GB2588759A

GB2588759A - Blowout preventer for oil drilling

Info

Publication number: GB2588759A
Application number: GB1915650.4A
Authority: GB
Inventors: Aalto Juhani
Original assignee: Softatalo Aida Oy
Current assignee: Softatalo Aida Oy
Priority date: 2019-10-29
Filing date: 2019-10-29
Publication date: 2021-05-12
Anticipated expiration: 2039-10-29
Also published as: GB2588759B; GB201915650D0

Abstract

A blowout preventer comprising at least three pipe rams 11, 21 and a control system for closing the pipe rams, wherein each pipe ram forms a layer and are stacked to form a sandwich structure, and wherein at least two of the pipe rams have holes for oil passing. Preferably at least two of the pipe rams do not have holes for oil passing. Preferably, the control system is adapted to sequentially close the pipe rams of the blowout preventer one at a time.

Description

BLOWOUT PREVENTER FOR OIL DRILLING

FIELD

[0001] The subject of this invention is a blowout preventer for oil drilling ascending pipes. This blowout preventer is required, for instance, in the event of oil well fires, to close the oil pipe and then prevent oil leakage.

BACKGROUND

[0002] Blowout preventer (BOP) is a large valve or similar mechanical device used to seal, control and monitor oil and gas wells to prevent blowouts; the uncontrolled release of crude oil and/or natural gas from a wellbore. BOPs are developed to cope with extreme erratic pressures and uncontrolled flow emanating from a well reservoir during drilling.

[0003] A typical BOP stack system includes one to eight ram-type preventers and optionally, one or two annular-type preventers. Subsea BOP stack systems are secured on the top of the wellbore, known as the well head. A typical stack system configuration has the ram preventers on the bottom and the annular preventers at the top. The configuration of the stack preventers is optimized to provide maximum pressure integrity, safety and flexibility in the event of a well control incident.

[0004] WO 2019/013632 relates to a subsea blowout preventer stack system. This configuration uses multiple rams to ensure the stop of the oil flow. There are several blind shear rams and at least one pipe ram.

[0005] US Patent 6,026,905 relates to a subsea test tree with multiple safety valves.

This configuration has a combination of shear rams and pipe rams in its ramlock assembly.

[0006] An example BOP includes a main body or housing with a vertical bore Ram bonnet assemblies may be bolted to opposing sides of the main body using a number of high tensile fasteners, such as bolts or studs. These fasteners are required to hold the bonnet in position to enable the sealing arrangements to work effectively. An elastomeric sealing element may be used between the ram bonnet and the main body. There are several configurations, but essentially they are all directed to preventing a leakage bypass between the mating faces of the ram bonnet and the main body. Each bonnet assembly includes a piston which is laterally movable within a ram cavity of the bonnet assembly by pressurized hydraulic fluid acting on one side of the piston. The opposite side of each piston has a connecting rod attached thereto which in turn has a ram mounted thereon. The rams can be shear rams for shearing an object within the bore of a BOP. Alternatively, the rams can be pipe rams for sealing off around an object within the bore of a BOP, such as a pipe, thereby sealing the annular space between the object and the BOP bore.

[0007] The rams are designed to move laterally toward the vertical bore of the BOP to shear or seal off on any object located therein. For instance, opposing pipe rams utilize seals that close in on and seal off on a tubular within the vertical bore of the BOP, such as a section of drill pipe used during drilling operations. Each pipe ram typically has a semicircular opening in its front face to form a seal about half of the outer periphery of the object within the BOP vertical bore. When the opposing pipe rams are closed, the opposing pipe rams engage each other and seal the entire periphery of the object, thereby closing off the annulus between the object and the BOP bore. Typical pipe ram assemblies can include a ram packer which is composed of an elastomeric or rubber material configured to seal off against the tubular within the vertical bore of the BOP when the opposing rams are run into the closed position.

[0008] US Patent Application Publication 2019/0145217 describes a blowout preventer having two rams to close the oil flow in the main passage. This configuration uses two different types of rams, one pipe ram and one shaft ram.

[0009] It has been noticed that sometimes BOPs are damaged during closure, which may lead to major oil spills and environmental disasters

SUMMARY OF THE INVENTION

[0010] The purpose of this invention is to make closure of oil wells more reliable and thereby to decrease the risk of oil spill and environmental disasters.

[0011] The invention is based on the idea that the BOP is structured in layers (sandwich structure) with at least three hydraulically closing, partly floating pairs of pipe rams, which are self-powered and hydraulically controlled to close (by constricting the pipe until it is closed) slowly and surely. The time chosen to close the pipe rams fully is two hours.

