RU2373364C2 - Stator of screw gerotor machine - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: invention is related to hydraulic drives for rotary drilling arranged in well. Stator comprises external pipe with internal surface made in the form of helicoid with internal screw teeth, elastomer facing fixed in external pipe and adjacent to internal surface of external pipe. Facing is made with internal screw teeth and matches in shape with internal screw teeth in external pipe, and facing thickness is maximum at teeth that are radially directed inside. In external pipe maximum thickness of facing along cavities of its internal screw surface arranged at maximum radial distance is equal to half of height of its internal screw teeth, at the same time minimum thickness of external pipe wall along cavities of its internal screw surface radially directed outside is equal to height of internal screw teeth in facing.

EFFECT: increased reliability and resource, and also provision of maximum power, force torque at output shaft in mode of maximum power and permissible axial load.

4 cl, 3 dwg

Description

The invention relates to hydraulic drives for rotary drilling, placed in the well, in particular to screw gerotor hydraulic motors for drilling oil and gas wells or to screw pumps for oil production from wells.

A known hydraulic screw mechanism used as a pump or motor, comprising a stator housing and a rotor, the rotor having an external helical surface, and the stator housing is made in the form of a monolithic rigid tubular element having a cylindrical outer surface and an inner surface also having helical teeth, and the aforementioned mechanism comprises a flexible layer made of an elastomer having a uniform thickness on the inner surface of the housing [1].

In the known hydraulic mechanism, a flexible layer made of an elastomer having a uniform, essentially the same thickness on the inner surface of the housing is subjected to deformation and bending during planetary-rotor rotation of the rotor inside the stator, which leads to the formation of zones on the protrusions and depressions of the teeth that differ from each other by the values of contact pressure, shear strength, hardness (elasticity) and thermal conductivity.

The temperature in the elastomeric casing can increase, for example, to 60 ° C, and the increase in interference in the working pair can be, for example, up to 0.05 mm per diameter for every 10 ° C of temperature increase.

A disadvantage of the known design is the incomplete use of the possibility of increasing the reliability and service life of the screw hydraulic mechanism when it is used in a downhole screw motor, as well as increasing the maximum power, the torque on the output shaft in the maximum power mode and the fatigue endurance (resource) of the elastomer plate - not less than 100 thousand cycles.

The disadvantages of the known design are explained by the incomplete possibility of optimizing the thickness of the lining of elastomer along the protrusions and depressions of the helical teeth.

This leads to a deterioration in the removal of internal heat from the lining from the elastomer through the walls of the housing to the drilling fluid of the annulus, to the formation in the centers of the profile of the elastomeric lining of the zones of destruction of the material from the influence of the temperature gradient, to an increase in the tension in the working pair.

As a result, the center of the profile becomes less flexible (brittle and brittle), the mechanical properties of the elastomer, for example rubber, in these areas are significantly deteriorated, while the pressure acting in the chambers between the rotor and the stator can exceed the shear strength of the elastomer, and the tops of the teeth in the lining are deformed or torn off the body.

A known stator of a screw gerotor hydraulic pump or motor, comprising a housing with an inner surface made with internal helical teeth, a male and female elastomer covers fixed to the housing, the male shell being made with internal helical teeth designed to accommodate a rotor having an outer surface with with helical teeth, the female lining is fastened to the male lining and to the inner surface of the housing, and the number of rotor teeth per unit it bigger number of teeth housing [2].

In one embodiment, on the inner surface of the stator profile, the elastomer lining has an almost uniform thickness.

The known hydraulic mechanism contains a flexible layer made of an elastomer having a uniform, substantially the same thickness on the inner surface of the housing, which leads to the formation of zones on the protrusions and depressions of the teeth of the teeth that differ from each other in terms of contact pressure, shear strength, hardness (elasticity) and thermal conductivity, which are subjected to deformation and bending during planetary-rotor rotation of the rotor inside the stator.

The disadvantages of the known design are explained by the incomplete possibility of optimizing the thickness of the plate of elastomer along the troughs of its internal helical surface located at the maximum radial distance, as well as along the protrusions and troughs of the helical teeth.

This leads to a deterioration in the removal of internal heat from the lining from the elastomer through the walls of the housing to the drilling fluid of the annulus, to the formation in the centers of the profile of the elastomeric lining of the zones of destruction of the material from the influence of the temperature gradient, to an increase in the tension in the working pair.

