WO2021158591A1

WO2021158591A1 - Strain gauge flow meter for downhole applications

Info

Publication number: WO2021158591A1
Application number: PCT/US2021/016303
Authority: WO
Inventors: Luis Phillipe C. F. TOSI; Kristopher V. Sherrill; Stewart Sherrit; Linda Y. Del Castillo; Mina Rais-Zadeh; Dyung Tien VO; Pamela Isobel CHACON; Wajahat Ali
Original assignee: California Institute Of Technology; Chevron U.S.A. Inc.
Priority date: 2020-02-07
Filing date: 2021-02-03
Publication date: 2021-08-12
Also published as: AR121264A1

Abstract

Systems and methods for measuring fluid flow rate in a lateral section of a downhole oil/gas well are presented. According to one aspect, a fluid flow rate is sensed by a sensing surface of a cantilever (250b) that is mounted on an arm (250a). The sensing surface of the cantilever is provided by a flat sheet that includes a strain gauge transducer (250b2) that senses strain exerted onto the surface of the sheet. According to another aspect, the arm can rotate so to allow measurement of azimuthal profiles of the flow rate. Rotation of the arm is provided by a rotation of an element of a mobile vessel (200) to which the arm is rigidly coupled. The rotation of the arm is provided by a rotation of a nose (220) of the mobile vessel that rotates independently from a main body of the mobile vessel.

Description

STRAIN GAUGE FLOW METER FOR DOWNHOLE APPLICATIONS

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to and the benefit of co-pending US provisional patent application Serial No. 62/971,696 entitled “Strain Gauge Flow Meter For Downhole Applications”, filed on February 7, 2020, the disclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] The present disclosure generally relates to systems and methods for measuring fluid flow rate in lateral oil/gas wells.

BACKGROUND

[0003] Detailed information about physical properties (e.g., reservoir inflow) in the downhole of an oil-gas producing well, is important to help optimize production and field development. Inflow data points such as oil-gas-water flow rates, pressure, and temperature, for example, are key to understanding the nature of the reservoir properties and the effect of well drilling and completion methods. Although useful, the inflow data are not often measured in real-time, or with considerable frequency (weekly or more frequently), along the lateral section of the well due to technical or cost-prohibitive challenges. Instead, surface well-head production data (total flow rates, pressure, temperature, etc.) are measured for well performance diagnostics and for reporting purposes.

[0004] Attempts to instrument the well for real time or at least weekly measurements with continuous electrical or fiber optic cables for powering sensors to measure and deliver physical properties in the downhole of a well have been tested and have not been cost effective. This is particularly true for shale and tight development wells that have, for example, long laterals and multiple perforation entry points of their casing pipe (to contact the rock formation) which then undergo high-pressure hydraulic fracturing to increase hydrocarbon inflows from oil-bearing rock formations. Such harsh activities can easily damage not only the sensors but also power and data cables in the downhole of a well.

[0005] Production-logging tools (PLTs) are used routinely within long, horizontal wells to make measurements of local pressure, temperature, composition and flow rates. PLTs, however, are provided as a service and require well intervention for data to be collected; the operational cost and complexity limiting the frequency the data can be collected within a well.

[0006] Unconventional tight rock geologic formations may require a large number of oil/gas wells (holes) drilled in close proximity to each other to effectively extract the hydrocarbon contained in a field. Horizontally-drilled wells may be used in these applications since the hydrocarbon-bearing rock formations tend to exist in stratified layers aligned perpendicular to the gravity vector.

[0007] The typical vertical section of these wells can be 1-3 km below the surface and can extend laterally (e.g., in a generally horizontal direction) for distances of, for example, 2-3 km or even more. Oil, natural gas, and water may enter the well at many locations (production intervals/zones open to perforations and fracturing) formed along a lateral distance (e.g., 2-3 km or more) of the well with local flow rates and composition (e.g. oil/water fractions) varying due to inherent geology and the accuracy with which the well intersects (e.g., at the production intervals or sections) the oil-bearing rock formations. In general, information about the performance or hydrocarbon delivery and capacity of a well, such as, for example, flow rate, pressure, and composition, can practically be measured at the surface of the well as-combined values and with little or no knowledge of individual contributions from each of the production intervals or zones. Lack of local information of the inflow details of the well, at, for example, the production intervals or zones, can be a barrier to improving the efficiency of oil-gas extraction from the overall field.

[0008] Better knowledge of local interval inflow data across each or multiple entry points (e.g. physical properties such as flow rates, pressure, temperature, etc.) at the downhole of a well (e.g., along the horizontal/lateral section of the well) may help in making better decisions about placement of subsequent perforation/completion intervals for production in a well and/or subsequent drilling of other wells in the field. [0009] For example, an oil production field may have a variety of drilled wells, including an unconventional horizontal oil well that extracts oil from shale and tight formation through a plurality of production intervals or zones (shown as rectangles). In order to develop the field, producing the hydrocarbon-bearing rock formations, a number of wells (i.e., holes) may be drilled and spaced, for example, in the order of 500 feet apart from each other. These wells are drilled and completed serially so that information may be gathered from a downhole of a first well, for example, and can aid in determining where to perforate the casing and to apply hydraulic fracturing at selected intervals of the formation in a second and following well.

