Long-stroke pumping unit

Patent metadata

Field	Value
Publication number	US-2016201664-A1
Application number	US-201614992799-A
Country	US
Kind code	A1
Filing date	Jan 11, 2016
Priority date	Jan 9, 2015
Publication date	Jul 14, 2016
Grant date	—

Abstract

A long-stroke pumping unit includes: a tower; a counterweight assembly movable along the tower; a drum connected to an upper end of the tower and rotatable relative thereto; a belt having a first end connected to the counterweight assembly, extending over the drum, and having a second end connectable to a rod string; a prime mover for reciprocating the counterweight assembly along the tower; a sensor for detecting sudden acceleration of the counterweight assembly due to failure of the rod string; at least one of: a braking system for halting free-fall of the counterweight assembly; and an arrestor system for absorbing kinetic energy of the falling counterweight assembly; and a controller in communication with the sensor and operable to activate the braking or arrestor system in response to detection of the sudden acceleration.

First claim

1 . A long-stroke pumping unit, comprising:
a tower; a counterweight assembly movable along the tower; a drum connected to an upper end of the tower and rotatable relative thereto; a belt having a first end connected to the counterweight assembly, extending over the drum, and having a second end connectable to a rod string; a prime mover for reciprocating the counterweight assembly along the tower; a sensor for detecting acceleration of the counterweight assembly due to failure of the rod string; at least one of:
a braking system for halting movement of the counterweight assembly; and
an arrestor system for absorbing kinetic energy of the moving counterweight assembly; and
a controller in communication with the sensor and operable to activate the braking system or arrestor system in response to detection of the acceleration.

2 . The unit of claim 1 , wherein:
the unit comprises the braking system; and the unit further comprises:
a crown mounted atop the tower; and
a shaft connected to the drum and rotatable relative to the crown.

3 . The unit of claim 2 , wherein:
the braking system comprises:
a disk disposed around and torsionally connected to the shaft;
a caliper mounted to the crown;
a piston disposed in a chamber formed in the caliper and movable relative to the caliper between an engaged position and a disengaged position;
a brake shoe connected to the piston; and
a brake pad mounted to the brake shoe; and
the brake pad is clear of the disk in the disengaged position and pressed against the disk in the engaged position.

4 . The unit of claim 2 , wherein:
the braking system comprises:
a hood mounted to the crown;
a caliper mounted to the hood;
a piston disposed in a chamber formed in the caliper and movable relative to the caliper between an engaged position and a disengaged position; and
a brake shoe connected to the piston, and
the brake shoe is clear of the belt in the disengaged position and pressed against the belt in the engaged position

5 . The unit of claim 4 , wherein:
the braking system further comprises a pad mounted to the brake shoe, and the pad is pressed against the belt in the engaged position.

6 . The unit of claim 2 , wherein:
the braking system comprises:
a rope having an end connected to a base of the tower and an end connected to the crown and extending through a rope brake;
the rope brake movable between an engaged position and a disengaged position and comprising:
a caliper mounted to the counterweight assembly; and
a pair of opposing brake shoes and pads; and

the brake pads are clear of the rope in the disengaged position and pressed against the rope in the engaged position.

7 . The unit of claim 6 , wherein:
one of the brake shoes and pads is connected to the caliper; the other one of the brake shoes and pads is movable relative to the caliper; and the rope brake further comprises:
a spring biasing the other one toward the engaged position; and
a trigger restraining the other one in the disengaged position.

8 . The unit of claim 2 , wherein:
the braking system comprises:
a brake shoe hinged to the counterweight assembly and carrying a brake pad;
an actuator mounted to the counterweight assembly for swinging the brake shoe between an engaged position and a disengaged position; and
the brake pad is clear of the tower in the disengaged position and pressed against the tower in the engaged position.

9 . The unit of claim 8 , wherein the actuator comprises:
a housing mounted to the counterweight assembly; a mandrel disposed in the housing and longitudinally movable relative thereto; and a lever having a first end hinged to the brake shoe and a second end hinged to the mandrel.