As a result, the center of the profile becomes less flexible (brittle and brittle), the mechanical properties of rubber or elastomer in these areas significantly deteriorate, while the pressure acting in the chambers between the rotor and the stator can exceed the shear strength of the elastomer, and the tooth tips in the lining are deformed or come off the case.

A disadvantage of the known design is also the low strength of the stator housing, as well as the loss of its stability mainly with axial load on the bit and impact from jars in the curved string of drill pipes in directional wells, for example, when passing through the radius sections of the wellbore during horizontal drilling, which is explained by the fact that it is made composite: from the body - a smooth pipe, covered and covering plates of elastomer, made in the form of a helicoid.

An elastomeric male lining (of constant thickness) is made of a material, for example, Ultra-Flex 114, and an additional female lining with an internal surface in the form of a helicoid, essentially with internal helical multiple teeth, is made of a harder and stronger material.

Moreover, the known stator when used in a screw hydraulic motor does not provide significant advantages, for example, the maximum rate of set of curvature (when drilling a directional well), due to the destruction of the body, for example, when passing through the radius sections of the wellbore during horizontal drilling using drill string pipes of hydraulic and (or) hydromechanical jar, with rotation (from the rotor of the drill) of a curved string of drill pipes (20 ... 40 rpm), with shock loads and impact E pulses of hydraulic jar, as well as due to relaxation of the tensile stress at a bent drill string, wherein the motor stator is mounted.

The disadvantages of the known stator for the motor are also explained by the cyclic loading of helical teeth made, for example, of elastomers of different shear strength, hardness and thermal conductivity, which undergo deformation and bending during planetary-rotor rotation of the rotor inside the stator, which leads to heat generation inside the tooth material, violation interference in the working pair, delamination of the elastomeric lining from the body, as well as to delamination between the elastomeric lining due to the deterioration of internal heat removal from the elastomeric ernoy electrode through the layer of material through the body wall to the annulus drilling fluid.

In this case, the temperature in the elastomeric casing can increase, for example, to 85 ° C, and the increase in interference in the working pair can be, for example, up to 0.08 mm per diameter for every 10 ° C of temperature increase, which leads to non-calculated operating modes, not provides maximum power, torque on the output shaft in maximum power mode and permissible axial load with increasing maximum pressure drop (inter-turn, on the stator teeth) in maximum power mode.

Closest to the claimed design is a stator for a hydraulic downhole motor, forming an outer pipe with an inner surface made of at least two internal helical teeth (or blades), a lining, for example, made of elastomer, adjacent to the inner surface of the outer pipe, while the lining is made with internal helical teeth (or blades), coincides in shape with the internal helical teeth (or blades) in the outer pipe, and the thickness of the lining is max imal on the teeth (or lobes) radially directed inward (at least two) [3].

A disadvantage of the known design is the incomplete use of the possibility of increasing the reliability and service life of a downhole screw motor, maximum power, torque on the output shaft in the maximum power mode and fatigue endurance (resource) of the elastomeric lining - at least 100 thousand cycles.

Since the elastomer is characterized by high insulating properties, it delays the transfer of heat to a greater extent along the protrusions of the helical teeth compared to the depressions of these helical teeth.

The temperature in the lining of the elastomer can increase, for example, to 85 ° C, and the increase in interference in the working pair can be, for example, up to 0.08 mm per diameter for every 10 ° C of temperature increase, which leads to off-design operating modes, does not provide maximum power, torque on the output shaft in maximum power mode and permissible axial load with increasing maximum pressure drop (inter-turn, on the stator teeth) in maximum power mode.

The disadvantages of the known stator for a screw gerotor hydraulic machine are explained by the incomplete use of the possibility of optimizing the thickness of the lining along the hollows of the inner screw surface and the minimum wall thickness of the outer pipe with respect to the height of the teeth in the lining, and are also explained by the formation of zones on the protrusions and hollows of the teeth that differ in contact pressure, shear strength, hardness (elasticity) and thermal conductivity, which are subjected to deformation and bending during planetary rotary rotation and the rotor inside the stator, which leads to an increased temperature gradient when heat is generated inside the tooth material and violation of the interference fit in the working pair, to a deterioration in the removal of internal heat from the elastomeric sheath through the walls of the outer pipe to the drilling fluid from the outside of the outer pipe (annulus), flow which is directed from the bottom (from the bit) to the wellhead.