[0012] With the aid of this invention the risk of bursting is eliminated (slow closing instead of fast), the pressure is reduced on five different levels (formerly in one spot) and by using several rams, the BOP will close certainly. The layered structure ensures that the invention endures high pressure and high temperature.

[0013] The invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.

[0014] According to a first aspect of the present invention, there is provided a blowout preventer that comprises at least three pipe rams and a control system for closing the pipe rams.

[0015] According to a second aspect of the present invention, there is provided a method of preventing blowouts in oil drilling by locating the before mentioned blowout preventer on the sea floor.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIGURE 1 illustrates a side view of the BOP with at least some embodiments of the present invention; [0017] FIGURE 2 illustrates a top view of the first pipe ram; and [0018] FIGURE 3 illustrates the hydraulic control system.

EMBODIMENTS

[0019] In prior solutions it has been normal to have rams which are closed fast. This causes the pressure on the BOP to increase suddenly and this has caused the BOP to break or leak. This may lead to major oil spills and environmental disasters.

[0020] Therefore, it is a purpose of embodiments to close the pipe rams reasonably slowly and thus ensure that the BOP will not break down due to the great forces of nature (pressures of up to 1050 bar and temperatures of 550°C).

[0021] The BOP referred to in a first embodiment is composed of three pairs of pipe rams; the lower two of these rams are lightened by drilling holes in them. The hydraulic control pipe system closes the pipe rams slowly by hydraulic pressure. It is started by closing slowly the pipe ram closest to the base of the BOP, which is lightened most of all by drilling the most holes in the ram. After about 15 minutes the pipe ram second closest to the base of the BOP starts to close slowly. This has fewer holes than the pipe ram closest to the base. After about 30 minutes the pipe ram third closest to the base of the BOP starts closing slowly. This one does not have holes.

[0022] In one embodiment the BOP is composed of five pairs of pipe rams; the lower three of these rams are lightened by drilling holes in them. By closing in three different stages, such a great reduction is achieved in the pressure within the oil main passage that the final constriction can be started by closing the two pipe rams furthest away from the base of the BOP. These two pipe rams are identical without holes. The pipe ram furthest away from the base of the BOP is only to ensure full closing in case of mud or something else preventing the second furthest pipe ram from the base of the BOP from closing completely. After about 45 minutes the second furthest pipe ram from the base of the BOP starts closing slowly; this is not lightened by holes drilled into it. This pipe ram closes the oil leak completely. After another 60 minutes the closing of the oil well is further ensured by starting closing slowly the pipe ram that is furthest away from the base of the BOP.

[0023] The closing of the pipe rams can be controlled either automatically by pressure from the hydraulic pump, or by self-powering it with the pressure of the oil well, or manually from the platform level.

[0024] The BOP is totally of fire-proof construction and is so massive that even great pressures cannot damage it. Steel rollers between the disks and the framework act as a sealing face and remove friction [0025] FIGURE 1 illustrates a side view of the BOP in accordance with at least some embodiments of the present invention The BOP has an inlet and an outlet. The direction of the oil flow is in the main passage 14 of the BOP from the inlet to the outlet. The BOP has many layers of which the base layer 15 is located nearest to the inlet. The function of the base 15 is to keep the BOP in place on the sea floor when it is in use The base 15 only has a main passage for the oil flow.

[0026] On top of the base layer 15 are at least three layers. The layers are bolted to each other so that the one closest to the base 15 is bolted to the base 15 and the layer second closest to the base is bolted to layer the closest to the base and so on.

[0027] Each of the three layers has a pipe ram 11, 21, a main passage for the oil flow 14, a frame 28, a piston 17, 27, a bonnet 16, 26, a cylinder 13, 23 and steel rollers 19, 29.

The frame 28 surrounds the rest of the parts of the BOP. The frame 28 is made from an oxidation-corrosion-resistant material as the conditions in the sea floor are very harsh with high pressure, salty water and heat of the oil. Also, the frame 28 is where the layers are bolted to each other as explained above.

[0028] Within the frame 28 is the pipe ram 11, 21 which is attached into a piston 17, 27 that moves in a cylinder 13, 23. The piston 17, 27 moves perpendicularly in relation to the main passage 14. As the pipe rams 11, 21 close the main passage 14 in their closed position, they too, move perpendicularly. To help the pipe rams 11, 21 close, there are steel rollers 19, 29 located at the point where the pipe rams 11, 21 come out from the cylinder 13,23 into the main passage 14. The steel rollers 19,29 help the pipe rams 11,21 to move without friction and minimize the jamming of the pipe rams 11, 21.

