EP2553216B1 - Wear-resistant separator for separating sand and rock particles - Google Patents

Description

Field of the invention

The invention relates to a novel separation device with improved erosion and abrasion resistance, which is an integral part of a production equipment for use in the extraction of oil, water and gas mixtures or their individual components from deep wells, with their help solids such as sand and rock particles can be separated from the liquids and gases to be delivered. The separator is used in particular to prevent the erosive and abrasive removal of the conveyor equipment by sand and rock particles. At the same time the separator is corrosion resistant to treatment liquids.

Background of the invention

When producing liquids and gases, such as oil and gas from deep wells, there is often the problem that sand inflows from the oil and gas deposits make it difficult to produce. This is particularly the case when hydrocarbon production occurs from unconsolidated formations of oil and gas deposits, or when, as the life of the deposits increases, the flow rates and thus the dilution of hydrocarbon production increase and the sand inflow is triggered, so that reservoir particles are increasingly promoted ,

To combat sand inflows from the deposits special filter equipment is used, such as slotted filter or filter with metallic wire windings, which are usually made of steel materials and have the disadvantage that they can not fulfill their task for the separation of the sands due to the high flow forces, because they erode quickly. The remedy is the regular replacement of the sand filter device, which is performed in an overhaul of the hole, in a so-called "workover".

State of the art

Usually metallic wire mesh, metallic wire mesh or metallic wire windings are used for this task. A solution with wire mesh is in the US 5,624,560 described. These wire mesh or wire mesh solutions are still supported by a metallic support structure, such as a perforated tube, to remain mechanically stable.

In the US 5,890,533 is described a solution with a wire winding, wherein a plurality of filter units with metallic wire windings can be connected to each other via fasteners with screw threads.

In the US 5,515,915 is described a solution with wire winding on a perforated tube, in which for supporting the wire winding between the inner perforated tube and the wire winding still spacer and support rods are mounted. In addition, a filter gravel pack is additionally inserted between the perforated tube and the wire winding. This filter gravel pack serves as a secondary filter.

A major disadvantage of these designs with metallic wire mesh, wire mesh or wire windings is their low resistance to wear. Due to the abrasive or erosive effect of the sand and rock particles flowing in with high flow velocity, the filters are destroyed and the delivery pipes are damaged. At the same time the productivity of the promotion decreases, since now the sand is no longer effectively filtered out but is transported on with the pumped medium. Another problem is the corrosive wear on the filters and delivery pipes caused by the use of treatment liquids. This corrosive wear in turn increases the abrasive wear. Treatment liquids, such as acids, alkalis, water or superheated steam, are used to clean the separator and to stimulate the wellbore.

It is necessary to increase the resistance of the downhole equipment to abrasive erosion and to ensure that it is not corrosively attacked.

In the US2004 / 0050217 A1 and WO2008 / 080402 A1 solutions are described in which instead of the metallic gap sieves separating devices made of porous permeable materials are used. The porous filter materials of US2004 / 0050217 A1 can be metallic, ceramic or organic, in the WO2008 / 080402 A1 Porous ceramic materials are used.

A problem of the solutions described in these two documents is that filters made of porous ceramic materials tend to break due to bending stress due to their low fracture toughness. The bending strength is usually less than 30% of that of the corresponding dense material and is therefore not sufficient for the mechanical loads under the conditions of use in rock boreholes.

Another problem is that the abrasion resistance of porous ceramic materials is significantly lower than that of dense ceramic materials.

Another solution with a separator of porous materials is in the WO2004 / 099560 A1 described, which also has the disadvantages described above. In a further embodiment (page 7, line 24 - page 8, line 2 and claim 20) sees the WO2004 / 099560 A1 In addition to protect a conventional sand filter outside by a cuff made of erosion-resistant, dense rings, which additionally have ribs or pits on their upper and lower surfaces. On the stacked rings, a convoluted fluid channel forms, on the walls of which the energy of the flowing medium is reduced by impact, so that the wear of the underlying, conventional sand filter is reduced. Preferably, the rings are formed of carbides or nitrides such as silicon carbide or tungsten carbide. A disadvantage of this solution is that the improved wear protection is accompanied by an energy dissipation of the flowing medium; the outer sleeve does not act as a filter but as a flow resistance that degrades the flow rate. It is not disclosed how the cuff is mounted on the conveyor tube.

In the US 5,249,626 a cylindrical sieve filter is presented which includes a plurality of stacked annular filter segments. The ring stack is held together by a plurality of threaded rods with threaded nuts or double nuts made of stainless steel at the top and bottom. The separation of the particles takes place at the variable annular gap, which is formed between opposite filter segments. The rings are made of plastic, preferably of glass-reinforced polypropylene (column 4, Z. 50-54). The threaded rods are guided through openings provided in the rings (column 4, lines 31-33). This solution can not be realized from ceramics. The cross-sectional transitions are edged; The filter segments have a typical plastic design. The central feedthroughs for the threaded rods would weaken ceramic elements and reduce the load capacity. The spacers are flat, so bending stresses can not be compensated. Other disadvantages of in the US 5,249,626 glass-reinforced polypropylene screen filter described are its insufficient erosion / abrasion resistance and insufficient corrosion resistance.

In the WO99 / 06669 Another solution is described with spirally wound metallic wire winding. In addition, for a second embodiment (page 3, lines 8-14 and page 10, lines 8-19), rings are formed from the V-shaped wire by welding. These rings are then interconnected by spacers having upper and lower surfaces, the spacers being fixed by their upper surface to the upper wire ring and by their lower surface to the lower wire ring by welding so as to obtain a mechanically strong and rigid structure , For this construction, the possibility is mentioned to use ceramic for this purpose. The rigid design with the firmly connected flat spacers would, however, lead in ceramic that occurring tensile and bending stresses can not be absorbed, which would lead to a considerable risk of breakage and possible complete destruction of the sand filter. In addition, the production of such a ceramic construction would be very complex.

Object of the invention

The invention has for its object, overcoming the disadvantages of the prior art, to provide a separator for the separation of sand and rock particles in the promotion of liquids or gases from rock drilling available, the better wear and abrasion resistance and a lower tendency to fracture as the known in the prior art separation devices, and which is also resistant to corrosion treatment fluids, and can withstand the loads occurring during the promotion, has a longer life and with their help higher flow rates can be achieved. The separator should moreover be suitable as an integral part of a conveying equipment for conveying liquids or gases from deep wells.

Summary of the invention

The above object is achieved by a separating device according to claim 1 and their use according to claim 27. Advantageous and particularly useful embodiments of the subject of the application are specified in the dependent claims.

1. a) einen Ringstapel aus sprödharten ringförmigen Scheiben, deren Oberseite mindestens drei über den Kreisumfang der Scheiben gleichmäßig verteilte Erhebungen aufweist, wobei die Scheiben so gestapelt und verspannt sind, dass zwischen den einzelnen Scheiben jeweils ein Trennspalt zur Abtrennung von Sand- und Gesteinspartikeln vorhanden ist,
2. b) ein Ankopplungselement am oberen Ende und ein Ankopplungselement am unteren Ende des Ringstapels,
3. c) eine Spannvorrichtung zur axialen Verspannung des Ringstapels,
4. d) einen Außenkäfig zum mechanischen Schutz des Filtermoduls,
5. e) ein Kupplungselement am oberen Ende und ein Kupplungselement am unteren Ende des Filtermodul zur Verbindung des Filtermoduls mit weiteren Komponenten der Förderausrüstung.