Due to the heat generated in the tooth centers, secondary polymerization occurs: molecular crosslinking of the elastomer (rubber), which leads to the destruction of the material.

As a result, the center of the profile of the elastomeric lining becomes inflexible (brittle and brittle), the mechanical properties of rubber or elastomer in these areas significantly deteriorate, while the pressure acting in the chambers between the rotor and the stator can exceed the shear strength of the elastomer, and the stator vertices are deformed or tear off from the stator.

The technical result of the invention is to increase reliability and resource, as well as providing maximum power, torque on the output shaft in the maximum power mode and permissible axial load by reducing the temperature gradient when heat is generated inside the tooth material, improving the removal of internal heat from the elastomeric lining through the outer walls pipes to the drilling fluid of the annulus, ensuring uniform contact pressure and increasing the fatigue endurance of the elastomeric lining , as well as ensuring maximum pressure drop (inter-turn, on the stator teeth) in maximum power mode.

The essence of the technical solution lies in the fact that in the stator of a screw gerotor hydraulic machine containing an outer tube with an inner surface made in the form of a helicoid, essentially with internal helical teeth, a lining, for example, made of elastomer, adjacent to the inner surface of the outer tube is fixed while the lining is made with internal helical teeth and coincides in shape with the internal helical teeth in the outer pipe, and the thickness of the lining is maximum on the teeth, radially directed According to the invention, in the outer pipe, the maximum thickness of the lining, for example, from an elastomer along the valleys of its internal helical surface located at the maximum radial distance, is equal to half the height of its internal helical teeth, while the minimum wall thickness of the outer tube is along its radially outward the internal helical surface is equal to the height of the internal helical teeth in the lining, for example, of elastomer.

The thickness Δ _{height of the} lining, for example, of rubber along the teeth radially directed inward and the thickness Δ _vp along the troughs of its inner helical surface located at the maximum radial distance, are related by the ratio: Δ _height = (0.85 ... 1.15) · Ф · Δ _cp , where f is a constant equal to 1.618 ...

ΔR _armature wall thickness of the outer tube along the radially inwardly directed teeth at its inner surface a screw and a wall thickness of ΔR _ch outer tube disposed along the maximum radial depressions removing its internal helical surface are related by: ΔR = _armature (0.85 ... 1.15) · F · ΔR _ch, where P - constant equal to 1,618 ...

The hardness of the lining with internal helical teeth made of rubber is 75 ± 3 units. Shore A.

In the claimed design, due to the fact that in the outer pipe the maximum thickness of the lining, for example, from an elastomer along the hollows of its internal helical surface located at maximum radial distance, is equal to half the height of its internal helical teeth, while the minimum wall thickness of the outer pipe is along radially directed outward depressions of its internal helical surface is equal to the height of the internal helical teeth in the lining, for example, of elastomer, zones of identical shear strength, hardness and eploprovodnosti ensured reduction of the temperature gradient during heat generation inside the tooth material is improved removal of internal heat from the elastomeric sheath through the outer wall of the pipe to the drilling fluid from the outside of the outer tube (annular space), the flow of which is directed from the bottom (from the bit) to the wellhead.

At the same time, reliability and service life are increased, as well as maximum power, moment of force on the output shaft in maximum power mode and permissible axial load due to increased fatigue endurance of the elastomeric casing and ensuring maximum pressure drop (inter-turn, on the stator teeth) at maximum power are increased.

The reliability of the inventive stator for a screw gerotor hydraulic motor is ensured by less stressful conditions of operation of the elastomeric casing: if there is a necessary interference between the rotor and the elastomeric casing of the outer pipe, the contact pressure is 2.5 ... 3 MPa, the sliding speed is 0.5 ... 2 , 5 m / s, while the hydrostatic pressure can reach 50 MPa, and the moment of force on the output shaft in the maximum power mode can reach 30 kN · m.

