NON-INTRUSIVE TRACKING OF OBJECTS AND FLUIDS IN WELLS

Abstract

The systems and methods described herein relate to the non-intrusive monitoring of a fluid level or object in a conduit. A system comprises a component positioned to control flow into or out of the conduit to induce pressure waves in the conduit; a pressure transducer in fluid communication with the conduit, the pressure transducer being positioned to measure the pressure responses in the conduit due to the contact of the pressure waves with the fluid level or object; and a system controller that can be operated to: receive pressure data from the pressure transducer, where the pressure data comprises the pressure responses; and determine a distance of the fluid level or object in the conduit, with respect to the pressure component or transducer, based on the pressure responses.

Description

NON-INTRUSIVE TRACKING OF OBJECTS AND FLUIDS IN WELLS Field of Invention In the oil field, knowledge of a well's condition, such as fluid level, can facilitate optimal production operations. Existing technologies can employ various sensors, such as pressure gauges or density meters, to determine fluid level. However, the deployment of these meters can be limited by distance. Therefore, these meters can only be installed at particular depths in a well. Furthermore, older wells may not include these meters, which can limit the techniques for determining fluid level in them. Background of the Invention Although well intervention can be another option for determining the fluid level in the well, this type of operation may not allow for continuous monitoring of the fluid level throughout the well's life cycle. Furthermore, well intervention can involve a substantial amount of time, resources, or risk. For example, maintaining an offshore installation, such as a Normally Non-Operated Installation (NUI), may require the mobilization of a drilling rig. I laughed. 342656 Brief Description of the Figures These figures illustrate certain aspects of some examples in the present description and should not be used to limit or define the description. Figure 1A illustrates a well that includes a target to be located, according to the examples in this description; Figure IB illustrates a well ring that includes a target to be located, according to the examples in this description; Figure IC illustrates an underground fluid storage facility, in accordance with the examples in this description; Figure 2 illustrates a flowchart for locating and tracking targets such as moving or stationary objects and / or fluids within conduits, according to examples in this description; Figure 3 illustrates a pressure response during a scan of targets arranged in a duct, according to the examples in this description; and Figure 4 illustrates a measured pressure response with noise, according to the examples in this description. Detailed Description of the Invention This description generally refers to real-time, non-intrusive techniques for monitoring targets such as fluid levels or objects within conduits such as a well or underground storage facility. Targets to be tracked may include various objects or fluids such as hydrates, phase-change fluids, fluid inlets in a well, and / or fluid levels in gas storage wells or cavern storage facilities that may store various fluids such as hydrogen. In some examples, hydrates may be tracked during hydrate repair operations. Targets may also include bottomhole plugs, tools, or debris disposed in the well or an annular space. In specific examples, a system controller and a pressure measuring device can be implemented in existing infrastructure, which may include components such as a wellhead, piping, a valve, a pump, or a vessel. The existing infrastructure can be used to control the flow of a fluid to induce positive and / or negative pressure waves within the conduit. Each component can be positioned to control the flow of fluid within a conduit to induce pressure waves. Target tracking can occur in real time through analysis of induced pressure waves and their corresponding responses that travel along the conduit back to the origin or source of the pressure wave induction. Tracking can be performed by inducing pressure waves in the conduit and analyzing the pressure responses to determine real-time locations, such as the depth or distance of the target within the wellbore, relative to the position of the pressure wave induction source. Location updates or location information, such as fluid levels or the position of objects, can be transmitted to a web portal or remote hardware to provide live tracking. In some examples, at least two pressure waves can be induced within a well to elicit or generate at least two corresponding pressure responses that can be reflected off a desired target positioned within the well and travel back along the well to the source of the pressure wave induction for analysis by a system controller. An interaction due to contact between the induced pressure waves and the desired target can result in the pressure responses. The system controller can then determine a target location based on the pressure wave responses. An automated system, without human intervention, can adjust a production parameter such as the inflow or outflow rate of the well; reduce the water load in the well (for example, by adding a foaming agent to the 5 well); or adjust a valve such as a choke, all of which can be done based on pressure responses. In some examples, real-time monitoring of fluid levels in a production well can provide information for reservoir analysis. In certain examples, real-time tracking can allow for accurate assessment of the duration of cementing operations (e.g., tracking