The invention thus provides a separation device for separating sand and rock particles, which is suitable as an integral Bestanteil a conveying equipment for the promotion of liquids or gases from deep wells, wherein the separation device comprises at least one ceramic filter module, wherein the filter module comprises

1. a) a ring stack of brittle-hard annular disks whose upper side has at least three projections distributed uniformly over the circumference of the disks, wherein the disks are stacked and braced such that there is a separating gap between the individual disks for separating sand and rock particles;
2. b) a coupling element at the upper end and a coupling element at the lower end of the ring stack,
3. c) a clamping device for the axial clamping of the ring stack,
4. d) an outer cage for mechanical protection of the filter module,
5. e) a coupling element at the upper end and a coupling element at the lower end of the filter module for connecting the filter module with other components of the conveying equipment.

The invention also relates to the use of the separation device according to the invention for the separation of sand and rock particles in a process for the promotion of liquids or gases from rock or deep wells.

The annular disks of the separating device according to the invention are stacked and braced so that they are axially fixed and forms between the individual disks each have a defined separation gap for the separation of sand and rock particles. In the radial and tangential direction, however, the rings are movable relative to each other to a certain extent, whereby a stress build-up in the ring stack is effectively reduced by external loads such as bending.

The ring stack is fixed on the tensioning device only in itself, the sand filter module requires no additional mechanical support. For example, it is not fastened to an inner conveyor tube which carries the dead weight of ring stack and tensioning device and optionally further coupling elements, intermediate modules and / or the filter module tip.

In a preferred embodiment, the separation device further comprises one or more protective sheaths for protecting the intermediate modules and the coupling elements.

The separation device according to the invention constructed from brittle-hard ring elements is more resistant to abrasion and corrosion than conventional sand-combing devices. It therefore has a longer service life than the sand filters of the prior art. The separation device according to the invention must therefore, in contrast to the sand filters of State of the art can not be replaced at regular intervals, so that the intervals until an existing hole has to be overhauled (workover), significantly longer.

Due to the more effective filtration over the filters of the prior art, i. the better sand separation, higher production rates can be achieved.

The present invention allows the favorable ceramic material properties of the ceramic materials, in particular their abrasion resistance and their high deformation resistance, to be used for the highly abrasive sand filter by the ceramic design solution. The unfavorable for this class of materials loads, in particular point, bending, tensile and impact loads are avoided constructively by the inventive solution.

Due to the high resistance of the brittle-hard discs against deformation, the annular discs must in contrast to the prior art (such as in the US 5,515,915 ) are not supported by spacer and support rods on an inner tube to increase their stability in the stack and each other. They can be free-standing.

Once the annular discs are axially braced, they form a very stable separation gap, which has a small tolerance width, which is due only to the manufacturing tolerance of the rings and not by material deformability. The separation gap widths comply with the standard API guidelines (American Petroleum Institute) and can even surpass these standards.

The high resistance to mechanical deformation caused, for example, by incident sand layers prevents the separation gaps from changing. In contrast to the prior art sand filters of wire mesh and wire windings, clogging of the separation gaps is inhibited.

Even with sudden sand inflow, the brittle-hard discs do not deform, the set separation gap width is maintained.

In prior art metallic filter fabrics, multi-ply filter fabrics are common and necessary for protecting the fine filter. However, the multi-layer fabric arrangement increases the flow resistance. Multi-ply fabrics also tend to become clogged by the deposition of sands in the cavities, and thus to further increased flow resistance. In contrast, the inventive ceramic sand filter modules can be made in one layer due to the good abrasion resistance and the high resistance to deformation of the brittle ring stack and be charged directly with the flow. An additionally introduced filter gravel pack between filter and inner tube as a secondary filter is not necessary in the ceramic sand filter modules according to the invention. Instead, the sand and rock particles to be separated can build up on the outer peripheral surface of the stable, brittle-hard discs as a secondary filter cake. Its stability is favored by the separator according to the invention, which leads to an increase in the well integrity.

The separation of the particles is ensured in direct inflow and through flow, without the flow being negatively influenced by deflection or energy dissipation. The pressure loss of the separator according to the invention is negligible and the separator according to the invention is flowed through laminar.

Another advantage is that the separation device according to the invention requires no mechanical support as the plastic filter segments in the US 5,249,626 or the metallic wire mesh of the US 5,624,560 , The ring stack according to the invention is fixed on the clamping device only in itself and is not supported or supported by an inner conveyor pipe. Since the inner delivery pipe is eliminated, thus also the existing inside the free conveying cross section and thus the delivery rate is increased.

The resilient mounting of the ring stack allows bends to be accommodated and different thermal expansions of the different materials to be compensated.

The rings are stacked and braced so that they are movable in the radial and tangential direction to a certain extent against each other, whereby a stress build-up in the ring stack is effectively reduced by external stresses such as bending.

About the coupling elements conventional intermediate modules can be used. The sand filter modules can be attached to existing delivery systems using conventional connection technology. This applies both to the attachment at the end of the conveyor linkage as well as for a subsequent insertion of the filter modules and hanging on a landing nipple.

The individual sand filter modules can be connected via the coupling elements and intermediate modules to filter systems of any length.

The separating device according to the invention can be used under any wellbore deflection, both in the horizontal and in the vertical wellbore and also under any other borehole inclination, for example at a borehole inclination of 60 °. This is an advantage over the conventionally used metallic wire mesh.

In order to prevent premature termination of the use of the abrasion-resistant and thus durable sand filter modules according to the invention by this abrasive damage or destruction of a commercially available filter module tip, the separating device according to the invention preferably comprises filter module tips with increased abrasion protection.

Brief description of the drawings

• Figur 1 schematisch die Gesamtansicht einer erfindungsgemäßen Trennvorrichtung einschließlich einer Filtermodulspitze;
• Figuren 2 a - 2 d verschiedene Ansichten einer erfindungsgemäßen ringförmigen Scheibe gemäß einer ersten Ausführungsform;
• Figuren 3 a - 3 d verschiedene Ansichten einer erfindungsgemäßen ringförmigen Scheibe gemäß einer zweiten Ausführungsform;
• Figuren 4 a - 4 c schematisch verschiedene Ansichten eines Ringstapels mit Ankopplungselementen gemäß einer ersten Ausführungsform;
• Figuren 5 a - 5 c schematisch verschiedene Ansichten eines Ringstapels mit Ankopplungselementen gemäß einer zweiten Ausführungsform;
• Figur 6 eine Querschnittsansicht einer erfindungsgemäßen Trennvorrichtung gemäß einer ersten Ausführungsform;
• Figur 7 eine Querschnittsansicht einer erfindungsgemäße Trennvorrichtung gemäß einer zweiten Ausführungsform;
• Figuren 8 a - 8 c Detail-Querschnittsansichten der Trennvorrichtung gemäß Figur 6;
• Figuren 9 a - 9 c Detail-Querschnittsansichten der Trennvorrichtung gemäß Figur 7; und
• Figur 10 eine Querschnittsansicht einer erfindungsgemäß bevorzugten Filtermodulspitze.

The invention will be explained in more detail with reference to the drawings. Show here

• FIG. 1 schematically the overall view of a separation device according to the invention including a filter module tip;
• Figures 2 a - 2 d are different views of an annular disc according to the invention according to a first embodiment;
• Figures 3 a - 3 d different views of an annular disc according to the invention according to a second embodiment;
• FIGS. 4 a - 4 c schematically show different views of a ring stack with coupling elements according to a first embodiment;
• Figures 5 a - 5 c schematically illustrate various views of an annular stack with coupling elements according to a second embodiment;
• FIG. 6 a cross-sectional view of a separating device according to the invention according to a first embodiment;
• FIG. 7 a cross-sectional view of a separating device according to the invention according to a second embodiment;
• FIGS. 8 a - 8 c detailed cross-sectional views of the separator according to FIG. 6 ;
• Figures 9 a - 9 c detailed cross-sectional views of the separator according to FIG. 7 ; and
• FIG. 10 a cross-sectional view of a preferred invention filter module tip.

