Arrangement for sand collection

Abstract

The present invention regards a subsea sand handling system for limiting abrasion of specific subsea equipment (5), comprising an inlet (10) connectable to a sand separation system (2) upstream of the specific equipment (5) and an outlet (18, 22) connectable to a pipeline (6) downstream of the specific equipment (5), wherein it comprises at least two collection vessels (11,14) and means for flushing (16,17,19,21) the sand out of at least one of the collection vessels (11,14), and the vessels (11,14) and the means for flushing (16,17,19,21) the sand out of said vessels (11,14) are configured such that sand is flushed from one vessel (11,14) while sand is collected in the other vessel (14,11). The present invention also regards a method for limiting abrasion of subsea rotating equipment.

Claims

1. A subsea sand handling system for limiting abrasion of specific subsea equipment, comprising: an inlet connectable to a sand outlet of a sand separation system located upstream of the specific equipment; an outlet connectable to a pipeline downstream of the specific equipment; at least two collection vessels connected between the inlet and the outlet; and means for flushing sand out of one of the collection vessels and into the outlet while at the same time sand passing through the inlet is collected in the other collection vessel; wherein at least a part of each vessel is configured to be rotatable about an axis, such that in one position one of the vessels is in connection with the sand separation system and in a second position that vessel is in connection with the flushing means.

2. The subsea sand handling system according to claim 1, wherein sand is collected in a first collection vessel, the flushing means is connected to a second collection vessel, and the system further comprises a connection between the first and second collection vessels through which sand from the first vessel is emptied into the second vessel.

3. The subsea sand handling system according to claim 2, wherein the first vessel is arranged relatively above the second vessel such that sand may be transferred through the connection from the first vessel to the second vessel with the aid of gravity.

4. The subsea sand handling system according to claim 3, wherein the connection comprises a rotating ball valve comprising chambers for collecting sand to be emptied from the first vessel to the second vessel.

5. The subsea sand handling system according to claim 1, wherein a connection between the vessels and the inlet is so configured that sand is alternately collected in the first and the second vessels; and wherein the flushing means is so configured that sand is flushed from the vessels when the vessel is not collecting sand.

6. The subsea sand handling system according to claim 5, wherein the flushing means comprises respective connections to both vessels and valves positioned in said connections for regulating the flushing of the separate vessels.

7. The subsea sand handling system according to claim 1, further comprising means for leading fluid from downstream of the specific equipment into the flushing means to flush the vessels.

8. A subsea sand handling system for use in connection with a subsea system component, the sand handling system comprising: an inlet which is connected to a sand outlet of a sand separation system located upstream of the component; an outlet which is connected to a pipeline located downstream of the component; and at least two collection vessels which are connected between the inlet and the outlet; wherein in operation of the sand handling system sand from the sand separation system is conveyed through the inlet into one of the collection vessels while at the same time sand in the other of the collection vessels is conveyed through the outlet and into the pipeline; wherein the inlet is connected to a first of the collection vessel, the outlet is connected to a second of the collection vessels, and the system further comprises a connection member which connects the first vessel to the second vessel and through which sand in the first vessel is transferred into the second vessel.

9. The subsea sand handling system of claim 8, wherein the first vessel is positioned vertically above the second vessel and the sand is transferred through the connection member with the aid of gravity.

10. The subsea sand handling system of claim 9, wherein the connection member comprises a rotating ball valve which includes at least one chamber in which sand in the first vessel is collected, and wherein upon rotation of the ball valve the sand in the first chamber is deposited into the second vessel.

11. The subsea sand handling system of claim 8, further comprising: a fluid line which is connected between the second collection vessel and the pipeline at a location upstream of the outlet; wherein in operation of the sand handling system sand from the sand separation system is conveyed through the inlet into the first vessel while at the same time fluid in the pipeline downstream of the component is conveyed through the fluid line and the second vessel to thereby flush sand from the second vessel into the outlet.

12. The subsea sand handling system of claim 11, further comprising an ejector which is positioned in the outlet and is operated by fluid conveyed through the fluid line.

13. The subsea sand handling system of claim 8, wherein both a first and second of the vessels are connected to the inlet through a first three-way valve and both the first and second vessels are connected to the outlet through a second three-way valve, and wherein in operation of the sand handling system sand is alternately conveyed through the inlet into one of the first and second vessels while at the same time sand is conveyed through the outlet from the other of the first and second vessels.

14. The subsea sand handling system of claim 13, further comprising: a fluid line which is connected on one end to both the first and second vessels through a third three-way valve and on the other end to the pipeline at a location upstream of the outlet; wherein while sand is conveyed through the inlet into one of the first and second vessels, fluid is conveyed through the fluid line and the other of the first and second vessels to thereby flush sand from said vessel into the outlet.

15. The subsea sand handling system of claim 14, further comprising an ejector which is positioned in the outlet and is operated by fluid conveyed through the fluid line.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention shall now be explained with non-limiting embodiments with reference to the attached drawing where;

(2) FIG. 1 shows a first embodiment of a system according to the invention

(3) FIG. 2 shows a second embodiment, and

(4) FIG. 3 shows a third embodiment.