[0029] Figure 1 also illustrates the dimensions of the BOP according to one embodiment. The dimensions are labelled a -e. a is the height of the layers with pipe rams. This can be for example 1000 mm. b is the length of the bonnet 16. This can be for example 350 mm. c is the length of the cylinder 13. This can be for example 450 mm. d is the width of the main passage 14. This can be for example 400 mm. e is the length of the whole BOP. This can be for example 2000 mm. All the dimensions can be in the range of -2 times the dimensions listed here, for instance.

[0030] Figure 2 illustrates the top view of the pipe ram 11, 21 closest to the base 15.

In this figure it is seen that the pipe rams have holes. The holes let some of the oil through to ease the pressure on the ram. This makes the BOP durable so that it does not break when the pipe rams are closed and put under a lot of pressure. The pipe ram 11, 21 closest to the base 15 has the most holes. There are two or three layers of pipe rams with holes, so that the pipe ram 11, 21 second closest to the base 15 has less holes than the one closest to the pipe ram 11, 21 and optionally the pipe ram It, 21 third closest to the base has less holes than the pipe ram 11, 21 second closest to the base. Of course, also other configurations are possible so that the number or order of holed pipe rams can differ from the described embodiments. There is also at least one, preferably two, layers that have pipe rams 11, 21 without any holes. These pipe rams 11, 21 completely block the flow of oil.

[0031] In Figure 2 the pipe ram is closed so that the main passage 14 for the oil is not visible. In the middle of the pipe ram is the hole for the drill 12. The piston 17, 27 is fully in the closed position in the cylinder 13, 23 [0032] Figure 2 also illustrates the width of the BOP according to one embodiment.

The width is labelled f in this figure. f is for example 600 mm The width can be in the range of 300 mm -1200 mm, for instance.

[0033] Figure 3 illustrates the hydraulic control system. When the fire hazard detector 31 detects a fire, or the manually operated push button 32 is pressed, the control system is activated to close the pipe rams 11, 21, which are numbered in Figure 3 as L -5.. A pump 33 pumps oil from the hydraulic oil reservoir 34 to the hydraulically operated pipe rams 11, 21. Each pipe ram 11, 21 has a valve 35 to control the flow of the hydraulic oil. The valve 35 to each pipe ram 11, 21 is closed only when it is wanted to close as explained above. The valves 35 are situated in the bonnets 16, 26 of each layer seen in figures 1 and 2.

[0034] According to an embodiment a blowout preventer comprises at least three pipe rams 11, 21 and a control system for closing the pipe rams 11, 21. Each pipe ram 11, 21 forms a layer, which are on top of each other to form a sandwich structure. At least two of the pipe rams 11, 21 have holes for oil passing so that the pipe ram closest to base has the most holes for oil passing and at least one pipe ram 11, 21 located closest to the top does not have holes for oil passing. The pipe rams that do not have holes are solid so that no oil passes through them.

[0035] According to a second and third embodiment the blowout preventer comprises at least four or preferably five pipe rams 11, 21. In these embodiments, one or preferably two of the pipe rams located furthest from the base 15 do not have holes for oil passing.

[0036] According to an embodiment the blowout preventer has an inlet and an outlet so that the direction of the oil flow is from inlet to outlet.

[0037] According to an embodiment, the before mentioned blowout preventer further comprises a frame 28, steel rollers 19, 29 and a base 15. The inlet of the blowout preventer is located at the base 15 and the layers are located on top of the base in direction of the outlet.

[0038] According to an embodiment the control system is hydraulic, self-powered or manually operated. The control system the control system comprises a control pipe system, a fire hazard detector 31, control unit 36, a pump 33, hydraulic oil reservoir 34, manually operated push button 32 and hydraulic valves 35. When the fire hazard detector 31 detects a fire, the control system works as a self-powered system. In other situations the control system is controlled manually.

[0039] According to an embodiment the frame 28 of the blowout preventer is made from oxidation-corrosion-resistant material, for example austenitic nickel-chromium-based superalloy. Other materials can be used, but as the BOP is located in the sea and is in touch with drilled oil, the material has to tolerate salty water, high pressure and high temperatures.

[0040] According to an embodiment the above described blowout preventer located on the sea floor and is made for preventing blowouts in oil drilling.

[0041] According to an embodiment the pipe rams 11, 21 of the blowout preventer are sequentially closed one at a time so that the one closest to the base 15 starts closing first. Each pipe ram 11, 21 starts closing after a period of time, for example 15 minutes, after the pipe ram 11, 21 located below it has started to close. In a fire hazard situation, when the pipe rams are closed automatically, the next pipe ram does not start closing before the previous one is completely closed. In a manually controlled situation, the pipe rams can be closed partially at the same time. However, even in this situation the pipe rams start to close sequentially and not at the same time as the previous ram.

