Patent Application
20170074089
Field of the Disclosure
Certain aspects of the present disclosure generally relate to hydrocarbon production using artificial lift and, more particularly, to sensing an event associated with cavitation in an artificial lift system.
Description of the Related Art
Several artificial lift techniques are currently available to initiate and/or increase hydrocarbon production from drilled wells. These artificial lift techniques include rod pumping, plunger lift, gas lift, hydraulic lift, progressing cavity pumping, and electric submersible pumping, for example.
Sensors are often used to monitor various aspects when operating artificial lift systems. For example, U.S. Pat. No. 6,634,426 to McCoy et al., entitled “Determination of Plunger Location and Well Performance Parameters in a Borehole Plunger Lift System” and issued Oct. 21, 2003, describes monitoring acoustic signals in the production tubing at the surface to determine depth of a plunger based on sound made as the plunger passes by a tubing collar recess.
Certain aspects of the present disclosure provide a method for operating an artificial lift system for a wellbore. The method generally includes monitoring the wellbore for an indication of an event associated with cavitation in the artificial lift system and adjusting at least one parameter of the artificial lift system if the event is detected.
Certain aspects of the present disclosure provide a system for hydrocarbon production. The system generally includes an artificial lift system for a wellbore and at least one sensor configured to detect an indication of an event associated with cavitation in the artificial lift system.
According to certain aspects, the sensor is configured to detect the event before the cavitation occurs in the artificial lift system.
[000s] According to certain aspects, the artificial lift system includes a downhole fluid pump disposed in the wellbore. For certain aspects, the fluid pump is a hydraulic jet pump. In this case, the hydraulic jet pump may include a nozzle and a throat, wherein fluid is passed through the nozzle into the throat. Cavitation damage may occur to the throat. For certain aspects, the sensor is coupled to the downhole fluid pump.
According to certain aspects, the artificial lift system includes a power fluid pump.
According to certain aspects, the system further includes a wellhead. For certain aspects, the sensor is positioned at the wellhead.
According to certain aspects, the sensor is positioned in the wellbore.
According to certain aspects, the event comprises an onset of cavitation occurring or actual cavitation occurring.
According to certain aspects, the indication is an acoustic or vibrational indication having a frequency of about 5.6 kHz.
According to certain aspects, the sensor comprises at least one of a microphone, an accelerometer, or a gyroscope.
Certain aspects of the present disclosure provide a sensor configured to detect an indication of an event associated with cavitation in an artificial lift system.
According to certain aspects, the sensor is configured for coupling to a wellhead of the wellbore. For other aspects, the sensor is configured for positioning in the wellbore. For example, the sensor may be configured for coupling to a fluid pump of the artificial lift system.
According to certain aspects, the sensor comprises a microphone, an accelerometer, or a gyroscope.
Certain aspects of the present disclosure provide an apparatus for operating an artificial lift system for a wellbore. The apparatus generally includes means for monitoring the wellbore for an indication of an event associated with cavitation in the artificial lift system; and means for adjusting at least one parameter of the artificial lift system, if the event is detected.
Certain aspects of the present disclosure provide a non-transitory computer-readable medium containing a program. The program, when executed by a processing system, causes the processing system to perform operations generally including monitoring a wellbore for an indication of an event associated with cavitation in an artificial lift system and adjusting at least one parameter of the artificial lift system, if the event is detected.
So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to certain aspects, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects.
Certain aspects of the disclosure provide techniques and apparatus for monitoring a wellbore for an indication of an event associated with cavitation in an artificial lift system and adjusting at least one parameter of the artificial lift system if the event is detected.
Artificial lift systems (e.g., system 100) may suffer from production problems associated with cavitation. Cavitation occurs when negative gage pressure vapor filled bubbles form in wellbore fluid and higher pressure in the fluid surrounding the bubbles causes the bubbles to implode violently. Bubbles can form, for example, when a pump intake is starved for fluid or when localized fluid pressure drops below the vapor pressure of the solution. Micro-jets that may be due to the bubble implosions can cause severe damage to artificial lift system components. In some cases, incorrect pump selection (e.g., selecting a pump that generates enough suction at the pump intake to lower pressure below the vapor pressure of the solution) can lead to cavitation. In other cases, altered well conditions (e.g., a change in the fluid entering the pump intake) can lead to cavitation. Cavitation may damage or even destroy pumps, thereby reducing artificial lift system efficiency and sometimes completely disabling an artificial lift system.