SUMMARY

[0010] Although the present systems and methods are described with reference to wells used in the oil industry, such systems and methods may equally apply to other industries, such as, for example, deep sea exploration or through-ice exploration.

[0011] According to one embodiment the present disclosure, a system for gathering information about physical properties in a lateral section of a well is presented, the system comprising: a mobile vessel configured for submersion in the lateral section of the well; and a fluid flow meter attached to the mobile vessel, the fluid flow meter comprising: one or more cantilevers attached to a first arm, each of the one or more cantilevers comprising: a sensing surface that is planar; and a strain gauge transducer coupled to the sensing surface.

[0012] According to a second embodiment of the present disclosure, a fluid flow meter is presented, the fluid flow meter comprising: a rotating base element; an arm radially attached to the rotating base element; one or more cantilevers attached to the first arm, each of the one or more cantilevers comprising: a sensing surface that is planar; and a strain gauge transducer coupled to the sensing surface.

[0013] Further aspects of the disclosure are shown in the specification, drawings and claims of the present application.

BRIEF DESCRIPTION OF DRAWINGS [0014] The accompanying drawings, which are incorporated into and constitute a part of this specification, illustrate one or more embodiments of the present disclosure and, together with the description of example embodiments, serve to explain the principles and implementations of the disclosure.

[0015] FIG. 1 illustrates a cross sectional view of an exemplary known oil production field, comprising one or more drilled wells for production of oil and/or gas in which a mobile vessel constructed in accordance with this disclosure may be disposed.

[0016] FIG. 2 shows a lateral section of a well of the oil production field shown in FIG. 1 comprising a plurality of production zones in which a mobile vessel constructed in accordance with this disclosure may be disposed.

[0017] FIG. 3 shows an exemplary embodiment of a mobile vessel comprising a strain gauge flow meter according to the present disclosure, the mobile vessel positioned in a lateral section of a well of the oil production field shown in FIG. 1.

[0018] FIG. 4A shows a front view of the mobile vessel of FIG. 3 with the strain gauge flow meter positioned at a first angular position.

[0019] FIG. 4B shows a front view of the vessel of FIG. 3 with the strain gauge flow meter positioned at a second angular position.

[0020] FIG. 4C shows a strain gauge flow meter according to an embodiment of the present disclosure for simultaneous measurement of flow rate at a plurality of angular positions.

[0021] FIG. 5 shows a strain gauge flow meter according to an embodiment of the present disclosure comprising a plurality of sensors arranged on two opposing arms.

[0022] FIG. 6A shows a top view of the strain gauge flow meter of FIG. 4A at rest.

[0023] FIG. 6B shows a top view of the strain gauge flow meter of FIG. 4A under local strain. [0024] FIG. 6C show graphs representative of local strain as a function of flow rate for various fluids.

[0025] FIG. 7 A shows layout of a sensor of the strain gauge flow meter according to an exemplary embodiment of the present disclosure.

[0026] FIG. 7B shows layout of a sensor of the strain gauge flow meter according to another exemplary embodiment of the present disclosure.

[0027] FIG. 7C shows layout of a sensor of the strain gauge flow meter according to yet another exemplary embodiment of the present disclosure.

[0028] FIG. 8 shows a strain gauge flow meter according to another embodiment of the present disclosure.

[0029] FIG. 9A shows the mobile vessel of FIG. 3 with the strain gauge flow meter in a retracted position.

[0030] FIG. 9B shows the mobile vessel of FIG. 3 with the strain gauge flow meter in a folded position.

[0031] FIG. 9C shows the mobile vessel of FIG. 3 with the strain gauge flow meter arranged in a main body of the mobile vessel.

[0032] FIG. 9D shows an exemplary embodiment of another mobile vessel comprising the strain gauge flow meter according to the present disclosure.

[0033] FIG. 10A shows an exemplary embodiment of a stain gauge flow meter comprising a bow shaped arm attached to a mobile vessel.

[0034] FIG. 10B is a front view of the embodiment shown in FIG. 10A.

DEFINITIONS [0035] As used herein the term “flow velocity” of a fluid may refer to the motion of the fluid per unit of time and may be represented locally by a corresponding “fluid velocity vector”. As used herein, the term “flow rate” of a fluid may refer to a volume of the fluid flowing past a point per unit of time. Therefore, considering a cross-sectional area of a flow of fluid, such as a flow of fluid through a lateral section of an oil well, the flow rate through the cross-sectional area can be provided by the flow velocity at that area.