S

[0042] According to an embodiment all the pipe rams 11, 21 are closed within two hours after the pipe ram closest to the base has started to close.

[0043] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0044] Reference throughout this specification to one embodiment" or "an embodiment-means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment.

[0045] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.

[0046] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

[0047] While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

[0048] The verbs "to comprise and "to include" are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated Furthermore, it is to be understood that the use of "a" or "an", i.e a singular form, throughout this document does not exclude a plurality.

INDUSTRIAL APPLICABILITY

[0049] The disclosed blowout preventer can be used in oil drilling to prevent oil blowouts.

ACRONYMS LIST

BOP Blowout preventer 11,21 REFERENCE SIGNS LIST Pipe ram 12 Drill 13, 23 Cylinder 14 Main passage Base 16, 26 Bonnet 17, 27 Piston 28 Frame 19, 29 Steel rollers 31 Fire hazard detector 32 Push button 33 Pump 34 Hydraulic oil reservoir Hydraulic valve 36 Control unit

CITATION LIST

Patent Literature WO 2019/013632 I5 US 6,026,905 US 2019/0145217

Claims

CLAIMS: 1. A blowout preventer for oil drilling, comprising: -at least three pipe rams (11, 21), and -a control system for closing the pipe rams (11, 21), wherein each pipe ram (11,21) forms a layer, said layers are on top of each other to form a sandwich structure, and wherein at least two of the pipe rams (11, 21) have holes for oil passing.
2. The blowout preventer according to claim 1, wherein the blowout preventer has an inlet and an outlet so that the direction of the oil flow is from the inlet to the outlet.
3. The blowout preventer according to claim 2, comprising a frame (28), steel rollers (19, 29) and a base (15).
4 The blowout preventer according to claim 2 or 3, wherein the inlet is located at the base (15) of the blowout preventer and the layers are located on top of the base (15).
5. The blowout preventer according to any one of claims 2 -4, wherein at least two of the pipe rams (11, 21) have holes for oil passing so that the pipe ram (11, 21) closest to the inlet (15) has the most holes for oil passing and at least one of the other pipe rams (11, 21) does not have holes for oil passing.
6. The blowout preventer according to any one of the preceding claims, comprising at least four pipe rams (11, 21).
7. The blowout preventer according to any one of the preceding claims, comprising at least five pipe rams (11, 21)
8. The blowout preventer according to claim 6 or 7, wherein at least two of the pipe rams (11, 21) do not have holes for oil passing.
9. The blowout preventer according to any one of the preceding claims, wherein the control system is hydraulic, self-powered or manual.
10. The blowout preventer according to any one of the preceding claims, wherein the frame (28) is made of oxidation-corrosion-resistant material, for example austenitic nickelchromium-based superalloy.
11. The blowout preventer according to any one of the preceding claims, wherein the control system comprises a control pipe system, a fire hazard detector (31), a control unit (36), a pump (33), a hydraulic oil reservoir (34), a manually operated push button (32) and hydraulic valves (35).
12. The blowout preventer according to any one of the preceding claims, wherein the control system is adapted to sequentially close the pipe rams (11, 21) of the blowout preventer one at a time
13 The blowout preventer according to claim 2, wherein the control system is adapted to sequentially close the pipe rams (11, 21) of the blowout preventer one at a time so that the one closest to the inlet starts closing first.
14. The blowout preventer according to any one of the preceding claims, wherein the control system is adapted to sequentially close the pipe rams (H, 21) of the blowout preventer one at a time and wherein the blowout preventer comprises at least four pipe rams (11, 21).
15. The blowout preventer according to any one of the preceding claims, wherein the 25 control system is adapted to sequentially close the pipe rams (11, 21) of the blowout preventer one at a time and wherein the blowout preventer comprises at least five pipe rams (11, 21).
16. The blowout preventer according to any one of the preceding claims, wherein the control system is adapted to sequentially close the pipe rams (H, 21) of the blowout preventer one at a time so that all the pipe rams (11, 21) are closed within two hours after the pipe ram (11, 21) closest to the inlet started to close.
17. A method of preventing blowouts, wherein a blowout preventer according any of the preceding claims is located on the sea floor.
18. A method of preventing blowouts according to claim 17, the method comprising sequentially closing the pipe rams (11, 21) of the blowout preventer one at a time so that the one closest to the inlet starts closing first.
19. A method of preventing blowouts according to claim 17 or 18, comprising starting to dose each pipe ram (11, 21) after a period of time, for example 15 minutes, after the pipe ram (11, 21) located below it has started to close.
20. A method of preventing blowouts according any one of claims 17 -19, comprising closing all the pipe rams (11, 21) within two hours after the ram closest to the inlet started to close.