WO2010068110A2

WO2010068110A2 - Device for separating particles from a well fluid

Info

Publication number: WO2010068110A2
Application number: PCT/NO2009/000405
Authority: WO
Inventors: Bjørn DAHL
Original assignee: Optipro AS
Current assignee: Optipro AS
Priority date: 2008-11-24
Filing date: 2009-11-24
Publication date: 2010-06-17
Anticipated expiration: 2011-05-24
Also published as: WO2010068110A3; NO329443B1; NO20084934L

Abstract

The invention relates to a separator (1) for separating particles from a well fluid, wherein the separator (1) comprises: an inlet (2) for the well fluid with the particles, to a main channel (3) from an inlet (2) to a first outlet (4) for partly or fully filtered well fluid from the main channel (3); one or more sump (8) for catching particles, wherein the sump generally are arranged under the main channel (3), wherein one or more sumps (8) comprising a second outlet (10) with one or more transportation devices (12) for particles to an outlet pjpe (14) with a particle outlet (16) for the particles. The separator (1) comprising at least one filter screen frame (6a) with a bottom edge (63a) directed towards the sump (8).

Description

Device for separating particles from a well fluid

The invention relates to a separator for separating particles from a well fluid. The separated particles may comprise cuttings, rock particles, metal particles, additives and chemicals. The well fluid may be mainly a water based well fluid or mainly an oil based well fluid when filtering during drilling, or a so-called completion fluid when circulating fluid during other conditions than drilling. The separator according to the invention is arranged to separate particles such as cuttings, sand, rock particles, salts, metal shavings, metal dust, particles of additives, fragments of gaskets and other foreign substances, down to a desired size.

Background art

Several devices for separating particles are known. Those are so-called "shale shakers" and comprise mainly horizontal filter screen frames of coarser and successive finer screen cloth, where used cuttings and particles containing well fluid, as described above, are passing from the upstream well side. Cuttings and particles are retained at a screen cloth according to the so-called cut point of the screen while the filtrate passes trough forced by gravity.

An essential problem with the known devices is the need of extensive vibration for transporting the retained particles over the edge of the screen frames and thereby out of the well fluid cycle. Another substantial problem is that the gravity does not in an efficient way force the fluid trough the screen, especially at finer cut points. The efficiency of the known shale shakers are thus low with regard to volume.

A third problem with the known shale shakers is the undesirable wear of the screen cloths caused by vibrating particles and internal friction between the support wire and the screen cloth which incurs. Combined with lack of maintenance methodology the result of the above mentioned problem is a historical achievement of only about 2.7m³/screen (cubic meter drilled out formation rock mass per screen consumed), while we here expect a multiplication of lifetime for each screen - possibly more than 100 m³/sc.

A fourth problem with the known shale shakers is the amount of oil vapour, oil mist and other aerosols and degassing from the drilling mud due to the open design. This is anticipated to be harmful for lung tissue and may induce chemical pneumonia. There is a need for encasing and change such drilling mud separation processes to avoid this kind of evaporation in order to prevent health damages. Short summary of the invention

According to the invention a solution to the above mentioned problems is a closed separator for separating particles from a well fluid, wherein the separator comprises: an inlet for well fluid with particles, to a closed main channel from the inlet to a first outlet for partly or fully filtered well fluid from the main channel, one or more sumps for catching the particles, the sump generally arranged beneath the main channel wherein one or more of the sumps comprises a second outlet with one or more transportation devices for the particles to an outlet pipe with a particle outlet for the particles.

Further features of the invention are given in the dependent claims.

A first advantage of the invention is that the apparatus is a closed device, and that one should not expect evaporation or aerosol formation from the separator. A second advantage of the invention is that the transportation device (12) comprises a feed screw (13) that transports particles away from the sump, and that the particle outlet (16) is arranged in level with or above the outlet (4) so the fluid is allowed to return to the sump while the particles will be transported out. This prevents the fluid from leaving together with the cuttings which are transported out.

I one embodiment of the invention, the apparatus may operate in a rather crude mode without filter screen frames. A third advantage according to the invention is that the main channel (3) comprises at least one filter screen frame (6a), with a lower edge (63a) directed towards the sump (8).