Detailed description of the invention

Preferred embodiments and details of the separation device according to the invention for the separation of sand and rock particles are explained in more detail below with reference to the drawings.

FIG. 1 shows the overall view of a separation device according to the invention, which is modularly composed of at least one ceramic filter module 1 (hereinafter also referred to as "sand filter module").

According to the borehole conditions, the separation device can be arbitrarily extended by the modular structure. Usually, the separator comprises at the lower end of the lowermost sand filter module and thus at the end of the drill string a filter module tip 2. The ceramic sand filter modules take over the sand separation or sand control.

The sand filter modules can also be connected via intermediate modules 3 with other sand filter modules. The intermediate modules can perform various tasks, such as ensuring sufficient bending when introducing the separator into the well, the centering of the separator in the well casing or the attachment / anchoring of the separator to the production tubing or well casing. It is also possible to use active elements as intermediate modules, by means of which backwashing or free-flowing of added filter elements is realized.

The separation device according to the invention can be installed both in the re-equipment of sand-carrying holes as well as in the overhaul of the hole (Workover) in the conveyor system, further it can also be introduced in an existing hole through the interior of the production tubing and anchored to the landing nipples of the well casing , Depending on the application variant, the intermediate modules and the geometric data of the ceramic sand filter modules differ, but the design principles can be retained.

• einen Ringstapel 6 (s. Figuren 4 und 5) aus sprödharten ringförmigen Scheiben 7 (s. Figuren 2 und 3), deren Oberseite 16 mindestens drei über den Kreisumfang der Scheiben gleichmäßig verteilte Erhebungen 8 aufweist. Die bevorzugte Ausführungsform mit drei als Kugelabschnitten ausgebildeten Erhebungen 8 verhindert das Einbringen von Punktlasten auf die sprödharten Filterringe. Die Scheiben sind so gestapelt und verspannt, dass sie axial fixiert sind und sich zwischen den einzelnen Scheiben jeweils ein definierter Trennspalt 9 zur Abtrennung von Sand- und Gesteinspartikeln ausbildet. In radialer und tangentialer Richtung sind die Ringe jedoch in einem bestimmten Maß gegeneinander beweglich, wodurch ein Spannungsaufbau im Ringstapel durch äußere Belastungen wie Biegung wirkungsvoll reduziert wird.
• zwei Ankopplungselemente 10, 11 (s. Figuren 4 und 5) am oberen und unteren Ende des Ringstapels 6;
• eine Spannvorrichtung zur axialen Verspannung des Ringstapels;
• einen Außenkäfig 5 (s. Figur 1);
• zwei Kupplungselemente 12, 13 (s. Figuren 6 und 7) am oberen und unteren Ende des Sandfiltermoduls zur Verbindung der Sandfiltermodule mit weiteren Komponenten der Förderausrüstung, wie beispielsweise der Filtermodulspitze und den Zwischenmodulen.

In the following, various embodiments of the sand filter modules according to the invention will be described, the ceramic sand filter modules always comprising the following material-appropriate designed, coordinated basic elements:

• a ring stack 6 (s. FIGS. 4 and 5 ) from brittle-hard annular discs 7 (s. Figures 2 and 3 ), the top 16 has at least three evenly distributed over the circumference of the discs elevations 8. The preferred embodiment with three elevations 8 designed as spherical sections prevents the introduction of point loads on the brittle filter rings. The discs are stacked and braced so that they are axially fixed and forms a defined separation gap 9 for the separation of sand and rock particles between the individual discs. In the radial and tangential direction, however, the rings are movable relative to each other to a certain extent, whereby a stress build-up in the ring stack is effectively reduced by external loads such as bending.
• two coupling elements 10, 11 (s. FIGS. 4 and 5 ) at the upper and lower ends of the ring stack 6;
• a tensioning device for axial clamping of the ring stack;
• an outer cage 5 (s. FIG. 1 );
• two coupling elements 12, 13 (s. FIGS. 6 and 7 ) at the top and bottom of the sand filter module for connecting the sand filter modules to other components of the conveyor equipment, such as the filter module tip and the intermediate modules.

ring stack

The annular discs 7 used in the ceramic sand filter module are in the Figures 2a - 2d and 3a - 3d for two preferred embodiments of the sand filter module shown. Figure block 2 shows the design of the annular discs for a first embodiment, at the internal clamping rods 14 (s. FIG. 6 ) are used for clamping the ring stack. In a second embodiment, the ring stack is placed on an inner, perforated tube 15 (see FIG. FIG. 7 ) and braced, the rings used for this shows Figure block 3.

The annular discs are made of a brittle-hard material, preferably made of a ceramic material that is resistant to abrasion and erosion against the sand and rock particles and corrosion resistant to the fluids and the media used for cleaning such as acids.

The separation of the sand and rock particles takes place at a radial, preferably tapered gap 9 (s. Figures 5 and 6 ), which forms between two superimposed, strained ring elements. The ring elements are designed ceramics appropriate or brittle hard materials, ie cross-sectional transitions are performed without notches and the formation of bending stresses is constructively avoided or compensated.

The height (thickness) of the annular discs depends on the required flow rate.

The annular discs 7 have on their upper side 16 at least three evenly distributed over the circumference of the discs elevations 8 with a defined height, with the help of the height of the separating gap (gap width) is set. The elevations are not separately applied or subsequently welded spacers. They are formed directly during manufacture during the shaping of the annular discs.

When stacking the individual surveys in the stack are aligned over each other.

The elevations are preferably in the form of spherical sections in order to achieve a point contact between opposing annular discs and to avoid surface contacts.

The annular discs preferably have on their outer peripheral surface a recess / marking groove 17, by means of which the annular discs are more easily positioned one above the other during installation and thus fail-safe mounting is allowed. The marking groove is preferably rounded.

The upper surface 16 of the annular discs may be made at right angles to the disc axis or sloping inwardly or outwardly sloping with a plane or curved surface.

The underside 18 of the annular discs may be designed to slope outwards or inwards, preferably inwardly sloping, more preferably it is concave. An inwardly sloping design is advantageous in terms of a reduced tendency to clog the separator. The concave shape is to understand the ring bottom as a whole, see Figures 2d and 3d , Here, the ring bottom is designed with a radius R.

The annular discs in the ring stack are movable relative to each other in the radial and tangential direction, whereby a stress build-up in the ring stack is effectively reduced by external stresses such as bending.

Due to the concave shape of the ring base in combination with the three-point support also possible shape and dimensional deviations can be easily compensated.

The cross-sectional shape of the annular discs is preferably non-rectangular and not trapezoidal due to the concavely curved surfaces. It also has no sharp edges and cross-sectional transitions.

In a preferred embodiment, the outer contours 19 of the annular discs are chamfered, as in FIG Figures 2d and 3d illustrated. According to another preferred embodiment, the edges may also be rounded. This represents an even better protection of the edges from the edge load which is critical for brittle-hard materials. The peripheral surfaces (cladding surfaces) of the annular discs are preferably cylindrical (even). But it is also possible to form the peripheral surfaces outwardly convex, for example, in order to achieve a better flow.

The radial wall thickness of the annular discs is preferably at least 2 mm, more preferably at least 5 mm. The height or thickness of the discs is preferably 1 to 20 mm, more preferably 1 to 10 mm.

