National Oilwell Varco, L.p.

National Oilwell Varco Norway as

National Oilwell Norway as

Age Kyllingstad

Pal Jacob Nessjoen

Magne Mathias Moe

Arne Austefjord

Robert Lewis Bloom

Pal Jakob Nessjoen

Hege Kverneland

A method and apparatus for estimating the instantaneous rotational speed of a bottom hole assembly at the lower end of a drill string. In one embodiment, a method includes driving the drill string by a drilling mechanism at the upper end of the drill string. A fundamental frequency of stick-slip oscillations suffered by the drill string is estimated. Variations in a drive torque of the drilling mechanism are determined. Known torsional compliance of the drill string is combined with the variations in the drive torque. An output signal representing the instantaneous rotational speed is provided.

Methods and apparatus for reducing stick-slip

A method and apparatus for damping stick-slip oscillations in a drill string. In one embodiment a method includes damping the stick-slip oscillations using a drilling mechanism at the top of said drill string. The speed of rotation of the drilling mechanism is controlled using a PI controller. The control is characterized by tuning the PI controller so that the drilling mechanism absorbs most torsional energy from the drill string at a frequency that is at or near a frequency of the stick-slip oscillations.

Method and apparatus for reducing stick-slip

A method and related device for reducing resonant vibrations and dynamic loads of cranes, where vertical motion of a pay load is controlled by a boom winch and a hoist winch. In an embodiment, the method includes determining resonance frequencies of the crane boom and pay load from inertia data of the boom and stiffness on at least the boom and hoist ropes, the resonance frequencies including a first frequency and a lower second frequency. In addition, the method includes automatically modifying the motion of the boom winch or the hoist winch to induce a damping inducing winch motion in the boom or hoist winch, by tuning a proportional integral (PI)-type boom winch speed controller or a PI-type hoist winch speed controller. The boom winch speed controller is tuned to absorb energy at the second frequency, the hoist winch speed controller is tuned to absorb energy at the first frequency.

Method for reducing dynamic loads of cranes

Apparatus and method for measuring the compressibility (K) of a fluid circulated by a positive displacement pump that comprises: a pressure sensor for sensing a pressure P of a fluid confined in a fluid module of the pump; a position sensor for sensing the position X, of a piston in the fluid module and a control unit communicating with the pressure sensor and the position sensor adapted to: log the pressure (P) and piston position (X) substantially synchronously; using (X), calculate the volume (V) of the confined fluid in the fluid module; and using (P) and (V), calculate the compressibility (K).

Method and apparatus for real-time fluid compressibility measurements

A drillstring with a bit is characterized by controllable variables of vertical and rotational speeds and response variables of axial tension force and torque, referenced to the top of the drillstring. A method of reducing or avoiding at least an axial or a torsional oscillation mode in the drillstring includes:

System and method for reducing drillstring oscillations

A device for preventing a primary relief valve in a mud system from opening at a pressure lower than a nominal opening pressure includes a flow restrictor between a mud pump of the mud system and the primary relief valve. In addition, the device includes a cavity between the flow restrictor and the primary relief valve.

Method and device for preventing a mud relief valve from incorrect opening

A method for detection of a leak in a fluid affected component of a piston machine includes obtaining a vibration signal from a vibration sensor disposed proximate to at least one valve block of the piston machine. The vibration signal includes vibration generated by valves in the valve block. The method further includes presenting the obtained vibration signal for analysis by at least one of a human or a computer, analyzing the obtained vibration signal with respect to revealing a malfunction related to a fluid affected component of the piston machine, and selecting the obtained vibration signal emitted from the valve block during the closed periods of the valves for presentation.

Method for detection of a malfunction related to a fluid affected component in a piston machine

A machine includes at least one piston and a pump shaft. A method for detecting a leak in the machine includes receiving a vibration signal from a vibration sensor disposed on at least one of an upstream pipe and a downstream pipe of the machine, receiving a rotational speed signal and an angular shaft position signal from a speed and position sensor disposed on the machine, calculating a rotational speed and an angular shaft position of the pump shaft, calculating at least one complex harmonic Fourier amplitude of the received vibration signal, low pass filtering the at least one complex harmonic Fourier amplitude, calculating a deviation amplitude as a magnitude of a complex difference between the filtered amplitude and a base amplitude, and monitoring the deviation amplitude to detect a leakage.

Method for detection of a fluid leak related to a piston machine

A method for detection of a fluid leak related to at least one piston machine (), where the method includes: &#x2014;attaching a pressure sensor () to at least a pressure side of the at least one piston machine (); &#x2014;measuring the pressure on the pressure side of the at least one piston machine (); &#x2014;attaching a transmitter () to the at least one piston machine (), said transmitter () rendering a signal for calculating the rotational speed of the at least one piston machine (); &#x2014;calculating the speed of the at least one piston machine (); &#x2014;calculating the sum of nominal flow rates from all piston machines (); &#x2014;calculating a flow rate compensation factor; &#x2014;calculating a normalized pressure () to be equal to the discharge pressure multiplied by the said compensation factor for the flow rate; and &#x2014;monitoring the normalized pressure () to detect a leakage.

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Algard, Norway

Age Kyllingstad