In the separator, according to the invention, in the main channel (3), in addition to the first, coarser filter screen frame (6a), there may be arranged one or more separate and successively finer second, third etc filter screen frames (6b, 6c, ...), each with a lower edge (63b, 63c, ..) directed towards said sump (8). According to the fourth advantage of the invention one or more filter screen frame (6a) is arranged mainly vertically and transverse to the main channel (3), so that the separated particles are guided into the sump (8). Here their falling velocity may be increased by applying ultrasound.

Figure captions

The invention is illustrated in the attached drawing figures, wherein

Fig. 1 is an isometric view of a closed separator according to the invention, with the inlet from the left and the outlet to the right, the sump in the bottom, and the outlet for separated particles in the pipe running behind the main vessel.

Fig.2 is an isometric view and a partial section of the separator according to the invention with an inlet from the left, a main channel extending horizontally from the inlet to a first outlet to the right, and with tilted and sub vertical filter screen frames in the main channel and a sump for particles below the main channel. An outlet, arranged to remove the filtered particles is arranged below the sump. Fig. 2 further illustrates a longitudinal section through a particle trap according to the invention, wherein, ahead of the coarsest, approximately vertically arranged main filter is arranged a so-called "gumbo" -filter running vertically and transversely relative to the main channel, which is arranged for, by the movement indicated by the steps (a) - (f), to remove crude expanded masses which may arise in a well stream. This is arranged to avoid gumbo from blocking the screens. Fig. 3 illustrates in addition to Fig. 2, guide vanes arranged between the sub vertical filter screen frames and the outlet from the sump.

Fig. 4 indicates an embodiment of the invention in a cross-sectional perspective and a cross section view of the main channel of the device and illustrates that the level of the fluid in the outlet pipe and in the main channel are generally the same and that the device works as a water trap concerning the filtered well fluid.

Fig. 5 illustrates schematically the flow of a well fluid from a well, through the separator, wherein the particles are separated the filtered well fluid is removed and may be returned to the well. A flow drawn as a solid line and a broken line through the inlet indicates solid particles and fluids from the well fluid. Normally the filtered fluid runs back into the well and the separated particles run via the sump for being deposited. The dotted rectangles illustrate an ultrasound field in the area between the filter screen frames and the sump.

In addition to Fig. 5, Fig. 6 illustrates that the distribution of separated particles to deposition and recycling may be controlled according to desire by partitioning of the outlet from the sump into separate chambers, possibly by separate screw pumps. By this embodiment desired fractions may be returned to the well fluid to obtain a desired particle distributions in the returned well fluid, for instance for sealing certain parts of the geological formation.

Fig. 7a are rough illustrations in longitudinal view and end view of an embodiment of the invention where separate fraction chambers and sumps each are provided with transportation devices, for instance screw pumps.

Fig. 7b illustrates sketches, in a somewhat reduced size, of an embodiment of the invention in views: right elevation with inlet to the left, the sumps down and the outlet for filtrate to the right; rear end view with the outlet for filtrate towards the observer and the sump with the outlets for solids from the bottom and upwards to the right; front view with the inlet towards the observer and the sumps with the outlets for solids from the bottom and up to the left; left elevation view with the inlet to the right, the sumps down, the outlet for solids towards the observer and the outlet for filtrate to the left; bottom view with the inlet on top and the outlet for filtrate in the bottom, and top view with the inlet in the bottom and the outlet for filtrate at the top of the drawing.

Fig. 7c is an end view as seen from the inlet side wherein an A-A section is indicated and wherein the right part of the drawing shows this section.

Description of preferred embodiments of the invention

The invention is illustrated in the attached drawings and relates to a closed separator for separating particles from a well fluid. The separator (1) is illustrated in Figs. 1-4 and Fig.7, and comprises the following features: An inlet (2) for well fluid containing particles, which receives well fluid from a riser pipe or another return channel from a petroleum well or other geological well, and leads into a closed main channel (3). The main channel ends up in its opposite end at a first outlet (4) for partly or fully filtered well fluid from the main channel (4). A substantial part of the separation process takes place in a sump (8) for receiving the particles, generally arranged under the main channel (3). A large quantity of the desired separated particles, generally between 20 and 80 %, are separated in the first sump. One or more sumps may be arranged under the main channel (3). The at least one sump (8) comprises a second outlet (10) with one or more transportation devices (12) for particles to an outlet pipe (14) with a particle outlet (16) for the particles. The transportation device (12) may be a screw pump comprising a feed screw (13) for transportation of unequal sized particles from the coarsest to the finest, initially in a more or less wet condition.