The outer diameter of the annular discs is smaller than the inner diameter of the borehole or as the inner diameter of the Bohrlochfutterrohres. It is usually 50-200 mm. Also possible are smaller diameters than 50 mm and larger than 200 mm.

The inner diameter of the annular discs is preferably less than 90%, more preferably less than 85% of the outer diameter of the annular discs. Alternatively, the contour of the inner diameter of the annular discs can also be approximated by a polygon, for example a hexagon.

In the embodiment with the tension rods only the ratio to the outer diameter must be considered. In the embodiment with the tensioning tube, the inner diameter of the annular discs must additionally be greater than the diameter of the inner, perforated tube. The annular discs must not rest on the inner tube. This ensures that the deflection occurring during the insertion into the borehole can be absorbed via the construction of the ring stack and a breakage of the ceramic elements is avoided.

In the embodiment with the tension rods 14 (s. FIG. 6 ), the annular discs preferably have at least three recesses / grooves 20 (s. FIG. 2 a) , which serve to accommodate the tension rods. If the contour of the inner diameter of the annular discs is formed as a polygon, the recesses can be omitted since the tension rods can be guided in the corners. These recesses 20 are offset from the distributed on the top elevations 8 are mounted in a preferred embodiment, six grooves 20 are introduced on the peripheral surface. The three elevations 8 on the top 16 are arranged so that they are located in each second space between two grooves 20. The recesses 20 are preferably formed rounded (s. FIG. 2 a) ,

In the embodiment with the clamping tube 15 (s. FIG. 7 ) No recesses / grooves are incorporated on the inner peripheral surface of the annular discs.

In the embodiment with the tension rods, the discs allow a very simple assembly by means of the grooves on the inner diameter of the annular discs. Since the wall thickness in the region of the grooves is reduced, however, it is possible in this variant, especially with small available Bohrlochfutterrohr- and delivery pipe diameters, to reduce the ring stability and thus to restrictions in use. On the other hand, in the clamping tube variant, the panes have an almost uniform wall thickness over the entire circumference and can thus be used under extreme geometric requirements.

In the embodiment with the clamping tube, there are on the underside 18 of the rings additionally at least three recesses 21, (s. FIG. 3 c) in which the elevations 8 of the opposite top of the next ring segment can be positioned. The number and the distance of the recesses depend on the number and distance of the elevations on the ring top. The recesses are used to prevent rotation of the rings and support the self-centering of the rings in the stack.

In the embodiment with the tension rods, these recesses are not necessary, since here the rotation takes place sufficiently over the tension rods. It can still be made recesses on the underside of the ring. Since these are associated with overhead in the production, they are preferably eliminated.

The depressions are preferably surfaces displaced parallel to the radius R (see FIG. FIG. 3 a) , In this way, point contact with the surveys is ensured, and the three-point support compensates for possible deviations in shape and dimensions. The depressions can also be formed in the form of spherical or cylindrical sections. Also a rounded trapezoidal shape or a wavy structure is possible.

The gap width 9 (s. FIG. 4 and 5 ) is selected depending on the sand fraction to be separated. At the outer diameter, the gap width is the smallest, in order to avoid clogging of the annular gap. The gap width is set by the height of the elevations on the top of the ring, the depth of the recesses on the underside of the ring (if present) and the shape of the underside of the ring, ie the radius of the concave surface. The selected gap geometry ensures that the flow processes in the gap are laminar and that the pressure loss between outer and inner diameter is low.

The separation device can be backwashed by liquid treatment media, possibly introduced particles in the separation gap can be rinsed free.

The brittle-hard material of the annular discs is preferably selected from oxidic and non-oxidic ceramic materials, mixed ceramics from these materials, ceramic materials with the addition of secondary phases, mixed materials with shares of ceramic hard materials and metallic binder phase, precipitation hardened cast materials, powder metallurgy materials with in-situ formed hard material phases and long and / or short fiber reinforced ceramic materials.

Examples of oxidic ceramic materials are Al ₂ O ₃ , ZrO ₂ , mullite, spinel and mixed oxides. Examples of non-oxidic ceramic materials are SiC, B ₄ C, TiB ₂ and Si ₃ N ₄ . Ceramic hard materials are, for example, carbides and borides. Examples of mixed materials with metallic binder phase are WC-Co, TiC-Fe and TiB ₂ -FeNiCr. Examples of in-situ formed hard material phases are chromium carbides. An example of fiber-reinforced ceramic materials is C-SiC.

The above-mentioned materials are characterized by being harder than the typically occurring rock particles, ie the HV or HRC hardness values of these materials are above the corresponding values of the surrounding rock. For the ceramic sand filter modules suitable materials have HV hardness values greater than 15 GPa, preferably greater than 23 GPa.

All of these materials are characterized by the fact that they have a greater brittleness than typical unhardened steel alloys. In this sense, these materials are referred to herein as "brittle hard".

In addition, all these materials have a very high deformation resistance, which is reflected in their modulus of elasticity. The high rigidity has a positive effect on the abrasion behavior of the materials. A peeling of material and a plastic deformation as in metals is not possible here.

The structure of the sand filter module is also positively influenced by the high resistance to deformation. The annular discs made of these materials need not be supported by webs on an inner tube in order to increase their stability in the stack and each other. They can be free-standing. As soon as they are braced axially, they form a very stable separating gap, which has a small tolerance width, which is only due to the manufacturing tolerance of the rings and not due to material deformability. Even with sudden loads they do not deform, the set separation gap width is retained.

In addition, a very stable, homogeneous filter cake of the incoming sand can form on the rigid ring elements.

For the ceramic sand filter modules suitable materials have elastic moduli greater than 200 GPa, preferably greater than 350 GPa.

Preferably, materials with a density of at least 90%, more preferably at least 95%, of the theoretical density are used in order to achieve the highest possible hardness values and high abrasion and corrosion resistance. The sintered silicon carbide (SSiC) or boron carbide is preferably used as the brittle-hard material. These materials are not only abrasion resistant, but also corrosion resistant to the treatment fluids commonly used for flushing the separator and stimulating the well, such as acids, e.g. HCl, lyes, e.g. NaOH, or water vapor.

Are particularly suitable, for example, SSiC materials with fine-grained microstructure (mean particle size <5 microns), as they are selling KG, for example, under the name EKasic ^® F and EKasic ^® F plus from ESK Ceramics GmbH & Co.. In addition, however, it is also possible to use coarse-grained SSiC materials, for example with a bimodal microstructure, with preferably 50 to 90% by volume of the particle size distribution consisting of prismatic, platelet-shaped SiC crystallites having a length of 100 to 1500 μm and 10 to 50% by volume. of prismatic, platelet-shaped SiC crystallites of a length of 5 to less than 100 microns (EKasic ^® C from ESK Ceramics GmbH & Co. KG).

The production of the annular disks is possible by means of powder metallurgy or ceramic processes in an automated mass production. The ring-shaped disks can be produced in the so-called net-shape process, in which the annular disks (including elevations) are pressed out of near-net shape powders. A complex mechanical processing of the annular discs is not required. The shape and dimensional deviations in the individual annular disks, which are sometimes unavoidable in a sintering process, can be tolerated in a design according to the invention of the separating device.