Due to the fact that the thickness Δ _{height of the} lining, for example, from rubber along the teeth radially directed inward and the thickness Δ _vp along the troughs of its internal helical surface located at the maximum radial distance, are related by the ratio: Δ _height = (0.85 ... 1.15) · Ф · Δ _vp , where Ф is a constant equal to 1.618 ... (Fibonacci number), the "golden ratio" and (or) the "golden ratio" are provided, for example, the values of contact pressure, shear strength, hardness (elasticity) and thermal conductivity in the lining from elastomer, which reduces the temperature gradient when heat, inside the tooth material, maintains interference in the working pair, improves the removal of internal heat from the elastomeric lining through the walls of the outer pipe to the drilling fluid from the outside of the outer pipe (annulus), the flow of which is directed from the bottom (from the bit) to the wellhead.

This provides the opportunity to increase energy characteristics, reliability and life using the inventive stator, essentially increasing the maximum power, the torque on the output shaft in the maximum power mode and the permissible axial load by increasing the maximum pressure drop (inter-turn, on the stator teeth) in maximum power, as well as increasing the fatigue endurance of the elastomeric lining.

Due to the fact that the wall thickness ΔR _armature outer tube along the radially inwardly directed teeth at its inner surface a screw and a wall thickness of ΔR _ch outer tube disposed along the maximum radial depressions removing its internal helical surface are related by: ΔR = _armature (0.85 ... 1 15) · F · dr _ch, where P - constant equal to 1.618 ... (Fibonacci number), provides significant advantages:

- the strength of the outer pipe in the maximum set of curvature when passing through the radius sections of the wellbore during horizontal drilling;

- when using a hydraulic and (or) hydromechanical jar in a drill pipe string with rotation (from the drill rotor) of a curved drill pipe string (20 ... 40 rpm);

- during shock loads and shock pulses from a hydraulic and (or) hydromechanical jar and relaxation of tensile stresses in a curved drill pipe string in which a stator for the engine is installed.

Due to the fact that the hardness of the lining with internal helical teeth made of rubber is 75 ± 3 units. Shore A, provides increased fatigue endurance (resource) - at least 150 thousand cycles, increased durability: abrasive and in the environment of petroleum products, as well as high elasticity, elasticity and reliability of sealing of the working pair of the rotor-lining of the stator in maximum power mode.

When using the inventive design increases the resource of the working pair of the rotor-stator by 30 ... 50%, and the mechanical speed by 30 ... 40% more. Due to the increase in resource and mechanical speed, the penetration of the rotor-stator working pair increases by 0.9 ... 1.2 times.

Below is the best embodiment of a stator design for a downhole motor for drilling oil wells.

Figure 1 shows a longitudinal section of the stator of a helical downhole motor.

In Fig.2 shows a section aa in Fig.1 across the stator and rotor of the downhole motor, option 1, the ratio of the number of teeth of the rotor lining is 5/6.

In Fig.3 shows a section aa in Fig.1 across the stator and rotor of the downhole motor, option 2, the ratio of the number of teeth of the rotor lining is 6/7.

The stator of a screw gerotor hydraulic machine, for example, a downhole motor for rotating the rotor from the pump fluid supply (drilling fluid), contains an outer pipe 1 with an inner surface 2 made in the form of a helicoid, essentially with internal helical teeth 3, fixed in the outer tube 1 lining 4 of an elastomer adjacent to the inner surface 2 of the outer tube 1, the liner 4 is provided with internal helical teeth 5 and coincides in form with internal helical teeth 3 in the outer tube 1 and the thickness 6, Δ _height of LadKom 4 is maximum at the teeth 5, a radially inwardly directed, as compared with the thickness 7, Δ _sn depressions 8 along the inner surface of the helical electrode 4, shown in Figures 1, 2, 3.

The stator is designed for a downhole screw motor, where pos. 9 is the rotor, pos. 10 is the central axis of the rotor 9, pos. 11 is the central axis of the outer pipe 1, pos. 12 is the magnitude of the eccentricity of the rotor 9 installed in the lining 4, for example, rubber bonded to the inner surface 2 of the outer pipe 1, and each of the end parts 13, 14 of the outer pipe 1 is made with an internal tapered thread 15, 16, shown in figures 1, 2, 3.

In the outer pipe 1, the maximum thickness 7, Δ _{vp of the} plate 4 of rubber along the depressions 8 of its inner helical surface located at a maximum radial distance of 17 is equal to half the height 18 of its inner helical teeth 5, while the minimum wall thickness 19 of the outer pipe 1 is radially along outwardly directed troughs 21 of its internal helical surface is equal to the height 18 of the internal helical teeth 5 in the lining 4, shown in figures 1, 2, 3.