The separated particles may comprise cuttings, rock particles, metal particles, additives and chemicals. The well fluid may be mainly a water based well fluid or mainly an oil based well fluid when filtering during drilling, or a so-called completion fluid when circulating fluid during other conditions than drilling. The separator according to the invention is arranged to separate particles such as cuttings, sand, rock particles, salts, metal shavings, metal dust, particles of additives, fragments of gaskets and other foreign substances, down to a desired size.

Generally the inventor desires the well fluid to run horizontally from the inlet to the outlet, where the main channel (3) comprises a mainly horizontal section (3h). In a preferred embodiment of the invention the particle outlet (16) is elevated equal to or higher than the first outlet (4). The outlet pipe (14) is arranged with a mud level with an elevation that generally balances the back pressure of the liquid or mud level in the main channel (3) or the first outlet (4). In this way the separator works similarly to a water trap. Otherwise generally all the fluid would have run out trough the sump (8) and out trough the first outlet (4), without any separation

In one embodiment of the invention the separator (1) comprises, in the main channel (3), one or more first filter screen frames (6a), with a lower edge (63a) directed towards the sump (8). This may contribute to a high proportion of separated particles already in the first sump. This first filter screen frame (6a) is necessarily the coarsest one. The largest particles of the well fluid, down to the cut point of the first filter screen frame (6a) will be separated from the well fluid. The separated particles will start sedimenting through the well fluid upstream of the filter screen (6a) and move down towards the sump, while the rough filtered well fluid, containing fluid and finer particles, will pass through the coarse filter screen (6a) and end up downstream of this. In an embodiment without further filter screen frames the rough filtered well fluid may run out of the first outlet for further filtering and processing.

In a preferred embodiment of the invention the cross-section of the main channel (3) is largest near the inlet. The increased cross-section reduces the velocity of the liquid inversely to the area ratio between this cross-section and the cross-section of the inlet channel. This will contribute to an increased precipitation towards the first sump. This is illustrated in Fig. 7b, especially the bottom- and top-view.

In a preferred embodiment of the invention wherein in the main channel (3), in addition to the first, coarser filter screen frame (6a), there is arranged one or more separate and successively finer second, third etc filter screen frames (6b, 6c, ...), each with a lower edge (63b, 63c, ..) directed towards said sump (8). Each finer filter screen frame (6b, 6c, ...) will have a finer cut point than the previous, and each filter screen frame will lead its separated particle fraction down to the sump (8), and let the successively finer filtered well fluid pass through downstream.

From Fig.^bone may see that the width of the screens may be reduced from a wider/bigger filter nearer to the inlet, to successively more narrow filters nearer to the filtrate outlet.

A result of the invention is that concentrated particle fluid accumulates in the sump (8). This will collect coarse cuttings, coarse sand, rock particles, metal particles, fragments of gaskets and so on, all originating from the borehole.

In a preferred embodiment of the invention one or more filter screen frames (6a) are arranged mainly vertically and perpendicularly to the main channel (3), so that the separated particles are directed towards the sump (8). The second, third, etc filter screen frames (6b,6c, ...) are arranged mainly vertically and perpendicularly to the main channel (3) as well, so that the separated particles are directed towards the sump (8). In an embodiment, the filter screen frames are not arranged vertically but slightly aslant in downstream direction. The retained particles upstream of each filter screen will then, due to the gravity, be enabled to fall off more or less down and away from the filter screen. .

The well fluid should not be allowed to pass outside of the finest filter screen (6a, 6b, 6c,...). The filter screens are therefore arranged to generally cover the cross section of the main channel (3).

In a preferred embodiment of the invention the apparatus is provided with one or more actuator (7) arranged to move at least one of said filter screen frames (6a, 6b, 6c, ...) in a repeating pattern. Such actuators are illustrated in Fig. 7a. This may be a vibrator or a motor: The actuator (7) may comprise a vibrator (71) arranged to vibrate one or more of the filter screen frames (6a, 6b, 6c, ...). The vibrator thus helps particles fall off the filter screens and the well fluid to pass through the filter screens. In addition, or as an alternative, the actuator (7) may also comprise a motor (72) for moving or rotating one or more of the filter screen frames (6a, 6b, 6c, ...). In an alternative embodiment of the invention one may arrange the filter screens to rotate axial, flat and parallel to the main channel (3), so that they rotate out laterally relative to the main channel to a semi separate arranged sump ,for the particles coarser than each screen, to be dumped, and returns without particles to the main channel, for picking up more of the cut point dedicated particles.

