Systems and methods for well monitoring

Devices capable of being disposed in a wellbore for outputting acoustical signals for monitoring downhole parameters are described. Receiving devices positioned remote from the devices and can receive the acoustical signals and determine the downhole parameters. The devices can output acoustical signals in response to fluid flow or otherwise.

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to monitoring a well in a subterranean formation and, more particularly (although not necessarily exclusively), to devices positioned in the well for providing acoustical signals representing a downhole parameter.

BACKGROUND

It can be useful to monitor a wellbore traversing a subterranean formation for a variety of reasons, including for safety, determining the presence and type of fluid downhole, determining whether one or more components are positioned properly downhole, determining which component should be run downhole, and otherwise determining the state of the wellbore environment. It can be difficult to monitor complicated wellbores, including those that have one or more deviated wellbores or multiple zones, and long wellbores, such as those extending one to three or more miles below sea level.

Various techniques have been used to monitor wellbore environments. One technique is a smart well implementation that includes positioning downhole a cord that has sensors. The sensors are electronic-based (e.g. powered by batteries or power from the cord) sensors that can detect well conditions and transmit signals through the cord to a receiver. The signals can represent information about the well conditions, such as the presence and source of water. The receiver can interpret the signals and output the information.

Some smart well implementations use resonant sensors positioned downhole that respond to electromagnetic energy transmitted from the surface via a transmission line. The resonant sensors respond to the electromagnetic energy and information about the well condition can be derived by processing the response signal.

Other techniques include running a wireline tool downhole to log the well and determine well conditions, such as the presence and type of fluid downhole, or using a wireless telemetry system by running battery-powered devices downhole to perform measurements and wirelessly transmit the signals to the surface. Another technique includes positioning an acoustical signal generating device downhole that transmits an acoustical signal through a medium and the acoustical signal can be received by a device at the surface. The device analyzes the acoustical properties of the signal to determine information about the medium by comparing the properties to known properties of the acoustical signal generated by the generating device downhole.

Although effective, these techniques use electronic-based components that have a limited lifespan in a downhole environment. Furthermore, it can be difficult to implement most of these techniques in complicated or long wellbores and in existing wellbores. Implementing at least the wireline tool, for example, requires shutting off the well to run the wireline tool and log the well.

Therefore, assemblies are desirable that can be used throughout more of the life of a well, that are easily useable in complicated or long wellbores, and/or that are implemented easily in existing wellbores.

SUMMARY

Certain embodiments of the present invention are directed to devices capable of outputting acoustical signals representing downhole parameters in response to fluid flow or otherwise. Examples of devices include bells and whistles capable of outputting a vibration, sound, or other acoustical signal that represents a downhole parameter.

In one aspect, a system is provided for use with a bore in a subterranean formation. The system includes a device that can be disposed in the bore and that can respond to fluid flow by providing an acoustical signal that represents a downhole parameter. The device can output the acoustical signal to a medium for receipt by a receiving device. The receiving device can be positioned remote from the device.

In another aspect, a system is provided for use with a bore in a subterranean formation. The system includes a device and a receiving device. The device can be disposed in the bore and can respond to fluid flow by providing an acoustical signal that represents a downhole parameter. The receiving device can be positioned remote from the device. The receiving device can receive the acoustical signal.

These illustrative aspects and embodiments are mentioned not to limit or define the invention, but to provide examples to aid understanding of the inventive concepts disclosed in this application. Other aspects, advantages, and features of the present invention will become apparent after review of the entire application.

DETAILED DESCRIPTION

Certain aspects and embodiments of the present invention relate to devices, such as acoustical devices, that are capable of being disposed in a bore, such as a wellbore, of a subterranean formation for use in producing hydrocarbon fluids from the formation. The devices can be capable of outputting acoustical signals in response to downhole parameters. For example, the devices can output a natural response to a downhole parameter or enhance the downhole parameter, such as by amplifying a change in an acoustical signal in response to the downhole parameter. Receiving devices positioned remote from the devices can receive the acoustical signals and determine the downhole parameters. An “acoustical signal” as used herein includes any sound, pulse, vibration, or other similar energy that is capable of being received by the receiving device.

Downhole parameters can include—but are not limited to—(i) a position of a component, such as a safety valve, choke, or sliding door; (ii) flow rate through a component, such as a choke or sliding door; (iii) temperature, pressure, viscosity, composition, or density of fluid at a location in the wellbore; or (iv) other energy source in the wellbore. The receiving device can use information about the downhole parameters to control components at the surface or downhole, determine whether additional components, such as water control devices, should be run downhole, or otherwise.