plug positions) and fishing operations for downhole tools that may be stuck in the wellbore. Furthermore, real-time tracking can enable the location of objects or fluids within an annular space, which may include a portion of the open hole. The techniques described herein can provide greater accuracy and range compared to other methods, such as acoustic diagnostics, downhole measurement with fiber optics, or fiber optic cables. For example, numerous sensors positioned along a conduit are not required; rather, flow velocities and pressures in the conduit can be measured at or near the wellhead using one or more pressure waves. Additionally, the locations may overlap with well completion diagrams. Figure 1A illustrates a target 100 arranged in a conduit such as a well 102 extending into a subsurface formation 104, as described herein. In some examples, the target 100 may include various objects and / or fluids. For example, the target 100 may include debris, the top of a cement column, plugs, downhole tools (for example, a downhole assembly including measurement modules), completion collapse, various fluids, and / or fluid changes (for example, based on density or viscosity) in the well 102. In some examples, techniques as described herein can non-intrusively provide a depth of a downhole tool top, such as a stuck tool, enabling an effective fishing operation. Well 102 may include conduits 106 such as a casing string which may include a first section 108, a second section 110, and a third section 112 arranged concentrically within well 102. Each section 108, 110, and 112 of the casing string may include a corresponding valve 114 located in a wellhead 116 (or adjacent pipes in fluid communication with the wellhead 116). The valves 114 may permit the entry or exit of fluid into or out of well 102 to induce a pressure wave 118. Manipulation, such as the rapid opening and closing of a valve 114, can induce pressure waves within well 102. Valve 114 can be opened and closed in seconds. ai? / 1 nniern? / b / v In some examples, 5 seconds may be the maximum opening time. In other examples, valve 114 may remain open for 1 second or less before closing. Longer durations may also be possible (subject to system parameters and object depth / fluid position). Following the manipulation of valve 114, the pressure wave 118 may travel within and along the corresponding conduit 106 (e.g., at the speed of sound) and may be reflected off target 100 as a reflected pressure wave 120 to travel back to valve 114. The reflected pressure wave 120 may correspond to features detected in well 102, such as target 100, for example. The reflected pressure wave may be considered a pressure response in some examples. The pressure wave 118 may include a positive and / or negative pressure wave that can be induced within well 102. Several suitable techniques, in addition to valve 114, can be used to induce pressure waves. For example, an oscillating pump 128 can draw fluid from well 102 to induce negative pressure waves. Pumping can occur at intervals. In further examples, existing pressure waves in the system can be used as a source for pressure logging and data collection. In particular examples, valve 114 may be a hydrodynamic valve that can be operated manually. In other examples, valve 114 may be automated and / or remotely controlled. As further examples, fluid can be released from well 102 into an expansion vessel 130, or valve 114 can be used to purge fluid from well 102. In addition to, or in combination with, negative pressure, a positive pressure wave can also be induced in well 102. In particular examples, a supply tank or a supply vessel 132 can supply fluid to well 102 to induce a positive pressure wave in well 102. In some examples, the supply vessel 132 can use a pump 134 to move the fluid into well 102. The supply vessel 132 can provide any suitable fluid to well 102. Additionally, pump 128 can pump fluid into well 102. Non-limiting examples of fluids passing into well 102 can include gas, such as nitrogen, carbon dioxide, and / or natural gas, to a gas system, or water (or another suitable liquid) to a liquid system. In some examples, hydrodynamic waves can be induced by injecting gas into well 102. The oscillating pump 128 and the vessels 130 and 132 can be in fluid communication with the well 102 through valves 114 and / or conduits 136. It should be noted that, in some examples, the mechanisms for inducing pressure waves such as those described herein can be arranged in an above-ground location, such as on the surface of the well 102. The pressure waves can be induced at regular intervals, or the intervals can be variable. In particular examples, sonic waves can be induced at regular or variable intervals and can be used in accordance with the examples in this description. Pressure transducer 122 can be in seamless communication with well 102 to measure pressure variations at a high or ultra-high sampling frequency (e.g., 1 kilohertz (kHz), 1–4 kHz, or greater than 4 kHz). In certain examples, the sampling frequency may be less than 1 kHz or greater than 4 kHz. In some examples, pressure transducer 122 can measure pressures up to (among others) approximately 22,500 pounds per square inch (psi) or approximately 1550 bar. Signals from pressure transducer 122 can be logged with system controller 124. Once the data is collected, analyzed, and / or extrapolated to profiles, for example, through the system controller 124, a diagnosis of the well condition can be provided. In some examples, this may include reports to facilitate decision-making and repair plans without sacrificing production time or production performance. In some examples, the system controller 124 can