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Apparatus and method for operating a downhole sucker rod pump in which a downhole linear motor is controlled by a surface digital computer. The motor includes a number of coil sections circumfusing and spaced along the length of a non-magnetic tube, and an armature positioned coaxially inside the tu

Apparatus and method for operating a downhole sucker rod pump in which a downhole linear motor is controlled by a surface digital computer. The motor includes a number of coil sections circumfusing and spaced along the length of a non-magnetic tube, and an armature positioned coaxially inside the tube. The armature section includes a central mandrel of a non-magnetic material and a number of laminated armature sections circumfusing and spaced along the length of the mandrel. The tube is sized substantially the same as the production tubing, and the armature is not physically connected to the tube, such that the armature and the attached pump can be removed without removing the tubing. The coils are energized by electric power supplied by three electric conductors running from the surface. The power is selectively applied to each of the conductors in a predetermined sequence by a number of SCR switching devices controlled by the digital computer, such that the field coils are energized in manner to provide the proper attractive and repulsive forces to the armature section to cause it to move in the desired direction. By properly controlling the power switching sequence, the stroke length, speed, and duty cycle can be programmed and controlled.

대표청구항 ▼

In a production tubing string: a tube of non-magnetic material substantially of the same internal diameter as the tubing string; a plurality of electromagnetic coil assemblies disposed about the tube and equidistantly spaced along the length thereof; each of said coil assemblies comprising a coil ci

In a production tubing string: a tube of non-magnetic material substantially of the same internal diameter as the tubing string; a plurality of electromagnetic coil assemblies disposed about the tube and equidistantly spaced along the length thereof; each of said coil assemblies comprising a coil circumfusing said tube, a first annular pole piece circumfusing said tube and positioned above said coil, a second annular pole piece circumfusing said tube and positioned below said coil, and a sleeve of magnetic material positioned about said coil and said first and second pole pieces and coextensive with the combined length thereof, a cylindrical case coextensive with and enclosing said tube and said coil assemblies; a separate mandrel of a non-magnetic material centrally positioned in said tube and removable therefrom; said mandrel having a central bore therein to permit the passage of production fluids therethrough; a plurality of armature sections equidistantly spaced along the mandrel, said spacing being different from the spacing of the coil assemblies along said tube; said armature sections being formed as a stack of disks of a magnetic material; a plurality of annular centralizers separating said armature sections; a fishing neck on said mandrel, whereby said mandrel and the components attached thereto may be removed through the tubing string without removing said tubing and components attached thereto; and means for energizing said coil assemblies in a predetermined sequence, whereby electromagnetic attractive and repulsive forces are created between said coil assemblies and the armature sections to thereby move said mandrel longitudinally inside said tube.