Devices and Methods for Electromagnetic Measurement of Axial Flow
An embodiment method for measuring fluid flow in a casing includes inserting a logging tool into the casing, wherein the logging tool having an internal axial flow channel and an electromagnetic flowmeter sensor disposed in the internal flow channel. The method also includes measuring an axial conductive fluid flow through the flow channel with the electromagnetic flowmeter sensor, while allowing bypass axial fluid flow to bypass the internal flow channel substantially unimpeded between an exterior of the logging tool and an interior wall of the casing.
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This application is related to the following co-pending and commonly-assigned patent applications: U.S. patent application Ser. No. 13/561,973, entitled “Fluid Flow Measuring Device and Method,” filed Jul. 30, 2012; U.S. patent application Ser. No. 13/681,047, entitled “Apparatus and Method for Fluid Flow Measurement with Sensor Shielding,” filed Nov. 19, 2012; U.S. patent application Ser. No. 13/447,962, entitled “Rotating Fluid Measurement Device and Method,” filed Apr. 16, 2012; and International Application No. PCT/US2012/036951, entitled “Fluid Flow Measurement Sensor, Method, and Analysis,” filed on May 25, 2012, all of which applications are hereby incorporated herein by reference.
TECHNICAL FIELDThe present invention relates generally to devices and methods for flow measurement, and, in particular embodiments, to devices and methods for electromagnetic measurement of axial flow.
BACKGROUNDThere are many types of sensors used for flowmeters, and various ones of these have been used or proposed to measure fluid flow in boreholes and wells. One example of a flowmeter is a mechanical spinner/impeller flowmeter, where moving fluid drives the impeller, and the rate of rotation of the impeller provides an indication of the fluid velocity. Such impellers may not properly operate at low fluid flow rates, and thus may not correctly measure slowly-moving fluid.
Another example is an electromagnetic flowmeter, which functions by inducing a voltage when a medium (such as water) moves in a magnetic field. The induced voltage is perpendicular both to the direction of the magnetic field and to the direction of the movement of the medium. When the moving medium is at least slightly conductive, an induced voltage provides an indication of the velocity of the medium. This induced voltage is directly proportional to the velocity of the moving medium.
U.S. Pat. Nos. 5,297,425 and 5,388,455 to Hamby et al., which applications are hereby incorporated herein by reference, describe the use of an electromagnetic flowmeter in water producing wells. A single flow channel with a single pair of electrodes are used with an inflatable packer filled with water pumped in from the surface to attempt to force all the flow in the well to go through the single flow channel. Alternatively, a hard collar may be used instead of a packer to prevent fluid from around the single flow channel. Generally, with such schemes there is leakage around the packer or collar, causing an inaccurate reading of the fluid flow. Also, the possibility of the tool becoming stuck in the well can be a significant problem.
SUMMARY OF THE INVENTIONAn embodiment method for measuring fluid flow in a casing includes inserting a logging tool into the casing, wherein the logging tool having an internal axial flow channel and an electromagnetic flowmeter sensor disposed in the internal flow channel. The method also includes measuring an axial conductive fluid flow through the flow channel with the electromagnetic flowmeter sensor, while allowing bypass axial fluid flow to bypass the internal flow channel substantially unimpeded between an exterior of the logging tool and an interior wall of the casing.
Another embodiment method for measuring fluid flow in a casing includes inserting a logging tool into the casing, wherein the logging tool includes a tool body and an electromagnetic flowmeter sensor, wherein the electromagnetic flow sensor has a pair of electrodes disposed on an exterior of the tool body. The method also includes measuring an axial conductive fluid flow in the casing with the pair of electrodes of the electromagnetic flowmeter sensor, wherein an imaginary line between the pair of electrodes is orthogonal to the axial conductive fluid flow.
