Filter pack for fluid FLUX monitoring with internal compartments

Abstract

The current invention relates to a filter pack for a flow meter, the filter pack comprising a cage comprising a central cavity for receiving at least one flow meter, a plurality of radially extending chambers allow a fluid flow to reach said central cavity, and therefore the flow meter. Each end of each radially is further equipped with at least one filter. The present invention provides also a monitoring assembly comprising a filter pack and a flow meter, the flow meter having a number of funneling chambers configured as diametrically opposing pairs configured to funnel a fluid into a channel connecting each pair of funneling chambers, said channels being equipped with sensors.

Description

[0001] FILTER PACK FOR FLUID FLUX MONITORING WITH INTERNAL COMPARTMENTS

[0002] FIELD OF THE INVENTION

[0003] The present invention pertains to the technical field of monitoring devices for wells.

[0004] BACKGROUND

[0005] US9988883 describes a screen for screening particulates in wellbore fluid. The wellbore screen comprises a base pipe. The base pipe has a screen section that is formed by an outer jacket and an inner wall. The outer jacket comprises apertures and the inner wall comprises ports. An annulus is formed in between the outer jacket and the inner jacket. A filter medium is placed at the inside of the outer jacket to filter water flowing through the apertures. Filter disks are placed in the ports. The filter medium is not filling completely the annulus. Flow channels are formed on the inner wall. Flow emanating from each flow channel may be predominantly from selected apertures. The flow channels form a kind of internal compartmentation.

[0006] This known device has the drawback that water can flow through the filter medium around the inner wall instead of through the ports.

[0007] The present invention aims to resolve at least some of the problems and disadvantages mentioned above.

[0008] SUMMARY OF THE INVENTION

[0009] To this end, the present invention relates to a filter pack for a flow meter according to claim 1.

[0010] Preferred embodiments of the filter pack are shown in any of the claims 2 to 12.

[0011] In a second aspect the present invention relates to an assembly for monitoring a fluid flux according to claim 13. The assembly comprises a filter pack and a flow meter. Preferred embodiments of the assembly are shown in any of the claims 14 to 18. In a third aspect, the present invention relates to a method according to claim 19. More particular, the method provides the use of a filter pack according to claims 1- 12. Preferred embodiments of the method are shown in any of the claims 20 to 25, including steps for preparing and using an assembly for measuring a plurality of fluid flux values and subsequently calculate a final magnitude and direction based on said fluxes.

[0012] DESCRIPTION OF FIGURES

[0013] The following description of the figures of specific embodiments of the invention is merely exemplary in nature and is not intended to limit the present teachings, their application or uses. Throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

[0014] Figure 1 shows the cage of the filter pack.

[0015] Figure 2 shows another embodiment of the cage of the filter pack.

[0016] Figure 3 shows an exploded view of the filter pack of Figure 1.

[0017] Figure 4 presents a flow meter equipped with two sensors in a support structure.

[0018] Figure 5 shows a top view of the filter pack of Figure 2.

[0019] Figure 6 shows a top view of the filter pack of Figure 1 and Figure 3.

[0020] Figure 7 presents another embodiment of a flow meter equipped with two sensors in a support structure.

[0021] Figure 8 shows an assembly according to an embodiment of the current invention. DETAILED DESCRIPTION OF THE INVENTION

[0022] Unless otherwise defined, all terms used in disclosing the invention, including technical and scientific terms, have the meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. By means of further guidance, term definitions are included to better appreciate the teaching of the present invention.

[0023] As used herein, the following terms have the following meanings:

[0024] "A", "an", and "the" as used herein refers to both singular and plural referents unless the context clearly dictates otherwise. By way of example, "a compartment" refers to one or more than one compartment.

[0025] "Comprise", "comprising", and "comprises" and "comprised of" as used herein are synonymous with "include", "including", "includes" or "contain", "containing", "contains" and are inclusive or open-ended terms that specifies the presence of what follows e.g. component and do not exclude or preclude the presence of additional, non-recited components, features, element, members, steps, known in the art or disclosed therein.

[0026] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequential or chronological order, unless specified. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other sequences than described or illustrated herein.

[0027] The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within that range, as well as the recited endpoints.

[0028] Whereas the terms "one or more" or "at least one", such as one or more or at least one member(s) of a group of members, is clear per se, by means of further exemplification, the term encompasses inter alia a reference to any one of said members, or to any two or more of said members, such as, e.g., any >3, >4, >5, >6 or >7 etc. of said members, and up to all said members. Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment, but may. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner, as would be apparent to a person skilled in the art from this disclosure, in one or more embodiments. Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0029] In a first aspect, the invention provides a filter pack for a flow meter, the filter pack comprises:

[0030] - a cage comprising a top end and a bottom end, a central cavity opening to both of said ends; and at least one filter configured to cover any lateral fluid communication channels between the central cavity and the outside.

[0031] The cage as described above provides a central cavity for receiving at least one flow meter. The cage is preferably a body of revolution. The cage is more preferably a conical cage or a cylindrical cage. Most preferably the cage is a cylindrical cage. The filter advantageously provides protection to said at least one flow meter from any debris which could otherwise result in malfunctions and inaccurate readings.