be made operational remotely (for example, wirelessly or via cable) through a device 126 that may include a personal computer, tablet, smartphone, or other digital device. In some examples, the induction of pressure waves in well 102 can occur manually or can be automated through system controller 124. System controller 124 can control the flow of fluid 10 into and out of well 102 based on pressure responses or fluid levels in well 102. For example, system controller 124 can be operated to control various components such as valves 114 and / or pumps 128 and 134 to induce pressure waves 15 that can travel through well 102, causing a pressure response. The pressure response includes a reflected pressure wave that is reflected from target 100 back to the source of the pressure wave induction.The reflected pressure response can be measured with the pressure transducer 122 and recorded at a high or ultra-high frequency (e.g., at least 1 kHz) with the system controller 124 for analysis, such as for determining fluid levels within well 102, single-phase and multi-phase fluid pressure profiles in well 102, and / or determining the location of an object in well 102. By manipulating a component (e.g., a valve, pump, and / or vessel) of a hydraulic system, a fluid flow can be temporarily stopped or restricted to induce a pressure wave in well 102, and a pressure in well 102 can be continuously recorded at a point upstream of the component, using the Joukowsky equation, for example: — Í,, / Íl10(I) where hpa represents a pressure increase; p represents a fluid density, u represents a fluid flow velocity and ya represents the speed of sound in the fluid, to estimate the magnitude of the water hammer and by using the Darcy-Weisbach equation: - (£O- (2) where f is the friction factor, L is the length of the pipe, d is the diameter of the pipe, ρ is the fluid density, and u is the fluid velocity. To determine the pressure drop due to friction, a time record of the pressure change in the conduit is obtained. A distance record of the pressure change can be obtained from the time record, and an estimate of the speed of sound in the actual multiphase flow medium can be obtained using the formula: 11. — 0.5 uAt (3) to have the relationship between time (tt) and distance (AL). This technique can allow the monitoring of fluids or objects within a conduit, for example. In some examples, a system controller can determine the location of a target in a well with respect to a measured pressure response location or a pressure wave induction location through Equations 1 to 3. For example, the system controller can calculate the distance from a pressure transducer to the target as half the distance a pressure wave travels from the time of pressure wave induction to the time the pressure transducer measures or receives the pressure response. The distance between the pressure transducer and the target can be used to calculate a distance to the target with respect to a pressure induction location, such as a valve or a pump, for example. The system controller 124 may include a display, a storage unit, and / or any means or combination of means operating to calculate, estimate, classify, process, transmit, receive, retrieve, originate, change, store, display, manifest, detect, record, reproduce, handle, or use any form of information, intelligence, or data for commercial, scientific, control, or other purposes. For example, the system controller 124 may be a computer, a network storage device, or any other suitable device and may vary in size, form, performance, functionality, and price. The system controller 124 may include a processing unit (for example, a microprocessor, central processing unit, programmable logic controller (PLC), etc.).) that can process data by executing software or instructions obtained from a local non-transient computer-readable medium (e.g., optical disks, magnetic disks). Non-transient computer-readable media may store software or instructions of the methods described herein. Non-transient computer-readable media may include any medium or combination of media that can retain data and / or instructions for a period of time. Non-transient computer-readable media may include, for example, storage media such as a direct-access storage device (e.g., a hard disk drive or floppy disk), a sequential-access storage device (e.g., a tape drive), a compact disc, CD-ROM, DVD, RAM, ROM, electrically erasable programmable read-only memory (EEPROM), and / or flash memory; as well as communication media such as cables, optical fibers, microwaves, or radio waves, and other optical and / or electromagnetic carriers; and / or any combination thereof.The 124 system controller can also include input devices (e.g., keyboard, mouse, touchpad, etc.) and output devices (e.g., monitor, printer, etc.). Input and output devices provide a user interface. For example, the 124 system controller can allow an operator to select and perform analyses, view collected data, see analysis results, and / or perform other tasks. The system controller 124 can communicate (e.g., wired or wirelessly) with various components via various communication channels and can be operated to control those components. In some examples, the system controller 124 can be operated remotely (e.g., wirelessly) via a device 126, which may include a personal computer, tablet, smartphone, or other digital device. In some examples, the system controller 124 can be battery-powered (e.g., rechargeable lithium-ion or other battery type) with up to 15 hours (or more) of operating time and may include piezoelectric switches. In other examples, the system controller 124 can be powered by a mains electrical supply and / or a portable