The ring discs made of brittle-hard materials are mounted together with the coupling elements as a ring stack of any height. The ring stack height and thus the sand filter module length is based on the hole diameter requirements, the resulting loads, the required bending and the load capacity of the metallic clamping structure. A preferred height of the ring stack or the filter length is 1000 mm.

coupling elements

The FIGS. 4 a - 4 c and 5a - 5 c show inventive ring stack 6 with the coupling elements 10 and 11. Die FIGS. 4 a - 4 c show the embodiment with the tension rods 14 (s. FIG. 6 ). The Figures 5 a - 5 c show the embodiment with the inner clamping tube 15 (s. FIG. 7 ). The FIGS. 4a and 5a are plan views of the upper coupling element 10. The Figures 4b, 4c . 5b and 5c are respectively cross-sectional views along each of the line BB in the FIGS. 4a and 5a or along each of the line AA in the FIGS. 4 a and 5 a.

The coupling elements in each case form the end-side, lateral terminations of the ring stack, via which the ring stack is coupled to the tensioning device. They are designed so that the clamping forces are transmitted evenly to the ring stack.

The coupling elements are preferably made of the same material as the rings. Alternatively, however, corrosion-resistant steels and plastics such as fluoroelastomers or PEEK (polyetherketone) can be used.

The upper surface of the upper coupling element 10, which is directed to the clamping device, preferably has a flat / flat surface. The surface directed toward the ring stack, that is to say the underside of the coupling element 10, is preferably designed with a radius, ie, like the ring elements, it is concave. The outer circumferential surface preferably has a circumferential groove 22 (FIG. FIGS. 4 and 5 ) for receiving a sealing ring (O-ring) 23 (in FIGS. 8 a and 9 a) and preferably a recess / marking groove 24 (FIG. FIGS. 4 and 5 ) for positioning the coupling elements in relation to the ring elements. The marking groove 24 is preferably rounded.

The lower surface of the lower coupling member 11, which faces the tensioning device, preferably has a flat surface. The surface directed toward the ring stack, that is to say the top side of the coupling element 11, has at least three elevations distributed uniformly over the circumference of the disks. The outer peripheral surface is preferably a circumferential groove 22 for receiving a sealing ring (O-ring) 23 (in FIGS. 8 a and 9 a) and preferably a recess / marking groove 24 for positioning the coupling elements in relation to the ring elements. The marking groove 24 is preferably rounded.

The inner diameter of the coupling elements corresponds to that of the ring elements. The outer diameter of the coupling elements is preferably equal to or greater than that of the annular discs (s. FIGS. 4 or 5). Due to the geometric conditions, however, it may be necessary constructively that the outer diameter fails slightly smaller than the outer diameter of the annular discs. However, this is only possible if the smallest wall thickness does not fall below 2 mm and the component and handling stability is not endangered.

In the embodiment according to FIG. 4 with the tension rods 14, at least three recesses / grooves 25 are preferably additionally provided on the inner peripheral surface of the coupling elements 10 and 11, which serve to receive the tension rods. These recesses are offset from the distributed on the top of the annular discs surveys attached. In a preferred embodiment, six grooves 25 are formed on the inner circumferential surface. The three elevations on the top are arranged so that they are located in each second space between two grooves. The recesses 25 are preferably formed rounded (s. FIG. 4 a) ,

In the embodiment according to FIG. 5 with the clamping tube 15 no recesses / grooves are incorporated on the inner circumferential surface.

The tolerances of the two coupling elements 10, 11 are selected to be narrower than those of the annular discs in order to optimally couple the brittle-hard components to the metallic components of the clamping device; In contrast to the as-sintered ring disks, the coupling elements must be machined.

In an alternative embodiment, the upper surface of the upper coupling element 10 and / or the lower surface of the lower coupling element 11 is not flat / flat but designed as a spring seat. In this way, the springs are directly absorbed and additionally protected against the fluid.

Clamping device for axial clamping of the ring stack

The annular discs are mounted together with the coupling elements as a ring stack of any height and fixed by means of the clamping device in itself.

The task of the tensioning device is to brace the axially stacked ring elements in itself and set the defined separation gap between the individual discs set. The width of the separating gap preferably has a value in the range of 0.05-1 mm, more preferably 0.05-0.5 mm.

The ring stack is fixed in the inventive sand filter module on the tensioning device only in itself, the sand filter module requires no additional mechanical support. For example, it is not fastened to an inner conveyor tube which carries the dead weight of the ring stack and the tensioning device and optionally further coupling elements, intermediate modules and / or the filter module tip. For this reason, the tensioning device must be able to absorb the tensile loads resulting from its own weight.

The clamping device preferably consists of an upper and lower clamping set and one or more clamping elements which connect the clamping sets and extend along the inner circumference of the ring stack. In the preferred embodiments, the clamping element can be used, for example, as a clamping tube 15 (FIG. FIG. 7 ) or by at least three evenly distributed tension rods 14 ( FIG. 6 ). The clamping set consists of clamping bush 26, compression springs 27 (both in FIG. 6 and 7 ) and clamping nuts 28 (in the embodiment with the tension rods, FIG. 6 ) and clamping ring 29 (in the embodiment with the tension tube, FIG. 7 ).

The clamping device allows a controlled and uniform force on the coupling elements and thus on the ring stack. This is achieved to a large extent by the at least three evenly distributed compression springs 27. In a preferred embodiment, there are six evenly distributed compression springs 27.

In addition, different thermal expansions of the various materials as well as annular disc heights that fluctuate due to manufacturing tolerances can be compensated by the compression springs 27. This achieves uniform load distribution over the lifetime. A uniform load distribution is important because otherwise there is an increased risk of breakage for the ceramic ring elements.

The compression springs are preferably selected from corrosion-resistant steel, coated steel or corrosion-resistant elastomer such as rubber or Viton.

The clamping elements are preferably made of steel, more preferably made of corrosion-resistant steel. Since the clamping elements in the inner space of the ring stack are made of brittle-hard material, they are protected by it from abrasion and thus ensures the tension within the sand filter module over its entire life.

In a preferred embodiment, the clamping element is designed as a clamping tube 15 (FIG. FIGS. 7 and 9 ), which must have through flow openings for the promotion of oil, water and gas mixtures or their individual components from deep wells. It may be a perforated or slotted tube or a cylindrical perforated plate. The shape, arrangement and number of flow openings is determined on the one hand by the required flow rate and on the other by the desired tensile and torsional strength of the clamping tube. In the preferred embodiment in FIG FIG. 9a the flow openings are formed as rounded slots 41. They are introduced into the clamping tube only in the area of the annular discs, from the coupling segments, the circumferential surface consists of solid material. On the upper and lower peripheral surface of the clamping tube 15 is preferably in each case an external thread 30 for attachment to the clamping ring.

As an alternative to a clamping tube with flow openings, a coarse-mesh sieve or a rigid wire mesh can be constructed and used as a tube.

The outer diameter of the clamping tube 15 is smaller than the inner diameter of the annular discs, so that a gap between clamping tube and ring stack is present. The ring-shaped discs must not rest on the tensioning tube, so that external loads such as bending are not transferred by load transfer from the metallic tensioning tube to the rings. To ensure this, spacers 31 (FIG. FIGS. 9b and 9c ) made of an elastic, compressible polymer material between clamping tube and ring stack. This may be a wound polymer tape, polymer rings or polymer strips. Preferably, at least 3 are each offset by 120 ° from each other, the entire length of the ring stack and the coupling elements covering the polymer strips used, whereby the washers are additionally centered on the clamping tube.

In a further preferred embodiment, a plurality of clamping elements in the form of tension rods 14 (FIG. FIGS. 6 and 8th ), evenly distributed over the inner circumference of the ring stack. The tension rods can be received in the recesses / grooves 20 of the annular discs and correspond in number to the number of recesses / grooves 20. Preferably, there are at least three tension rods, more preferably six tension rods. The number of tension rods is selected depending on the required tension on the ring stack and the capacity for resulting from its own weight tensile loads of the modules.