[0032] In known filter packs, two filter meshes surround the central cavity of the cage about its axis, an inner filter mesh and an outer filter mesh. Both the inner and outer meshes are supported by the cage and are disposed concentrically to each other such that an at least partially annular void is provided between said inner and outer filter meshes. While the filter meshes provide a valuable protection to any flow meter placed inside the central cavity of the cage, the same meshes, and in particular, the void interposed between said filter meshes has shown a tendency to either divert fluid flows away from the central cavity of the cage and / or to cause these flows to erratically change direction. As will be obvious to one skilled in the art, this presents a problem to the obtention of accurate flow values. This problem is solved by the present invention by way of at least one of the embodiments detailed below. In a preferred embodiment, the lateral fluid communication channels are at least two identical radially extending cavities interposed between both ends of the cage, said cavities providing fluid communication between the central cavity and the outer perimeter of the cage. The lateral walls of each radially extending cavity being substantially aligned with the longitudinal axis of the cage, the lateral walls separating fluid flow between every two adjacent radially extending cavities. In this way the volume around the central cavity of the cage is advantageously partitioned in such a way as to prevent any flow from bypassing said central cavity. Once fluid ingresses the filter pack past it outer perimeter, said fluid cannot pass anywhere but through the central cavity of the cage, only to leave through the opposite side of said cavity and out of the filter pack. The cage is provided with an even number of radially extending cavities, each radially extending cavity having a corresponding diametrically opposite radially extending cavity with which it is in substantial alignment. Preferably the lateral fluid communication channels are at least four identical radially extending cavities.

[0033] In an embodiment the filter comprises at least one filter mesh. A filter mesh is advantageous to prevent coarse particles entering the central cavity, which in its turn is advantageous for protecting the flow meter.

[0034] In an embodiment every radially extending cavity comprises packing material as a filter. By preference, said packing material is an inert granular material, such as glass beads, sand, pebbles or, most preferably, gravel. The latter provides an effective, readily available and inexpensive packing which permits lowering manufacturing costs of the filter pack. Alternatively said packing material is a non-woven filter. The packing material may be compacted. This is beneficial to place the packing material directly in the radially extending cavities, without need for additional elements to keep the packing material in place.

[0035] This embodiment may be advantageously combined with a previous embodiment, wherein the filer comprises at least one filter mesh. The filter mesh prevents coarse particles entering the central cavity, while the packing material prevents fine particles entering the central cavity. Preferably the filter mesh comprises at least one outer filter mesh and at least one inner filter mesh. The packing material is held between the at least one outer mesh and the at least one inner mesh. The outer filter mesh is advantageously supported by the packing material so as to prevent damages and / or displacement of said filter mesh due to external collisions.

[0036] In an embodiment, said central cavity has a cylindrical shape. A cylindrical shape is beneficial for insertion of a flow meter in the central cavity. A cylindrical shape has as disadvantage that a vertical movement of the flow meter will not be automatically limited by the central cavity. In this case, it will be required to foresee additional means to keep the flow meter in position.

[0037] In a preferred embodiment said central cavity has a frustoconical shape. By preference, larger diameter portion of said frustoconical central cavity is directed upwards, in this way facilitating the insertion and extraction of any element or device, such as a flow meter, into said central cavity. The angle of the lateral wall of said central cavity relative to its axis is between 2° and 40°, more preferably between 3° and 35°, 4° and 30°, most preferably between 5° and 25°. The frustoconical shape is beneficial to keep the flow meter in position.

[0038] In a preferred embodiment the filter pack comprises at least one tubular connection piece immediately adjacent to the top end of the cage, said connection piece being configured to be removably attachable to a probe pipe. This advantageously permits connecting the filter pack to a probe pipe, making deployment, installation and replacement of the filter pack advantageously easier. The connection piece is welded to the top end of the cage, screwed on the top end or attached by means of a sleeve connection or any other suited means to the top end of the cage. Alternatively, the connection piece is an integral part of the cage. By preference the connection piece attaches to the distal end of a pipe by means of a latch mechanism, more preferably bayonet connection, an interrupted thread, most preferably a threaded connection. By preference, said connection further comprises a detent in order to guarantee the same positioning of the filter pack relative to the pipe, every time said filter pack is installed. In this way, a user will not be left doubting as to the orientation of the filter pack relative to the pipe. By preference, the filter pack is also provided with a bottom connection piece. In this way, the filter pack can be provided with, for example a conical bottom for facilitating its insertion underground, any locating features to prevent any unwanted displacement once underground, or to permit carrying other additional sensors, depth adjusters of the like. The bottom connection piece is welded to the bottom end of the cage, screwed on the bottom end or attached by means of a sleeve connection or any other suited means to the bottom end of the cage.

[0039] Alternatively, the bottom connection piece is an integral part of the cage.

[0040] In a further embodiment, the at least one connection piece comprises at least one alignment mark complementary to at least one alignment mark on at least one end of the cage, said at least one alignment mark on said connection piece being visible from the outside of the filter pack. This allows the user to visually confirm the correct alignment between the filter pack and any of its connection pieces. This is particularly useful to detect if any damage to a connection between the filter pack and any of its connection pieces has occurred. The alignment mark is preferably also present and visible on the pipes attached to the connection piece attached to the top of the cage. This is beneficial during installation of the filter pack in a bore hole to assure that the filter pack is correctly aligned in the bore hole. The alignment mark is preferably aligned with a center point of one of the lateral fluid communication channels.