DETAILED DESCRIPTION OF THE INVENTION

(5) In FIG. 1 there is shown a pipeline 1 leading fluid from a well into a de-sander unit 2, Out of the de-sander unit 2 a de-sanded fluid is guided through a pipeline 3 and a restriction 4 in this pipeline 3 to a pump 5. Pressure is added to the fluid by the pump 5, and the fluid exists through pipeline 6, which also comprises a restriction 7. The sand separated out from the well fluid in the de-sander 2 is guided through a second outlet from the de-sander 2 to a pipeline forming the inlet 10 of the present invention. The pipeline 10 leads to a first vessel 11. Sand is collected from the de-sander unit 2 substantially without interruptions giving that the flow from the well is also without interruptions. The first vessel 11 is connected to a second vessel 14 through a connection 12. In this connection 12 there is arranged a valve 13. The first vessel 11 is in this embodiment arranged relatively vertically above the second vessel 14, such that when valve 13 is opened, the sand will due to gravity flow from the first vessel 11 to the second vessel 14. There is in addition a fluid line 15 leading from an upper part of the first vessel 11 to the fluid line 3 downstream of the first restriction 4 but upstream of the pump 5, for fluid separated from the sand in the first vessel 11. The second vessel 14 then has a sand inlet formed by the connection 12 and a sand outlet 16 leading to an ejector 19. In addition there is a second inlet connected to a pipeline 17, leading a fluid from the high pressure side of the pump into the second vessel 14 and also into the ejector 19. The high pressure fluid lead through pipeline 17 into the ejector will act as the active driving fluid in the ejector and create a suction pressure thereby drawing out fluid with sand from the second vessel 14 through sand outlet 16. From the ejector 17 the fluid containing the sand is guided through pipeline 18 to an inlet in the pipeline 6 downstream of the second restriction 7. This forms the flushing system of the first embodiment. There are also arranged suitable sensors in the system for operation of the different elements.

(6) In FIG. 2 there is shown a second embodiment of the invention. Similar elements to the first embodiment are given the same reference numerals, and it is referred to the explanation above. In this embodiment there is shown an actuator 20 for the operation of moving sand through the connection 12 between the first and second vessels 11, 14. In this embodiment there is shown a ball valve 13, with a first chamber 13a and a second chamber 13b. When the actuator 20 turns the ball valve 13 the chamber 13a is moved from the first vessel 11 into the second vessel 14 and there emptied of sand, and chamber 13b is moved from the second vessel 14 to the first vessel 1 to collect sand. Sand is thereby moved between the vessels. Sand in this embodiment is emptied from the second vessel 14 with fluid through a fluid line 21 leading to the second vessel from a point in the pipeline 6 downstream of the pump 5 but upstream the restriction 7, and is guided out of the second vessel through a sand outlet line 22 which leads to the pipeline 6 downstream of the second restriction 7. This forms the flushing system of the second embodiment.

(7) In FIG. 3 there is shown a third embodiment of the invention. Similar elements are given same reference number as above, and it is referred to the explanation given. In this embodiment the pipeline 10 leading from the sand outlet of the de-sander 2 comprises a three-way valve 10a, a pipeline connection 10 leading to the first vessel 11, and a second pipeline connection 10 leading to the second vessel 14. By regulating the valve 10a, sand is collected substantially continuously and guided into the first or the second vessel, 11,14. Each of the vessels 11, 14 is connected to a flushing system with a pipeline 17 connected to the pipeline 6 downstream of the pump 5 but upstream of the second restriction 7. The pipeline 17 leads to an ejector 19 and also to a three-way valve 17a, which regulates the flow of fluid to either the first vessel 11 through a fluid connection 17 or the second vessel 14 through a second fluid connection 17. Both vessels 11,14 comprise an outlet connected through respective fluid connections 16,16 and a three-way valve 16a to a pipeline 16 leading to the ejector 19. The outlet of the ejector is guided through pipeline 18 into the pipeline 6 downstream of the second restriction 7. This forms the flushing system of the third embodiment. Both vessels 11,14 also have a fluid connection 15, which is connected through a three-way valve 15a between the upper part of the vessels and the pipeline 3, downstream of the restriction 4 but upstream of the pump 5. There are also arranged suitable sensors in the system.

(8) The invention has now been explained with reference to three different embodiments. A skilled person would understand that there may be made alterations and modifications to these embodiments that are within the scope of the invention as defined in the attached claims. It is possible to combine features from the different embodiments, as for instance, a flushing system as described in relation to the first embodiment may be used with the second embodiment and the flushing system in the second embodiment may be used in the first and the third embodiment. One may omit the fluid connection between the upper part of the vessels and the pipeline upstream of the pump. The de-sander may be any kind of de-sander or even a separator separating the well fluid into oil, water, gas and sand or combinations of these different elements. The fluid used in the flushing system may be any of the three fluids separated in the separator, or a combination.