The tension rods 14 may be designed with a round or ellipsoidal cross-sectional area. To increase the material cross-section and thus the tensile and torsional strength of the tension rods are preferably used as profile bars 32 (FIG. Figures 8b and 8c ). The cross-sectional area of the profiled bars may, for example, correspond to that of a circle segment or, as in the preferred embodiment, in FIG FIGS. 8b or c a combination of ring and circle segments.

The tension rods can be provided with a powder coating to avoid direct contact of the steel material of the rods on the ceramic ring elements.

At the two ends of the tie rods the connection with the clamping nuts must be possible. In the illustrated preferred embodiment ( FIG. 8 a) Therefore, the profile cross section does not extend over the entire length of the clamping rods, but goes in the region of the clamping bushes in a round cross-sectional area 33 (FIGS. FIG. 8 a) above. Strictly speaking, the circular segment of the profile is extended in a round cross-sectional area. At the upper and lower end of the tension rods is in each case a thread 34 ( FIG. 8 a) for fastening the clamping nuts.

The clamping bush serves as a compression spring seat and has inner guides 35 (FIG. FIGS. 8 a, 8 c, 9 a) for receiving the compression springs, on the other hand it allows the tension on the clamping element / the clamping elements. The clamping device is sealed to the outside, ie between clamping tube and coupling element by means of O-rings (23 in FIG. 9 a) , The clamping bush is preferably made of steel, more preferably made of corrosion-resistant steel.

The clamping bushes are designed differently for the two preferred embodiments of the clamping elements. In the embodiment in which the clamping element is realized as a clamping tube, the clamping bush is cylindrical ( FIG. 9 a) , Passing the outer peripheral surface of the outer cage is guided past the inner circumferential surface passes over the clamping tube. On the surface facing the clamping ring is preferably a circumferential groove for receiving a sealing ring (O-ring, 36, FIG. 9 a) ,

In the embodiment with the tension rods, the clamping bush is cylindrical on the inner circumferential surface, outside three areas can be distinguished: an outer guide 37 (FIG. FIG. 8 a) for receiving the outer cage, a recess 38 ( FIG. 8 a) for receiving an O-ring and a thread 39 for attachment to the coupling element. In addition, in the clamping bushing in this embodiment through-holes 40 ( FIG. 8 c) introduced for the implementation of the tension rods. The holes are on the to the clamping nuts aligned side designed as round holes, on the aligned to the coupling elements side they have a profile that can accommodate the profile of the tension rods.

In the embodiment with clamping tube for clamping is preferably a clamping ring (29 in FIG. 9 a) used. This is cylindrical on the inner circumferential surface and has a recess with internal thread 42 for screwing to the clamping tube to the side of the ring stack. Outside, three areas can be distinguished: an outer guide 43 for receiving the outer cage, a recess 44 for receiving an O-ring and a thread 45 for attachment to the coupling element.

The clamping of the ring stack is parallel to the assembly.

About the screwing of upper clamping ring with clamping tube of the ring stack can be clamped defined. Since the clamping ring and clamping bushing are not connected, it is ensured that no load is transferred from the compression springs to the coupling elements during clamping and that they remain undamaged.

The fixation of the tie rods or of the tensioning tube is preferably done via clamping nuts or a clamping ring, as applied as a defined torque and length tolerances can be compensated. Alternative types of attachment to thread and locknut represent the combinations of groove and circlip and counterbore and grub screw. An attachment by welding, jamming or shrinking is possible.

In the embodiment with tie rods, the ring stack is braced more flexibly with the aid of the somewhat flexible tie rods in comparison to the embodiment with clamping tube. Although tensile and torsional strength are higher in the embodiment with tension tube, the profile cross section of the tension rods ensures sufficient tensile strength to support the dead load. The tie rods have sufficient strength to prevent large-scale twisting of the construction. However, smaller deformations are possible and allow the rings in the ring stack in the radial and tangential direction in to move to a certain degree. Thus, stress build-up in the ring stack can be more effectively reduced by bending than in the tension tube embodiment.

As an alternative to the described, preferred embodiments of the sand filter module, a further embodiment is conceivable, in particular for the embodiment with clamping tube, in which the clamping device and coupling element are provided on one side 46 (FIG. FIG. 7 ) or combined on both sides. In the combined execution of clamping device and coupling element, it is also possible to dispense with the clamping ring. In these cases, the separation of functions of the individual components is canceled, but the stress principle can be taken over as far as possible.

outer cage

The sand filter module according to the invention is preferably protected against damage during installation such as impact load or friction on the well casing and when starting the promotion by rapidly flowing rock particles by a freely permeable outer cage 5 ( FIG. 1 ).

This can for example be designed as a coarse mesh screen and preferably as a perforated plate. The material used is preferably steel, more preferably stainless steel. Alternatively, however, the use of fiber-reinforced polymer materials is conceivable, since here the load-bearing capacity and the resistance to torsional and bending moments can be adjusted according to requirements.

The outer cage is loosely clamped in the outer diameter of the clamping device, but can also be firmly connected to the stiffening of the separator against bending and torsional and tensile and compressive stresses with the jig. This fixation is possible for example by gluing, screwing, pinning or shrinking, preferably the outer cage is welded to the clamping device after assembly.

Coupling elements (for connecting the sand filter modules with other components of the conveying equipment)

The coupling elements 12, 13 ( FIGS. 6 and 7 ) are used to connect the strained ring stack / sand filter module with other components of the conveying equipment such as the filter module tip 2 and intermediate modules. The individual sand filter modules can be connected via the coupling elements and intermediate modules to filter systems of any length.

The coupling elements are preferably made of steel, more preferably made of corrosion-resistant steel.

They have an identical with the clamping device outer diameter and are cylindrical outside. Towards the intermediate module, they preferably show an outer conical wedge surface 47 (FIG. FIGS. 6 and 7 ). The inner peripheral surface can be divided into three areas: In the middle region, the coupling element is tubular and has a consistently thick wall thickness. To the clamping device towards the pipe is tapered and reduces the wall thickness. In this area there is a thread 48 ( FIGS. 6 and 7 ) for attachment to the tensioning device. At the outer end is a further recess 49 ( FIG. 7 ), which receives a sealing ring (O-ring) 50. At the side facing the intermediate module, in the preferred embodiment, the inner circumferential surface has an internal thread 51 (FIG. FIGS. 6 and 7 ). However, it is also conceivable that the thread is incorporated as an external thread in the outer peripheral surface.

For reasons of space, coupling elements which connect to a filter module tip 2 are generally designed to be shorter than those which receive intermediate modules. As an alternative to a version with an internal thread, here also an embodiment with internal cone 52 (FIG. FIGS. 6 . 7 and 10 ) and at least one circumferential groove 53, 54 (FIG. FIGS. 6 . 7 and 10 ) for receiving a sealing ring (O-ring) 55 ( FIGS. 6 . 7 and 10 ) or a snap ring 56 ( FIGS. 6 . 7 and 10 ) possible.

The length of the coupling elements; take the intermediate modules, is not critical and preferably rather to choose longer, since the coupling elements and intermediate modules must contribute depending on the chosen embodiment and thus rigidity of the tensioning device in addition to receiving external loads such as bending and resulting from its own weight tensile loads.

