APPARATUS AND METHOD FOR PREVENTING PARTICLE INTERFERENCE OF DOWNHOLE DEVICES
A device and method for inhibiting particle (e.g., sand) accumulation on down hole equipment, such as an ESP, particularly when the equipment is not in use. The device and methods permit the equipment to start and stop with fewer break downs and at greater efficiency. The device includes a central tubular section connecting the equipment to the production tubing string. The tubular section is surrounded by an annulus and a number of ports in the tubular section angled to allow fluid communication between the tubular section and the annulus during operation, but prevent particles from flowing from the annulus into the tubular section when not in use. A check valve between the tube and ESP assists in isolating the ESP from sand.
This application is a continuation of U.S. patent application Ser. No. 15/589,115, filed on May 8, 2017, which claims priority to U.S. Provisional Patent Application Ser. No. 62/334,174, filed on May 10, 2016, the contents of each are herein incorporated by reference in their entirety.
BACKGROUND FieldThis invention relates to systems and methods to prevent particle interference with downhole equipment, such as an electrical submersible pump (ESP).
Description of the Related ArtManagement of sand in the well bore has long been an issue. Many oil and gas wells are in sand-producing intervals, such as sandstones. There are several forms of artificial lift of the production fluids, with the most common being the electrical submersible pump (ESP). In recent years, unconventional wells have gained wide spread acceptance and often involve horizontal production tubing, ESP's for lift, and multiple, highly fractured production intervals, often in shale or other unconsolidated formations.
In such highly fractured, horizontal wells, the use of proppants, such as sand, to maintain the frac efficiency has increased. That is, there is a trend to use even more proppant per lateral foot of wellbore. Many ESP pumps have been manufactured to operate on sand filled fluid without significant numbers of failure. However, ESP's are often stopped, both intentionally and unintentionally. For example, electric reliability and power fluctuations often stop ESP operation or the ESP is stopped for maintenance or production issues. “Sand, particles and proppants” are sometimes used interchangeably for simplicity herein.
When an ESP stops operating, the sand in the production fluid tends to settle in the production tubing. The sand settles on the ESP which not only induces component failures in the ESP, but also makes restart of the ESP difficult because the ESP must first clear substantial amounts of sand from the production tubing. Failure and replacement of an ESP is not only expensive because of the rework required in the well, but also because of the lost production time.
Several attempts have been made to prevent sand accumulation on ESP's particularly when the ESP is idle. See e.g., CN Pat. Pub. No. 1,955,438, PCT App. Pub. No. WO2007083192, U.S. Pat. No. 6,289,990, U.S. Pat. No. 7,048,057, U.S. Pat. No. 9,181,785 and U.S. Pat. No. 9,441,435 (incorporated by reference). However, each of these existing tool designs has limitations which lead to suboptimal performance, and many are unnecessarily complex and expensive. Thus, a need continues to exist for a tool design that will automatically and cost effectively prevent the accumulation of sand on an ESP, without redepositing the sand below the ESP, potentially preventing the restarting of the ESP or requiring other steps to purge the production tubing of accumulated sand.
SUMMARYProblems with ESP operation are addressed by the device and methods of the present invention which tend to prevent particle accumulation on the ESP when not in use and provide for more efficient operation. Therefore the reliability, efficiency, timeliness and the likelihood of a successful restart of an ESP is greatly increased. Generally, the device prevents particle interference with lifting equipment, such as an ESP, in a well bore having a production tubing string using a tube positioned between the lifting equipment and the surface and in fluid communication with the lifting equipment and the production tubing string. An annulus portion is defined around the tube, e.g. with a cylinder spaced from and surrounding the tube. The device includes a check valve proximate at least one end of the tube which operates to permit fluid flow from the lifting equipment to the surface, but prevents fluid flow from the tube to the lifting equipment. The device has a plurality of ports positioned in the wall of the tube which operate to permit fluid flow from the tube into the annulus during operation of the lifting equipment and operable to inhibit particles from entering the tube when the lifting equipment is not operating. Preferably, the ports are angled in the direction of the lifting equipment and can be more dense closest to the lifting equipment.
One method of the present invention operates to inhibit particle impediment to lifting equipment, such as an ESP, when not in use. Generally, the lifting equipment is positioned in the well bore downhole from the surface and operable to pump fluid through a production tubing string to the surface. A particle-excluding device is connected to the production tubing string between the lifting equipment and the surface, the device having a central tubular portion, a surrounding annulus portion, a plurality of spaced ports communicating between the tube and the annulus and a check valve between the ports and the lifting equipment. The lifting equipment is operated so that fluid flows through the check valve, ports, tubular portion and at least some of the annulus portion and into the production tubing. The method inhibits particles in the fluid from accumulating on the lifting equipment when the lifting equipment is not in use by trapping a substantial portion of particles in the annulus, whereby the ports inhibit particle flow into the tubing portion. The check valve prevents reverse fluid flow to the lifting equipment when not in use, and thus prevents the ESP from spinning backwards due to a reversal of the fluid flow.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the accompanying drawings.
Turning to the drawings, a first embodiment of a device 10 in accordance with the present invention is illustrated in
Generally, the device 10 includes a central production tube 16 surrounded by an enlarged cylinder housing 18. Thus, the area between the tube 16 and the inner walls of the cylinder 18 define an annulus 20. At each end of the tube 16 is a check valve 21, 22.