DETAILED DESCRIPTION

[0036] As set forth above, information may be gathered from a downhole of a first well, for example, and can aid in determining where to perforate the casing and to apply hydraulic fracturing at selected intervals of the formation in a second and following well. Other useful information that may be collected within a well includes, by way of non-limiting example, fluid flow rates. Certain sensors for measuring flow rates (velocity) in an oil well are based on spinners (e.g., impellers) that rotate with angular speeds as a function of incident flow rates. When considering an oil- water- gas- sand environment as provided in a lateral section of a well, spinner technology is challenged primarily for its robustness and longevity within the environment. This includes difficulties with calibration and survivability incited by moving parts of the spinner-based sensors in a downhole environment, especially when considering operation over a length of months and/or years. Teachings according to the present disclosure solve these and other problems by providing a strain gauge based flow sensor configuration for integration on a mobile vessel that may be considered as a “solid state” solution with the ability of measuring flow velocity profiles for potentially longer lifetimes and with greater accuracy.

[0037] The mobile vessel described herein may be used in a number of settings, an example of which is depicted in FIG. 1, which illustrates a cross sectional view of an exemplary oil production field (100), comprising one or more drilled wells (Well_l, Well_2, ...) for production and extraction of oil and/or gas from various regions of the field.. In particular, as can be seen in FIG. 1, a vertical section of the Well_l may be drilled to reach and penetrate an oil- or gas-rich shale (e.g., rock formation), and a lateral (e.g., horizontal) section of the Well_l, which, in the exemplary case of FIG. 1 is substantially horizontal, may be drilled along the shale, starting from a heel section of the Well_l, and ending at a toe section of the Well_l. Generally, the vertical section of the Well_l may extend 1 to 3 km below the surface and the lateral section of the Well_l may extend for distances of, for example, 2-3 km or more.

[0038] With continued reference to FIG. 1, fluids, including oil, water, and natural gas, may enter the Well_l, for example, through open-hole or a casing of the Well_l, at production perforated intervals / zones that may be formed in the lateral section of the Well_l. Each of such production intervals / zones may include holes and/or openings that extract the fluid from the shale and route into the casing of the Well_l. As shown in FIG. 1, the perforated intervals / production zones may be separated by distances of, for example, about 100 meters (i.e., about 300 feet), and between each of the intervals (or stages) there are several clusters of perforations with closer spacing in order to cover a lengthy lateral and extract more hydrocarbon from shale/tight formations. Since there are many production zones, the inflow contribution for each of the intervals (or zones or clusters), such as, for example, local pressure, temperature, flow rates, and composition, may vary due to inherent geology and the accuracy with which the lateral section of the Well_l intersects the oil-bearing rock formations at the production zones.

[0039] As described above, collecting data at regions of the Well_l, for example close to each of the production zones, can help evaluate effectiveness of inflow contribution for each of the production zones and further help in optimizing production (e.g. by altering the perforation / completion design). The strain gauge flow meter according to the present disclosure, integrated with a mobile vessel as described herein, may be used to measure a flow rate of the fluid in the lateral section of the Well_l, the flow rate inferred by a strain exerted on one or more sensors of the flow meter. Because for a given flow rate, different fluids and different phases of a fluid may exert different strains at different (local) temperatures and/or pressures, mapping of the exerted strain to a flow rate value may be in view of data sensed by other sensors that are placed inside of the lateral section of the well. Data sensed by such other sensors may include data related to, for example, pressure, temperature and composition (e.g., fraction of oil, gas, water).

[0040] FIG. 2 shows a lateral section of a well of the oil production field shown in FIG. 1 comprising a plurality of production zones indicated as (Zl, Z’l, ..., Zn, Z’n). Also shown in FIG. 2 are local fluid velocity vectors (VFI, Vm) at vicinity of respective production zones. For example, the fluid velocity vector VFI, may be considered solely based on an inflow (of fluid) contribution by the last production zone (Zl, Z’l) close to the toe section of the well. On the other hand, the fluid velocity vector V_F2 may be considered based on a combination of the inflow contribution of the production zone (Z2, Z’2) combined with the inflow contribution of the last production zone (Zl, Z’ 1). In other words, a magnitude of the fluid velocity vector (VFI, VF2, . . ., VF_II) along the lateral section of the well shown in FIG. 2 may be considered as an incremental magnitude with increments based on inflows provided by the respective production zones (Zl, Z’l, ..., Zn, Z’n). Accordingly, a performance of each of the production zones (Zl, Z’ l, ..., Zn, Z’n) based on a corresponding inflow contribution may be assessed by measuring a difference between a magnitude of a fluid velocity vector before and after each production zone. For example, a difference between a magnitude of VF2 and a magnitude of VFI may indicate an inflow performance of the production zone (Z2, Z’2).