An embodiment logging tool for measuring fluid flow in a casing includes an elongated tool body having a central axis. The logging tool also includes a first non-centralized flow channel mechanically coupled to the tool body, wherein a first axis of the first flow channel is parallel to the central axis of the tool body, and wherein the first flow channel is radially offset from the central axis of the tool body, and a first electromagnetic flowmeter sensor, wherein the first electromagnetic flow sensor has a first pair of electrodes disposed inside the first flow channel, wherein a first imaginary line between the first pair of electrodes is orthogonal to the first axis of the first flow channel. The logging tool further includes a second non-centralized flow channel mechanically coupled to the tool body, wherein a second axis of the second flow channel is parallel to the central axis of the tool body, and wherein the second flow channel is radially offset from the central axis of the tool body, and a second electromagnetic flowmeter sensor, wherein the second electromagnetic flow sensor has a second pair of electrodes disposed inside the second flow channel, wherein a second imaginary line between the second pair of electrodes is orthogonal to the second axis of the second flow channel.
Another embodiment logging tool for measuring fluid flow in a casing includes an elongated tool body having a central axis, and a plurality of electromagnetic flowmeter sensors mechanically coupled to the tool body and disposed in a first plane perpendicular to the central axis of the tool body, wherein each of the electromagnetic flowmeter sensors has a flow channel with a flow channel axis parallel to the central axis of the tool body.
For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawing, in which:
The making and using of the presently preferred embodiments are discussed in detail below. It should be appreciated, however, that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed are merely illustrative of specific ways to make and use the invention, and do not limit the scope of the invention.
The co-assigned patent applications cross-referenced hereinabove generally describe the use of an electromagnetic flowmeter oriented to measure radial fluid flow into/out of a borehole wall, where the electromagnetic flowmeter is disposed adjacent the borehole wall. These applications, which are hereby incorporated herein by reference, describe detailed devices and methods for implementing electromagnetic flowmeters, and these devices and methods may be used to implement the electromagnetic flowmeters provided herein. These applications also describe systems and methods for reading, retrieving, interpreting, and analyzing data provided by electromagnetic sensors, and these systems and methods may be combined with the electromagnetic flowmeter devices and methods provided herein.
The present invention will be described with respect to preferred embodiments in a specific context, namely electromagnetic flowmeter devices and methods for measuring longitudinal axial flow in a well borehole. The invention may also be applied, however, to other applications where the detection of fluid flow is useful, such as in pipes, casings, drill shafts, tanks, and swimming pools. Embodiments may be used in vertical, deviated, and horizontal wells, and may be used in tubing, casing, slotted screens, slotted liners, and almost any well completion. Any type of conduit, wellbore, borehole, cylinder, pipe, shaft, tube, etc., is referred to herein generally as a casing.
In one embodiment, an electromagnetic flow meter device and method measure fluid flow in a casing without bypass prevention. In another embodiment, an electromagnetic flow meter device and method measure fluid flow using electrodes disposed on an exterior of a tool instead of or in addition to electrodes disposed internally in a tool, that is, in a tool flow channel. In another embodiment, an electromagnetic flow meter device and method measure fluid flow using non-centralized flow channels in the logging tool body. In another embodiment, an electromagnetic flow meter device and method measure fluid flow using multiple electromagnetic flowmeter sensors in the flow stream. The sensors may be stationary, or they may rotate around the longitudinal axis of the tool, or they may move radially in and out relative to the logging tool.
Again, an embodiment electromagnetic flow meter device and method measure fluid flow using an electromagnetic flowmeter without bypass prevention. An embodiment uses an electromagnetic flow meter only, without a packer, collar, or other flow by-pass prevention device, to measure axial flow in a wellbore. The electromagnetic flow meter can be positioned approximately centralized in the cross section of the logging tool and in the borehole, but may be positioned off-center.