In some embodiments, devices are capable of responding to fluid flow at the devices by outputting the acoustical signals. Devices can be configured to output acoustical signals without requiring batteries. Changes in fluid flow, such as changes in fluid temperature, pressure, viscosity, or density, or changes in fluid flow caused by a component changing position, can cause properties of the acoustical signals outputted by the device to change. The acoustical signals can be outputted to a medium, such as fluid media, an oilfield tubular (e.g. casing or tubing), wire, or the subterranean formation. A receiving device can receive the acoustical signals from the medium, determine the change in the acoustical signals and determine the corresponding downhole parameters. In some embodiments, the acoustical signals can be analyzed to determine a downhole parameter that is a status of the medium through which the acoustical signals propagate. For example, a change in signal amplitude or phase may indicate a change in the thickness of a tubular that is the medium. The change in thickness of the tubular may indicate tubular erosion or clogging.

Various types of devices can be used to output the acoustical signals. Examples of such devices include bells, whistles, and other types of resonators or vibrating devices. Bells according to some embodiments can output an acoustical signal with certain properties (such as cadence, signal frequency, and signal amplitude) that change in response to a downhole parameter. Whistles according to some embodiments can output an acoustical signal with certain properties (such a signal frequency and signal amplitude) that change in response to a downhole parameter. For example, fluid flow in a well can cause a device to output an acoustical signal having a tone that depends on the fluid flow. Using relationships applicable to incompressible fluids, downhole parameters can be determined from the tone. Other devices include well components, such as a choke, that output acoustical signals with properties that change based on a configuration of the device. In some embodiments, a bell or whistle is positioned in proximity to a well component, such as a choke, and the bell or whistle can output an acoustical signal in response to fluid flow affected by a position or other configuration of the well component. Devices can be configured to output acoustical signals at various frequencies. An example of a range of frequencies is 2 Hz to 30 kHz.

Systems according to various embodiments of the present invention can include positioning two or more devices downhole, each being capable of outputting acoustical signals. The acoustical signals can be received and analyzed, individually or as a group, to determine downhole conditions. For example, the devices can be configured to output acoustical signals at different frequencies (e.g. one at 500 Hz, another at 1000 Hz, and a third at 2000 Hz). Properties of the acoustical signals outputted by one device can change indicating a downhole parameter at the one device, but not at the location of the other devices. In another example, the acoustical signals outputted by the devices can each change properties in different ways in response to a downhole parameter and, by analyzing the acoustical signals, the downhole parameter can be identified and located. Furthermore, acoustical signals from devices can be characterized against known mediums and flow rates prior to deployment downhole. Acoustical signals can be compared to this characterization to determine downhole parameters represented by the acoustical signals. Acoustical signals from deployed devices can also be compared over time to determine the downhole parameters represented by later received acoustical signals. In some embodiments, a device in one well can output an acoustical signal that can be received by a receiving device positioned in a second well, on the seafloor, or at a platform, such as by using cross-well acoustic tomography or otherwise.

Information about the downhole parameters can be used to determine downhole conditions and output control signals in response to those conditions. For example, the receiving device can be configured such that when an acoustical signal is received having a property (e.g. frequency, amplitude, tone, beat, frequency change, amplitude change, etc.) that crosses a selected threshold, the receiving device outputs a control signal to trigger a blowout preventer, alarm, or other device.

FIG. 1depicts a well system100with acoustical devices according to certain embodiments of the present invention. The well system100includes a bore that is a wellbore102extending through various earth strata. The wellbore102has a substantially vertical section104and two substantially horizontal sections106,108. The substantially vertical section104may include a casing string cemented at an upper portion of the substantially vertical section104. The substantially horizontal sections106,108are open hole and extend through a hydrocarbon bearing subterranean formation110.

A tubing string112extends from the surface within wellbore102. The tubing string112can provide a conduit for formation fluids to travel from the substantially horizontal sections106,108to the surface. Acoustical devices114,116are positioned with the tubing string112in the respective substantially horizontal sections106,108. Other components (not shown), such as production tubing, screens, packers, inflow control devices, can be positioned in the wellbore102.

The acoustical devices114,116depicted inFIG. 1are coupled with bridge plugs118,120. Bridge plug118can be run downhole with acoustical device114. Bridge plug118can latch onto a profile122in the tubing string112to secure the bridge plug118and associated acoustical device114at a desired position. Fluid flow (as indicated by arrows121) can be directed through an inner diameter of the bridge plug118. In response to the fluid flow, the acoustical device114can output acoustical signals124to the fluid in the wellbore102, tubing string112, or other media. The acoustical signals124can be received by a receiving device126positioned at or near the surface. The receiving device126can analyze the acoustical signals124, such as by determining changes in the acoustical signals124over time, to determine a downhole parameter represented by the fluid flow.

