Abstract: Embodiments of the invention provide a system and method for induction heating a helical rotor of a progressing cavity pump in order to reduce the surface roughness of the rotor. In order to heat the rotor most evenly, it is desired to space the coil as closely around the rotor as possible. The invention provides a mechanism for threading the helical rotor through an induction coil having an interior diameter which is less than the major diameter of the rotor. The induction coil may include one loop and overlapping ends. The rotor to be heated is rotated about its longitudinal axis and advanced axially through the coil as it rotates. The axial speed and rotational speed are synchronized so that the rotor moves one pitch through the coil for each complete rotation.

Abstract: A centrifugal brake system for retarding shaft backspin includes a brake drum, a brake hub attachable to the shaft and two or more brake shoes mounted on the hub for braking engagement with the drum. A mechanical linkage transfers the generated braking force from the brake shoes to the hub and permits radial displacement of the brake shoes relative to the hub, upon rotational shifting of the hub relative to the brake shoes between deactivated and activated positions. In the deactivated position of the hub, the brake shoes are maintained in a radially inward, disengaged position. In the activated position, the brake shoes are radially displaceable by centrifugal force from the disengaged position to a radially outward, engaged position, wherein the brake shoes are in braking engagement. The rotational shifting of the hub is achieved through frictional drag between the brake shoes and the brake drum.

Abstract: Embodiments of the invention provide a system and method for induction heating a helical rotor of a progressing cavity pump in order to reduce the surface roughness of the rotor. In order to heat the rotor most evenly, it is desired to space the coil as closely around the rotor as possible. The invention provides a mechanism for threading the helical rotor through an induction coil having an interior diameter which is less than the major diameter of the rotor. The induction coil may include one loop and overlapping ends. The rotor to be heated is rotated about its longitudinal axis and advanced axially through the coil as it rotates. The axial speed and rotational speed are synchronized so that the rotor moves one pitch through the coil for each complete rotation.

Abstract: Embodiments of the invention provide a system and method for induction heating a helical rotor of a progressing cavity pump in order to reduce the surface roughness of the rotor. In order to heat the rotor most evenly, it is desired to space the coil as closely around the rotor as possible. The invention provides a mechanism for threading the helical rotor through an induction coil having an interior diameter which is less than the major diameter of the rotor. The induction coil may include one loop and overlapping ends. The rotor to be heated is rotated about its longitudinal axis and advanced axially through the coil as it rotates. The axial speed and rotational speed are synchronized so that the rotor moves one pitch through the coil for each complete rotation.

Abstract: A centrifugal brake system for retarding shaft backspin includes a brake drum, a brake hub attachable to the shaft and two or more brake shoes mounted on the hub for braking engagement with the drum. A mechanical linkage transfers the generated braking force from the brake shoes to the hub and permits radial displacement of the brake shoes relative to the hub, upon rotational shifting of the hub relative to the brake shoes between deactivated and activated positions. In the deactivated position of the hub, the brake shoes are maintained in a radially inward, disengaged position. In the activated position, the brake shoes are radially displaceable by centrifugal force from the disengaged position to a radially outward, engaged position, wherein the brake shoes are in braking engagement. The rotational shifting of the hub is achieved through frictional drag between the brake shoes and the brake drum.

Abstract: Embodiments of the invention provide a system and method for induction heating a helical rotor of a progressing cavity pump in order to reduce the surface roughness of the rotor. In order to heat the rotor most evenly, it is desired to space the coil as closely around the rotor as possible. The invention provides a mechanism for threading the helical rotor through an induction coil having an interior diameter which is less than the major diameter of the rotor. The induction coil may include one loop and overlapping ends. The rotor to be heated is rotated about its longitudinal axis and advanced axially through the coil as it rotates. The axial speed and rotational speed are synchronized so that the rotor moves one pitch through the coil for each complete rotation.

Abstract: A method for stripping a fused thermal spray metal coating from the surface of a soft metallic substrate. The steps for the method include: immersing the coated metallic substrate in an aqueous solution of chromic acid, peroxide, and a second acid; immersing a metal cathode in the aqueous solution; applying a positive potential to the fused spray metal coated substrate and a negative potential to the metal cathode to generate a direct current between the substrate and the cathode; where the current is applied for a sufficient time to remove the coating. This method permits the electrochemical removal of fused and impermeable thermal spray metal coatings.