The thickness 6, Δ _{height of the} lining 4 of rubber along the teeth 5 radially directed inward and the thickness 7, Δ _vp along the depressions 8 of its inner helical surface located at a maximum radial distance of 17, are related by the ratio:

Δ _height = (0.85 ... 1.15) · Ф · Δ _vp , where Ф is a constant equal to 1.618 ... shown in Fig.2, 3.

Wall thickness 20, ΔR _armature outer tube 1 along the radially inwardly directed teeth 3 on its internal helical surface and the wall thickness 19, ΔR _ch outer tube 1 along disposed at a maximum radial removing troughs 21 of its internal helical surface are related by: ΔR _cor = (0 85 ... 1.15) · F · ΔR _ch, where P - constant equal to 1.618 ..., 2, 3.

The hardness of the lining 4 with internal helical teeth 5, made of rubber, is 75 ± 3 units. Shore A.

In addition, figure 2, 3 shows: pos.22 - multi-helical chambers between the teeth 23 of the rotor 9 and the teeth 5 of the elastomeric lining 4; figure 1 shows: POS.24 - the direction of flow of the fluid (drilling fluid); figure 3: pos.25 - the height of the internal helical teeth 3 in the outer tube 1.

The design of the stator when it is used in a downhole screw motor works as follows: the mud flow 24 under pressure, for example, 25 ... 30 MPa in maximum power mode, is supplied through the drill pipe string to multi-helical chambers 22 between the teeth 23 of the rotor 9 and the teeth 5 of the elastomeric lining 4 and forms a region of high pressure and a moment from hydraulic forces, which leads to planetary-rotor rotation of the rotor 9 inside the lining 4, fixed in the outer tube 1.

Helical teeth 5 of the elastomeric plate 4, mounted in the outer tube 1, undergo complex deformation and bending during planetary-rotor rotation of the rotor 9 inside the stator.

The screw chambers 22 between the teeth 23 of the rotor 9 and the teeth 5 of the elastomeric plate 4 have a variable volume and periodically move along the mud stream 24, which has a density of up to 1500 kg / m ³ , contains up to 2% sand and up to 5% oil products.

Due to the fact that in the outer pipe 1, the maximum thickness 7, Δ _{vp of the} lining 4 of rubber along the depressions 8 of its inner helical surface located at a maximum radial distance 17 is equal to half the height 18 of its inner helical teeth 5, essentially equal to the eccentricity 12 of the central the longitudinal axis 10 of the rotor 9 relative to the Central longitudinal axis 11 of the plate 4 and the outer tube 1 of the stator, the minimum thickness 19 of the wall of the outer tube 1 along the radially outward troughs 21 of its inner screw surface is equal to e 18 internal helical teeth 5 in the lining 4, zones of identical shear strength, hardness and heat conductivity are provided, a temperature gradient is reduced when heat is generated inside the tooth material 5, internal heat is removed from the elastomeric lining 4 through the walls of the outer pipe 1 to the drilling fluid with the outer side of the outer pipe 1 (annulus), the flow of which is directed from the bottom (from the bit) to the wellhead.

In this case, the lining 4, made, for example, of rubber ИРП-1226-5, operates under less stressful conditions: if the working pair (rotor 9 - lining 4) has the necessary interference, the contact pressure is 2.5 ... 3 MPa, sliding speed 0 , 5 ... 2.5 m / s, while the hydrostatic pressure can reach, for example, 50 MPa, and the torque on the output shaft in maximum power mode can reach, for example, 30 kN · m.

Due to the fact that the thickness 6, Δ _{height of the} plate 4 made of rubber along the teeth 5 radially inwardly directed and the thickness 7, Δ _{vp of the} plate 4 along the depressions 8 of its inner screw surface located at the maximum radial distance 17 are related by the ratio:

Δ _height = (0.85 ... 1.15) · Ф · Δ _VP , where Ф is a constant equal to 1.618 ... (where Ф is the Fibonacci number), a "golden ratio" and (or) a "golden ratio" is provided, for example, the values of contact pressure, shear strength, hardness (elasticity) and thermal conductivity in the lining 4, which leads to a decrease in the temperature gradient when heat is generated inside the tooth material 5 and the tightness in the working pair is preserved rotor 9 - lining 4, to improve the removal of internal heat from the lining 4 through the walls of the outer pipe 1 to the drilling fluid annulus, the flow of which apravlen from the bottom (from the bit) to the wellhead.