[0041] In an embodiment the filter pack comprises an alignment detection element. The alignment detection element is suited for detecting a correct angular alignment of a flow meter in the filter pack, a correct vertical alignment of a flow meter in the filter pack or for both a correct angular and vertical alignment of a flow meter in the filter pack. A correct angular alignment means that each of the radially extending cavities of the filter pack are aligned with one funneling chamber of the flow meter. The funneling chamber is a described in a later embodiment of the assembly. A correct vertical alignment means that the flow meter is installed at a correct depth in the filter pack.

[0042] In an embodiment the alignment detection element is a visual indication at an inside of the filter pack. The visual indication is for instance a horizontal line in case of vertical alignment, a vertical line in case of angular alignment or a cross in case of both angular and vertical alignment. The flow meter comprises a complementary alignment element. The alignment element is a visual indication on the flow meter, as described in a later embodiment of the assembly. When the visual indication on the filter pack and the visual indication on the flow meter are aligned, the flow meter is correctly aligned in the filter pack. The alignment can be checked with a camera that is lowered in the bore hole. In case of an angular alignment, the visual indication on the filter pack is preferably aligned with a center point of one of the lateral fluid communication channels. In an alternative embodiment the alignment detection element is a magnet. The magnet is preferably aligned with a center point of one of the lateral fluid communication channels. The magnet is beneficial to detect a correct alignment of the filter pack in a bore hole with the use of a magnetometer or a reed contact. The magnet can be used for both detecting a correct angular alignment as well as a vertical alignment. The magnetometer or the reed contact is preferably part of the flow meter, as described in a later embodiment of the assembly.

[0043] In an alternative embodiment the alignment detection is an RFID. The RFID is preferably aligned with a center point of one of the lateral fluid communication channels. The RFID is beneficial to detect a correct alignment of the filter pack in a bore hole with the use of an RFID-reader. The RFID can be used for both detecting a correct angular alignment as well as a vertical alignment. The RFID-reader is preferably part of the flow meter, as described in a later embodiment of the assembly.

[0044] In a preferred embodiment, at least one of the walls interposed between two radially extending cavities comprises a first marker, such as a protrusion, groove, or a functionally equivalent feature, extending into the central cavity towards its axis. Preferably, each wall interposed between two radially extending cavities comprises said first marker extending into the central cavity towards its axis. This embodiment is particularly advantageous in combination with a flow meter comprising sealing rubbers between adjacent funneling chambers. The first marker engages with the sealing rubbers. This ensures that any gap between the flow meter and the filter pack is sealed by the sealing rubbers. Preferably the sealing rubbers comprise a complementary second marker such as a groove, protrusion, or a functionally equivalent feature. In this way, a flow meter having a second marker, for instance a groove, complementary to said first marker, for instance a protrusion, will not leave a user in doubt as to the orientation of the flow meter relative to the filter pack.

[0045] As used herein, the term "first marker" refers to any structural or functional feature provided on the filter pack— preferably on one or more of the walls interposed between adjacent radially extending cavities— that is configured to cooperate with a complementary element on the flow meter, such as a sealing element or alignment interface. A first marker may serve purposes such as positioning, alignment, orientation control, sealing guidance, or secure engagement. Examples of a first marker include, but are not limited to: a protrusion such as a rib or ridge, a groove, a notch or slot, a recess or cavity, a raised pattern, a magnetic or conductive feature detectable by a sensor, a visual alignment indicator such as a printed symbol or marking, or an electronic tag such as an RFID chip or NFC marker. The first marker may be integrally formed with the cage of the filter pack or may be attached or applied to it. The first marker may also be passive or active, provided it contributes to the functional interaction with the flow meter - hence reference to a 'functionally equivalent feature'.

[0046] As used herein, the term "second marker" refers to any structural or functional feature provided on the flow meter— preferably on or within a sealing element such as a sealing rubber— that is configured to engage with a first marker of the filter pack. The second marker acts as the complementary counterpart to the first marker and facilitates precise positioning, secure assembly, alignment verification, and / or effective sealing between the flow meter and the filter pack - hence reference to a 'functionally equivalent feature'. Examples of a second marker include, but are not limited to: a groove, slot, notch or channel designed to receive a protrusion, a protrusion, peg or tab designed to enter a recess or groove, a mechanical detent or click feature, a magnet or ferromagnetic insert responsive to a magnetic marker, an optical marker such as a barcode or colored alignment zone, or a digital identifier such as a microchip, sensor array or alignment sensor. The second marker may be formed integrally with the sealing rubber or the support structure of the flow meter, or it may be applied post-production.

[0047] Preferably, the second marker, where said marker is a groove, has smaller dimensions than the corresponding first marker, where said marker is a protrusion, to ensure that the sealing rubber fits closely to the protrusion.

[0048] In a further embodiment, said at least one first marker such as a protrusion is a rib having a triangular section running along at least part of the height of the wall from which it extends. Such a rib advantageously provides early feedback to the user regarding the position of a flow meter relative to the cage, as any contact between said flow meter with any part of the internal cavity of the cage will result in tactile feedback reaching the user. This allows the user to carry out faster corrections and consequently a faster installation of a flow meter inside the filter pack. Additionally beneficial is that a triangular section will gradually displace a sealing rubber of a flow meter, ensuring a tight fit of the sealing rubber against the protrusion and against the central cavity of the filter pack. In a preferred embodiment, the cage comprises near the bottom end of at least one reference engagement feature such as a protrusion for aligning a flow meter inside the cavity. This reference engagement feature advantageously permit an even more refined positioning of a flow meter inside the central cavity of the filter pack.