[0041] When fitted in a mobile vessel, such as a mobile robot, the strain gauge flow meter according to the present disclosure may be used to measure the magnitude of the local fluid velocity vectors (VFI, ..., VF_II). This is shown in FIG. 3, where the mobile vessel (200), including for example an element (210) and an element (220), fitted with the strain gauge flow meter (250) according to the present teachings is positioned downstream (e.g., towards the heel section of the well) of the production zone (Zk, Z’k) for measurement of a magnitude of the local fluid velocity vector V_Fk. In this case, the mobile vessel (200) may be controlled to remain stationary during the gathering/sensing of corresponding measurement data, and move to a next production zone for a next measurement. In some embodiments, actual derivation of the magnitude of the local fluid velocity vector may be performed either in real-time or non-real-time based on data sensed by the strain gauge flow meter (250) which may be combined with data sensed by other sensors as described above. It should be noted that the term “data” as used herein may relate to an ensemble of data values representative of signals gathered/sensed by one or more sensors of, for example, the strain gauge flow meter of the present teachings. Such data may be stored on local or remote memory for immediate or future use. [0042] FIG. 4A shows a front view of the vessel of FIG. 3 with the strain gauge flow meter (250) positioned at a first angular position about a center axis, C, of the element (220, e.g., nose) of the mobile vessel (200) shown in FIG. 3. The center axis C may be a common axis of the elements (210) and (220) of the mobile vessel (200), or may be an axis that is different from (e.g., parallel to) a center axis of the element (210, e.g., main body) of the mobile vessel. According to some exemplary embodiments, the elements (210) and (220) of the mobile vessel (e.g., 200 of FIG. 3) may include a tubular or cylindrical shape about the center axis C, or about a respective center axis. Also shown in FIG. 4A is a direction of the local fluid velocity vector Vi_¾ which in the exemplary configuration of FIG. 4A is assumed (substantially) parallel to an axial direction of the lateral portion of the well, as also shown in FIG. 3.

[0043] According to an embodiment of the present disclosure, the strain gauge flow meter (250) of FIG. 4A comprises one or more (sensing) cantilevers (250b) mounted on an arm (250a), each of the cantilevers (250b) having a sensing surface for interaction with the local fluid velocity vector, V_Fk. In the exemplary configuration of FIG. 4A, the local fluid velocity vector V_Fk is shown in a normal direction to the (planar) sensing surfaces of the cantilevers (250b). It should be noted that orientation of the sensing surfaces of the cantilevers (250b) may be controlled via positioning of the mobile vessel (200) within the lateral portion of the well such as to measure components of the local fluid velocity vector VFK in directions different from the axial direction of the lateral portion of the well. Furthermore, it should be noted that although in the exemplary configuration of FIG. 4A the arm (250a) is shown as radial with respect to the center axis, C, such radial configuration should not be considered as limiting the scope of the present disclosure as other non- radial configurations may be envisioned. Furthermore, it should be noted that by construction, the sensing surfaces of the cantilevers (250b) are normal to a direction of the center axis, C, at least when considering the strain gauge flow meter (250) at rest (e.g., VFK = 0)

[0044] With continued reference to FIG. 4A, a strain exerted by the local fluid velocity vector V_Fk on the sensing surface of each cantilever (250b) may be sensed by a strain gauge sensor (e.g., 250b2 of FIG. 6A later described) arranged, for example, at a base of the cantilever (250b). The strain sensed by each cantilever (250b) maps to an integrated net pressure over the sensing surface from which the flow velocity (rate) for a given fluid at known thermodynamic conditions can be derived. As known to a person skilled in the art, scaling of a magnitude of the flow rate may be provided by: e ~ U², where e is the strain and U is the magnitude of the flow velocity (e.g., illustrated in FIG. 6C later described) for a given fluid. This scaling is only exact in the Reynolds number independent portion of fluid drag force, but approximate in weakly dependent Reynolds number portion of the same force.

[0045] According to an embodiment of the present disclosure, a number of cantilevers (250b) mounted of the arm (250a) may be in a range from one to ten, and up to one hundred. The number of cantilevers (250b) mounted on the arm (250a) may allow measurement of the local fluid velocity vector VFK at different radial positions along the length of the arm (250a), and therefore derivation of a radial profile of the flow rate. In some cases, it may be advantageous to measure the local fluid velocity vector VFK at different angular positions about the center axis C of the element (220) for derivation of an angular profile of the flow rate. It follows that according to an exemplary embodiment of the present disclosure and as shown in FIG.4B, the arm (250a) may rotate about the center axis C of the element (220). For example, FIG. 4B shows the arm (250a), and therefore the cantilevers (250b), at an angular position that is different by an angle Q from the angular position of the arm (250a) shown in FIG. 4A. Such rotation of the arm (250a) about the center axis C may be considered as a rotation in the azimuth direction of the lateral portion of the well which therefore allows derivation of azimuthal profiles of the flow rate.