generator. Figure IB illustrates target 100 positioned within annular space 144 extending into a subsurface formation 104, as per the examples in this description. In some examples, target 100 may be positioned in the annular space 144 between the first section 108 and the second section 110 of the casing. In some examples, target 100 may include debris from an unlined section or an open hole interval 150 that may be in fluid communication with the annular space 148. Following manipulation of a valve 114, a pressure wave 152 or wave can travel within and along sections 10E and 110 in the annular space 144 (worst example, at the speed of sound) and can be reflected off target 100 as a reflected pressure wave 154. The reflected pressure wave 154 can correspond to features or fluids detected in the annular space 148, such as target 100. In certain examples, the system controller 124 can manipulate the valves 114 based on the fluid levels within the annular space 144. Pressure transducer 122 can be in fluid communication with the annular space 144 to measure pressure variations therein. Signals from pressure transducer 122 can be recorded by system controller 124. As noted above, system controller 124 can be operated to control valves 114, pump 128, pump 134 (which is fluidly coupled to the supply vessel 132), and / or valves 114 to induce pressure waves that can travel through well 102 and cause a pressure response. This data can be collected, analyzed and / or extrapolated to profiles through the 124 system controller to provide a diagnosis of the well condition. In some examples, the system controller 124 can be operated remotely (e.g., wirelessly) via a device 126, which may include a personal computer, tablet, smartphone, or other digital device suitable for surface and underwater use. It should be noted that configurations as shown in Figures 1A and 1B can be used on land or offshore and can also be applied to underground caverns or storage facilities. Figure 1C illustrates an underground storage facility 160, as described in the examples provided herein. The underground storage facility 160 (e.g., a salt cavern) may be located in an underground formation 164. Various types of fluids may be stored within the underground storage facility 160. Non-limiting examples of fluids may include a liquid and / or a gas, such as brine, natural gas, and / or hydrogen. A first conduit 166 and a second conduit 168 may extend into the cavern 162 from a location 170 that may be above ground level 172 (for example, a surface location). Conduits 166 and 168 may carry liquids or gas into or out of the underground storage facility 160. For example, a gas 175 can flow into the underground storage facility 160 through the first conduit 166. A valve 114 can be operated to control the flow of the gas 175 into the underground storage facility 160. The gas 175 can flow into the underground storage facility 160 from a fluid source 182, such as a pipe or a vessel. In some examples, a liquid 183 can flow through a second valve 114 from the underground storage facility 160 into a structure 184, such as a pipe or a vessel. As previously stated, manipulation, such as the rapid opening and closing of a valve 114, can induce pressure waves within the underground storage facility 160. The valve 114 can be opened and closed in seconds. In some examples, 5 seconds may be the maximum opening time. In other examples, the valve 114 may remain open for 1 second or less before closing. In still other examples, longer durations of 5 seconds may also be possible (subject to system parameters and the depth of the object / fluid position). Following the manipulation of valves 114, pressure waves (e.g., negative or positive pressure) can travel within and along the 10 conduits 166 and 168 through the gas 175, liquid 183, or a gas-liquid interface. These pressure waves can be reflected by the various fluids or interfaces within the underground storage facility 160 and can correspond to fluid levels therein. The 15 pressure transducers 122 can receive the reflected pressure waves and analyze them using the system controller 124 and / or the device 126, as previously described. The system controller 124 can communicate with and / or be operated to control various components such as valves 114, pressure transducers 122, fluid source 182, and / or structure 184 via wired and / or wireless communication channels. In certain examples, the system controller 124 can operate 25 components based on fluid levels within ai? / 1 nniern? / b / v 9 the underground storage facility 160. Figure 2 illustrates a flowchart for locating and tracking moving or stationary targets within wells, according to the examples in this description. At stage 200, at least two pressure waves can be induced within a conduit (e.g., well 102 shown in Figures 1A and 1B; or underground storage facility 160 shown in Figure 1C). As described above, pressure waves can be induced within the conduit by controlling the flow into or out of the conduit. The pressure waves may have similar or different properties, such as frequencies and / or amplitudes, in some examples. The pressure waves can travel along an orifice in the conduit to target 100 (e.g., as shown in Figures 1A and 1B) and reflect back to the end of well 102 where the pressure wave was induced or the source of the pressure wave induction.Reflected pressure waves can be considered pressure responses in some examples. In stage 202, pressure responses can be measured with a pressure transducer (e.g., pressure transducer 122 shown in Figures 1A and 1B) at an ultra-high sampling rate and recorded with a high-frequency data logger (e.g., system controller 124 shown in Figures 1A and 