[0049] In a further embodiment, the cage comprises at least two reference engagement features at opposite sides of the central cavity, the at least two reference engagement features merging each other at the axis of the central cavity. Preferably, the cage comprises four reference engagement features forming a cross at the axis of the central cavity. In this case the reference engagement features permit a refined position of the flow meter inside the central cavity, while also increasing the rigidity and robustness of the cage of the filter pack. Said reference engagement features are additionally beneficial as a support for holding the flow meter.

[0050] In a preferred embodiment, the cage is made of HDPE, PA12 or PVC. Preferably the cage is made of HDPE. These materials allow for an easy and cost effective manufacture of the cage while being also lightweight. In this way, installation of the filter pack advantageously requires less effort from the user, allowing installation to be performed by a single person or a lower payload robot. Additionally beneficial is that these materials have a good chemical resistance and a good resistance against moisture.

[0051] In a preferred embodiment, the at least one filter comprises at least one inner filter mesh. The at least one inner filter mesh is integral to the cage and comprises a wall with a plurality of orifices, said wall laterally delimiting the central cavity of the cage. In this way at least one of the filter meshes is produced at the same time as the cage. By preference, the cage is injection molded in order to further reduce costs while increasing geometrical uniformity of each of the produced cages.

[0052] In a preferred embodiment, the at least one filter comprises at least one outer filter mesh. The at least one outer filter mesh is a woven wire cloth. This allows the cage to be provided with a wider diversity of mash gauges in other to match different operational environments while making said mesh more resistant than a plastic mesh. Said woven wire cloth may be made of any low corrosion material or alloy, by preference a titanium or ferrous alloy. More by preference, the wire of the woven wire cloth is made of stainless steel, more preferably 304 alloy, most preferably 316. These alloys provide excellent strength and corrosion resistance even in acidic and caustic environments, thus ensuring a long useful life for the filter pack.

[0053] In an embodiment, the at least one filter comprises at least one inner filter mesh. The at least one inner filter mesh is a woven wire cloth. This embodiment has similar advantages as an outer filter mesh made of a woven wire cloth. The woven wire cloth can be made of similar materials as the at least one outer filter mesh.

[0054] A second aspect of the invention relates to an assembly for monitoring a fluid flux, the assembly comprising a filter pack according to any of the embodiments of the first aspect of the invention, and a flow meter to be placed inside the central cavity of the filter pack or placed inside the central cavity of the filter pack.

[0055] In an embodiment, the flow meter comprises a support structure complementary to the central cavity of the cage, said support structure further comprising a plurality of funneling chambers, each funneling chamber being configured to funnel a fluid flow towards a central channel providing fluid connection with an opposing funneling chamber, each channel being provided with a sensor to measure a flow along the longitudinal direction of said channel.

[0056] The assembly permits an optimal placement of the at least one flow meter inside the filter pack. In this way greatly improving the reliability and accuracy of the monitoring.

[0057] In a preferred embodiment, each radially extending cavity is aligned with one funneling chamber. The operational reliability and accuracy of the assembly is greatly increased by ensuring that each radially extending cavity is aligned with one funneling chamber. This effectively negates any ways for a flow to bypass the at least one flow meter, which results in the capturing of real results by each of the flowmeters used. By preference, the support structure comprises at least two sensors, each end of each sensor opening to a funneling chamber, each sensor being placed along a vertical direction relative to other sensors. In this way, the assembly permits the monitoring of a flow in at least two directions, thereby allowing collection and calculation of more accurate data regarding flow dynamics. Preferably, the flow meter comprises two sensors oriented in mutually perpendicular directions. In a preferred embodiment, the support structure further comprises a sealing rubber between each two adjacent funneling chambers. The funneling chambers are preferably surrounded by the sealing rubbers. The sealing rubber comprises a second marker such as a groove, protrusion, or a functionally equivalent feature. Said second marker is complementary to a first marker extending into the central cavity of the cage. The first marker is extending from a wall interposed between two radially extending cavities into the central cavity towards its axis. The first marker is preferably as described in a previous embodiment of the filter pack according to the first aspect. The first marker protrudes into the sealing rubber. This ensures that any gap between the flow meter and the filter pack is sealed by the sealing rubbers. Preferably, the second marker has smaller dimensions than the corresponding first marker to ensure that the sealing rubber fits closely to the first marker. Additionally beneficial, the user will not be left in doubt as to the positioning of the support structure, and therefore the at least one flow meter, inside the central cavity of the cage. The second marker in the sealing rubbers of the support structure and the first marker(s) extending into the central cavity of the cage also permit retaining the position of the support structure relative to the cage of the filter pack. This advantageously permits avoid reading errors due to misalignment of the at least one flow meter relative to the fluid flow, thus greatly contributing to the accuracy of the data collected by said at least one flow meter.

[0058] It is clear that the sealing rubbers between each two adjacent funneling chambers can be united in a single sealing rubber. In that case, the single sealing rubber comprises a second marker such as a groove between each two adjacent funneling chambers.

[0059] It is clear to the skilled person that the first marker, such as a protrusion, on said wall and the second marker, such as a groove, in the sealing rubber are elements that can be interchanged, but are preferably complementary to each other. The first and second markers may optionally be any type of marker suitable for this function. A non-limiting list of possible first and second markers is provided above.