[0046] With continued reference to FIG. 4B, according to an exemplary embodiment of the present disclosure, the rotation of the arm (250a) may be based on a rotation of the element (220) to which the arm (250a) is rigidly coupled. In such configuration, the element (220), which may be referred to as a nose of the mobile vessel (200 of FIG. 3), may be a rotating part of the mobile vessel. Rotation of the nose (220) may be dependent to or independent from a rotation of the vessel itself (i.e., 210 and 220 rotating in unison). The nose (220) may rotate clockwise and/or counterclockwise to achieve a desired angular position of the arm (250a).

[0047] FIG. 4C shows a strain gauge flow meter (400c) according to an embodiment of the present disclosure for simultaneous measurement of flow rate at a plurality of angular positions. Measurement of the flow rate at each of the plurality of angular positions is provided by a strain gauge flow meter similar to the strain gauge flow meter (250) described above with reference to FIGs. 4A and 4B. As can be seen in FIG. 4C, each of the (radial) arms (250a) is positioned (e.g., fixed) at a different angular position. Although the exemplary configuration of FIG. 4C shows four flow meters (250) arranged in quadrature, other configurations including more or less flow meters (250) arranged at different angular positions may be envisioned. The configuration shown in FIG. 4C may allow simultaneous measurement of flow rate at a plurality of angular positions without requiring the arms (250a) to rotate about the center axis C. If desired, more flexibility (e.g., more angular data points) in measurement may be provided by rotating the arms (250a) in a fashion similar to one described above with reference to FIG. 4B (e.g., rotation of nose 220).

[0048] FIG. 5 shows a strain gauge flow meter according to an embodiment of the present disclosure comprising two sets of cantilevers (250b, 250’b), each set mounted on a respective one of two (opposing) arms (250a, 250’a), the two arms rigidly coupled to one another via a base element (250c). The configuration shown in FIG. 5 is based on the configurations of FIGs. 4A and 4B where like reference designators indicate like elements. In particular, as described above with reference to FIG. 4A, each of the cantilevers (250b) and (250’b) includes a sensing surface for interaction with the local fluid velocity vector, Vp_k. According to an exemplary embodiment of the present disclosure and as shown in FIG. 5, an axis of symmetry, S, of the two arms (250b, 250’b) coupled to the base element (250c) may pass through center axis, C. In other words, the axis of symmetry, S, may be radial to the center axis, C. It should be noted that although the configuration of FIG. 5 shows the one or more cantilevers (250b) interleaved with the one or more cantilevers (250’b), such interleaved (alternating between one and the other) arrangement may not be considered as limiting the scope of the present disclosure as other non-interleaved arrangements of the two sets of the cantilevers (250b. 250’b) may be envisioned. Furthermore, the strain gauge flow meter shown in FIG. 5 may be used as basis for other configurations similar to ones described above with reference to FIGs. 4B and 4C.

[0049] FIG. 6A shows a top view of the strain gauge flow meter (250) of FIG. 4A at rest (i.e., VFK = 0). Shown in the top view of FIG. 6A are the arm (250a) and the (sensing) cantilever (250b). As shown in FIG. 6A, the cantilever (250b) comprises a (flat) sheet (250b 1, plate) that is supported (fixed) at one end of the sheet (250b 1) by the arm (250a) such as to create a cantilevered effect. The (cantilevered) sheet (250b 1) provides the sensing surface of the strain gauge flow meter (250) for interaction with the local fluid velocity vector Vi_t Geometry and material of the sheet (250b 1) may be selected such as to allow deformation of the sheet (250b 1) when subjected to surface strain from typical magnitudes of the local fluid velocity vector Vi_t A strain gauge transducer (250b2) may be mounted (attached, fixed) at a base of the cantilevered sheet (250b 1) close to the arm (250a) to sense the surface strain. The geometry of the cantilevered sheet (250b 1) is an exemplary embodiment of a mechanical strain amplifier, which provides a structure with which strain can be induced to a threshold that can be measured by the strain gauge transducer (250b2).

[0050] According to an exemplary embodiment of the present disclosure, the sheet (250b 1) may be supported by the arm (250a) via a clamping effect as shown in FIG. 6A. In this case, the arm (250a) may include two elements (250al, 250a2) that are pressed against one another (e.g., via bolts or other fasteners) to clamp the sheet (250b 1). Furthermore, as shown in FIG. 6A, to relieve concentration of stress at a region where the sheet (250b 1) is freed from the arm (250a), contour of the arm (250a) at that region is made curved (e.g., circular, rounded). Such curved contour of the arm (250a) may allow reduction in concentration of stress at the base on the sheet (250bl) as the sheet (250bl) deforms. In turn, such reduction in concentration of the stress can increase the robustness (i.e., fatigue life) of the sheet (250bl). In the detail (660a) illustrated embodiment of FIG. 6A, a clamping surface (Sci, S_d) of the arm (250a) that is in contact with the front or back surface of the sheet (250bl) and a front surface (SFI, SF2) of the arm adjacent the clamping surface (Sci, Sc2) make a rounded corner or edge. Other comer or edges may be used in certain embodiments, such as shown in the details (660b, e.g., beveled edge) and (660c, e.g., chamfered edge) illustrated embodiments of FIG. 6A. In such embodiments, respective adjacent surfaces (Sci, Sc2) and (SFI, SF2) may form a respective obtuse angle a.

