Systems and methods for controlling downhole linear motors

Patent metadata

Field	Value
Publication number	US-10408208-B2
Application number	US-201615075195-A
Country	US
Kind code	B2
Filing date	Mar 20, 2016
Priority date	Mar 20, 2015
Publication date	Sep 10, 2019
Grant date	Sep 10, 2019

Abstract

Systems and methods for controlling downhole linear motors to minimize connections to surface equipment. In one embodiment, an ESP system is coupled by a power cable to equipment at the surface of a well. The ESP system includes a linear motor and a reciprocating pump. The motor has a set of position sensors that sense the position of a mover in the motor. Combining circuitry (E.G., XOR gate) combines the outputs of the position sensors into a single composite signal in which signal components corresponding to the position sensors are indistinguishable. A single channel carries the composite signal from the ESP system to the surface equipment. A control system determines a starting position of the motor and determines its subsequent position based on transitions in the composite signal. The motor is then operated based on the position determined from the composite signal.

First claim

What is claimed is:

1. A system comprising:
one or more pieces of surface equipment positioned at the surface of a well;
an electric submersible pump (ESP) system positioned downhole in the well; and
a power cable coupled between the one or more pieces of surface equipment and the ESP system;
wherein the ESP system includes a linear motor and a reciprocating pump coupled to be driven by the motor;
wherein the motor includes a plurality of position sensors located at different positions along a stroke of a mover within the motor, wherein each position sensor is configured to sense that the mover of the motor is in a corresponding, different position within the motor;
wherein the ESP system includes circuitry that combines outputs of each of the plurality of position sensors into a single composite signal, wherein for each of the plurality of position sensors, a corresponding component of the composite signal which results from the output of the position sensor is indistinguishable from components of the composite signal which result from the output of other ones of the position sensors; and
wherein the system includes a single channel coupled between the ESP system and the one or more pieces of surface equipment that carries the composite signal from the ESP system to the one or more pieces of surface equipment;
wherein the surface equipment includes a control system that receives the composite signal, wherein an absolute position of the mover within the linear motor is not communicated to the control system, and wherein the control system tracks a position of the mover by counting transitions in the composite signal and produces output power in dependence on the transitions in the composite signal, wherein the output power is carried to the ESP system via the power cable.

2. The system of claim 1 , wherein the control system comprises a variable speed drive (VSD).

3. The system of claim 2 , wherein the VSD comprises a speed controller, wherein the speed controller determines a current speed of the motor and controls the VSD to produce output power which drives the ESP system at a desired speed.

4. The system of claim 1 , wherein the control system performs an initialization procedure at startup and thereby identifies a starting position of the mover in the linear motor and thereafter produces output power that drives the linear motor based on the identified starting position of the mover in the linear motor.

5. The system of claim 4 , wherein the control system: produces an initial power stroke voltage; monitors the composite signal; determines from the composite signal whether the mover has moved in response to the initial power stroke voltage; if the mover has moved in response to the initial power stroke voltage, continues to produce the initial power stroke voltage; and if the mover has not moved in response to the initial power stroke voltage, increases the power stroke voltage and continues monitoring the composite signal and determines from the composite signal whether the mover has moved in response to the increased power stroke voltage.

6. The system of claim 1 , wherein the single channel that carries the composite signal from the ESP system to the one or more pieces of surface equipment comprises a dedicated electrical line.

7. The system of claim 1 , wherein the circuitry that combines outputs of the plurality of position sensors into the composite signal comprises an XOR gate that receives each of the outputs of the plurality of position sensors as inputs and produces the composite signal as an output.

8. The system of claim 1 , wherein the plurality of position sensors comprise Hall effect sensors.

9. The system of claim 8 , wherein the composite signal comprises a includes a signal transition corresponding to each signal output by each of the Hall effect sensors.

Assignees

• Baker Hughes Inc

Inventors

• Williams Gary
• Mackay Evan G

Classifications

• F04B47/06

  having motor-pump units situated at great depth · CPC title

• F04B2201/0201

  Position of the piston · CPC title

• F04B51/00

  Testing machines, pumps, or pumping installations · CPC title

• F04B49/20 Primary

  by changing the driving speed · CPC title

• F04B17/03

  driven by electric motors · CPC title