At least two events can be associated with cavitation: onset of cavitation (also referred to as “incipient cavitation”) and cavitation. Onset of cavitation occurs before cavitation and may be accompanied by an acoustic indication, such as a loud, high-pitched noise or a vibrational indication. As an example, the acoustic indication may have a frequency of about 5.6 kHz, where “about” as used herein generally refers to a range within ±20% of the nominal value. During onset of cavitation, fluid conditions are nearly ripe for cavitation to begin occurring, but no cavitation-related pump damage has occurred. However, once cavitation occurs, pump damage may be certain and nearly instantaneous, resulting in a substantial reduction in hydrocarbon production efficiency.
Under current artificial lift system operating procedures, cavitation is only detected post hoc (i.e., after cavitation has already occurred); there is no procedure for detecting onset of cavitation. The only indication of a cavitation event is a drop in production efficiency, and the system production rate may fall significantly, sometimes to zero. In any case, the system may have to be shut down or set to a maintenance mode to allow for repairs, e.g., to a pump or other artificial lift equipment. Before production at full capacity can be resumed, the downhole fluid pump may be drawn out of the wellbore, and damaged pump components may be replaced by other components (or the entire pump may be replaced). This typically involves waiting for the replacement components to be shipped, which can result in significant system downtime and production loss.
Losses due to cavitation can be reduced if system operating parameters can be adjusted to prevent cavitation before the cavitation occurs. Accordingly, techniques and apparatus for detecting cavitation or an onset of cavitation in an artificial lift system and adjusting one or more parameters of the artificial lift system to avoid cavitation damage and production losses are desired.
According to aspects of the present disclosure, to help prevent production loss associated with cavitation, the artificial lift system 100 may include at least one sensor 108, which may be positioned at and acoustically, mechanically, and/or otherwise coupled to the wellhead 102, for example. The sensor 108 is configured to detect an indication of an event associated with cavitation (e.g., that actual cavitation is occurring or an onset of cavitation). For example, the sensor 108 may be a microphone, an accelerometer or other vibrational sensor, or a gyroscope configured to detect vibrations or other indications of cavitation. The sensor 108 may be capable of detecting an indication associated with actual cavitation and/or an indication associated with the onset of cavitation and sending a signal (e.g., to the surface controller 107 or another control system of the artificial lift system 100). The signal may be an electrical signal conveyed via a wire or wirelessly and/or an optical signal (e.g., a light pulse) conveyed via an optical waveguide (e.g., an optical fiber). In cases where the sensor 108 detects an indication associated with the onset of cavitation, the sensor 108 may be instrumental in helping prevent cavitation in the artificial lift system 100. For example, a control system and/or an operator of the artificial lift system 100 may adjust a parameter (e.g., decrease a flow rate), to prevent cavitation in the artificial lift system 100, in response to a signal from the sensor 108. Alternatively, in cases where the sensor 108 detects an indication associated with actual cavitation, the sensor 108 may be useful in helping prevent further damage to the system 100. For example, a control system and/or an operator of the artificial lift system 100 may adjust a parameter (e.g., inspect a pump for damage, replace a pump component, etc.), to prevent further cavitation in the artificial lift system 100, in response to a signal from the sensor 108.
Similar to sensor 108, sensor 204 is configured to detect an indication of an event associated with cavitation in the artificial lift system. For example, the sensor 204 may be a microphone, an accelerometer, or a gyroscope configured to detect sound or vibration. The sensor 204 may detect an indication associated with onset of cavitation, and/or an indication associated with cavitation. In cases where the sensor 204 detects an indication associated with onset of cavitation, the sensor 204 may help prevent cavitation in the system by detecting onset of cavitation and sending a signal (e.g., to a control system of an artificial lift system) indicating the onset of cavitation before cavitation occurs. The signal may be an electrical signal conveyed via a wire or wirelessly and/or an optical signal (e.g., a light pulse) conveyed via an optical waveguide (e.g., an optical fiber). A control system and/or an operator of the artificial lift system may respond to the signal by adjusting a parameter of the artificial lift system to prevent cavitation from occurring. Alternatively, in cases where the sensor 204 detects an indication associated with cavitation, the sensor 204 may help prevent further damage to the artificial lift system by sending a signal indicating that cavitation is occurring. The signal may be an electrical signal conveyed via a wire or wirelessly and/or an optical signal (e.g., a light pulse) conveyed via an optical waveguide (e.g., an optical fiber). A control system and/or an operator of the artificial lift system may respond to the signal by adjusting a parameter of the artificial lift system to prevent further cavitation from occurring.