[0051] FIG. 6B shows a top view of the strain gauge flow meter (250) of FIG. 4A under local stress (i.e., VFK ¹ 0). As shown in FIG. 6B, under local stress the sheet (250bl) is subjected to a deformation which is sensed by the strain gauge transducer (250b2). Amount of local strain, which may be observed, for example, as a deviation in position of the free end/edge of the sheet (250bl), may be an increasing function of the magnitude of the local fluid velocity vector Vi_¾ as shown in the graphs of FIG. 6C. As shown in FIG. 6C, for a given magnitude of the local fluid velocity vector V_f¾, the local strain may be different in dependence of type of fluid, such as, water, oil or gas. Such difference may be a function of a density of the fluid at a given thermodynamic condition.

[0052] With reference back to FIG. 6A, the strain gauge transducer (250b2) may be mounted on either face of the cantilevered sheet (250b 1) and therefore the configuration shown in FIG. 6A should not be considered as limiting the scope of the present disclosure. Indeed, the strain gauge transducer (250b2) may sense a positive or negative sign of a strain in dependence of a positive axial direction or a negative axial direction of the local fluid velocity vector V_Fk. The positive and negative signs of the strain may respectively correspond to a tension and a compression of the cantilevered sheet (250b 1). Accordingly, both (front and back) surfaces of the cantilevered sheet (250b 1) may be considered as sensing surfaces. The strain gauge transducer (250b2) in the exemplary embodiment shown in FIG. 6A may be a foil-type resistive gauge. Strain can be measured via a number of methods, sensors, and apparatuses, including, for example, piezoelectric transducers, quartz crystals, capacitors, and digital-image-correlation. To those skilled in the art, it is known that a bimorph-type transducer, consisting of two piezoelectric sheets sandwiched by electrodes, can provide the mechanical amplification as well as the strain sensing capability of the cantilevered sheet (250b 1) and the strain gauge transducer (250b2), respectively. Therefore, the cantilever (250b) of FIG. 6A can be replaced in its entirety by such bimorph-type transducer to provide a same functionality.

[0053] FIG. 7A shows a layout according to an exemplary embodiment of the present disclosure of the sensing cantilever (250b) of the strain gauge flow meter (250) described above, including the cantilevered sheet (250bl) and the strain gauge transducer (250b2). According to an exemplary embodiment of the present disclosure, the cantilevered sheet (250b 1) may include one or more interferences (e.g., an interference pattern) that may be used for alignment with the supporting arm (e.g., 250a of FIG. 6A). In the illustrated embodiment of FIG. 7A, the one or more interferences include two holes (750a) and a cutout (750b). Such interferences, including interferences shown in FIG. 7C later described, may be coupled to complementary interferences designed in the supporting arm (250a of FIG. 6A) to position the cantilevered sheet (250b 1) according to a specific orientation.

[0054] With continued reference to FIG. 7A, according to an exemplary embodiment of the present disclosure, the cantilevered sheet (250b 1) may have a quadrilateral shape, such as, for example, the shape of a rectangle. A length, L, and a width, W, of the rectangle may be on the order of a few centimeters, such as, for example, in a range from one centimeter to ten centimeters. A thickness, d, of the sheet (250bl) may be several orders of magnitudes smaller than the length, L, and the width, W. For example, the thickness, d, may be in a range from two micrometers to twenty micrometers. In terms of ratios, a ratio between the thickness, d, and any one of the length, L, or the width, W, may be in a range from 1/500 to 1/50,000.

[0055] With further reference to FIG. 7A, the sheet (250bl) may be made by any material, including a metal or an organic solid. Such material may be selected to be resistant to the harsh environmental conditions the sheet (250bl) may be subjected to. In some embodiments, the sheet (250b 1) and the strain gauge transducer (250b2) may be completely or partially covered by a protective coating (not shown in the figures). In some embodiments, the protective coating may cover the base portion of the sensing cantilever (250b), including the strain gauge transducer (250b2) and corresponding wires (760). It should be noted that the strain gauge transducer (250b2) may include but is not limited to, a resistive (foil) strain gauge, a semiconductor (piezo-resistor) strain gauge, or a fiber optic based strain gauge.