An end packer 26 is illustrated in
During normal operation (
In
In
The “downward” angle of the port 24 is greater than perpendicular, but the optimum angle is dependent on the orientation of the device 10 (vertical vs. horizontal), the density of the sand 30 and the composition of the fluid. It is believed that about a 45′ angle will work for most vertical applications, and preferably between 30-60′. The use of the angled ports 24 is believed advantageous over resistive mesh screens to prevent sand from entering the tube and hindering operation of the ESP 14. The design of ports 24 includes consideration not only of the angle, but also the diameter of the port 24. The design of the ports 24 also takes into consideration the wall thickness (weight) of the tube 16. In
While the device 10 is illustrated in the context of a vertical well bore in the figures, it will be understood that horizontal wells can benefit from the use of the device 10. In fact, horizontal wells make extensive use of proppants for fracking which is a prime contributor to particles in the production tubing which can settle onto an ESP and hinder operation. Additionally, while protection of ESP's is a prime use of the device 10, other downhole equipment can be protected from particle interference as well.
A second embodiment of a device 50 in accordance with the present invention is illustrated in
Generally, the device 50 includes a central cylindrical tube 56 surrounded by an enlarged cylinder housing 58. Thus, the area between the tube 56 and the inner walls of the cylinder 18 define an annulus 60. At the distal end 72 of the tube 56, nearest the ESP 14, is a check valve 62. At the proximal end 74 of the tube 56, nearest the surface, is a cap 66. As with the first embodiment check valves known in the art can be used, such as ball type check valves, diaphragm check valve, swing check valve or tilting disc check valve, stop-check valve, lift-check valve, in-line check valve, duckbill valve, or pneumatic non-return valve. The cap 66 is fixed to prevent fluid flow to or from the tube 56 in the region of the cap 66. The check valve 62 of
An end packer 68 is illustrated in
During normal operation (
In
Advantageously, the fluid in the production tubing is retained while the ESP is off in
The check valve 62 is largely free from impingement by sand 30 during all phases of operation of the device 50. The check valve 62 in
In
In the case where sand covers substantially all of the ports 24 in the region of the distal end 72, the few ports 24 in the region of the proximal end 74 are substantially clear. Restart of ESP 14 in this case causes a pressure differential build-up between the distal and proximal ends 72, 74. In this case, the entire column of sand 30 in the annulus 60 clears through the production tubing 12 almost immediately. In this case, having a large number of ports 24 near the distal end widely spaced from a few ports 24 at the proximal end is advantageous.
While the devices 10, 50 are illustrated in the context of a vertical well bore in the figures, it will be understood that horizontal wells can benefit from the use of the devices 10, 50. In fact, horizontal wells make extensive use of proppants for fracking which is a prime contributor to particles in the production tubing which can settle onto an ESP and hinder operation. Additionally, while protection and efficient operation of an ESP are prime uses of the devices 10, 50, other downhole equipment can be protected from particle interference as well.
Claims
1. A device for preventing particle interference with downhole lifting equipment in a well bore having a production tubing string, comprising:
- a tube positioned between the downhole lifting equipment and the surface and in fluid communication with the downhole lifting equipment and the production tubing string;
- a housing positioned around the tube defining an annulus portion between the tube and the housing;
- an upper check valve connected to a proximal end of the tube nearest the surface that is biased into a closed position to prevent flow into the tube through the proximal end;
- a lower check valve connected to a distal end of the tube that is biased into a closed position to prevent flow out of the tube through the distal end; and
- a plurality of ports disposed through the tube that are configured to permit flow from the tube into the annulus, wherein the ports are spaced along the tube and oriented at a downward angle relative to the longitudinal axis of the tube.
2. The device of claim 1, wherein the downward angle of the ports is between 30 degrees and 60 degrees relative to the longitudinal axis of the tube.
3. The device of claim 1, wherein the largest number of ports are positioned nearest the distal end.
4. The device of claim 3, wherein the fewest number of ports are positioned nearest the proximal end.
5. The device of claim 1, wherein the upper check valve is movable into an open position to permit flow out of the tube through the proximal end.
6. The device of claim 1, wherein the lower check valve is movable into an open position to permit flow into the tube through the distal end.
7. A system for preventing particle interference with downhole lifting equipment in a well bore having a production tubing string, comprising:
- downhole lifting equipment;
- a tube positioned between the downhole lifting equipment and the surface and in fluid communication with the downhole lifting equipment and the production tubing string;
- a housing positioned around the tube defining an annulus portion between the tube and the housing;
- an upper check valve connected to a proximal end of the tube nearest the surface that is biased into a closed position to prevent flow into the tube through the proximal end;
- a lower check valve connected to a distal end of the tube that is biased into a closed position to prevent flow out of the tube through the distal end; and
- a plurality of ports disposed through the tube that are configured to permit flow from the tube into the annulus, wherein the ports are spaced along the tube and oriented at a downward angle relative to the longitudinal axis of the tube.
8. The system of claim 7, wherein the downward angle of the ports is between 30 degrees and 60 degrees relative to the longitudinal axis of the tube.
9. The system of claim 7, wherein the largest number of ports are positioned nearest the distal end.
10. The system of claim 9, wherein the fewest number of ports are positioned nearest the proximal end.
11. The system of claim 7, wherein the upper check valve is movable into an open position to permit flow out of the tube through the proximal end.
12. The system of claim 7, wherein the lower check valve is movable into an open position to permit flow into the tube through the distal end.
13. The system of claim 7, wherein the downhole lifting equipment comprises an electric submersible pump.
Type: Application
Filed: Sep 7, 2018
Publication Date: Jan 3, 2019
Inventors: Robert P. FIELDER, III (Houston, TX), Kyle Meier (Houston, TX), Evan Sheline (Sugar Land, TX)
Application Number: 16/124,547