1B). In some examples, pressure waves can be induced before the pressure response is measured. In other examples, a first response can be measured before a second response is measured. The pressure responses can be either analyzed on-site or transmitted off-site to determine a target distance 100 relative to the location of the wave induction. In stage 204, the preceding stages can be repeated at intervals to provide continuous real-time location updates using the Io Equations, for example. A current location can be compared to a previous location to determine the movement of target 100. An automated warning system (e.g., the system controller 124 shown in Figures 1A-1C) can send a message (e.g., text, email) to a user when the fluid level fails to reach a threshold or is considered too high or too low. In some examples, the interval may be variable or fixed. A time period for each interval may include any interval longer than the time required for a wave to travel the entire length of the well and return to the data logger (e.g., the pressure transducer). This may be calculated on a case-by-case basis and be as short as possible. Location updates or location information, such as fluid levels, may be transmitted to a web portal to provide live tracking. Figures 3 and 4 illustrate pressure responses during target tracking, according to examples in this description. As shown in Figure 3, a pressure wave 300 can be induced to come into contact with the target and cause a pressure response 302 (e.g., a reflection of the pressure wave 300) and corresponding residual data 304, such as residual pressure waves. The residual data 304 cannot be relied upon to track the target. As stated earlier, the speed of sound in the fluid and the time from the induction of the pressure wave to the first pressure response (e.g., the pressure response) can be calculated. 302). Furthermore, the distance from a pressure transducer to the target location in the duct can be calculated using Equations 1 to 3. For example, the target distance from the pressure transducer can be determined as 20 half the distance traveled by the pressure wave 300 from the moment of pressure wave induction until the moment a pressure transducer measures or receives a pressure response 302. The distance between the pressure transducer and the target can be used to calculate a target distance 25 with respect to a pressure induction location, such as a valve or pump, for example. In some examples, as illustrated in Figure 4, the measured pressures may include an induced wave 400, noise 402, and a pressure response 404. In certain examples, the systems and methods described herein can be applied to either a temporary or a permanent installation. For a permanent installation, the system or method can be activated by an operator who manually initiates the techniques described herein using a button or a software interface, for example. Accordingly, the systems and methods described herein may allow the determination of the fluid level or the location of an object in a conduit such as a well or underground storage facility. The systems and methods may include any of the various features described herein, including one or more of the following statements. Declaration 1. A system for non-intrusively monitoring a fluid level or an object in a conduit, wherein the system comprises a component positioned to control flow into or out of the conduit to induce pressure waves in the conduit, the conduit extending into an underground formation; a pressure transducer in fluid communication with the conduit, the pressure transducer being positioned to measure the pressure responses in the conduit due to the contact of the pressure waves with the fluid level or object; and a system controller that can be operated to: or receive pressure data from the pressure transducer, where the pressure data comprises the pressure responses; and determine a distance of the fluid or object in the conduit, with respect to the component or pressure transducer, based on the pressure responses. Declaration 2. The system in accordance with the declaration 1, wherein the pressure transducer is located in a wellhead that is in fluid communication with the conduit. Declaration 3. The system in accordance with the declaration 1 or statement 2, where the wellhead comprises the component. Statement 4. The system in accordance with any of the above statements, wherein the sampling frequency of the pressure transducer is 1 kilohertz or more. Declaration 5. The system in accordance with any of the above declarations, wherein the conduit comprises a well or an annular well space (pipe-in-pipe). Statement 6. The system in accordance with any of the above statements, wherein the conduit extends into an underground storage facility. Declaration 7. The system in accordance with any of the above declarations, wherein the underground storage facility comprises an underground cavern. Declaration 8. The system in accordance with any of the 5 above declarations, wherein the underground storage facility comprises a gas. Declaration 9. A method for non-intrusively monitoring a target in a pore, wherein the method comprises: controlling a component to induce at least two pressure waves in the well; measuring, with a pressure transducer, the pressure responses in the well due to the contact of the pressure waves with the target; and determining a distance of the target in the well, with respect to the component or the pressure transducer, as a function of the pressure responses. Statement 10. The method in accordance with statement 9, further comprising inducing at least two positive pressure waves in the well by adding fluid to the well. Statement 11. The method