The electromagnetic flowmeter is oriented to measure the axial flow of fluid in the casing. That is, both an electromagnetic field generated by the electromagnetic flowmeter, and an imaginary line between voltage-sensing electrodes in the flowmeter, are perpendicular to the axial flow of fluid in the casing, as well as to each other. The electromagnetic field and the imaginary line thus are oriented to be in the plane of the casing cross-section. Within this plane, they may be oriented in any direction, as long as they remain perpendicular to each other for the sensor to provide maximum sensitivity to axial fluid flow. It is possible for the electromagnetic field and the imaginary line to deviate from being at right angles to each other and to the axis of the casing, but the higher these deviations, the less sensitive the sensor is to the axial flow.
Thus an electromagnetic flow meter may be used in a similar manner as a conventional spinner (impeller) flowmeter, except that an electromagnetic flow meter measures only the flow of conductive fluids, such as water, and does not measure the flow of non-conductive fluids such as oil and gas. The electromagnetic flow meter optionally may have a funnel shaped entrance to facilitate the entry of fluid into its cavity/cavities containing the sensor/sensors.
The electromagnetic flow meter may include any of a number of combinations of a flow channel, a magnetic flux generator, and a pair of electrodes to detect the induced voltage that is indicative of the axial flow velocity of the conductive fluid. Such variations are described in the previously-mentioned cross-referenced patent applications.
Further, standard methods of deriving the flow rate of the conductive fluid through the entire wellbore may be used, as well as those methods described in the previously-mentioned cross-referenced patent applications.
Advantageously, in an embodiment, the bypass flow 106 can be accounted for with an area of flowmeter to area of internal diameter of the casing correction. Therefore, assumptions about or corrections for a packer or collar leaking do not need to be made. Packers and collars frequently leak, causing interpretation errors. Also, packers tend to become stuck in the casing, causing serious and expensive operational problems.
Additionally, for deeper wells, the running of fluid line(s), which is used to fill an expandable packer, becomes impractical. Also, running with a fixed collar around the sensor to prevent bypass flow is usually not practical in oil and gas wells due to the small diameter tubing that is normally used in portions of the wellbore.
In addition, an embodiment electromagnetic flow meter sensor has several advantages over conventional spinners. For example, there generally are no moving parts in an electromagnetic flow sensor, and moving parts, such as spinners, generally require frequent and expensive maintenance. A rotating spinner also frequently becomes jammed and stops rotating, thereby providing no useful information about flow rate. In contrast, an embodiment electromagnetic flow meter simply has an essentially open flow channel, and thus has fewer obstructions and is much more insensitive to debris in the flow stream.
Electromagnetic flow meters also have no threshold (i.e., have a zero threshold) flow rate, unlike mechanical spinners, which have thresholds typically from 4 feet per minute (FPM) to 20 FPM or more. Electromagnetic flow meters also have a linear response to velocity, whereas mechanical spinners have a linear response over higher ranges of fluid velocity, but not at low velocities where the response is very non-linear. There also is a dead zone at flow rates lower than the threshold.
Another embodiment system and method use an electromagnetic flowmeter with external electrodes. Instead of an electromagnetic flow meter with electrodes inside a flow channel in the sensor, an embodiment provides an alternative, namely a sensor that has electrodes external to the body of the sensor. This embodiment may be used in conjunction with the previous embodiment, where a bypass flow can occur inside the logging tool. Alternatively, there may be sensors disposed both internally and externally to the body of the sensor.
An embodiment with external electrodes provides a smaller, more compact device, which in some cases is a significant operational advantage, as normally one has to run the sensor through smaller diameter tubing and other restrictions before encountering the larger diameter casing where the measurements usually are taken.
Additionally, external electrodes operationally make maintenance of the sensor easier, as external electrodes can be more accessible and easier to clean, and/or replace, if needed.
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Another embodiment system and method use an electromagnetic flowmeter with non-centralized flow channels in the logging tool body. There may be any number of such flow channels, including any specific number between two and eight, or more, disposed on the tool body. One or more of the flow channels may be located fully or partially inside the body of the logging tool. The electrode pairs can have various arrangements, such as circumferential, radial, etc. This embodiment may be used in conjunction with the previous embodiments, where there may be a non-centralized flow channel in combination with a centralized flow channel. Alternatively, there may be non-centralized flow channel in combination with an external electrode pair without a dedicated flow channel.