Bridge plug120can be run downhole with the acoustical device116. Bridge plug120can include one or more locks that can latch into a smooth portion of the wellbore102to secure the acoustical device116at a desired position. Fluid flow (as indicated by arrows127) can be directed to an outer diameter of the bridge plug120and acoustical device116. In response to the fluid flow, the acoustical device116can output acoustical signals128to the fluid in the wellbore102, tubing string112, or other media. The receiving device126can receive the acoustical signals128and analyze them to determine a downhole parameter represented by the fluid flow.

In some embodiments, the receiving device126includes a processor and code that is tangibly embodied on a computer-readable medium. The processor can execute the code to cause the receiving device126to analyze the acoustical signals and output control signals, a display, alarms, or otherwise, in response to the analysis. In other embodiments, the receiving device126is coupled to a processing device that is capable of performing signal analysis of the received acoustical signals. An example of a receiving device126is a DynaLink™ acoustic receiver provided by Halliburton of Houston, Tex.

AlthoughFIG. 1depicts a receiving device126positioned at or near the surface, receiving devices according to various embodiments of the present invention can be located at other positions. For example, receiving device126can be located in the substantially vertical section104, in one or more of the substantially horizontal sections106,108, at another location on the surface, or in another wellbore (not shown). Similarly, acoustical devices114,116can be positioned at various locations in the wellbore102, including in the substantially vertical section104or both in one of the substantially horizontal sections106,108. Acoustical devices according to some embodiments can be positioned in wellbores without using bridge plugs. For example, other coupling devices can be used to position acoustical devices in the wellbore at desired locations or acoustical devices can be coupled with wellbore components that are run downhole to a desired position. Furthermore, acoustical devices and receiving devices according to certain embodiments can be disposed in simpler wellbores, such as wellbores having only a substantially vertical section.

Various types of acoustical devices can be used.FIGS. 2-7depict examples of suitable acoustical devices according to certain embodiments of the present invention.FIG. 2depicts an acoustical device that is a Helmholtz resonator202with respect to a portion of a casing or tubing string204. The Helmholtz resonator202is an example of a “whistle-type” acoustical device. It includes a first opening206over which fluid can flow. The first opening206is in fluid communication with a tank208through a tube210. The Helmholtz resonator202may include a second opening212to provide for continuous flow through the Helmholtz resonator202to flush particulate material and ensure suitable response to fluid flow over the first opening206.

The Helmholtz resonator202can be configured to output acoustical signals at a frequency according to following relationship:

c is the speed of fluid flow;

A is the cross-sectional area of the first opening206;

V is the volume of the tank208; and

d is the length of the tube210.

In one example, the speed of fluid flow (c) may be 1500 m/s in water, the cross-sectional area of the first opening206(A) may be 2.5 e^-5 m2, the volume of the tank208(V) may be 1 e^-5 m3, and the length of the tube (d) may be 0.01 m. The frequency (f) for the example is around 4 kHz, although input impedance of the first opening206may change the frequency slightly. The volume of the tank208, cross-sectional area of the first opening206, and/or the length of the tube210can be modified to change the base frequency at which the Helmholtz resonator202resonates. Changes in the speed of fluid flow, such as those caused by changes in temperature, pressure, viscosity, or density of the fluid, can be reflected by a change in the frequency of the acoustical signals. These changes can be detected by a receiving device to determine the downhole parameter.

FIG. 2depicts another embodiment of an acoustical device that is a Helmholtz resonator302with respect to a portion of a casing or tubing string304. The Helmholtz resonator302includes an opening306in communication with a tank308by a tube310. An expandable material312and sealing member314are disposed in the tank308at an opposite end to the tube310. The expandable material312can expand as temperature (or other property) increases in the environment at which the Helmholtz resonator302is positioned. The expandable material312displaces the sealing member314toward the tube310to reduce the volume of the tank308. Reducing the volume of the tank308can increase the frequency of acoustical signals outputted by the Helmholtz resonator302. A receiving device can receive the acoustical signals and analyze them to determine, based on a change in frequency, a temperature (or other property) in the environment at which the Helmholtz resonator302is located.