in accordance with statement 20 9 or statement 10, further comprising measuring the pressure responses induced by an oscillating pump that draws fluid from the well to induce at least two negative pressure waves in the well. Statement 12. The method in accordance with any of 25 statements 9-11, further comprising controlling the component to allow fluid entry into the well or into the annular space of the well (pipe-in-pipe). Statement 13. The method in accordance with any of statements 9-12, further comprising controlling component 5 to allow fluid to exit the well or annular space of the well (pipe-in-pipe). Statement 14. The method in accordance with any of statements 9-13, further comprising receiving pressure data at intervals. Statement 15. The method in accordance with any of statements 9-14, which further comprises recording pressure data at a frequency ranging from 1 kilohertz (kHz) to 4 kHz, or at a frequency greater than 4 kHz or less than 1 kHz. Declaration 16. A method for non-intrusively monitoring a target in a conduit extending into an underground formation, wherein the method comprises: controlling a component to induce pressure waves in the conduit extending into the underground formation; measure the pressure responses in the duct due to the interactions of the pressure waves with the target; and determine a distance of the target in the duct, with respect to the component, as a function of the ρ res ó n responses. Statement 17. The method in accordance with the statement 16, which also includes controlling the component to allow fluid to enter the conduit to induce pressure waves. Statement 18. The method in accordance with the statement 16 or 17, which also includes sampling pressure data at a frequency of at least 1 Edlz. Statement 19. The method in accordance with any of statements 16-18, further comprising extracting fluid while controlling the component. Statement 20. The method in accordance with any of statements 16-19, which further comprises locating carbohydrates based on pressure responses. Although the present description and its advantages have been described in detail, it should be understood that various changes, substitutions, and alterations may be made herein without departing from the spirit and scope of the description as defined in the appended claims. The foregoing description provides various examples of the systems and methods of use described herein, which may contain different steps of the method and alternative combinations of components. It should be understood that, although individual examples may be discussed herein, the present description covers all combinations of the examples described, including, but not limited to, different combinations of components, combinations of steps of the method, and system properties.It should be understood that, although the compositions and methods are described in terms of comprising, containing, or including various components or steps, the compositions and methods may also essentially consist of or comprise the various components and steps. Furthermore, the indefinite article "a" or "an," as used in the claims, means, according to its definition herein, one or more of the elements introduced. For the sake of brevity, only certain intervals are explicitly described herein. However, intervals from any lower bound may be combined with any upper bound to refer to an interval not explicitly stated, and intervals from any lower bound may be combined with any other lower bound to refer to an interval not explicitly stated; similarly, intervals from any upper bound may be combined with any other upper bound to refer to an interval not explicitly stated. Furthermore, whenever a numerical interval is described with a lower and an upper bound, any number and any included intervals within that interval are specifically described.In particular, it should be understood that each interval of values ​​(of the form of around aa around b, or, equivalently, from ai? / 1 nniern? / b / v, or, equivalently, from approximately aab) described herein establishes each number and interval encompassed within the larger interval of values ​​even if not explicitly mentioned. Therefore, each individual point or value can serve as its own lower or upper limit combined with any other individual point or value or any other lower or upper limit, to enumerate an interval not explicitly enumerated. Therefore, the present examples are well suited to achieving the aforementioned purposes and advantages, as well as those inherent therein. The particular examples described above are merely illustrative and may be modified and implemented in different but equivalent ways that are obvious to persons of a mid-level skill who benefit from the teachings herein. While individual examples are discussed, the description covers all combinations of all examples. Furthermore, it is not intended to limit the details of construction or design shown herein, except as described in the claims below. Furthermore, the terms in the claims have their plain and ordinary meaning unless the patent holder explicitly and clearly defines otherwise. Therefore, it is evident that the particular illustrative examples described above may be altered or modified, and all such variations are considered to be within the scope and spirit of these examples. If there is any conflict between the uses of a word or term in this description and one or more patents or other documents that may be incorporated herein by reference, the definitions consistent with this description shall be adopted. It is hereby stated that, as of this date, the best method known to the applicant for putting the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

