An apparatus and method for drilling is disclosed, including a drill string with at least one jar and one reaction valve. Drilling fluid flows through the reaction valve. The reaction valve is selectively throttled, which creates a differential pressure across the valve seat. The differential pressure creates an axial force that is transferred to the jar, which aids in cocking or firing the jar. In an embodiment, a reaction valve throttles downward fluid flow to create a downward compressional force on the jar, while in another embodiment, a reaction valve throttles upward fluid flow to create an upward tensile force on the jar. Upward and downward fluid flow may be alternatively throttled for alternately firing the jar upwards and downwards. A bypass valve may be included in the drill string for establishing a drilling fluid flow path when such may be otherwise obstructed by foreign matter in the wellbore.

Apparatus and methods for creating a downhole impact. The apparatus may be an impact tool operable to be coupled between portions of a tool string conveyable within a wellbore extending into a subterranean formation. The impact tool may include a housing, a chamber within the housing, a piston slidably disposed within the chamber and dividing the chamber into a first chamber volume and a second chamber volume, and a shaft connected with the piston and axially movable with respect to the housing. The first chamber volume may be open to a space external to the housing and the second chamber volume may be fluidly isolated from the space external to the housing. The piston may be maintained in a predetermined position within the chamber to maintain pressure within the second chamber volume appreciably lower than pressure within the first chamber volume while the impact tool is conveyed along the wellbore.

A release mechanism for a jarring tool is formed by a plurality of segmented release lugs. Each lug includes a plurality of axial spaced projections on an inner surface and a plurality of grooves on an outer surface. The projections have either different widths or are separated by varying distances and releasably engage corresponding grooves in a mandrel located within a housing of the tool. The release lugs are positioned between a trigger sleeve and the mandrel.

A drilling jar in an oil and gas drilling operation or fishing operation includes a control unit having one or more transceivers configured to communicate wirelessly with a surface control unit. The control unit is configured to receive an activation signal from the surface control unit, and cause to activate the drilling jar in response to the activation signal. The wireless transceivers may communicate using any wireless communication technology, including but not limited to Wi-Fi, Wi-Fi Direct, and BLE. A method for operating a drilling jar includes receiving, by a control unit comprising one or more transceivers configured to communicate wirelessly with a surface control unit, an activation signal from the surface control unit, and causing to activate the drilling jar in response to the activation signal.

A downhole tool for connecting and selectively disconnecting within a wellbore first and second portions of a downhole tool string from each other. The downhole tool may include a first connector sub connectable with the first portion of the downhole tool string, a second connector sub connectable with the second portion of the downhole tool string, an internal chamber, and a fastener connecting the first and second connector subs. The fastener may fluidly separate the internal chamber into a first chamber portion and a second chamber portion. The first chamber portion may be fluidly connected with a space external to the downhole tool. The downhole tool may be selectively operable to disconnect the first and second connector subs from each other to disconnect the first and second portions of the downhole tool string from each other.

A release mechanism for a jarring tool is formed by a plurality of segmented release lugs. Each lug includes a plurality of axial spaced projections on an inner surface and a plurality of grooves on an outer surface. The projections have either different widths or are separated by varying distances and releaseably engage corresponding grooves in a mandrel located within a housing of the tool. The release lugs are positioned between a trigger sleeve and the mandrel.

Methods and apparatus for alleviating a stuck condition of a tool string, including using a jarring assembly to collide a plurality of impact surfaces together. The collision results in at least a shock wave inducing i) translational motion along the longitudinal axis of the tool string, and ii) motion in at least one other degree of freedom sufficient to alleviate the stuck condition of the tool string, which may be at least one of: i) translational motion along an axis substantially normal to the longitudinal axis, and ii) rotational motion. Methods may include generating at least one test impact load using a jarring assembly; generating movement information from a sensor responsive to the at least one test impact load; and generating further impact loads using the jarring assembly in dependence upon the movement information.

An apparatus and method for connecting and selectively disconnecting within a wellbore first and second portions of a downhole tool string from each other. The apparatus may be a downhole tool having a first connector sub connectable with the first portion of the downhole tool string, a second connector sub connectable with the second portion of the downhole tool string, an internal chamber, and a fastener connecting the first and second connector subs. At least a portion of the fastener fluidly separates the internal chamber into a first chamber portion and a second chamber portion. The first chamber portion is fluidly connected with the space external to the downhole tool. The downhole tool is selectively operable to disconnect the first and second connector subs from each other to disconnect the first and second portions of the downhole tool string from each other.

A downhole impact apparatus operable to impart an impact to an object within a wellbore. The impact apparatus may include a housing, a first chamber within the housing, a second chamber within the housing, and a piston assembly slidably disposed within the housing. The piston assembly may include a first piston slidably disposed within the first chamber and dividing the first chamber into a first volume and a second volume, a second piston slidably disposed within the second chamber, and a shaft connecting the first and second pistons. The first volume may be open to a space external to the housing and the second volume may be fluidly isolated from the space external to the housing. Relative movement between the piston assembly and the housing ends with the impact. The second chamber may be configured to contain a fluid to prevent relative movement between the piston assembly and the housing.

An impact apparatus operable to be coupled along and impart an impact to a downhole tool string. The impact apparatus includes a housing, a first and second chambers within the housing, and a piston shaft assembly movable with respect to the housing. The piston shaft assembly includes a first piston slidably disposed within and dividing the first chamber into a first chamber portion and a second chamber portion, a first shaft connected with the first piston and axially movable into and out of the housing, a second piston slidably disposed within the second chamber, and a second shaft connecting the first and second pistons. The first chamber portion is open to a space external to the housing. The second chamber contains a fluid operable to maintain the piston shaft assembly and the housing in a predetermined relative position.