[0060] In a preferred embodiment, the flow meter further comprises a base piece comprising at least one downwards extending prong. The at least one prong comprises a reference engagement counterpart such as a slot. The slot is complementary to a reference engagement feature such as a protrusion near the bottom of the filter pack. The reference engagement feature is as described in previous embodiments of a filter pack according to the first aspect. Said prong advantageously displaces any debris during the insertion of the filter pack into the soil, making said insertion step much easier. The prong permits also a more consistent positioning of the filter pack as it can be fixed to the bottom of a hole or cavity in order to better resist lateral displacement due to forces exerted by stronger flows. Receiving the reference engagement feature in or around the reference engagement counterpart ensures a correct alignment of the flow meter in the filter pack. Preferably, the prong comprises a funnel shape towards the reference engagement counterpart. This is beneficial to receive the reference engagement feature in the reference engagement counterpart. The flow meter will rotate automatically when lowering the flow meter in the filter pack until the reference engagement feature enters the reference engagement counterpart. By preference, the base piece comprises a plurality of prongs, more preferably three, most preferably four. By preference, the distal ends of said prongs are locate offset relative to the axis of the cage. In this way, the prongs prevent also any unwanted rotation of the cage due to forces imparted by fluid flows, thereby guaranteeing long term positional stability of the cage.

[0061] As used herein, the term "reference engagement feature" refers to any structural or functional element located near the bottom of the filter pack that is configured to cooperate with a complementary reference engagement counterpart provided on the flow meter, preferably on a base piece or downwardly extending prong. Conversely, the term "reference engagement counterpart" refers to any structural or functional element provided on the flow meter, configured to engage with the reference engagement feature of the filter pack.

[0062] The reference engagement feature and its counterpart may serve one or more of the following purposes: ensuring proper rotational alignment, preventing undesired displacement or rotation during use, guiding the insertion of the flow meter, or providing mechanical resistance against lateral flow forces. Examples of a reference engagement feature include, but are not limited to: a protrusion, a pin, a ridge, a magnetic insert, a keyed alignment element, or an electronically detectable tag. Examples of a reference engagement counterpart include, but are not limited to: a slot, a groove, a notch, a cavity, a detent, a magnetic receiver, or a corresponding detection mechanism. Either element may alternatively be realized as a surface texture, visual indicator, or sensor-based alignment guide, provided that the elements are functionally complementary. It is to be understood that the reference engagement feature and reference engagement counterpart are interchangeable in form, meaning that either the feature or the counterpart may take the form of a projection or a recess. What matters is the functional cooperation between both elements, regardless of their physical shape or relative position.

[0063] In an embodiment the assembly comprises a pipe with a solid wall. The pipe with the solid wall is positioned directly below the filter pack. The pipe with the solid wall is preferably attached to a connection piece at the bottom end of the cage. The assembly comprises below the pipe with the solid wall a piece of perforated pipe. The perforated pipe comprises multiple holes in its circumference. The holes can be round holes, slits, slots or have another suited shape. Preferably the holes are filled or covered with a filter, such as packing material, filter meshes,... or a combination thereof. The pipe with the solid wall is beneficial to avoid disturbance of the monitoring of the fluid flux in the filter pack. The pipe with the solid wall avoids additional horizontal flows through the pipe directly below the flow meter. The perforated pipe is advantageous to allow fluid to enter the pipe at a distance below the flow meter. If the fluid could not enter the pipe below the flow meter, that fluid would propel the assembly upwards. The fluid can thanks to the perforated pipe enter and leave the assembly freely without disturbing the measurements in the flow meter.

[0064] In a further embodiment, the assembly comprises a sand trap below the perforated pipe. The sand trap is beneficial to avoid that sand or other debris is blocking the holes in the perforated pipe. The sand or other debris will settle in the sand trap.

[0065] In an embodiment the flow meter comprises a vertical channel through the flow meter. The vertical channel is advantageous for enabling a vertical fluid flow through the flow meter. When fluid is raising or lowering in the assembly, the fluid can pass through the flow meter. The flow meter will remain in position. Because the fluid can flow vertically through the flow meter, no pressure changes will be created in the sensor, which could otherwise cause disturbances in the horizontal flow measurements.

[0066] In an embodiment the flow meter comprises an alignment element for checking a correct alignment of the flow meter inside the filter pack. The alignment element is suited detecting a correct angular alignment of the flow meter in the filter pack, a correct vertical alignment of the flow meter in the filter pack or for both a correct angular and vertical alignment of the flow meter in the filter pack. A correct angular alignment means that each of the radially extending cavities of the filter pack are aligned with one funneling chamber of the flow meter. A correct vertical alignment means that the flow meter is installed at a correct depth in the filter pack.

[0067] In an embodiment the alignment element is a visual indication on the flow meter. The visual indication is for instance a horizontal line in case of vertical alignment, a vertical line in case of angular alignment or a cross in case of both angular and vertical alignment. The visual indication is preferably part of a protruding element of the flow meter. This is beneficial to assure that the visual indication is visible with a camera when the flow meter is installed in the filter pack. For instance is the visual indication an edge of a Z-shaped element at a top side of the flow meter. In case of an angular alignment, the visual indication on flow meter is preferably aligned with a center point of one of the funneling chambers of the flow meter.