As an alternative to the described preferred embodiment of the sand filter module with two coupling elements, a further embodiment is conceivable, in particular in the tensioning device with tensioning tube, in which tensioning device and coupling element are combined with one another at the top and / or at the bottom end of the sand filter module (46 in FIG FIG. 7 ). In these cases, the separation of functions of the individual components is canceled, but the coupling principle can be largely taken over.

protective sheathing

The outer, conical wedge surface of the coupling elements and the intermediate modules are preferably provided by one or more protective sheaths 4 (FIG. FIG. 1 ) against wear caused by abrasion / erosion by sand and rock particles as well as by corrosion.

Preferably, the wear protection of the above-mentioned metallic areas by means of a plastic coating, for example by means of a shrink tube: However, it is also possible to achieve wear protection by (powder) coatings or coatings by cover mats or foils, which are fixed for example by means of mechanical clamps , or by molded parts.

In order to prevent damage to the protective coating during installation, suitable spacers can be attached, which can be realized as sliding nubs on the perforated plate, for example.

The materials for the plastic coating are preferably chosen from the group of polyolefins, preferably polyethylene, polypropylene and poly (iso) butylane, since these on the one hand have sufficient resistance to abrasion / erosion and corrosion and on the other hand can be applied as a shrink tube. Other possible materials for the plastic coatings or heat shrink tubing are PVDF, Viton, PVC and PTFE.

The wall thickness of the shrink tubing is less than 7 mm, typically in the range of 1 to 3 mm.

• Es lassen sich dichte, nicht permeable Überzüge realisieren, eine Funktionstrennung durch Beschichtung mit verschiedenen Schrumpfschlauchmaterialien ist möglich. So könnte beispielsweise außen ein Material mit hohem Erosionswiderstand und innen ein Material mit hohem Korrosionswiderstand aufgebracht werden.
• Die Verbindung mit den zu schützenden Bereichen ist formschlüssig. Förder- oder Reinigungsmedien können nicht unter den Überzug "kriechen". Eine zusätzliche Abdichtung des Überzuges ist nicht erforderlich.
• Beliebige Längen können durch (überlappendes) Aneinanderfügen von Schlauchsegmenten geschützt werden.
• Durchmesser- und Querschnittsübergänge, wie hier an den Klemmsätzen, können überwunden werden aufgrund der Schrumpfraten bis zu 3:1 (Durchmesseränderung).
• Die Lösung ist kostengünstig, da kommerziell verfügbare Schrumpfschläuche eingesetzt werden können.

The use of a shrink tube has the following advantages over other solutions:

• It can be dense, non-permeable coatings realize a function separation by coating with different shrink tubing is possible. For example, on the outside, a material with high erosion resistance and, on the inside, a material with high corrosion resistance could be applied.
• The connection with the areas to be protected is positive. Conveyor or cleaning media can not "crawl" under the cover. An additional sealing of the coating is not required.
• Any length can be protected by (overlapping) joining of tube segments.
• Diameter and cross-sectional transitions, as here on the clamping sets, can be overcome due to the shrinkage rates up to 3: 1 (change in diameter).
• The solution is inexpensive because commercially available heat shrink tubing can be used.

Filter module tip with increased abrasion protection

The last sand filter module directed towards the lower end of the borehole must be lockable. This is done in practice by filter module tips 2 (so-called bull plugs) ( FIG. 1 ) realized. They are intended to ensure that the extraction of oil, water and gas mixtures or their individual components from the deep well always via the filter modules runs and the existing sand in the borehole is retained on the filter module. In addition, however, it is necessary that the filter module tip can be reopened or disconnected if necessary. This is possible, for example, via the blowing off of the filter module tip. Often lances are also used, which are introduced through the interior of the sand filter modules and push out the filter module tip with great force.

Filter module tips are preferably designed with a shock-elastic material. The prior art often uses metallic materials. But are also particularly suitable polymer materials, preferably highly elastic polymer materials, which allow an effective reduction of shock loads. Due to their high elasticity and the associated low hardness, all these materials are exposed to a strong abrasive erosion by sand or rock particles.

The use of the abrasion resistant and therefore durable sand filter modules according to the invention would be terminated by this abrasive damage or destruction of the filter module tip. Therefore, filter module tips with increased abrasion protection are preferably used in combination with ceramic sand filter modules. This can, for example, via the insertion of a wear protection plate 57 ( FIG. 10 ) can be realized in the filter module tip. The wear protection plate is made of a brittle-hard material, preferably made of the same material as the rings. After abrasion of the soft tip in the conveying operation, the wear protection plate prevents further abrasive abrasion by sand or rock particles.

Alternatively to the use of a wear protection plate, the filter module tip can also be manufactured with a wear protection core made of brittle-hard material. In this case, however, the tip must be provided with a preferably polymeric protective layer for cushioning impacts during drilling downhole.

A preferred embodiment of the filter module tip 2 with increased abrasion protection is in FIG. 10 described. It is designed as a solid material and consists essentially of two areas. In the rear, the sand filter module facing area, it has the shape a cylinder; in the front it runs to a point. In the transition of the two areas, a circumferential groove 58 for receiving a snap ring 56 is formed.

The filter module tip is pressed into the coupling element via this snap ring. Alternatively, the attachment to the coupling element can also be realized via a snap connection or via shrinking.

The wear protection plate 57 is preferably not completely cylindrical in the embodiment suitable for ceramics, but tapering towards the filter module tip. So it can be fixed via a cone / cone connection 52 in the coupling element. To increase the stability of the attachment, a sealing ring 55 can run between the wear protection plate and the groove 53 of the coupling element. In addition, there is a spacer ring 59 between the wear plate and the clamping elements, which prevents the wear plate can bounce against the clamping device in shock loads. This construction allows not only a simple assembly and the ejection of the tip by pressure surge or lance. About the size of the cone angle, the extrusion force can be varied.

Alternatively, the wear protection plate can also be fixed with a shape-cut through explosive or O-ring.

In a further embodiment, filter module tip and coupling elements can also be combined.

Multi-layer filter construction

In prior art metallic filter fabrics, multi-ply filter fabrics are common and necessary for protecting the fine filter. The multi-layer fabric arrangement increases the flow resistance. Multi-ply fabrics also tend to become clogged by the deposition of sands in the cavities, and thus to further increased flow resistance.

Due to the good abrasion resistance and the high resistance to deformation of the brittle ring stack, the ceramic sand filter modules according to the invention can be designed in one layer and be charged directly with the flow.

In order to improve the separation rates in the production of oil and gas and for specific filtering tasks in other areas, such as ultrafine filtration, but also a construction can be selected as a multi-layer filter.

For example, in the embodiment with tensioning tube, a second filter element can be introduced between the tensioning tube and the ring stack. This secondary filter can be designed according to the prior art as a wire mesh, wire winding, slot filter, filter sand packing or for Feinstfilterung as a filter fabric. A variant with an inner second ring stack made of brittle-hard materials can also be integrated into the construction.

In the embodiment with clamping tube, the clamping tube itself can assume a secondary filter function with a corresponding design, for example, slotted tube or wire mesh.

Examples

The following example serves to further explain the invention.

Example 1: Resistance to erosion

75 x 75 x 15 mm) of steel, a porous, sintered silicon carbide ceramic and fine-grained, densely sintered silicon carbide ceramic (SSiC) of the type EKasic® F (ESK Ceramics GmbH & Co.) Were used to determine the erosive wear KG) subjected to a sandblast test. The steel sample served as a reference.

The experiments were carried out by means of a sandblasting machine. The blasting media used were four different proppants typically used in offshore drilling: (1) 100 mesh frac sand, (2) 16/20 mesh frac sand, (3) 20/40 mesh frac sand, (4) 20/40 Mesh Frac Sand High Strength. The jet pressure was 2 bar and the jet duration 2 hours, the jet was quasi point-like applied at an angle of 90 ° to the surface. Depth and the width of the jet impression characterize the erosive wear (see Table 1).