5 1. A system for non-intrusively monitoring a fluid level or an object in a conduit, characterized in that it comprises: a component positioned to control flow into or out of the conduit to induce pressure waves 10 in the conduit, where the conduit extends into an underground formation; a pressure transducer in fluid communication with the conduit, the pressure transducer being positioned to measure the pressure responses in the conduit due to the contact of the pressure waves with the fluid level or object; and a system controller operable to: receive pressure data from the pressure transducer, the pressure data comprising the pressure responses 20; and determine the distance of the fluid level or object in the conduit, with respect to the pressure component or transducer, based on the pressure responses. 25 2. The system according to claim 1, characterized in that the pressure transducer is located in a wellhead that is in fluid communication with the conduit.

3. The system according to claim 2, 5 characterized in that the wellhead comprises the component.

4. The system according to claim 1, characterized in that the monitoring frequency of the pressure transducer is 1 kilohertz or more. 10 5. The system according to claim 1, characterized in that the conduit comprises a well.

6. The system according to claim 1, characterized in that the conduit extends into an underground storage facility. 15 7. The system according to claim 6, characterized in that the underground storage facility comprises an underground cavern.

8. The system according to claim 6, characterized in that the underground storage facility 20 comprises a gas.

9. A method for non-intrusively monitoring a target in a well characterized in that it comprises: controlling a component to induce at least two pressure waves in the well; measuring, with a pressure transducer, the pressure responses in the well due to the contact of the pressure waves with the target; and determining a distance of the target in the well, with respect to the component or the pressure transducer, based on the pressure responses.

10. The method according to claim 9, characterized in that it further comprises inducing at least two positive pressure waves in the well by adding fluid to the well.

11. The method according to claim 9, characterized in that it further comprises measuring the pressure responses induced by an oscillating pump that extracts fluid from the well to induce at least two negative pressure waves in the well. 15 12. The method according to claim 9, characterized in that it further comprises controlling the component to allow fluid to enter the well.

13. The method according to claim 9, characterized in that it further comprises controlling component 20 to allow fluid to flow out of the well.

14. The method according to claim 9, characterized in that it further comprises receiving pressure data at intervals.

15. The method according to claim 9, 25 characterized in that it further comprises recording pressure data at a frequency ranging from 1 kilohertz (kHz) to 4 kHz.

16. A method for non-intrusively monitoring a target in a conduit extending into an underground formation 5 characterized in that it comprises: controlling a component to induce pressure waves in the conduit extending into the underground formation; measuring the pressure responses in the conduit due to the contact of the pressure waves with the target; and determining a distance of the target in the conduit, with respect to the component, as a function of the pressure responses.

17. The method according to claim 16, characterized in that it further comprises controlling component 15 to allow fluid to enter the conduit.

18. The method according to claim 16, characterized in that it further comprises sampling pressure data at a frequency of 1 kilohertz or higher.

19. The method according to claim 16, 20 characterized in that it further comprises extracting fluid from the conduit while controlling the component.

20. The method according to claim 16, characterized in that it further comprises locating hydrates based on pressure responses.

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