Gumbo is very large, more or less porous lumps made during precipitation under certain pressure and chemical conditions. Such large particles may expand to an undesired degree and have to be taken out first in the separator, before blocking the filters. In a preferred embodiment of the separator (1) one or more motorized so-called gumbo-filters (66) are arranged upstream, axial and parallel in the main channel (3), arranged to circulate from an opposite side of the main channel (3) relative to the sump (8), and arranged to transport large so-called gumbo particles out of main channel (3) and towards the sump, for subsequently being rotated at right angles and returning to the origin, then being rotated back to an axial parallel position and repeat the movement. In this way gumbo is removed before such substances may block the main channel and the first filter screen (6a).

Small particles will fall out slower through the well fluid than larger particles of the same density. According to a preferred embodiment of the invention will, the particle trap is provided with an ultrasound transducer (9) in the section below the main channel (3) (to avoid effecting baryte particles in the main channel (3)), arranged to generate acoustic waves in the sump (8) for improving the sedimentation rate of particles. This will result in an improved separation rate of particles. Such a wave field is illustrated in Figs. 5 and 6.

A preferred embodiment of the invention is arranged in a way such that the lower edges (63a, 63b, 63c,...) of said one or more filter screen frames (6a, 6b, 6c, ...) end up directly to the second outlet (10) to the transportation device O^'j)_. Alternatively the filter screen frames may be arranged with guide vanes instead of extending all the way down to the second outlet (10) like this: lower edges (63a, 63b, 63c,...) of one or more filter screen frames (6a, 6b, 6c, ...) end up onto separate guide vanes (65a, 65b, 65c,...) which lead towards the second outlet (10) to the transportation device (12).

It is an advantage for vibrating the filter screens that there is some space between the screens and the separators walls, while still sealing onto a wall so as for preventing fluids from passing in an undesired way outside the screen frames. To solve this problem the main channel (3) and the sump (8) are enveloped by an inner chamber (5) between the inlet (2), the first outlet (4), and the second outlet (10) within the separator (1), the inner chamber (5) enclosing and sealing onto at least the lateral edges (61) and upper edges (62) of the filter screen frames (6a, 6b, 6c, ...) and with generally fluid tight gaskets (51) which envelope the inner chambers connections to the inlet (2) and the first outlet (4). In this way the entire inner chamber (5) may be vibrated and the gaskets prevent undesired unfiltered flow.

The separator's (1) inlet (2) may comprise one or more inlet channels and the first outlet (4) may comprise one or more outlet channels.

Fig. 5 illustrates schematically the flow of a well fluid from a well, through the separator, wherein the particles are separated, and wherein filtered well fluid is removed and may be returned to the well.

In addition to Fig. 5, Fig. 6 illustrates that the distribution of separated particles to deposition and recycling may be controlled according to desire by partitioning of the outlet from the sump into separate chambers, possibly by separate screw pumps.

Fig. 7a are rough illustrations in longitudinal view and end view of an embodiment of the invention wherein separate fraction chambers and sumps each are provided with transportation devices, for instance screw pumps.

Fig. 7b illustrates sketches, in a somewhat reduced size, of an embodiment of the invention in views: right elevation with inlet to the left, the sumps down and the outlet for filtrate to the right;

- rear end view with the outlet for filtrate towards the observer and the sump with the outlets for solids from the bottom and upwards to the right;

- front view with the inlet towards the observer and the sumps with the outlets for solids from the bottom and up to the left;

- left elevation view with the inlet to the right, the sumps down, the outlet for solids towards the observer and the outlet for filtrate to the left;

- bottom view with the inlet on top and the outlet for filtrate in the bottom, and top view with the inlet in the bottom ant the outlet for filtrate at the top of the drawing.

An embodiment of the invention may be combined with traditional separating devices for well fluid, where the apparatus according to the invention handles the preliminary filtering of the drilling mud, and the following traditional device handle the subsequent filtering, if required.

Components list

1 particle separator (1)

2 inlet (2) for particle containing well fluid

3 main channel (3)

4 first outlet channel (4)

5 inner chamber (5)

6 filter screen frame (6a, 6b, 6c, ...)

63a lower edge (63a) of filter screen frame (6a), etc.

64a upper edges (64a, 64b, 64c, ...) of separate guide vanes (65a, 65b, 65c, ...)