[0068] In an alternative embodiment the alignment element is a magnetometer. The magnetometer is preferably aligned with a center point of one of the funneling chambers of the flow meter. The magnetometer is preferably connected to a cable for reading values from the magnetometer. The cable is preferably common to a cable for reading values from the sensor of the flow meter. Alternatively the magnetometer is coupled to a radio for sending values from the magnetometer to a receiver outside a bore hole wherein the flow meter is installed. The magnetometer is suited for detecting both a correct angular alignment and a vertical alignment. This embodiment is advantageously combined with a previous embodiment of the filter pack comprising a magnet.

[0069] In an alternative embodiment the alignment element is a reed contact. The reed contact is preferably aligned with a center point of one of the funneling chambers of the flow meter. The reed contact is preferably connected to a cable for detecting a closed or open reed contact. The cable is preferably common to a cable for reading values from the sensor of the flow meter. Alternatively the read contact is coupled to a radio for sending a closed or open status of the reed contact to a receiver outside a bore hole wherein the flow meter is installed. The reed contact is suited for detecting both a correct angular alignment and a vertical alignment. This embodiment is advantageously combined with a previous embodiment of the filter pack comprising a magnet. A reed contact is cheaper than a magnetometer at the cost of reduced accuracy.

[0070] In an alternative embodiment the alignment element is a RFID-read. The RFID-reader is preferably aligned with a center point of one of the funneling chambers of the flow meter. The RFID-reader is preferably connected to a cable for reading values from the RFID-reader. The cable is preferably common to a cable for reading values from the sensor of the flow meter. Alternatively the RFID-reader is coupled to a radio for sending values from the RFID-reader to a receiver outside a bore hole wherein the flow meter is installed. The RFID-reader is suited for detecting both a correct angular alignment and a vertical alignment. This embodiment is advantageously combined with a previous embodiment of the filter pack comprising a RFID.

[0071] A third aspect of the invention provides a method for monitoring a fluid flux, comprising the use of a filter pack according to any of the embodiments of the first aspect.

[0072] In an embodiment, the method comprises the steps of:

[0073] - lowering the filter pack down a hole in a ground surface to a predetermined depth; and

[0074] - lowering a flow meter down said hole to the predetermined depth, wherein said flow meter is placed inside the central cavity of the filter pack.

[0075] In an embodiment, the method comprises the use of the assembly according to any of the embodiments of the second aspect.

[0076] In an embodiment, the flow meter comprising a support structure complementary to the central cavity of the cage, said support structure further comprising a plurality of funneling chambers, each funneling chamber being configured funnel a fluid flow towards a central channel providing fluid connection with an opposing funneling chamber, each channel being provided with a sensor to measure a flow along the longitudinal direction of said channel.

[0077] In an embodiment, the method comprises the steps of: measuring the flow values for each of the channels of the flowmeter support; and calculating the magnitude and directions of the flow inside said fluid by means of the measured flow values of at least two channels. In an embodiment, the method comprises a step of boring the hole in the ground surface.

[0078] In a preferred embodiment, each radially extending cavity is aligned with a funneling chamber. This effectively negates any ways for a flow to bypass the at least one flow meter, which results in the capturing of real results by each of the flowmeters used. By preference, each flow meter is placed along a vertical direction relative to other flow meters. In this way, the assembly permits a more reliable monitoring of a flow in at least two directions, thereby allowing collection and calculation of more accurate data regarding at least direction and magnitude of the monitored flow.

[0079] However, it is obvious that the invention is not limited to this application. The method according to the invention can be applied in all sorts of fluids in either gaseous or liquid form. The device can also be used to monitor fluid flows in industrial equipment, provided that any plastic material is replaced with a suitable material, such as ferrous metals, aluminum, coper alloys, titanium or the like, should the temperatures inside said equipment exceed that of the plastic materials mentioned in this description.

[0080] The skilled person will appreciate that a method according to the third aspect is preferably carried out with an assembly according to the second aspect and that an assembly according to the second aspect is preferably configured for carrying out a method according to the third aspect, first aspect. Each feature described in this document, above as well as below, may therefore relate to any of the three aspects of the present invention.

[0081] DESCRIPTION OF FIGURES

[0082] With as a goal illustrating better the properties of the invention the following presents, as an example and limiting in no way other potential applications, a description of a number of preferred embodiments and applications of the filter for well probes based on the invention, wherein:

[0083] Figure 1 shows the cage (2) of the filter pack (1). The figure shows the cage (2) interposed between two connection pieces (3) attached to its top and bottom end. A central frustoconical cavity (14) is shown surrounded by four radially extending chambers (4) divided by four walls (7). Figure 2 shows another embodiment of the cage (2) of the filter pack (1). In this embodiment, the radially extending cavities (4) are further equipped with an integral inner filter mesh (5) in an inner opening of the radially chamber (4).

[0084] Figure 3 shows an exploded view of the filter pack (1) of Figure 1. The figure shows the cage (2) interposed between two connection pieces (3) at its top end and bottom end. A central frustoconical cavity (14) is shown surrounded by four radially extending chambers (4) divided by four walls (7). The figure shows also an outer filter mesh (6) for covering the outer opening of all radially extending cavities (4). The void between each inner filter mesh (5) and the outer filter mesh (6) being configured to be filled with a granular material (not show), preferably gravel. The outer filter mesh (6) is in this embodiment a cylindrical filter mesh, but it could be as well four separate filter meshes, similar to the inner filter meshes (5). The cage (2) and the two connection pieces (3) comprise an alignment mark (8) that is visible at the outside of the filter pack (1). The alignment mark (8) is aligned with a center point of one of the radially extending chambers (4). Each wall (7) comprises a protrusion (19) extending into the central cavity (14) towards its axis. The protrusions (19) are a rib having a triangular section running along the wall (7) from which it extends. The protrusions (19) protrude into sealing rubbers (20) of a flow meter (2). This will be explained in more detail in Figure 7.