An example of the expandable material312includes thermally expandable wax. Expandable materials according to various embodiments of the present invention, however, can be any material capable of expanding or contracting in response to an environmental condition, such as temperature, pressure, oil content, pH levels, ion concentration, and flow rate. For example, the expandable material312may be an ionic polymer that can expand or contract in response to a pH or ion concentration of the fluid. In some embodiments, a biasing spring can be disposed in the tank308to provide reversible operation. In other embodiments, the expandable material312can change the shape or cross-sectional area of the inlet to create a change in frequency of an acoustical signal.

FIG. 4depicts an acoustical device that is a vortex shedding device402with respect to a portion of a casing or tubing string404. The vortex shedding device402is an example of a “whistle-type” acoustical device. The vortex shedding device402includes a body406that may be a bluff body capable of defining a first path408and a second path410. The body406can cause the fluid flow to shed into vortices in an alternating manner, such that the fluid flow sheds into one vortices in the first path408, a second vortices in the second path410, a third vortices in the first path408, and so on. During a “lock-in” period, vortex shedding in this manner causes the vortex shedding device402to vibrate and output acoustical signals having a frequency that is dependent on the fluid flow properties.

For example, the frequency can be determined from a Strouhal number that is determined from a Reynolds number. The Reynolds number is a measure of the ratio of inertial forces to viscous forces, quantifying the relative weight of these forces in a fluid flow. For example, in tubing string having a fluid flow rate of 4 m/s, a Reynolds number for a 2 cm wide vortex shedding device may be 1 e^5. The Strouhal number depends on the shape of the vortex shedding device and the Reynolds number. In this example, the Strouhal number may be 0.2. The frequency can be determined using the following relationship:

St is the Strouhal number;

v is the fluid flow velocity; and

w is the width of the vortex shedding device.

In the example, the frequency (f) is approximately 40 Hz. The frequency may be a base or expected frequency from which downhole parameters can be determined based on acoustic signals outputted by the vortex shedding device that deviates from this frequency.

In some embodiments, the vortex shedding device402is coupled to a dynamic mechanical device such that the frequency of the acoustical signals outputted by the vortex shedding device402matches the resonant frequency of the dynamic mechanical device. Furthermore, a series of dynamic mechanical devices can be configured to cover a range of possible frequencies of fluid flow. Monitoring the acoustical signals outputted by the vortex shedding device402with the known frequencies of the dynamic mechanical devices can allow downhole flow conditions to be determined.

FIG. 5depicts an acoustical device that is a downhole siren502. The downhole siren502includes a shaft504coupled to a blade506and a rotating restrictor508. The downhole siren502is a “whistle-type” device. An example of a rotating restrictor508is depicted inFIG. 5B. The rotating restrictor508includes openings510A-E through which fluid can flow. The downhole siren502also includes a non-rotating restrictor512. An example of a non-rotating restrictor512is depicted inFIG. 5C. The non-rotating restrictor512includes openings514A-E generally having the same or similar shape and size as the openings510A-E of the rotating restrictor508.

The downhole siren502can receive fluid flow by the blade506, which causes the shaft504to rotate the rotating restrictor508. In a low friction downhole siren502, the rotation rate of the rotating restrictor508can be proportional to the velocity of fluid flow. Through rotation of the rotating restrictor508, openings510A-E alternate between aligning with openings514A-E to allow fluid flow and aligning with solid surfaces of the non-rotating restrictor512to block fluid flow. Alternating allowing fluid flow and blocking fluid flow can cause acoustical signals to be outputted having a frequency that is proportional to the rate of rotation, and thus fluid flow rate. A receiving device can receive the acoustical signals and determine a downhole parameter based on the frequency.

FIGS. 6A-Bdepict a cross-sectional partial view of an acoustical device that is a bell device602with respect to production tubing604. The bell device602includes a bell606, a bell chamber608, a sleeve610having an opening612, and a clapper614having a pivoted wobble plate616. In some embodiments, the clapper614is a flexible clapper. The production tubing604can separate an inner diameter618of the production tubing604with an annulus area620between the production tubing604and casing string (not shown). The production tubing604includes a port622through which fluid can flow from the annulus area620.

The sleeve610can control fluid flow through the port622. The sleeve610can be (i) in a closed position, as shown inFIG. 6A, to block fluid flow; (ii) in an open position, as shown inFIG. 6B, to allow full fluid flow; or (iii) an intermediate position that allows less than full fluid flow. A mechanism (not shown) can change the position of the sleeve610.

