compliance curve, and at least two of the compliance curves being different from each other. A method of mitigating perforating effects produced by well perforating can include interconnecting multiple couplers spaced apart in a perforating string, each of the couplers having a compliance curve, and selecting the compliance curves based on predictions by a shock model of shock generated by the perforating string.

Abstract: A perforating gun can include at least one explosive component, and a shock mitigation device including a shock reflector which indirectly reflects a shock wave produced by detonation of the explosive component. Another perforating gun can include a gun housing, at least one explosive component, and a shock mitigation device in the gun housing. The shock mitigation device can include a shock attenuator which attenuates a shock wave produced by detonation of the explosive component. Yet another perforating gun can include a shock mitigation device with an explosive material which produces a shock wave that interacts with another shock wave produced by detonation of an explosive component in a gun housing.

Abstract: A perforating gun can include at least one explosive component, and a shock mitigation device including a shock reflector which indirectly reflects a shock wave produced by detonation of the explosive component. Another perforating gun can include a gun housing, at least one explosive component, and a shock mitigation device in the gun housing. The shock mitigation device can include a shock attenuator which attenuates a shock wave produced by detonation of the explosive component. Yet another perforating gun can include a shock mitigation device with an explosive material which produces a shock wave that interacts with another shock wave produced by detonation of an explosive component in a gun housing.

Abstract: A wellbore apparatus includes a connector sub assembly having a body, the body having a first end adapted to couple to a first perforating sub component and a second, axially opposed end adapted to couple to a second perforating sub component. The connector sub body defines a cavity proximate the second end of the connector sub body; and a flow path in fluid communication with the cavity and a location exterior to the wellbore apparatus. The apparatus includes a valve residing in the flow path and actuatable to block or allow fluid flow from the cavity, through the flow path, to the location exterior to the wellbore apparatus.

Abstract: A perforation tool assembly is provided. The perforation tool assembly comprises an energy train, a first perforation gun, and a second perforation gun. The energy train comprises a moderator to reduce the speed of propagation of a detonation in a direction parallel to the axis of the perforation tool assembly. The first perforation gun comprises a plurality of explosive charges coupled to a first portion of the energy train. The second perforation gun comprises a plurality of explosive charges coupled to a second portion of the energy train, wherein the second portion of the energy train is coupled to the first portion of the energy train.

Abstract: A perforating system and method for use in a wellbore. In operation, the perforating system is disposed in the wellbore and used to form perforations in the wellbore. Thereafter, the perforating system is used to perform a sequence of underbalance pulsations in the wellbore, wherein a first underbalance pulsation has a first underbalance signature and a second underbalance pulsation has a second underbalance signature that is different from the first underbalance signature such that perforating tunnel clean up can be optimized based upon wellbore conditions and without causing damage to the perforating tunnels.

Abstract: A perforation tool assembly is provided. The perforation tool assembly comprises an energy train, a first perforation gun, and a second perforation gun. The energy train comprises a moderator to reduce the speed of propagation of a detonation in a direction parallel to the axis of the perforation tool assembly. The first perforation gun comprises a plurality of explosive charges coupled to a first portion of the energy train. The second perforation gun comprises a plurality of explosive charges coupled to a second portion of the energy train, wherein the second portion of the energy train is coupled to the first portion of the energy train.

Abstract: A shock de-coupler for use with a perforating string can include perforating string connectors at opposite ends of the de-coupler, a longitudinal axis extending between the connectors, and a biasing device which resists displacement of one connector relative to the other connector in both opposite directions along the longitudinal axis, whereby the first connector is biased toward a predetermined position relative to the second connector. A perforating string can include a shock de-coupler interconnected longitudinally between components of the perforating string, with the shock de-coupler variably resisting displacement of one component away from a predetermined position relative to the other component in each longitudinal direction, and in which a compliance of the shock de-coupler substantially decreases in response to displacement of the first component a predetermined distance away from the predetermined position relative to the second component.