[0056] As shown in FIG. 7B, the strain gauge flow meter (250) according to the present disclosure may include more than one strain gauge transducer (250b2) located at different regions of the sheet (250b 1). Such higher number of strain gauge transducers (250b2) may improve sensing resolution of the flow meter (250) by sensing regions farther away from the base of the sheet (250b 1) that is clamped by the arm (e.g., 250a of FIG. 6A). In turn, thicker or more rigid sheet (250bl) may be selected for a longer lifespan. It should be noted that although the plurality of strain gauge transducers (250b2) of FIG. 7B are shown on a same surface of the sheet (250bl), other configurations where the transducers (250b2) are shared between both (front and back) surfaces of the sheet (250bl) are possible.

[0057] FIG. 7C shows a layout according to an exemplary embodiment of the present disclosure of the (sensing) cantilever (250b) of the strain gauge flow meter (250) described above. In the configuration shown in FIG. 7C, the cantilever (250b) consists of a strain gauge transducer (250b2). In other words, the entirety of a sensing surface is provided by the strain gauge transducer (250b2). As shown in FIG. 7C, alignment interferences (e.g., 750c) may be designed within the strain gauge transducer (250b2). As shown in FIG. 7C, the alignment interferences (760c) may include one or more notches (cutouts constrained within one edge) at a clamping edge of the cantilever (250b).

[0058] FIG. 8 shows a strain gauge flow meter (850) according to another embodiment of the present disclosure. In the configuration shown in FIG. 8, the cantilever (250b) consists of a strain gauge transducer (250b2) described above with reference to FIG. 7C. In other words, the entirety of a sensing surface is provided by the strain gauge transducer (250b2). As shown in FIG. 8, the strain gauge transducer (250b2) is supported by the arm (250a) such as the arm (250a) and the strain gauge transducer (250b2) extend according to a same radial direction with respect to the center axis, C. The strain gauge flow meter (850) shown in FIG. 8 may be used as basis for other configurations similar to ones described above with reference to FIGs. 4B and 4C.

[0059] It may be desirable to protect the strain gauge flow meter of the present teachings from the harsh downhole environment when possible. FIG. 9A shows one exemplary embodiment according to the present disclosure wherein the strain gauge flow meter (250) is retracted into a space within the nose (220) of the mobile vessel (200). In such configuration, the strain gauge flow meter (250) may remain in the retracted position so long flow velocity measurements are not performed. For measurement, the flow meter (250) may be extended outwards the nose (220) in a position as shown in FIG. 3. According to another exemplary embodiment of the present disclosure, protection of the flow meter (250) may be provided by folding the flow meter (250) as shown in FIG. 9B. Folding according to the configuration shown in FIG. 9B may position a longitudinal extension of the arm (e.g., 250a of FIG. 4A) of the flow meter (250) in a direction that is substantially parallel to the center axis, C. In this context, substantially parallel may encompass a relative angle between respective directions of the longitudinal extension and the center axis that is in a range from -30 degrees to +30 degrees. It should be noted that methods and structures for implementing protection of the strain gauge flow meter according to FIGs. 9A and 9B are well known to a person skilled in the art, and therefore their description in the present disclosure should not be considered necessary.

[0060] It should be noted that the strain gauge flow meter of the present teachings may be mounted on any part of the mobile vessel (200), including the main body (210) as shown in FIG. 9C. Furthermore, it should be noted that the strain gauge flow meter of the present teachings may be mounted on any mobile vessel configured for immersion in harsh environments such as, for example, a downhole of a well, including the lateral section of the well (e.g., lateral section of well_l shown in FIG. 1). In other words, the mobile vessel may not necessarily be a mobile robot with advanced technologies. Rather, it can be a simple submersion vessel (910) as shown in FIG. 9D fitted with the strain flow meter (250).

[0061] According to an exemplary embodiment of the present disclosure shown in FIG. 10A, an arm (950a) may include a shape of an arc, such as, for example, a bow that is attached to a simple submersion vessel (910) at two endpoints (950a_el, 950a_e2) of the bow-shaped arm (950a). In such configuration, the vessel (910) may be a simple rod that is submerged into a casing pipe (1050) of the lateral well. As shown in FIG. 10A, the two end points (950a_el, 950a_e2) may be attached at different regions of the vessel (910) along a longitudinal extension (i.e., axial direction) of the vessel (910). As shown in FIG. 10A, and corresponding front view of FIG. 10B, the shape of the arm (950a) may be such to include a region of an outer most radius (e.g., 950a_OR, region of minimum curvature radius) that extends to, or near, an inner edge of the casing pipe (1050). Furthermore, the cantilever (250b) may be mounted on the arm (950a) close to the region of the outer most radius (950a_OR). As shown in FIGs. 10A and 10B, the cantilever (250b) may be mounted on the arm (950a) such that the local fluid velocity vector Vi_¾ is in a normal direction to the (planar) sensing surface of the cantilevers (250b). Furthermore, as shown in FIGs. 10A and 10B, one or more (e.g., two as shown in FIGs. 10A and 10B) arms (950a) with corresponding cantilevers (250b) may be attached to the vessel (910) such as to allow derivation of azimuthal profiles of the flow rate as previously described.

