The invention relates to a threaded cylindrical member, which may be used for a segmented drilling tube. The member has opposing first and second ends and a central axis between said ends. The first end is threaded with a pin thread comprising a pressure flank, a crest and a root. The second end is threaded with a box thread comprising a pressure flank, a root, wherein said pin and box threads are configured whereby when threaded together a portion of the root of said pin thread is out of contact with the crest of said box thread to leave gap therebetween. The secondary geometries of the pin and box threads are configured to generate an interference fit between the pin and box threads. The roots and crests of the pin and box threads define parallel tapering conical frustrums that differ from each other in their taper angles.

A tubular connection comprising a longitudinal axis, a pin member comprising a distal pin end, a tapered pin thread having a constant pin taper angle α.sub.1 with respect to the longitudinal axis, and a pin sealing surface located between the pin thread and the distal pin end, and a box member comprising a distal box end, a box sealing surface, and a tapered box thread having a constant box taper angle β.sub.1 with respect to the longitudinal axis and located between the box sealing surface and the distal box end, and wherein the pin thread is configured to cooperate by make up with the box thread along a cooperating area, while having a radial thread interference between the pin thread and the box thread along at least part of the cooperating area, the pin sealing surface and the box sealing surface are configured to contact each other upon make-up in a sealing manner while forming a metal to metal seal, and the pin taper angle α.sub.1 is larger than the box taper angle β.sub.1.

A perforating gun assembly may include a first perforating gun housing, a first shaped charge provided within the first perforating gun housing, and an alignment sub coupled to the first perforating gun housing. The alignment sub may include a first sub body and a second sub body rotatably coupled to the first sub body.

A telemetry tool joint may comprise a tool joint body adapted for connection to a downhole tubular as part of a tool string. The tubular may be a drill pipe or a downhole tool such as a drill bit or component of a bottom hole assembly. The tool joint body may comprise an axial bore comprising a bore wall having an interior wall surface and a tapered outer wall surface. The tapered outer bore wall surface may comprise a first continuous thread form having multiple turns comprising a first thread start and a first thread end and a second continuous thread form having multiple turns comprising a second thread start and a second thread end. The respective thread forms may be separated by a gap along the tapered outer bore wall surface. The gap may comprise one or more annular recesses adapted for housing a radially oriented inductive coupler.

A threaded connection between adjacent drill string components comprises a threaded female connection end adapted to receive a correspondingly threaded male connection end, the two ends each having first and second portions of different tapers. Tubular members, drill string tools and other drill string components comprising the female or male ends described herein are also provided.

Systems and methods for damping torsional oscillations of downhole systems are described. The systems include a downhole drilling system disposed at an end of the downhole system in operative connection with a drill bit. A damping system is installed on the downhole drilling system, the damping system having at least one damper element configured to dampen at least one HFTO mode. At least one mode-shape tuning element is arranged on the drilling system. The at least one mode-shape tuning element is configured and positioned on the drilling system to modify at least one of a shape of the HFTO mode, a frequency of the HFTO mode, an excitability of the HFTO mode, and a damping efficiency of the at least one damper element.

An apparatus for damping vibrations includes an inertial mass disposed in a cavity in a rotatable downhole component, the rotatable component configured to be disposed in a borehole in a subsurface formation, such as a resource bearing formation, the inertial mass coupled to a surface of the cavity by a damping fluid and configured to move within the cavity relative to the downhole component. The apparatus also includes a damping fluid disposed in the cavity between the inertial mass and an inner surface of the cavity, where rotational acceleration of the rotatable downhole component causes shear in the damping fluid to dissipate energy from rotational acceleration of the rotatable downhole component and causing the rotational acceleration to be reduced.

In a threaded connection for pipe with intermediate shoulder surfaces provided between two thread steps for functioning as torque shoulders, the compression resistance under repeatedly applied combined loads is improved. The axial distance between the box intermediate shoulder surface 33 and box end shoulder surface 34 of the box 3 before make-up, L.sub.B, is larger than the axial distance between the pin intermediate shoulder surface 23 and pin end shoulder surface 24 of the pin 2 before make-up, L.sub.P, such that, upon completion of make-up, the pin and box intermediate shoulder surfaces 23 and 33 are in strong pressure contact to function as torque shoulders, while the pin and box end shoulder surfaces 24 and 34 are not in contact or are in light contact. The difference between the axial distances, (L.sub.B−L.sub.P), is such that, when the pin 2 and box 3 are made up and upon application of a certain magnitude of axial compressive load, the pin 2 and box 3 are slightly axially compressed by the compressive load and the pin end shoulder surface 24 comes into pressure contact with the box end shoulder surface 34 to bear part of the compressive load.

A downhole pump gas eliminating seating nipple system for preventing and eliminating the collection of gas such as a foam barrier during operations of a downhole pump assembly. The downhole pump gas eliminating seating nipple system generally includes a seating nipple including an upper end, a lower end, and a channel extending between the upper and lower ends. The channel includes a beveled edge below the upper end and a locking lip above the lower end. A plurality of upper gas eliminators are positioned below the beveled edge including one or more elongate upper gas eliminators. A plurality of lower gas eliminators are positioned below the locking lip. Each of the gas eliminators is angled upwardly from inlet to outlet so as to prevent accumulation of gasses within or below the seating nipple, which can lead to gas locking and/or gas interference.

A threaded tubular connection comprises a first tubular component and a second tubular component. The first tubular component includes a female portion defined on an interior surface of the first tubular component. The female portion includes an inner threaded portion and an outer threaded portion which are offset radially with respect to a longitudinal axis of the first tubular component by a first shoulder. The second tubular component includes a male portion defined on an exterior surface of the second tubular component. The male portion is to be inserted into the female portion, and includes an inner threaded portion and an outer threaded portion which are offset radially with respect to a longitudinal axis of the second tubular component by a second shoulder. The second shoulder is to abut the first shoulder once the male portion is connected to the female portion.