Abstract: A method for limiting the torque of a permanent magnet AC motor includes a torque limit controller. The torque limit controller at least in part bases the torque limit on a selected direct voltage limit. The selected direct voltage limit may be used in combination with other torque limit conditions to generate the torque demand for the AC motor.

Abstract: A power system for an electrical system with highly fluctuating loads is powered by one or more power sources that are slow to react to load changes. The power sources are connected to electrical equipment used on the drill rig which provide active load to the generators. One or more load banks may be positioned to provide passive load to the generators to maintain generally constant generator load, while allowing for instant access to power as active load increases. Generators may be run at 100% capacity, a maximum efficient capacity, or at a high enough level to allow for a sufficiently rapid increase in power output. At least one parameter of a drilling operation may be utilized to anticipate load demand changes.

Abstract: Spin-in and spin-out apparatus and methods are presented wherein an oilfield tubular spinner used in combination with a wrench detects the shouldering-up of tubulars during make-up and tubular thread disengagement during break-out. Sensors are employed to quantify measurables indicative of shouldering-up and thread disengagement, the measurables being used to shutdown spin-in and spin-out operations. Thresholds are employed to detect measurable values of interest. Timers may be employed to monitor and control the spin-in and spin-out operations.

Abstract: A method for field weakening control of a three phase permanent magnet AC motor in a VFD drive. The VFD drive calculates the three phase voltages to be supplied to the AC motor via a three phase inverter using feedback and feed-forward calculations of quadrature and direct demand currents.

Abstract: A low inertia permanent magnet motor includes a stator and rotor. The rotor includes a generally tubular and hollow rotor body coupled to the shaft of the motor by one or more spokes and/or webs. The permanent magnets of the rotor are coupled to the rotor body. In some embodiments, the low inertia permanent magnet motor may be used to power a drawworks. In some embodiments, the drawworks may be controlled by an active heave compensation controller.

Abstract: A weight-based tubular interlock apparatus adapted to determine whether a tubular is engagingly gripped by a rig-based hoisting device or a secondary gripping device is described. The apparatus includes at least two gripping mechanisms and an interlock system operatively connected that is adapted to measure a tubular load on at least one of the gripping mechanisms and to compare the tubular load to a predetermined load to deter nine whether the at least one gripping mechanism is gripping the tubular. The gripping mechanism is adapted to release the tubular only when the tubular load meets the predetermined load, upon which a release force sufficient to release the tubular from the gripping mechanism is applied to the tubular relative to the gripping mechanism. Methods of using the interlock apparatus are also described.

Abstract: Multiple methods and corresponding apparatuses for efficient and reliable defect diagnosis in components of mechanical systems, are described. According to one aspect, multi-scale enveloping-order spectrogram is used to diagnose, or detect, defects in a moving component of a mechanical system. According to another aspect, defect identification and diagnosis in a motor is performed based on spectral characteristics of motor current envelope. According to yet another aspect, a logic rule model, employing classification of features associated with single- or multi-sensor data, is employed for diagnosis of defects in components of mechanical systems.

Abstract: Apparatus and methods for guiding a drilling operation are disclosed. The apparatus includes a drilling apparatus, a receiving apparatus, and a display apparatus. The drill apparatus includes a bit with a steerable motor having a toolface and a rotary drive adapted to steer the bit during the drilling operation. The receiving apparatus is adapted to receive electronic data on a recurring basis, wherein the electronic data comprises quill position data, at least one of actual gravity-based toolface orientation data and actual magnetic-based toolface orientation data, and recommended toolface orientation data. The display apparatus is adapted to display the electronic data on a user-viewable display in a historical format depicting data resulting from a recent measurement and a plurality of immediately prior measurements.

Abstract: A tubular handling apparatus comprising a slotted member having a plurality of elongated slots each extending in a direction, a recessed member slidably coupled to the slotted member and having a plurality of recesses each tapered in the direction from a shallow end to a deep end, and a plurality of rolling members each retained between one of the recesses and one of the slots, wherein each rolling member partially extends through the adjacent slot when located in the shallow end of the recess, and wherein each rolling member retracts within an outer perimeter of the slotted member when located in a deep end of the recess. The apparatus may further comprise a plurality of biasing elements each biasing a corresponding one of the rolling members towards the shallow end of the corresponding recess.

Abstract: Spin-in and spin-out apparatus and methods are presented wherein an oilfield tubular spinner used in combination with a wrench detects the shouldering-up of tubulars during make-up and tubular thread disengagement during break-out. Sensors are employed to quantify measurables indicative of shouldering-up and thread disengagement, the measurables being used to shutdown spin-in and spin-out operations. Thresholds are employed to detect measurable values of interest. Timers are employed to monitor and control the spin-in and spin-out operations.