[0085] Figure 4 presents a flow meter (17) equipped with two sensors (9) on a support structure (10). The support structure (10) of the flow meter (17) comprises four funneling chambers (11). Each of the funneling chambers (11) is shown diametrically opposing another funneling chamber (11), wherein a channel (13) is shown connecting each pair of funneling chambers (11), said channels (13) being equipped with sensors (9). A base piece (12) equipped with four prongs (15) is also shown attached to the bottom of the flow meter (17). The funneling chambers (11) of the support structure (10) are to be aligned with a plurality of radially extending chambers (4) of a cage (2) of a filter pack (1), in this way allowing a fluid flow to better reach each sensor (9).

[0086] Figure 5 shows a top view of the filter pack of Figure 2. The four integral inner filter meshes (5) are clearly visible, just like the four walls (7) separating the radially extending cavities (4). The filter pack (1) comprises four reference protrusions (16) near the bottom of the filter pack (1). The four reference protrusions (16) merge each other at the axis of the central cavity (14). The four reference protrusions (16) form a cross at the axis of the central cavity (14). The filter pack (1) of this embodiment is very suited for use in combination with the flow meter (2) of Figure 4. The four prongs (15) comprise a slot (18) in between them, complementary with the four reference protrusions (16). The four prongs (15) comprise a funnel shape towards the slot (18). This is beneficial to receive the reference protrusions (16) in the slots (18). The flow meter (2) will rotate automatically when lowering the flow meter (2) in the filter pack (1) of Figure 4 until the reference protrusions (16) enter the slots (18).

[0087] Figure 6 shows a top view of the filter pack of Figure 1 and Figure 3. The inner filter mesh (5) and the outer filter mesh (6) are not shown. The connection piece (3) at the top end of the cage (2) is threaded on the inside. The filter pack (1) comprises a single reference protrusion (16) near the bottom of the filter pack (1). The filter pack (1) of this embodiment is very suited for use in combination with the flow meter (2) of Figure 7.

[0088] Figure 7 presents another embodiment of a flow meter equipped with two sensors in a support structure. The flow meter (2) has a very similar structure as the flow meter (2) of Figure 4. A first important difference is that a sealing rubber (20) is foreseen around the funneling chambers (11). The sealing rubber (20) comprises grooves (21) that are complementary with the protrusions (19) of the filter pack (1) of Figures 1, 3 and 6. The grooves (21) have smaller dimensions than the corresponding protrusions (19) to ensure that the sealing rubber (20) fits closely to the protrusions (19). A second important difference is that the base piece (12) comprise a single prong (15) with a single slot (18). The single slot (18) is configured to receive the reference protrusion (16). The prong (15) comprises a funnel shape towards the slot (18). Further the flow meter (17) comprises a vertical channel (22) for an unhindered vertical flow of fluid through the flow meter (17). Only a top part of the vertical channel (22) is visible on Figure 7. The flow meter comprises further a vertical alignment element (26). The vertical alignment element (26) is in this embodiment a Z-shaped element at a top side of the flow meter. A horizontal edge of the vertical alignment element (26) is to be aligned with an alignment detection element at an inside of a pipe or the filter pack (1). The alignment detection element is for instance a visual indication in the form of a horizontal line. When the vertical alignment element (26) is aligned with the visual indication, the flow meter is installed at a correct depth. The vertical alignment can be checked visually with a camera that is lowered inside the bore hole.

[0089] Figure 8 shows an assembly according to an embodiment of the current invention. The assembly comprises a filter pack (1) as shown in Figures 1, 3 and 6. The filter pack (1) comprises a connection piece (3) at the top end and the bottom end of the cage (2) of the filter pack (1). The cage (2) is hidden by the cylindrical outer filter mesh (6). A pipe with a closed wall (23) is connected to the connection piece (3) at the top end. It is clear to the skilled person that depending on a desired depth form monitoring a fluid flux, multiple pipes (23) can be connected to each other. A pipe with a closed wall (23) is connected to the connection piece (3) at the bottom end. Below the pipe with closed wall (23) at the bottom end, the assembly comprises a perforated pipe (24). The perforated pipe (24) comprises slits allowing fluid entering and leaving the pipes (23, 24). This is beneficial to avoid that the fluid propels the filter pack (1) upwards. Below the perforated pipe (24) is a sand trap (25).

[0090] List of numbered items:

[0091] 1 filter pack

[0092] 2 cage

[0093] 3 connection piece

[0094] 4 radially extending cavity

[0095] 5 inner filter mesh

[0096] 6 outer filter mesh

[0097] 7 wall

[0098] 8 alignment mark

[0099] 9 sensor

[0100] 10 support structure

[0101] 11 funneling chamber

[0102] 12 base piece

[0103] 13 channel

[0104] 14 central cavity

[0105] 15 prong

[0106] 16 reference protrusion

[0107] 17 flow meter

[0108] 18 slot

[0109] 19 protrusion 20 sealing rubber

[0110] 21 groove

[0111] 22 vertical channel

[0112] 23 pipe with closed wall 24 perforated pipe

[0113] 25 sand trap

[0114] 26 vertical alignment element

[0115] The present invention is in no way limited to the embodiments shown in the figures. On the contrary, methods according to the present invention may be realized in many different ways without departing from the scope of the invention.