[0062] A number of embodiments of the disclosure have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the present disclosure. Accordingly, other embodiments are within the scope of the following claims.

[0063] The examples set forth above are provided to those of ordinary skill in the art as a complete disclosure and description of how to make and use the embodiments of the disclosure and are not intended to limit the scope of what the inventor/inventors regard as their disclosure.

[0064] Modifications of the above-described modes for carrying out the methods and systems herein disclosed that are obvious to persons of skill in the art are intended to be within the scope of the following claims. All patents and publications mentioned in the specification are indicative of the levels of skill of those skilled in the art to which the disclosure pertains. All references cited in this disclosure are incorporated by reference to the same extent as if each reference had been incorporated by reference in its entirety individually.

[0065] It is to be understood that the disclosure is not limited to particular methods or systems, which can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. The term “plurality” includes two or more referents unless the content clearly dictates otherwise. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the disclosure pertains.

Claims

1. A system for gathering information about physical properties in a lateral section of a well, the system comprising: a mobile vessel configured for submersion in the lateral section of the well; and a fluid flow meter attached to the mobile vessel, the fluid flow meter comprising: one or more cantilevers attached to a first arm, each of the one or more cantilevers comprising: a sensing surface that is planar; and a strain gauge transducer coupled to the sensing surface.

2. The system according to claim 1, wherein: the mobile vessel comprises a first element having a substantially tubular shape about a center axis, the first element configured to rotate about the center axis, and the first arm of the fluid flow meter is attached to the first element.

3. The system according to claim 2, wherein: the first arm is radially attached to the first element.

4. The system according to claim 3, wherein: at rest, the sensing surface is normal to a direction of the center axis.

5. The system according to claim 1, wherein: the sensing surface is provided by a flat sheet that is configured to deform during interaction with a fluid flow in the lateral section of the well.

6. The system according to claim 5, wherein: the flat sheet is the strain gauge transducer.

7. The system according to claim 5 or claim 6, wherein: a ratio between a thickness of the flat sheet and any one of a length or a width of the flat sheet is in a range from 1/500 to 1/50,000.

8. The system according to claim 5 or claim 6, wherein: the first arm comprises a clamp that clamps the flat sheet via respective clamping surfaces.

9. The system according to claim 8, wherein: the clamping surfaces of the clamp and respective adjacent surfaces of the clamp form respective rounded, beveled, or chamfered edges.

10. The system according to claim 5 or claim 6, wherein: the flat sheet comprises an interference pattern for alignment with the first arm.

11. The system according to claim 10, wherein: the interference pattern comprises one or more of: a) a hole through the flat sheet; b) a cutout of the flat sheet; or c) a notch.

12. The system according to any one of claims 1 to 11, wherein: the strain gauge transducer is one of: a) a resistive foil strain gauge transducer; b) a piezo resistor strain gauge transducer; or c) a fiber optic based strain gauge transducer.

13. The system according to any one of claims 1 to 12, wherein: each of the one or more cantilevers comprise additional one or more strain gauge transducers coupled to the sensing surface.

14. The system according to any one of claims 1 to 13, wherein: the fluid flow meter further comprises: one or more additional cantilevers attached to a second arm, each of the one or more additional cantilevers comprising: a sensing surface that is planar; and a strain gauge transducer coupled to said sensing surface.

15. The system according to claim 14, wherein: the first arm and the second arm are arranged in parallel, one opposite the other with respect to an axis of symmetry, and said axis of symmetry is radial to the center axis.

16. The system according to claim 15, wherein: the one or more cantilevers attached to the first arm and the one or more additional cantilevers attached to the second arm are radially arranged according to an alternating arrangement.

17. The system according to claim 14, wherein: the first arm and the second arm are radially attached to the first element at different angular positions about the center axis.

18. The system according to any one of claims 1 to 17, wherein: the fluid flow meter is retractable to an interior space of the mobile vessel.

19. The system according to any one of claims 1 to 17, wherein: the fluid flow meter is foldable so to position a longitudinal extension of the first arm in a direction that is substantially parallel to the center axis.

20. The system according to claim 2, wherein: the first arm is attached at two locations of the first element along a direction of the center axis to form a shape of a bow.

21. A fluid flow meter, comprising: a rotating base element; an arm radially attached to the rotating base element; one or more cantilevers attached to the first arm, each of the one or more cantilevers comprising: a sensing surface that is planar; and a strain gauge transducer coupled to the sensing surface.