As an example operation of the fluid pump, the hydraulic jet pump 402 may be disposed in a wellbore, and power fluid may be pumped down the wellbore towards the hydraulic jet pump 402. Initially, the fluid may have a high pressure and low velocity. However, the nozzle 404 may constrict the flow of the power fluid, drastically increasing the power fluid's velocity and decreasing its pressure. This power fluid may then jet through the nozzle 404 into the throat 406. In some cases, the power fluid jetted from the nozzle 404 is at a lower pressure than production fluid in the production inlet chambers 408. The pressure gradient between the production inlet chambers 408 and the throat 406 can result in production fluid flowing into the throat. This may result in production fluids intersecting and mixing with power fluid.
The intersecting and mixing of fluids in the throat 406 may result in conditions that can lead to cavitation, as described above regarding cavitation-associated events. For example, fluid conditions and/or the nozzle-throat size combination may lead to cavitation-associated events, which may damage the throat 406.
As described above, an event associated with cavitation may be accompanied by an indication. For example, a cavitation-associated event at the throat 406 of the hydraulic jet pump 402 may lead to vibration of the fluid pump. In turn, the fluid pump vibration may lead to an indication 410 (e.g., an acoustic or vibrational indication). The indication 410 may have a frequency of about 5.6 kHz, for example. The indication 410 may be conveyed to a sensor, such as sensor 108, 202, or 300. In some aspects, the indication 410 travels up the wellbore to the sensor at the wellhead, where the sensor detects the indication 410. In other aspects, the sensor is disposed in the wellbore, and the indication 410 travels along the wellbore to the sensor. Alternatively, the sensor may be strapped to the fluid pump (as shown in
The operations 500 may begin, at block 502, by monitoring a wellbore for an indication of an event associated with cavitation in an artificial lift system. At block 504, at least one parameter of the artificial lift system may be adjusted if the event is detected. The event may, for example, be onset of cavitation, or the event may be cavitation. Additionally, the indication may have a frequency of about 5.6 kHz, for example.
Monitoring at block 502 may include using one or more sensors to detect the indication. For example, the sensor(s) may be sensor 108, 204, or 300, as described above. Thus, the sensor(s) may include a microphone, an accelerometer, and/or a gyroscope. Additionally, similar to aspects described above, the sensor(s) may be positioned at a wellhead for the wellbore and/or in the wellbore. As described regarding
Adjusting at block 504 may include changing any of various suitable parameters of the artificial lift system, such as replacing or repairing equipment or components; modifying, introducing, or removing control signals; storing and/or reporting the indication; setting a flag and/or outputting a signal based on the indication; and the like. Outputting a signal may include, for example, generating an analog or digital signal and transmitting the signal via a wire, wirelessly (e.g., via a radio transmission), and/or as one or more light pulses conveyed via an optical waveguide (e.g., an optical fiber). Other examples of outputting a signal include generating an audible sound, turning on a light, and/or causing a message to appear on a display screen.
For certain aspects, at least one parameter can be adjusted to avoid cavitation damage. These adjustments can be made before cavitation occurs in the artificial lift system, such as during onset of cavitation, or after cavitation occurs. For example, the parameter may be a production rate by the artificial lift system. In such aspects, adjusting may include increasing production, reducing production, or stopping production of the artificial lift system. If production is stopped, it may be helpful in certain situations to wait a sufficient time before resuming production for fluid to settle in the wellbore.
In some circumstances, such stop-and-go operation may not be sufficient to resolve the event. For example, the event may be occurring due to improper throat sizing and/or cavitation damage to the fluid pump. In any case, adjusting the parameter may include removing the fluid pump of the artificial lift system from the wellbore. The fluid pump can then be inspected for cavitation damage. If the damage is present, the fluid pump or one or more components thereof can be replaced. Alternatively, the adjusting may include replacing at least one component of the fluid pump with another component to avoid cavitation damage in subsequent wellbore operation. For example, the fluid pump may be a hydraulic jet pump, as depicted in
Any of the operations described above, such as the operations 500, may be included as instructions in a computer-readable medium for execution by the surface controller 107 or any suitable processing system. The computer-readable medium may comprise any suitable memory or other storage device for storing instructions, such as read-only memory (ROM), random access memory (RAM), flash memory, an electrically erasable programmable ROM (EEPROM), a compact disc ROM (CD-ROM), or a floppy disk.
While the foregoing is directed to certain aspects of the present disclosure, other and further aspects may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
The present Application for Patent claims priority to U.S. Provisional Application No. 62/216,812, filed Sep. 10, 2015, which is assigned to the assignee of the present application and hereby expressly incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 62216812 | Sep 2015 | US |