7 actuator (7)

71 vibrator (71)

72 motor (72)

66 gumbo filter (66)

8 sump beneath main channel

9 ultrasound transducer (9)

10 second outlet, particle outlet from the sump

12 transportation device, preferably a screw pump

13 feeder screw

14 outlet pipe from pump 16 outlet from outlet pipe

Claims

1. A separator (1) for separating particles from a well fluid, wherein said separator (1) comprises: an inlet (2) for said well fluid with said particles, to a closed main channel (3) from said inlet (2) to a first outlet (4) for partly or fully filtered well fluid from said main channel (3); one or more sump (8) for catching said particles, said sump generally arranged under said main channel (3), characterized by one or more of said sumps (8) comprising a second outlet (10) with one or more transportation devices (12) for said particles to an outlet pipe (14) with a particle outlet (16) for said particles.

2. The separator (1) of claim 1 , wherein said transportation device (12) comprises a transportation screw (13).

3. The separator (1) of claim 1, wherein said particle outlet (16) being arranged in level with or above said first outlet (4).

4. The separator (1) of claim 1, wherein said main channel (3) comprises at least one filter screen frame (6a) , with a lower edge (63a) directed towards said sump (8).

5. The separator (1) of claim 4, wherein in said main channel (3), in addition to said first, coarser filter screen frame (6a), there is arranged one or more separate and successively finer second, third etc filter screen frames (6b, 6c, ...), each with a lower edge (63b, 63c, ..) directed towards said sump (8).

6. The separator (1) of claim 4, wherein one or more said filter screen frame (6a) is arranged mainly vertically and perpendicular to said main channel (3), so that said separated particles are directed into the said sump (8).

7. The separator (1) of claim 5, wherein said second, third, etc filter screen frame (6b,6c, ...) are arranged mainly vertically and perpendicular to said main channel (3) so that said separated particles are directed into said sump (8).

8. The separator (1) of claim 4 or 5, wherein at least the finest of said filter screen frames (6a, 6b, 6c.) is arranged to mainly cover a cross-section of said main channel (3).

9. The separator (1) of claim 1 , with said outlet pipe (14) being arranged with a mud level with an elevation that balances the back pressure of the liquid level in said main channel (3) or said first outlet (4)

10. The separator (1) of claim 4 or 5, with one or more actuator (7) arranged to move in a repeating pattern at least one of said filter screen frames (6a, 6b, 6c, ...) .

11. The separator (1) of claim 10, wherein said actuator (7) comprises a vibrator (71) arranged to vibrate one or more of said filter screen frames (6a, 6b, 6c, ...).

12. The separator (1) of claim 10, where said actuator (7) comprises a motor (72) for moving or rotating one or more of said filter screen frames (6a, 6b, 6c, ...)

13. The separator (1) of claim 12, wherein a motorized so-called gumbo-filter (66) is arranged upstream in said main channel (3) and arranged to circulate from the opposite side of said main channel (3) relative to said sump (8), and arranged for transporting large so- called gumbo particles out of said main channel (3) towards said sump, turn mainly to a right angle and return to its initial point for repeating the movement.

14. The separator (1) of claim 1 with an ultrasound transducer (9) arranged to generate acoustic waves in said sump (8) to improve sedimentation rate of particles.

15. The separator (1) of claim 4, or 5, wherein lower edges (63a, 63b, 63c,...) of one or more of said filter screen frames (6a, 6b, 6c, ...) end up directly to said second outlet (10) to the transportation device {.i 2.X

16. The separator (1) of claim 4 or 5, wherein said lower edges (63a, 63b, 63c,...) of said one or more filter screen frames (6a, 6b, 6c, ...) end up onto separate guide plates (65a, 65b, 65c,...) which guide towards said second outlet (10) to said transportation device(12)

17. The separator (1) of claim 1 , wherein said main channel (3) and said sump (8) are enveloped by an inner chamber (5) between said inlet (2), said first outlet (4), and said second outlet (10) within said separator (1), said inner chamber (5) enclosing and sealing onto at least the lateral edges (61) and upper edges (62) of said filter screen frames (6a, 6b, 6c, ...) and with generally fluid tight gaskets (51) which envelope said inner chambers connections to said inlet (2) and said first outlet (4).

18. The separator (1) of claim , wherein a cross-section of said main channel (3), between said inlet (2) and said first outlet (4) forms a cross section expansion of said main channel (3) and further reduces towards said first outlet (4).