Abstract: The invention relates to a braking assembly for permitting axial rotation of a shaft in a first direction and inhibiting axial rotation of the shaft in a second, opposite direction, comprising: a hydraulic clutch having a torque generating member and a torque receiving member wherein the torque generating member is connected to the shaft and the torque receiving member is stationary and a guide means for maintaining the torque generating member in a first de-activated position when the shaft is rotated in the first direction and for moving the torque generating member to a second activated position when the shaft is rotated in the opposite direction whereby activation of the torque generating member inhibits rotation of the shaft in the second direction. The invention provides an effective emergency braking assembly for such systems as progressing cavity pumps in oil wells.

Abstract: The invention relates to a braking assembly for permitting axial rotation of a shaft in a first direction and inhibiting axial rotation of the shaft in a second, opposite direction, comprising: a hydraulic clutch having a torque generating member and a torque receiving member wherein the torque generating member is connected to the shaft and the torque receiving member is stationary and a guide means for maintaining the torque generating member in a first de-activated position when the shaft is rotated in the first direction and for moving the torque generating member to a second activated position when the shaft is rotated in the opposite direction whereby activation of the torque generating member inhibits rotation of the shaft in the second direction.

Abstract: A hardfacing for downhole progressing cavity pumps is disclosed as well as a method for producing same. The hardfacing consists of a ceramic layer applied to a ferrous pump rotor body by way of plasma spraying and a top layer of metallic material having a lower hardness than the ceramic. The ceramic layer has a grainy surface with a plurality of peaks and intermediate depressions, the peaks being formed by ceramic grains at the surface of the ceramic layer. The thickness of the top layer is adjusted such that the depressions between the peaks of the ceramic layer are completely filled thereby providing the rotor with a ceramic hardfacing of significantly reduced surface roughness. In the process of the invention, the pump rotor, which may be provided with a molybdenum bonding layer, is plasma coated with the ceramic and the resulting ceramic layer is covered with the metallic material top layer.

Abstract: The present invention provides a method and apparatus for controlling the production rate of a rotary downhole pump to prevent well pump-off. The method includes the steps of operating the pump at a first speed less than a maximum rate of the pump until well fluid is produced at the wellhead. The operation is continued at the first speed until a first dynamic fluid level in the annulus between the production tubing and the wellbore or the well casing is stabilized. A first static load on the drivehead at the first dynamic fluid level is determined. The pump is then operated at a second speed higher than the first speed until the fluid level in the annulus is stabilized at a second dynamic fluid level. A second static load on the drivehead at the second dynamic fluid level is determined. A linear function of the load on the drivehead is determined as a function of the fluid level in the annulus.

Abstract: A safety coupling for preventing backspin at excessive speeds of a torque transmitting drive string which stores reactive torque due to torsional stress. The safety coupling includes a rotatable driving member to be coupled with a rotatable driven member to be coupled with the driving string for axial rotation therewith. The driven member is movable relative to the driving member between an engaged position wherein the driving and driven members are coupled by a torque transfer structure to provide a positive driving connection between the torque transmitting drive and the shaft, and a disengaged position wherein the driving and the driven members are freely rotatable relative to each other so that back-spin of the torque transmitting drive is prevented. The driven member is biased into the disengaged position and forced into the engaged position only during forward rotation of the shaft.

Abstract: A method and an apparatus for producing fluid hydrocarbons through a single production tubing string from first and second zones which communicate with a hydrocarbon wellbore is disclosed. The apparatus includes a packer positioned in the wellbore for selectively preventing a flow of fluids through the wellbore from the first zone to the second zone, a production tubing string that extends through the wellbore and is in fluid communication through the packer with the second zone, and first and second pumps for displacing fluid through the production tubing string. The second pump displaces fluid from the lower zone into the production tubing string. A perforated joint is placed in the production tubing string between the second and the first pump. The second pump has a given displacement capacity at a given speed and is of a type that inhibits a flow of fluid in either direction through the pump when it is not pumping fluids from the second zone.

Abstract: A method and apparatus is disclosed which reduces or removes axial loads on the drive string of a rotary downhole pump, i.e. tensile loads due to the hydrostatic load of the pumped liquid on the pump rotor, and/or at least part of the weight of the drive string, or thrust loads caused during pressurized fluid injection operations by backpressure of injected fluid on the pump rotor. This substantially prevents drive string/production tubing friction, wear and/or buckle in downhole rotary pumping arrangements operated in straight or curved well bores. When used in connection with fluid production pumping arrangements, the apparatus reduces the friction between the drive string and the production tubing of a downhole rotary pump for the pumping of well fluids which pump has a pump rotor connected to the drive string and is operated in a well bore. When used in connection with fluid injection pumping arrangements, the apparatus prevents drive string buckle, especially in curved well bore situations.