10 . The unit of claim 9 , wherein the actuator further comprises:
a spring disposed between the housing and the mandrel and biasing the mandrel toward the engaged position; and a trigger connected to the housing and restraining the mandrel in the disengaged position.

11 . The unit of claim 1 , wherein:
the unit comprises the arrestor system; and the arrestor system comprises a shock absorber or bladder disposed in a base of the tower.

12 . The unit of claim 11 , wherein:
the arrestor system comprises the shock absorber and a hydraulic circuit; and the shock absorber comprises:
a cylinder having a rebound port and a damping port;
a pair of end caps connected to the cylinder;
damping fluid disposed in the cylinder;
a piston disposed in a bore of the cylinder and longitudinally movable relative thereto between a ready position and an idle position;
a piston rod connected to the piston and extending through one of the end caps;
a bumper connected to an end of the piston rod; and
a spring biasing the piston toward the ready position.

13 . The unit of claim 12 , wherein:
the hydraulic circuit comprises:
a shutoff valve connecting the rebound port to a reservoir; and
a check valve and choke connecting the damping port to the reservoir, closing of the shutoff valve restrains the piston in the idle position;
the bumper is clear of a path of the counterweight assembly in the idle position; and opening of the shutoff valve allows the spring to move the piston, piston rod, and bumper to the ready position.

14 . The unit of claim 11 , wherein:
the arrestor system comprises the bladder and an inflation circuit; the bladder has a port and is naturally biased toward a deflated position; the inflation circuit comprises a pressurized tank and shutoff valve connecting the bladder port to the pressurized tank; closing of the shutoff valve maintains the bladder in the deflated position; the bladder is clear of a path of the counterweight assembly in the deflated position; and opening of the shutoff valve allows the pressurized tank to inflate the bladder.

15 . The unit of claim 14 , further comprising a choke connecting the bladder port to a collection tank.

16 . The unit of claim 1 , wherein:
the unit comprises the arrestor system; and the unit further comprises:
a crown mounted atop the tower; and
a shaft connected to the drum and rotatable relative to the crown.

17 . The unit of claim 16 , wherein:
the arrestor system comprises:
a disk disposed around and torsionally connected to the shaft;
a housing disposed around the disk and the shaft and mounted to the crown;
electrorheological (ER) fluid disposed in the housing;
a pair of electrodes disposed through the housing and in communication with the ER fluid; and
the ER fluid behaves as a liquid when the electrodes are grounded and as a semi-solid when the electrodes are energized.

18 . The unit of claim 1 , wherein:
the unit comprises the arrestor system; and the arrestor system comprises:
a magnet set comprising a core mounted to the counterweight assembly and a pair of alternately polarized permanent magnets mounted to the core;
a winding set comprising a core mounted to the tower and extending along a length of the tower and windings spaced along the core, each winding wrapped around the core; and
one or more switches connected to the windings and operable between:
an open position preventing electrical contact between ends of the windings and allowing free longitudinal movement of the counterweight assembly relative to the tower; and
a closed position allowing the magnet set falling with the counterweight assembly to induce eddy currents in the winding set.

19 . The unit of claim 18 , wherein the winding set

Assignees

• Weatherford Technology Holdings Llc

Inventors

• Robison Clark E
• Thomas Benson
• Lane William C
• Yakimchuk Darius John
• Lembcke Jeffrey John
• Paulet Bryan A
• Cain Brandon M
• Christian Sean M
• Smith Paul L

Classifications

• E21B43/126 Primary

  Adaptations of down-hole pump systems powered by drives outside the borehole, e.g. by a rotary or oscillating drive (powered by fluid E21B43/129) · CPC title

• F04B47/14

  Counterbalancing · CPC title

• F16F15/023

  using fluid means · CPC title

• F04B47/02 Primary

  the driving mechanisms being situated at ground level (F04B47/12 takes precedence) · CPC title

• F16F15/03

  using {magnetic or} electromagnetic means (F16F9/53, {F16F15/005} take precedence) · CPC title