The experiments show that the dense-sintered silicon carbide ceramic is significantly more resistant to erosive wear than the porous, sintered silicon carbide ceramic and conventional steels. While the porous, sintered silicon carbide plates showed a hole after only 5 seconds, EKASIC® F shows no measurable or even negligible erosive wear even after two hours. <u> Table 1: </ u> Results of sandblast tests example material blasting agent Depth [mm] Width [mm] 1.1 EKasic® F (SSiC) 1 0.1 14 1.2 EKasic® F (SSiC) 2 not measurable 12 1.3 EKasic® F (SSiC) 3 not measurable 12 1.4 EKasic® F (SSiC) 4 0.2 8th 1.5 Porous SiC 1 10 19 1.6 Porous SiC 2 10 16 1.7 Porous SiC 3 10 19 1.8 Porous SiC 4 10 15 1.9 Steel (reference) 1 5.3 17 1.10 Steel (reference) 2 0.8 18 1.11 Steel (reference) 3 5.3 18 1.12 Steel (reference) 4 4.4 19

LIST OF REFERENCE NUMBERS

1

Sand filter module

2

Filter module tip

3

intermediate module

4

protective sheathing

5

outer cage

6

ring stack

7

annular disc

8th

surveys

9

separating gap

10

coupling element

11

coupling element

12

coupling member

13

coupling member

14

tie rod

15

clamping tube

16

Top of the disc 7

17

Recess / marking groove

18

Bottom of the disc 7

19

Outer contour with bevel of the disc 7

20

Recesses / grooves of the inner circumferential surface

21

Depressions on underside 18

22

circumferential groove of the coupling elements 10, 11th

23

Sealing ring (O-ring)

24

Recess / marking groove

25

Recesses / grooves

26

clamping bush

27

compression springs

28

clamping nuts

29

clamping ring

30

external thread

31

spacer

32

profile bars

33

round cross-sectional area

34

thread

35

interior guides

36

O-ring

37

outer leadership

38

deepening

39

thread

40

Through holes

41

rounded slots

42

inner thread

43

outer leadership

44

deepening

45

thread

46

combined with clamping device coupling element

47

conical wedge surface

48

thread

49

deepening

50

Seal / O-ring

51

inner thread

52

inner cone

53

circumferential groove

54

circumferential groove

55

Seal / O-ring

56

snap ring

57

Wear protective plate

58

circumferential groove

59

spacer ring

Claims (27)

1. Separating device for removing sand and rock particles which is suitable as an integral component part of extraction equipment for the extraction of liquids or gases from deep wells, the separating device comprising at least one ceramic filter module (1), the filter module (1) comprising

   a) an annular stack (6) of brittle-hard annular discs (7), the upper side (16) of which has at least three elevations (8) uniformly distributed over the circular circumference of the discs, the discs (7) being stacked and braced in such a way that a separating gap (9) for the removal of sand and rock particles is present in each case between the individual discs (7),

   b) a coupling-on element (10) at the upper end and a coupling-on element (11) at the lower end of the annular stack (6),

   c) a clamping device (14, 15) for the axial bracing of the annular stack (6),

   d) an outer cage (5) for the mechanical protection of the filter module (1),

   e) a coupling element (12) at the upper end and a coupling element (13) at the lower end of the filter module (1) for connecting the filter module (1) to further components of the extraction equipment.
2. Separating device according to Claim 1, the discs (7) being stacked and braced in the annular stack (6) in such a way that they are movable with respect to one another in the radial and tangential directions.
3. Separating device according to Claim 1 or 2, the clamping device comprising clamping rods (14) arranged within the annular stack (6).
4. Separating device according to Claim 1 or 2, the clamping device comprising a clamping tube (15) arranged within the annular stack (6).
5. Separating device according to at least one of the preceding claims, said device also comprising one or more protective enclosures (4).
6. Separating device according to at least one of the preceding claims, said device also comprising at the lower end a filter module tip (2) with increased abrasion protection.
7. Separating device according to at least one of the preceding claims, the elevations (8) on the upper side (16) of the discs (7) being given the form of spherical portions.
8. Separating device according to at least one of Claims 1 to 3 and 5 to 7, the annular discs (7) having on their inner circumferential surface at least three clearances (20), which serve for receiving the clamping rods (14).
9. Separating device according to at least one of the preceding claims, the annular discs (7) having on their underside (18) at least three depressions (21), in which the elevations (8) can be positioned.
10. Separating device according to at least one of the preceding claims, the upper side (16) of the annular discs (7) being formed at a right angle to the disc axis.
11. Separating device according to at least one of the preceding claims, the underside (18) of the annular discs (7) being formed sloping down outwards or inwards, preferably sloping down inwards, more preferably formed concavely.
12. Separating device according to at least one of the preceding claims, the radial wall thickness of the annular discs (7) being at least 2 mm, preferably at least 5 mm.
13. Separating device according to at least one of the preceding claims, the thickness of the annular discs (7) being 1 to 20 mm, preferably 1 to 10 mm.
14. Separating device according to at least one of the preceding claims, the separating gap (9) between the individual discs (7) having a height of 0.05-1 mm, preferably 0.05-0.5 mm.
15. Separating device according to at least one of the preceding claims, the brittle-hard material of the annular discs (7) being chosen from oxidic and non-oxidic ceramic materials, mixed ceramics of these materials, ceramic materials with the addition of secondary phases, mixed materials with fractions of ceramic hard materials and with a metallic binding phase, precipitation-hardened casting materials, powder-metallurgical materials with hard material phases formed in situ and long- and/or short-fibre-reinforced ceramic materials.
16. Separating device according to at least one of the preceding claims, the brittle-hard materials of the annular discs (7) having HV hardness values ≥ 15 GPa, preferably ≥ 23 GPa.
17. Separating device according to at least one of the preceding claims, the brittle-hard materials of the annular discs (7) having moduli of elasticity ≥ 200 GPa, preferably ≥ 350 GPa.
18. Separating device according to at least one of the preceding claims, the brittle-hard materials having a density of at least 90%, preferably at least 95%, of the theoretical density.
19. Separating device according to at least one of the preceding claims, the brittle-hard material being sintered silicon carbide (SSiC) or boron carbide.
20. Separating device according to at least one of the preceding claims, the coupling-on elements (10, 11) having on their outer circumferential surface at least one peripheral groove (22) for receiving a sealing ring (23).
21. Separating device according to at least one of the preceding claims, the outside diameter of the coupling-on elements (10, 11) being equal to or greater than that of the annular discs (7).
22. Separating device according to at least one of the preceding claims, the coupling-on elements (10, 11) being produced from the same brittle-hard material as the annular discs (7).
23. Separating device according to at least one of the preceding claims, the clamping device (14, 15) also comprising a clamping set, comprising a clamping bush (36), compression springs (27) and clamping nuts (28) for the clamping rods (14) or clamping rings (29) for the clamping tube (15).
24. Separating device according to at least one of the preceding claims, the clamping rods (14) or the clamping tube (15) being produced from steel, preferably corrosion-resistant steel.
25. Separating device according to at least one of the preceding claims, the coupling elements being produced from steel, preferably from corrosion-resistant steel.
26. Separating device according to at least one of the preceding claims, the outer cage being formed as a coarse-meshed screen or as a perforated plate and preferably being produced from steel, more preferably from corrosion-resistant steel.
27. Use of a separating device according to at least one of the preceding claims for removing sand and rock particles in a process for extracting liquids or gases from wells drilled in rock or deep wells.

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