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.

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.

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.

Provided is a temperature-driven valve assembly which can be manufactured in a cost-effective and simple manner as well as a gas pressure spring including the valve assembly which enables more reliable and safer operation of the gas pressure spring.

A vibration isolating coupler including a first coupler portion, a second coupler portion including an external surface and an internal surface portion, and a vibration isolating portion extending between the first coupler portion and the second coupler portion. The vibration isolating portion including a first solid annular portion and a second solid annular portion. The vibration isolating portion including a plurality of slots extending from the first solid annular portion toward the second solid annular portion forming a plurality of vibration isolating elements. Each of the plurality of vibration isolating elements is disconnected from adjacent ones of the plurality of vibration isolating elements by a corresponding one of the plurality of slots. The plurality of vibration isolating elements enabling torsional rotation of the first coupler portion relative to the second coupler portion.

A vibration isolating coupler including a first coupler portion, a second coupler portion including an external surface and an internal surface portion, and a vibration isolating portion extending between the first coupler portion and the second coupler portion. The vibration isolating portion including a first solid annular portion and a second solid annular portion. The vibration isolating portion including a plurality of slots extending from the first solid annular portion toward the second solid annular portion forming a plurality of vibration isolating elements. Each of the plurality of vibration isolating elements is disconnected from adjacent ones of the plurality of vibration isolating elements by a corresponding one of the plurality of slots. The plurality of vibration isolating elements enabling torsional rotation of the first coupler portion relative to the second coupler portion.

Provided is a gas strut, including: an outer working space arranged radially to the stroke axis between the working cylinder and the equalizing cylinder, the outer working space being connected to the inner working space in a gas-conducting manner; an equalizing piston enclosing the working cylinder radially to the stroke axis, the equalizing piston) being mounted displaceably along the stroke axis, delimiting the outer working space on one side transversely to the stroke axis and being subjected to a pressure of the working medium and a pressure of the equalizing medium so as to increase the volume of the outer working space; and a restoring medium arranged in a restoring space radially to the stroke axis between the working cylinder and the equalizing cylinder, the equalizing piston being subjected to a pressure of the restoring medium so as to decrease the volume of the outer working space.

Provided is a gas strut, including: an outer working space arranged radially to the stroke axis between the working cylinder and the equalizing cylinder, the outer working space being connected to the inner working space in a gas-conducting manner; an equalizing piston enclosing the working cylinder radially to the stroke axis, the equalizing piston) being mounted displaceably along the stroke axis, delimiting the outer working space on one side transversely to the stroke axis and being subjected to a pressure of the working medium and a pressure of the equalizing medium so as to increase the volume of the outer working space; and a restoring medium arranged in a restoring space radially to the stroke axis between the working cylinder and the equalizing cylinder, the equalizing piston being subjected to a pressure of the restoring medium so as to decrease the volume of the outer working space.

A gas pressure spring is provided including a working cylinder which, together with a slidably mounted compensating piston, encloses a working chamber filled with a working medium. A slidably mounted working piston is fastened to a working rod. In the event of a temperature increase, a compensating medium in a compensating chamber expands. The compensating piston is acted upon by the pressure of the working medium and the pressure of the compensating medium) such that the volume of the working chamber is increased. The temperature dependency of the gas spring force should be reduced by a design which is as simple as possible. For this purpose, the compensating chamber is at least partially surrounded by the working rod. Thus, the compensating medium can be compactly accommodated, and the assembly of the gas spring is simplified.