Abstract: Apparatus and method for adjusting spring preloading in a downhole tool. In an apparatus, a mechanism includes a nut and a piston. The nut is configured to axially compress a spring in the downhole tool. The piston is coupled to the nut. Extension of the piston causes the nut to rotate and compress the spring. The nut is configured to maintain compression of the spring after the piston retracts.

Abstract: Apparatus and method for adjusting spring preloading in a downhole tool. In one embodiment, a mechanism includes a nut and a piston. The nut is configured to axially compress a spring in the downhole tool. The piston is coupled to the nut. Extension of the piston causes the nut to rotate and compress the spring. The nut is configured to maintain compression of the spring after the piston retracts.

Abstract: An intelligent downhole impact jar device is described that is able to sense well bore angle or deviation and alter the effective jar impact load based upon the sensed information. The impact jar device includes a jarring portion for creating jarring impacts within a wellbore toolstring. The jarring portion is adjustable so that jarring forces of various levels can be produced. The jarring portion is adjusted in response to sensed wellbore conditions, such as the angle of deviation of the surrounding wellbore.

Abstract: A jar (10), for use in a downhole toolstring comprising: a hollow housing (11); a jar mandrel (13); a latch sub (14); one or more latch keys (16); a cam surface (17); a chamber (23); a compression spring; and an adjuster (24). The hollow housing (11) supports, moveably retained therein, the jar mandrel (13). The jar mandrel (13) and the latch sub (14) are releasably securable together by means of the one or more latch keys (16), and each latch key (16) is moveable between a latching position, in which the latching sub (14) and the jar mandrel (13) are connected together, and a release position permitting separation thereof. The cam surface (17) engages each latch key (16) to move it from its latching position to its release position when the jar mandrel (13) occupies a preselected position in the housing (11).

Abstract: A jar tool for inclusion into a well fishing operating string which provides resilient tensional stretch to operate the tool. The tool is adapted to compress an upper release spring to store energy corresponding to tensional force in the operating string force. A release latching lug array connects the spring to a central mandrel having an impact hammer. The tool housing forms an impact anvil. The spring is compressed to a designated compressional force by the distance that the latch lug array is moved in an adjustable latch release sleeve before suddenly releasing the spring from the mandrel. The tension in the operating string then pulls the mandrel hammer into jarring impact with the housing anvil. Provision is made for designating this pre-release movement of the latching lug array and also provides apparatus for adjusting the distance of the pre-release movement and thereby the compressional force imparted into the spring.

Abstract: A jar accelerator including an elongated tubular tool body and an elongated mandrel axially slidingly mounted within the tool body and having an outwardly facing shoulder. A composite plurality of frusto-conical disc springs are disposed inside the tool body about the mandrel and between the shoulders to provide a preselected accelerating function.

Abstract: A compensation device for deep-well drilling tools with a transversely divided outer pipe, the pipe members (1 and 2) of which can be rigidly connected to one another by a screw thread (8) and comprise adjacent end faces (5 and 6) as stop faces which approach one another when the pipe members are screwed together and move apart from one another during the unscrewing, comprises a spacing member (3) which can be inserted radially, from the outside, between the end faces. The screw thread (8) has a length of engagement which secures the firm connection between the pipe members within the whole preset compensating range.

Abstract: Adjustable torsional type latching means (5) for triggering a mechanical well jar tool comprises torsionally actuated gear racks (20,22) including acme threads or teeth which extend axially on opposite adjacent side portions of telescopic parts (1,2). The gear rack teeth which mesh in the latched position have incline tooth faces that can be disengaged by applying a strong axial force which torsionally stresses and rotates a torsion sleeve (16) portion of one telescoping part (1) and gear rack (20) thereon away from the other part (2) and gear rack (22). Upon release of the latching device (5) the telescopic parts (1,2) of the well jar and the kinetic energy stored therein are freed for a limited longitudinal jarring movement. The torsion sleeve portion (16) has an end portion connected to the other telescopic parts by a second slot-spline-gear (15) of relative short axial length, which serves as a torque support in the latched position and becomes deengaged during a jarring stroke.

Abstract: A downhole fishing jar mechanism for freeing stuck objects within a well bore which incorporates a housing structure defining an internal anvil element through which an upwardly-directly impact force is adapted to be transmitted to the body structure. A striker element, incorporated with an elongated operator element is adapted to strike the anvil with an impact force that is controlled by means of an adjustable compression spring. A spherical detente-type latching mechanism is adapted to establish a releasable interconnection with the operator element and further is operative to transmit the compression of the spring to the operator element. The latch mechanism releases automatically upon predetermined upward movement of the operator element and latch mechanism within the body structure, thereby allowing the operator element to move upwardly and cause the striker to impart a predetermined impact force to the anvil.

Abstract: A tapered screw joint with the thread profile whose bearing side is inclined at an angle of from about 86.degree. to about 98.degree. to the plane which is perpendicular to the thread axis.Such a tapered screw joint of parts makes it possible to disconnect them rapidly and repeatedly under the effect of axial tensile loads with subsequent reconnection under the effect of an applied torque. This screw joint will be used most effectively in a device for the emergency recovery of the boring tool from a borehole.

Abstract: An improvement on the tool shown in U.S. Pat. No. 3,853,187, this tool also embodies in a single structure inner and outer telescopically related tubular elements confining a body of operating liquid and comprising a hydraulically retarded up-blow jar, actuated by placing a lifting strain on the drill string, and a simple mechanically retarded down-blow jar actuated optionally by a controlled downward pressure of the drill string on the jar. This jar differs from the patented jar by inverting said structure and actuating said two jar mechanisms respectively by upward and downward movements of said inner element. It also embraces improved specific control devices for said up-blow and down-blow jar mechanisms.

Abstract: A jarring tool for use in a drill string to prevent sticking of the drill string during drilling operations. The jarring tool has a torque assembly for continually torquing the jar and thus the drilling operation need not be discontinued upon encountering an interfering object. The jarring tool is particularly suited for high viscosity drilling operations and eliminates hydrostatic sticking of the drill string by providing an immediate jarring action utilizing a simple hammer and anvil construction. The jarring tool is also suitable for use in a "fishing" string.

Abstract: A well jar is characterized by inner and outer telescoped members held from relative displacement by a latching member having an extending portion thereon. Imposition of an axially directed triggering force exceeding a predetermined magnitude is transmitted against the biasing force of a resilient member through a force transmitting arrangement to a latch release member provided with an opening therein sized to receive the extending portion of the latching member. The release member rotates in a predetermined angular direction to come into registry with the opening therein to receive the extending portion of the latching member as the latching member displaces radially outwardly to release the inner member. Upon release, the inner member responds to the axially directed force to drive impact surfaces disposed on the inner and outer members into an impact-producing engagement.