Claims

CLAIMS1. A filter pack for a flow meter, the filter pack comprises:- a cage comprising a top end and a bottom end, a central cavity opening to both of said ends; and at least one filter configured to cover any lateral fluid communication channels between the central cavity and the outside; characterized in that, said lateral fluid communication channels are at least two identical radially extending cavities interposed between both ends of the cage, said cavities providing fluid communication between the central cavity and the outer perimeter of the cage, the lateral walls of each radially extending cavity being substantially aligned with the longitudinal axis of the cage, the lateral walls separating fluid flow between every two adjacent radially extending cavities.

2. The filter pack according to any of the previous claims, characterized in that, said lateral fluid communication channels are at least four identical radially extending cavities interposed between both ends of the cage.

3. The filter pack according to any of the previous claims, characterized in that, said central cavity has a frustoconical shape.

4. The filter pack according to any of the previous claims, characterized in that, the filter pack comprises at least one tubular connection piece immediately adjacent to the top end of the cage, said connection piece being configured to be removably attachable to a probe pipe.

5. The filter pack according to claim 4, characterized in that, the at least one connection piece comprises at least one alignment mark, said at least one alignment mark on said connection piece being visible from the outside of the filter pack.

6. The filter pack according to any of the previous claims, characterized in that, at least one of said walls interposed between two radially extending cavities comprises a first marker, such as a protrusion, groove, or functionally equivalent feature, extending into the central cavity towards its axis.

7. The filter pack according to claim 6, wherein each wall interposed between two radially extending cavities comprises said first marker.

8. The filter pack according to previous claim 6 or 7, characterized in that, said first marker, such as a protrusion, is a rib having a triangular section running along at least part of the height of the wall from which it extends.

9. The filter pack according to any of the previous claims, characterized in that, the cage comprises near the bottom end at least one reference engagement feature such as a protrusion, for aligning a flow meter inside the cavity.

10. The filter pack according to any of the previous claims, characterized in that, the cage is made of HDPE, PA12 or PVC.

11. The filter pack according to any of the previous claims, characterized in that, the at least one filter comprises at least one inner filter mesh, wherein the at least one inner filter mesh is integral to the cage and comprises a wall with a plurality of orifices, said wall laterally delimiting the central cavity of the cage.

12. The filter pack according to any of the previous claims, characterized in that, the at least one filter comprises at least one outer filter mesh, wherein the at least one outer filter mesh is a woven wire cloth.

13. The filter pack according to claim 11, characterized in that, the wire of the woven wire cloth is made of stainless steel.

14. An assembly for monitoring a fluid flux, the assembly comprising a filter pack according to any one of the claims 1-12, the assembly further comprising a flow meter to be placed inside the central cavity of the filter pack.

15. The assembly according to claim 13, wherein said flow meter comprises a support structure complementary to the central cavity of the cage, said support structure further comprising a plurality of funneling chambers, each funneling chamber being configured to funnel a fluid flow towards a central channel providing fluid connection with an opposing funneling chamber, eachchannel being provided with a sensor to measure a flow along the longitudinal direction of said channel.

16. The assembly according to claim 14, wherein each radially extending cavity is aligned with one funneling chamber.

17. The assembly according to claim 14 or 15, characterized in that, support structure further comprises a sealing rubber between each two adjacent funneling chambers, the sealing rubber comprising a second marker such as a groove, protrusion, or functionally equivalent feature, said second marker being complementary to at least one first marker, such as a protrusion, groove, or functionally equivalent feature, extending into the central cavity of the cage.

18. The assembly according to any of the previous claims 13-16, characterized in that, the flow meter comprises a base piece comprising at least one downwards extending prong, the at least one prong comprising a reference engagement counterpart such as a slot, said reference engagement counterpart being complementary to a reference engagement feature, such as a protrusion, near the bottom of the filter pack.

19. The assembly according to any of the previous claims 13-17, characterized in that, the flow meter comprises an alignment element for checking a correct alignment of the flow meter inside the filter pack.

20. A method for monitoring a fluid flux, the method comprising the use of the filter pack according to any one of the claims 1-12.

21. The method according to claim 19, the method comprising the steps of: lowering the filter pack down a hole in a ground surface to a predetermined depth; and lowering a flow meter down said hole to the predetermined depth, wherein said flow meter is placed inside the central cavity of the filter pack.

22. The method according to claim 19 or 20, the method comprising the use of the assembly according to any one of the claims 13-18.

23. The method according to any one of the previous claims 20 - 21, wherein said flow meter comprises a support structure complementary to the central cavity of the cage, said support structure further comprising a plurality of funneling chambers, each funneling chamber being configured funnel a fluid flow towards a central channel providing fluid connection with an opposing funneling chamber, each channel being provided with a sensor to measure a flow along the longitudinal direction of said channel.

24. The method according to claim 22, further comprising the step of: measuring the flow values for each of the channels of the flowmeter support; and calculating the magnitude and directions of the flow inside said fluid by means of the measured flow values of at least two channels.

25. The method according to claim 22 or 23, wherein each radially extending cavity is aligned with a funneling chamber.

26. The method according to any one of the previous claims 19-24, comprising the step of boring the hole in the ground surface.

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