A safety mechanism and method for downhole perforating are disclosed. In one example, a mechanical firing head includes a firing pin carried on a pin carrier within a housing. The firing pin is movable from a retracted position to a firing position for striking an explosive initiator. A retention member retains the firing pin in the retracted position with the safety member in the armed position. A safety member is biased to a safety position that additionally blocks movement of the firing pin. The safety member is moveable to an armed position that unblocks movement of the firing pin in response to an arming pressure supplied to the housing bore. The retention member releases the firing pin in response to a firing pressure supplied to the housing in excess of the firing pressure.

A firing head assembly may include a tubular housing; a valve slidably disposed within the tubular housing; a lock mandrel disposed in the tubular housing between the valve and the tubular housing second end; a firing pin holder disposed in the tubular housing between the lock mandrel and the tubular housing second end; an engagement mechanism operably contacting the lock mandrel and the firing pin holder latch. The valve may have a piston end exposed to the lumen. The lock mandrel may be restrained from axial movement by a shear element. The firing pin holder may include a firing pin and latch. The engagement mechanism may be switchable between an engaged arrangement and a disengaged arrangement. The engagement mechanism may be configured to transition from the engaged arrangement to the disengaged arrangement in response to an axial movement of the lock mandrel.

A time delay tool and method in a wellbore casing is disclosed. The tool/method includes a mechanical restraining element, a reservoir for containing a reactive fluid, an actuating device and a wellbore device. When a stored energy is applied on the wellbore device, the actuation device is actuated and enables the reactive fluid in the reservoir to come in contact with the mechanical restraining element. While the mechanical restraining element undergoes a change in shape due to a chemical reaction, a stored energy applied on the wellbore device is delayed by a pre-determined time delay. The amount of the pre-determined time delay is determined by factors that include the reactive fluids, concentration of the reactive fluids, geometry and size of the mechanical restraining element.

A firing head assembly may include a tubular housing; a valve slidably disposed within the tubular housing; a lock mandrel disposed in the tubular housing between the valve and the tubular housing second end; a firing pin holder disposed in the tubular housing between the lock mandrel and the tubular housing second end; an engagement mechanism operably contacting the lock mandrel and the firing pin holder latch. The valve may have a piston end exposed to the lumen. The lock mandrel may be restrained from axial movement by a shear element. The firing pin holder may include a firing pin and latch. The engagement mechanism may be switchable between an engaged arrangement and a disengaged arrangement. The engagement mechanism may be configured to transition from the engaged arrangement to the disengaged arrangement in response to an axial movement of the lock mandrel.

A mechanical firing system is used to detonate energetic material, such as external perforating charges, disposed on an apparatus deployed on tubing in a wellbore. In one embodiment, a through-bulkhead explosive energy transfer is used to deliver the detonation from the mechanical firing system to an external detonator. In another embodiment, the mechanical firing system delivers an electric pulse to initiate a detonator. A through-wire pressure bulkhead isolates the source of electric power from the wellbore environment. The electrical source can be a magneto-based device or can use a piezo-electric device.

A firing head configured to initiate the firing of an element in a perforating gun. The firing head includes an insert having a bore extending along a longitudinal direction X; a percussion detonator facing the bore and including an explosive material that is configured to detonate; a firing pin located partially in the bore; and a retention mechanism located on the firing pin and preventing the firing pin to move along the longitudinal direction X into the bore. The retention mechanism includes a degradable material that is configured to chemically react with a well fluid so that the retention mechanism degrades until freeing the firing pin so that the firing pin moves along the longitudinal direction X into the bore and strikes the percussion detonator.

A firing head assembly for use with a perforating gun is described. The firing head assembly includes a tubular housing, first and second pistons, and a compressible member arranged within a lumen of the tubular housing and positioned between the first and second pistons. According to an aspect, the assembly includes a plurality of upper locking arms and lower locking arms that engage with locking members formed in the tubular housing. The firing head assembly further includes upper and lower shear washers arranged at the second opening of the tubular body, in a sandwich type configuration with respect to the second piston. Pressures within the firing head assembly may be adjusted to activate the firing head assembly to either trigger an explosive reaction or to not trigger the explosive reaction.

An apparatus comprises perforating guns, bypass, and isolator mechanism. The first gun fires upon receipt of a first pressure signal delivered from a first axial side of the first gun. The second perforating gun is mounted on a second axial side of the first perforating gun, and fires upon receipt of a second pressure signal delivered from the first axial side of the first perforating gun. The bypass extends from the first axial side of the first gun to the second gun for communicating the second pressure signal to the second gun. The isolator mechanism is configurable between a first configuration in which the bypass is isolated from receiving a pressure signal to the second perforating gun, and a second configuration in which the bypass is permitted to receive a pressure signal. The isolator mechanism is reconfigurable from the first to the second configuration after the first gun has fired.

The disclosed embodiments include pressure-activated firing heads, perforating gun assemblies, and methods to set off a downhole explosion. A pressure-activated firing head includes a first chamber and a second chamber having an energy storage element disposed within the second chamber. The pressure-activated firing head also includes a port fluidly connecting the first chamber and the second chamber. The pressure-activated firing head further includes a flow restrictor that restricts fluid flow from the second chamber to the first chamber. The pressure-activated firing head further includes a firing pin shiftable from a first position to a second position to strike an initiator. The pressure-activated firing head further includes a shear pin that holds the firing pin in the first position and configured to shear in response to a threshold pressure applied to the shear pin to release the firing pin from the first position.

A method may include obtaining well operation data regarding various well operations for a well delivery. The well operations may be performed by various service entities at a first well site. The method may further include determining a contribution weighting factor using a machine-learning model and the well operation data. The contribution weighting factor may correspond to a contribution of a first service entity among the service entities toward the well delivery. The method may further include determining, using the contribution weighting factor and an adjusted weighting factor, various performance indicator values for the first service entity. The adjusted weighting factor may be a weighting factor that is modified based on a size of the contribution weighting factor. The method may further include transmitting, based on the performance indicator values, a command to a second well site.