Abstract: A method can include interconnecting a well tool in a well tool assembly with a shock mitigating connection, the interconnecting being performed without threading, and positioning the well tool assembly in a wellbore. A well perforating assembly can include at least two perforating devices, a detonation train extending through the perforating devices, and a shock absorber positioned between the perforating devices. A method of assembling a perforating assembly can include, prior to installing the perforating assembly in a wellbore, pushing one perforating device connector into another perforating device connector without threading the connectors together, thereby: a) preventing disconnection of the connectors and b) making a connection in a detonation train. A well system can include a perforating assembly including multiple perforating guns and multiple shock absorbers. Each shock absorber may be interconnected between at least two of the perforating guns.

Abstract: A method can include interconnecting a well tool in a well tool assembly with a shock mitigating connection, the interconnecting being performed without threading, and positioning the well tool assembly in a wellbore. A well perforating assembly can include at least two perforating devices, a detonation train extending through the perforating devices, and a shock absorber positioned between the perforating devices. A method of assembling a perforating assembly can include, prior to installing the perforating assembly in a wellbore, pushing one perforating device connector into another perforating device connector without threading the connectors together, thereby: a) preventing disconnection of the connectors and b) making a connection in a detonation train. A well system can include a perforating assembly including multiple perforating guns and multiple shock absorbers. Each shock absorber may be interconnected between at least two of the perforating guns.

Abstract: A bending shock de-coupler for use with a perforating string can include perforating string connectors at opposite ends of the de-coupler. A bending compliance of the de-coupler may substantially increase between the connectors. A well system can include a perforating string including at least one perforating gun and multiple bending shock de-couplers, each of the de-couplers having a bending compliance, and at least two of the bending compliances being different from each other. A perforating string can include a bending shock de-coupler interconnected longitudinally between two components of the perforating string. A bending compliance of the bending shock de-coupler may substantially decrease in response to angular displacement of one of the components a predetermined amount relative to the other component.

Abstract: A method of mitigating perforating effects produced by well perforating can include causing a shock model to predict perforating effects for a proposed perforating string, optimizing a compliance curve of at least one proposed coupler, thereby mitigating the perforating effects for the proposed perforating string, and providing at least one actual coupler having substantially the same compliance curve as the proposed coupler. A well system can comprise a perforating string including at least one perforating gun and multiple couplers, each of the couplers having a compliance curve, and at least two of the compliance curves being different from each other. A method of mitigating perforating effects produced by well perforating can include interconnecting multiple couplers spaced apart in a perforating string, each of the couplers having a compliance curve, and selecting the compliance curves based on predictions by a shock model of shock generated by the perforating string.

Abstract: A shock de-coupler for use with a perforating string can include perforating string connectors at opposite ends of the de-coupler, a longitudinal axis extending between the connectors, and a biasing device which resists displacement of one connector relative to the other connector in both opposite directions along the longitudinal axis, whereby the first connector is biased toward a predetermined position relative to the second connector. A perforating string can include a shock de-coupler interconnected longitudinally between components of the perforating string, with the shock de-coupler variably resisting displacement of one component away from a predetermined position relative to the other component in each longitudinal direction, and in which a compliance of the shock de-coupler substantially decreases in response to displacement of the first component a predetermined distance away from the predetermined position relative to the second component.

Abstract: A perforating gun gravitational orientation system includes a perforating gun and a swivel device connected to the perforating gun to permit rotation of the perforating gun within casing, and the perforating gun spaced apart from the casing by the swivel device. Another perforating gun gravitational orientation system includes the swivel device having an axis of rotation which is spaced apart from a center of gravity of the perforating gun. Yet another perforating gun gravitational orientation system includes the swivel device having an axis of rotation which is spaced apart from a center axis of the perforating gun.

Abstract: A perforating gun gravitational orientation system includes a perforating gun and a swivel device connected to the perforating gun to permit rotation of the perforating gun within casing, and the perforating gun spaced apart from the casing by the swivel device. Another perforating gun gravitational orientation system includes the swivel device having an axis of rotation which is spaced apart from a center of gravity of the perforating gun. Yet another perforating gun gravitational orientation system includes the swivel device having an axis of rotation which is spaced apart from a center axis of the perforating gun.