Another embodiment system and method use one or more electromagnetic flowmeter sensors external to the body of the logging tool. The sensors can be disposed at various locations in the cross-section of the flow stream in a wellbore, and can be disposed in a single plane or in multiple planes. In various embodiments, a variety of locations in the flow stream and a variety of sensor movements can be used. These embodiments may be used in conjunction with the previous embodiments disclosed herein. Further, as with other embodiments disclosed herein, the electromagnetic sensors, arm configurations, arm radial and circumferential movements, magnetic flux generators, electrical current shields, resistor and electrode networks, electronic control and measurement circuits, measurement procedures and analyses, etc., disclosed in the previously-mentioned cross-referenced patent applications may be used in conjunction with these embodiments.
A different number of sensors, such as any specific number between two and 12, or more, can be implemented in various embodiments. The radial locations of the sensors away from the tool body can be varied within an embodiment or between different embodiments. Also, the axial locations of the sensors along the logging tool body can be varied within an embodiment or between different embodiments. The electromagnetic sensors can be self-contained sensors, with the arm for each providing mechanical and positioning support, as well as a conduit or support for the wires carrying, e.g., data, control and power signals. Alternatively, each arm can be implemented as part of the core of its respective sensor. Further, there may be more than one sensor mounted on each arm, either at the end of the arm, or at multiple locations along the arm.
With a mesh arrangement, magnetic flux is generated over substantially the entire flow area within the wellbore, and measurements of the flow-induced voltages are made at a multitude of locations within the flow stream using a multitude of electrode pairs or the equivalent. The magnetic flux orientation and the electrode orientation are substantially perpendicular to each other, and they are both substantially perpendicular to the axial flow. This multitude of flow-induced voltages then can be used to determine the overall flow rate of the entire flow within the wellbore. When measuring the induced voltage due to fluid flow, several approaches can be taken.
While this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is therefore intended that the appended claims encompass any such modifications or embodiments.
Claims
1. A method for measuring fluid flow in a casing, the method comprising:
- inserting a logging tool into the casing, the logging tool having an internal axial flow channel and an electromagnetic flowmeter sensor disposed in the internal flow channel; and
- measuring an axial conductive fluid flow through the flow channel with the electromagnetic flowmeter sensor, while allowing bypass axial fluid flow to bypass the internal flow channel substantially unimpeded between an exterior of the logging tool and an interior wall of the casing.
2. The method of claim 1, further comprising generating a magnetic flux inside the flow channel orthogonal to the axial fluid flow through the flow channel.
3. The method of claim 2, wherein the electromagnetic flowmeter sensor comprises a pair of electrodes disposed in the flow channel, wherein an imaginary line between the pair of electrodes is orthogonal to the magnetic flux and to the axial fluid flow through the flow channel, and wherein the measuring comprises measuring a voltage difference between the pair of electrodes, wherein the voltage difference is proportional to a velocity of the axial conductive fluid flow.
4. The method of claim 1, further comprising repeating the measuring at different depths in the casing.
5. The method of claim 1, further comprising centering the flow channel in the casing prior to the measuring.
6. A method for measuring fluid flow in a casing, the method comprising:
- inserting a logging tool into the casing, the logging tool comprising a tool body and an electromagnetic flowmeter sensor, wherein the electromagnetic flow sensor has a pair of electrodes disposed on an exterior of the tool body; and
- measuring an axial conductive fluid flow in the casing with the pair of electrodes of the electromagnetic flowmeter sensor, wherein an imaginary line between the pair of electrodes is orthogonal to the axial conductive fluid flow.
7. The method of claim 6, further comprising generating a magnetic flux orthogonal to the axial fluid flow and to the imaginary line between the pair of electrodes.
