WO1987001157A1

WO1987001157A1 - Valve module, specially for undersea petroleum wells

Info

Publication number: WO1987001157A1
Application number: PCT/BR1986/000010
Authority: WO
Inventors: José Aciel MARTINS SOBRINHO; Mario Ruben Bella Pinto; Nelito De Mello Fachetti
Original assignee: Cbv Indústria Mecânica S.A.
Priority date: 1985-08-12
Filing date: 1986-07-24
Publication date: 1987-02-26
Also published as: EP0232333A1; AU6193586A; BR6501114U

Abstract

A valve module, specially for undersea petroleum wells, of the type consisting of a central block inside which are provided first and second flow lines fitted with valves; from the first line a production line fitted with a valve leaves the block, and from the second line also to outside the block, leaves a control line fitted with a valve, the referred production and control lines being interconnected by a connecting line outside of the block and which is also fitted with a valve. The central block (B) has two valves (2, 3) in tandem in its first line (L1); the production line (LP) leaves from a section of said first line (L1) located between these two valves (2, 3), the second line (L2) of the central block (B) being fitted with a valve (1), from under which leaves the control line (LC), and outside the central block (B), the control line (LC) is fitted with a valve (5) between the central block (B) and the take-off from the interconnecting line (LI).

Description

Title; "VALVE MODULE, SPECIALLY FOR UNDERSEA PETROLEUM WELLS".

The present invention refers to a valve module, specially for undersea petroleum wells, consisting of a central block inside which are provided first and second flow lines fitted with valves; from the first line derives a production line fitted with a valve and which leaves the block, and from ^* the second line derives, also to outside the block, a control line fitted with a valve, the production and control lines being interconnected by a connecting line exterior to the block, which is also fitted with a valve.

These valve modules, more generally designated "wet Christmas trees", are installed on heads of undersea wells, and their purpose is to permit a plurality of operating modes. Thewet Christmas trees have two inlets and two outlets for the flow of oil and gas, respectively.

The oil flow line serves for the extraction of this product, and has usually a nominal diameter of 10.16 cm (4 inches) , while the gas line serves for the injection of gas into the annular space of the well and, eventually, also for the extraction of oil, generally having a nominal diameter of 5.08 cm (2 inches).

Conventional trees or modules have a metallic central block of valves, that serves as a structural element of the unit. In addition to the valves in the interior of this block, the trees further have individual valves fixed by flanged connections to the central block or to other intermediate elements, such as crosspieces. All the valves can have remote hydraulic drive or local manual drive, carried out by divers. An embodiment of a tree which is fairly well known and widely used in practice, consists of a central block containing two lines, one of which being provided with three valves (10.16 cm (4 inches) line), and the other one being provided with two valves (5.08 cm (2 inches) line); from the 10.16 cm (4 inches) line emerges, between two valves, a production line which is fitted with another valve outside the block; from the 5.08 cm (2 inches) line emerges, also between the two valves, a control line having an additional valve out¬ side the block. A crossover line, fitted with a valve, connects the production and control lines, outside the block. Although very efficient for the purpose for which it is intended, this module or conventional tree represents a simple adaptation of equipment used in completion work done on shore. The purpose of this invention is to improve the known valve module in such a way that its manufacturing cost is reduced, its dimensions being reduced and it being made more suitable for underwater operations.

By the invention, this purpose is attained by the fact that the central block has, on its first line, only two valves in tandem; the production line leaves from a section of said first line located between these two valves, the second line of the central block being fitted with a valve, from under which leaves the control line, and that, outside the central block, the control line is fitted with a valve between the central block and the take-off from the interconnecting line of the control and production lines.

Elimination of one of the valves of the first line of the central block is possible, since the head of an under- sea well has in the production line, a subsurface valve that can be blocked in case of need, therefore continuing to exist a double safety against possible leakages arising from, for example, damage to the production line and/or to its valve. The fact that one of the valves of the second line is transferred to outside the block, eliminates the need for standardization of this valve with regard to the nominal diameter of the second line and eliminates the danger of possible damage to this valve when any kind of tool is introduced from the upper side of the tree, since this tool has to pass through the valves of the second line.

