Abstract:
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.
Abstract:
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.
Abstract:
A method of and device for detecting a leak in reciprocating machinery (1), comprising at least two pistons (2, 2′), by the volume flow at least out of the reciprocating machinery (1) being monitored and analysed, e.g. by means of Fourier analysis, in order to make it possible to detect a flow component, where the flow component has a frequency that differs from the fundamental frequency of the reciprocating machinery, the fundamental frequency of the reciprocating machinery being constituted by the rotational frequency of the reciprocating machinery multiplied by the number of pistons (2, 2′) in the reciprocating machinery.
Abstract:
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.
Abstract:
A method for detection of a fluid leak related to at least one piston machine (1), where the method includes: —attaching a pressure sensor (18, 24) to at least a pressure side of the at least one piston machine (1); —measuring the pressure on the pressure side of the at least one piston machine (1); —attaching a transmitter (28) to the at least one piston machine (1), said transmitter (28) rendering a signal for calculating the rotational speed of the at least one piston machine (1); —calculating the speed of the at least one piston machine (1); —calculating the sum of nominal flow rates from all piston machines (1); —calculating a flow rate compensation factor; —calculating a normalized pressure (42) to be equal to the discharge pressure multiplied by the said compensation factor for the flow rate; and —monitoring the normalized pressure (42) to detect a leakage.
Abstract:
A method for detection of a fluid leak related to at least one piston machine (1), where the method includes: —attaching a pressure sensor (18, 24) to at least a pressure side of the at least one piston machine (1); —measuring the pressure on the pressure side of the at least one piston machine (1); —attaching a transmitter (28) to the at least one piston machine (1), said transmitter (28) rendering a signal for calculating the rotational speed of the at least one piston machine (1); —calculating the speed of the at least one piston machine (1); —calculating the sum of nominal flow rates from all piston machines (1); —calculating a flow rate compensation factor; —calculating a normalized pressure (42) to be equal to the discharge pressure multiplied by the said compensation factor for the flow rate; and —monitoring the normalized pressure (42) to detect a leakage.
Abstract:
A method of determining a leakage in a piston machine comprising at least two pistons is provided. The rotational velocity of the piston machine, and therefore the volume flow through the piston machine, is varied periodically as part of a time-limited active test while measuring the differential pressure and the angular position. An angular position-based Fourier analysis of the measured values from differential pressure and rotational velocity measurements performed during the test are used to experimentally determine the amplitude ratio and phase angle difference between volume flow variations and pressure variations. The amplitude ratio and phase angle difference are used, together with an angular position-based Fourier analysis of the measurements of differential pressure and rotational speed made after the active test, to determine the amplitude and phase of the leakage flow.
Abstract:
A method of filtering out pressure noise generated by one or more piston pumps, where each pump is connected to a common downstream piping system, and where the discharge pressure is measured by a pressure sensitive gauge, wherein the instantaneous angular position(s) of the pump(s)' crankshaft or actuating cam is/are measured simultaneously with the discharge pressure and used as fundamental variables in an adaptive mathematical noise model.
Abstract:
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.
Abstract:
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.