8. The method of claim 6, wherein the measuring comprises measuring a voltage difference between the pair of electrodes, wherein the voltage difference is proportional to a velocity of the axial conductive fluid flow.
9. The method of claim 6, wherein the logging tool further comprises a plurality of electromagnetic flowmeter sensors each having a respective pair of electrodes disposed on the exterior of the tool body, and wherein the measuring further comprises, for each respective pair of electrodes, measuring a voltage difference between the respective pair of electrodes, wherein the voltage difference is proportional to a velocity of the axial conductive fluid flow between the respective pair of electrodes.
10. The method of claim 9, wherein the measuring further comprises measuring the axial conductive fluid flow at multiple angular locations around a perimeter of the tool body.
11. A logging tool for measuring fluid flow in a casing, the logging tool comprising:
- an elongated tool body having a central axis;
- a first non-centralized flow channel mechanically coupled to the tool body, wherein a first axis of the first flow channel is parallel to the central axis of the tool body, and wherein the first flow channel is radially offset from the central axis of the tool body;
- a first electromagnetic flowmeter sensor, wherein the first electromagnetic flow sensor has a first pair of electrodes disposed inside the first flow channel, wherein a first imaginary line between the first pair of electrodes is orthogonal to the first axis of the first flow channel;
- a second non-centralized flow channel mechanically coupled to the tool body, wherein a second axis of the second flow channel is parallel to the central axis of the tool body, and wherein the second flow channel is radially offset from the central axis of the tool body; and
- a second electromagnetic flowmeter sensor, wherein the second electromagnetic flow sensor has a second pair of electrodes disposed inside the second flow channel, wherein a second imaginary line between the second pair of electrodes is orthogonal to the second axis of the second flow channel.
12. The logging tool of claim 11, wherein:
- the first electromagnetic flowmeter sensor comprises a first magnetic flux generator configured to generate a first magnetic flux orthogonal both to the first imaginary line between the first pair of electrodes and to the first axis of the first flow channel; and
- the second electromagnetic flowmeter sensor comprises a second magnetic flux generator configured to generate a second magnetic flux orthogonal both to the second imaginary line between the second pair of electrodes and to the second axis of the second flow channel.
13. The logging tool of claim 11, wherein the tool body has a scalloped-out section, and wherein the first and second flow channels are disposed on the tool body in the scalloped-out section.
14. The logging tool of claim 11, wherein each of the first and second flow channels is partially embedded in a side of the tool body, and has an open side radially away from the tool body.
15. The logging tool of claim 11, wherein there are multiple pairs of electrodes disposed in each of the flow channels.
16. A logging tool for measuring fluid flow in a casing, the logging tool comprising:
- an elongated tool body having a central axis;
- a plurality of electromagnetic flowmeter sensors mechanically coupled to the tool body and disposed in a first plane perpendicular to the central axis of the tool body, wherein each of the electromagnetic flowmeter sensors has a flow channel with a flow channel axis parallel to the central axis of the tool body.
17. The logging tool of claim 16, further comprising additional electromagnetic flowmeter sensors mechanically coupled to the tool body, and disposed in a second plane perpendicular to the central axis of the tool body different from the first plane.
18. The logging tool of claim 16, wherein the electromagnetic flowmeter sensors are configured to move radially inward toward and outward from the tool body, and/or rotate about the central axis of the tool body.
19. The logging tool of claim 16, wherein the electromagnetic flowmeter sensors are mounted on a plurality of arms mechanically coupled to the tool body.
20. The logging tool of claim 19, wherein more than one of the electromagnetic flowmeter sensors is mounted on one of the arms.
Type: Application
Filed: Mar 12, 2013
Publication Date: Sep 18, 2014
Applicant: REM Scientific Enterprises, Inc. (Richardson, TX)
Inventors: Robert E. Maute (Richardson, TX), Feroze J. Sidhwa (Coppell, TX)
Application Number: 13/797,626
International Classification: E21B 47/10 (20060101);