The bell606can be vibrationally isolated from the production tubing604. When the sleeve610is in the open position as inFIG. 6B(or in an intermediate position) fluid can flow into the bell chamber608at a “port-side” or downhole side624of the bell chamber608and exit at an uphole side626of the bell chamber608. Fluid flowing past the pivoted wobble plate616causes the clapper614to strike the bell606and/or the production tubing604to produce acoustical signals. When the clapper614is short, the cadence is fast and when the clapper614is long, the cadence is slow.

Acoustical signals produced by the bell device602can include various properties capable of conveying information about one or more downhole parameters. The properties can include cadence, intensity of bell strike, intensity of production tubing strike, and pulse caused by changing flow rates from interrupted flow through the bell chamber608. A receiving device can determine the information by analyzing one property or by comparing various properties.

For example, the receiving device can determine that the sleeve610is partially open by analyzing the beats per minute of an acoustical signal. The receiving device can compare the intensity of the bell strike to the intensity of the production tubing strike to determine density of the fluid dampening the bell606. The receiving device can compare the time offset between the bell strike and the production tubing strike to determine fluid density as reflected by the speed of sound travelling through the production tubing604and the fluid. The receiving device can analyze cadence to determine fluid pressure and can analyze pulse decay in the acoustical signal to determine additional information. The receiving device can determine flow contribution from fluid flowing from below the bell device602(as opposed to through the port622) by comparing cadence with the sleeve610open to cadence with the sleeve610closed. The receiving device can determine downhole parameters based on the acoustical signal being a “dirty” signal as compared to a clear signal. A “dirty” signal may indicate a multi-phase fluid medium. For example, a clean signal may indicate a 100% fluid medium and the amount of noise in the signal may increase based on an increased percentage of gas in the fluid medium.

In some embodiments, the receiving device can analyze the various properties of one or more acoustical signals to confirm information obtained by analyzing one property or the receiving device can average the various properties to determine information about a downhole parameter. Bell devices according to some embodiments can include more than one clapper with differing lengths or differently configured wobble plates. These different clappers can output acoustical signals having additional properties that can be analyzed or compared to determine downhole parameters. For example, a bell can include a fixed pivot point and a clapper having a fixed length in addition to a clapper capable of changing position.

FIG. 7is a cross-sectional partial view of an acoustical device that is a slide device702with respect to production tubing704. The slide device702includes a slide706, a chamber708, and a plate710. The slide706is coupled to a sleeve712that includes an opening714. The production tubing704can separate an inner diameter716of the production tubing704with an annulus area718between the production tubing704and casing string (not shown). The production tubing704includes a port720through which fluid can flow from the annulus area718.

The slide706can change position based on the position of the sleeve712to change the volume of the chamber708. The volume of the chamber708can affect the tone or frequency of acoustical signals outputted by the slide device. A receiving device can analyze the acoustical signals to determine whether the sleeve712is in an open position, a closed position, or in an intermediate position. For example, tone (including tone quality) and intensity of the acoustical signals can provide information about the position of the sleeve712.

Other types of devices include “flute-type” whistles. A “flute-type” whistle can have openings that can be selectively covered or uncovered according to a downhole parameter. The “flute-type” whistle can output acoustical signals having a tone that depends on the particular openings that are covered or uncovered according to the downhole parameter.

Devices according to various embodiments can be deployed in multi-wellbore installations.FIG. 8depicts three wellbores802,804,806proximate to each other. Wellbore802includes two devices808,810disposed in the wellbore802. Wellbore804includes one device812disposed in the wellbore804. Each of the devices808,810,812can be capable of outputting acoustical signals representing a downhole parameter, for example in response to fluid flow at the respective devices808,810,812. The acoustical signals from one or more of the devices808,810,812can be received by (i) a receiving device814at or near the surface of wellbore802, (ii) a receiving device816disposed in wellbore804and in communication via wireline818with the surface, and/or (iii) a receiving device820disposed in wellbore806and in communication with telecommunications equipment, such as satellite transmitter822at the surface of wellbore806. The satellite transmitter822can communicate the acoustical signals or a representation of the acoustical signals to a remote monitoring center. Accordingly, one of the receiving devices816,818,820can be capable of receiving acoustical signals from devices808,810,812in more than one wellbore.

In some embodiments, the fluid properties in wellbores can be monitored using cross-well acoustic tomography. Cross-well acoustic tomography can use an electrically generated acoustical signal to evaluate the formation, such as by analyzing the amplitude degradation between two wellbores. A holographic image (e.g. three-dimensional) of the formation properties can be generated by using multiple devices outputting acoustical signals, each tuned to a different frequency.