Due to the fact that the thickness 20, ΔR _armature wall of the outer tube 1 along the radially inwardly directed teeth 3 on its inner surface and the thickness of the screw 19, ΔR _ch outer pipe wall 1 along disposed at a maximum radial removing troughs 21 of its internal helical surface are related by:

_Korean dr = (0.85 ... 1.15) · F · dr _ch, where P - constant equal to 1.618 ..., provides significant advantages:

- the strength of the outer pipe 1 in the maximum set of curvature when passing through the radius sections of the wellbore during horizontal drilling;

- when using a hydraulic and (or) hydromechanical jar in a drill pipe string with rotation (from the drill rotor) of a curved drill pipe string (20 ... 40 rpm);

- during shock loads and shock impulses from the hydraulic and (or) hydromechanical jar and relaxation of tensile stresses in a curved drill pipe string in which the outer pipe 1 (stator) of the engine is installed.

Due to the fact that the hardness of the lining 4 with internal helical teeth 5, made of rubber, is 75 ± 3 units. Shore A, provides increased fatigue endurance (resource) - at least 150 thousand cycles, increased durability: abrasive and in the environment of petroleum products, as well as high elasticity, elasticity and reliability of sealing of the working pair of rotor 9 - lining 4 in maximum power mode.

The invention improves reliability and resource, provides maximum power, the moment of force on the output shaft in maximum power mode and permissible axial load by reducing the temperature gradient when heat is generated inside the tooth material, improving the removal of internal heat from the lining through the walls of the outer pipe to the annular drilling mud to ensure uniform contact pressure and increase the fatigue endurance of the lining, as well as the maximum pressure drop (inter-turn, on the teeth stat ra) to the maximum power level which is substantially of 25 ... 30 MPa at a lower level of stress-deformed state of the elastomer plate.

Information sources

1. US 2005/0079083 A1, F01C 1/10, Apr. 14, 2005.

2. US 6881045 B2, F03C 2/08, Apr. 19, 2005.

3. US 6604921 B1, F01C 1/10, Aug, 12, 2003 - prototype.

Claims (4)

1. The stator of a screw gerotor hydraulic machine, for example, a motor for rotating a rotor from a pump fluid supply or a pump for supplying a fluid by rotating the rotor, comprising an outer pipe with an inner surface made in the form of a helicoid, essentially with internal helical teeth, fixed in the outer pipe lining, for example, from an elastomer adjacent to the inner surface of the outer pipe, while the lining is made with internal helical teeth and coincides in shape with the internal helical teeth in pipe, and the thickness of the lining is maximum on the teeth radially directed inward, characterized in that in the outer pipe the maximum thickness of the lining, for example, from an elastomer along the valleys of its internal helical surface located at the maximum radial distance, is equal to half the height of its internal helical teeth the minimum wall thickness of the outer pipe along the radially outward troughs of its inner helical surface is equal to the height of the inner helical teeth in the lining, for example, of astomera. 2. Gerotor stator screw hydraulic machine according to claim 1, characterized in that the thickness Δ _height of the electrode, such as rubber along the radially inwardly directed teeth and the thickness Δ _sn depressions along its inner helical surface disposed at a maximum radial removal, are related by: Δ _height = (0.85 ... 1.15) · Ф · Δ _vp , where Ф is a constant equal to 1.618 ... 3. Gerotor stator screw hydraulic machine according to claim 1, characterized in that the wall thickness ΔR _armature outer tube along the radially inwardly directed teeth at its internal helical surface and the wall thickness of ΔR _ch outer tube disposed along the maximum radial depressions removing its internal helical surface bound ratio:
_Armature ΔR = (0.85 ... 1.15) · F · ΔR _ch, where P - constant equal to 1,618 ... 4. The stator of a screw gerotor hydraulic machine according to claim 1, characterized in that the hardness of the lining with internal helical teeth made of rubber is 75 ± 3 units. Shore A.

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