Abstract: A hardfacing for downhole progressing cavity pumps is disclosed as well as a method for producing same. The hardfacing consists of a metal carbide layer applied to the ferrous pump rotor body by way of plasma spraying and a top layer of metallic material having a lower hardness than the metal carbide. The metal carbide layer has a grainy surface with a plurality of peaks and intermediate depressions, the peaks being formed by metal carbide grains at the surface of the metal carbide layer. The thickness of the top layer is adjusted such that the depressions between the peaks of the metal carbide layer are completely filled thereby providing the rotor with a metal carbide hardfacing of significantly reduced surface roughness. In the process of the invention, the pump rotor, which may be provided with a molybdenum bonding layer, is plasma coated with the metal carbide and the resulting carbide layer is covered with the metallic material top layer.

Abstract: A leakproof seal arrangement is disclosed for use in the drivehead of a downhole rotary pump, which pump is operated by a drive string suspended from the drivehead for rotation in a production tubing about a longitudinal axis, the drivehead having a bore in fluid communication and coaxial with the production tubing and sized to permit the passage of a polished rod attached to a top end of the drive string. The seal arrangement includes a centralizer sleeve for receiving a portion of the polished rod; a bearing for rotatably supporting the centralizer sleeve in the drivehead coaxial with the bore, whereby an annular gap is created between the centralizer sleeve and an opposite, cylindrical wall of the drivehead which gap is in fluid communication with the production tubing. The seal arrangement further includes a centering packing for sealingly and concentrically connecting the centralizer sleeve with the polished rod for simultaneous rotation about the longitudinal axis.

Abstract: A safety coupling for preventing backspin at excessive speeds of a torque transmitting drive powering a drive shaft which stores reactive torque due to torsional stress is disclosed. The safety coupling includes a rotatable driving member to be coupled with a torque producing power source, a rotatable driven member to be coupled with the drive shaft for axial rotation therewith, a support structure for coaxially and rotatably supporting the driving and driven members in relation to each other, a radial abutment provided on the driving member, and a centrifugal force responsive pawl pivotally mounted to the driven member for releasable engagement with the abutment.

Abstract: A hardfacing for downhole progressing cavity pumps is disclosed as well as a method for producing same. The hardfacing consists of a metal carbide layer applied to the ferrous pump rotor body by way of plasma spraying and a top layer of metallic material having a lower hardness than the metal carbide. The metal carbide layer has a grainy surface with a plurality of peaks and intermediate depressions, the peaks being formed by metal carbide grains at the surface of the metal carbide layer. The thickness of the top layer is adjusted such that the depressions between the peaks of the metal carbide layer are completely filled thereby providing the rotor with a metal carbide hardfacing of significantly reduced surface roughness. In the process of the invention, the pump rotor, which may be provided with a molybdenum bonding layer, is plasma coated with the metal carbide and the resulting carbide layer is covered with the metallic material top layer.

Abstract: A drive head for a down hole rotary pump driven from a well head assembly by a drive string that extends through the well to the pump is disclosed. The drive head includes a hollow rotatable drive shaft having an axial passage for accommodating a slip shaft, a housing attachable to the well head assembly, radial bearings centering the drive shaft in the housing and a thrust bearing for supporting the weight of the drive shaft and the drive string suspended therefrom. A pulley is mounted on the shaft for driving the drive shaft. The slip shaft is mounted to the top end of a polished rod which is attached to a top end of the drive string. The slip shaft and the passage in the drive shaft are preferably hexagonal so that drive torque is transmitted to the drive string without slippage of the shaft. The drive string is suspended in the well by a clamp that grips a top end of the slip shaft and rests on a top of the housing.

Abstract: A relatively simple hydraulically operated disc brake mechanism for drive systems which store reactive torque by reason of being under torsion is disclosed. Certain drive systems such as the drive strings for deep well submersible pumps store considerable reactive torque due to torsional stresses. Such torque must be controllably released if drive power is interrupted. The disc brake mechanism includes a housing that defines a reservoir for lubricating oil for the bearings of a shaft that drives a bi-directional hydraulic pump. When the shaft turns in an operating direction, the pump pumps the lubricating oil in a closed circuit through a filter and back to the reservoir. If normal operation is interrupted and the reactive torque in the system is released, the bi-directional pump forces oil through a control manifold to a disc brake caliper which brakes a disc rotor attached to the shaft. The faster the shaft turns as it releases reactive torque, the more braking force applied.