The invention will now be described in more detail, based on a preferred embodiment shown schematically in the drawings which show: Figure 1: the valve distribution system in a conventional wet Christmas trees;

Figures 1a to 1e: the various operating modes of the system of figure 1 ; and

Figure 2: the distribution system of the present invention.

The manner in which the valves are arranged in the conventional tree is observed in figure 1.

The usual terminology for these valves is as follows: - valve 1 : annulus swab

- valve 2: production swab

- valve 3: production upper master

- valve 4: production lower master

- valve 5: annulus master - valve 6: annulus wing

- valve 7: crossover

- valve 8: production wing.

Valves 1 , 5 and 6 allow access and control of the annular space of the well and are generally standardized at 5.08 cm (2 inches), while valves 2, 3, 4 and 8 permit access, the drainage of fluids and control of the production string or column, and are generally standardized at 10.16 cm (4 inches) .

Valves 2 to 4 are provided for along a first line, L1 , inside block B, and valves 1 and 5 are disposed in the second line, L2. The production line, LP, containing valve 8, stems from the first line, L1 , while the control line, LC, containing valve 6, branches off from line L2. The production line LP, and the control line, LC, are communicable between themselves by means of a crossover or interconnecting line LI, which is fitted with a valve 7. This latter line LI is only schematically represented above block B, since in reality it goes around the block sideways.

Figures 1a to 1e represent the five usual operating modes of the conventional module or tree. In these figures the closed valves are those represented filled-in, in black, the flow being indicated in boldface.

Operating modes, also applicable to this invention, are the following: a) Normal production flow: the oil flows along lines L1 and LP, vlaves 5 and 6 being opened only for control of the annular space. b) Washing of lines: all valves of the block are closed, while a suitable medium flows along the lines LC, LI and LP. c) Artificial elevation: gas is injected by the LC control line in order to ease the oil outlet while the oil flows normally as in case a) . d) Production by the control line: with valves 1, 2,

5 and 8 closed, the oil is extracted by means of the LC control line, whose nominal diameter is less than that of the produc¬ tion line LP. e), Intervention in the well: all valves of block B are opened and tools are introduced from the top down lines L1 and L2 for cleaning, inspection or testing.

The conventional tree-, represented in figure 1, has the disadvantage of housing five valves in the interior of block B. This block B is made from a large-sized billet, which makes all subsequent operations of processing and mill¬ ing difficult, apart from not being a raw material of low cost In addition, in the case of intervention of the well, the tools that are introduced for working in the well (under the tree), necessarily have to pass through valves 1, 5 and 2 to 4, with possible damage thereto. There existing, furthermore, a certain standardization of the production string in relation to its nominal diameter, valves 2 to 4 should attend to this standardization for carrying out the intervention, which also applies to valves 1 and 5. In the case of the invention, however, as shown in figure 2, these disadvantages of the conventional tree are minimized, insofar as one of the production^•valves 3 or 4 is eliminated, and the subsurface valve of the well guarantees a second option of blocking the flow-of oil in cases of emergency. With this elimination it is possible to reduce the height of block B. In addition, valve 5 has been transferred to the outside part of the block, thereby making unnecessary its standardization in relation to the nominal diameter of line L2 and of the annular space control column of the well.

It can immediately be perceived that all the operat¬ ing modes already reported are also possible with the module proposed here, since valves 3 and 4 of the conventional module are always operated simultaneously. Therefore, in order to carry out the conventional operations according to the five modes represented in figures 1a to 1e, the valves of the tree proposed here should be operated in the same way as previously, their correlation being observed by means of the reference numbers which coincide in both cases.

A preferred embodiment of the invention based on purely schematic drawings having been described, merely by way of example, it should be understood that the presente inven¬ tion is limited only by the following claim.

Claims

Claim:

A valve module, specially for undersea petroleum consisting of a central block inside which are provided first and second flow lines fitted with valves; from the first line derives a production line fitted with a valve and which leaves the block, and from the second line derives, also to outside the block, a control line fitted with a valve, the production and control lines being interconnected by a connecting line exterior to the block, which is also fitted with a valve, characterized by the fact that the central block (B) has, on its first line (L1), only two valves (2,3) in tandem; the production line (LP) leaves from a section of said first line (L1) located between these two valves (2,3), the second line of the central block being fitted with a valve (1), from under which leaves the control line (LC) , and that outside the central block (B) , the control line (LC) is fitted with a valve (5) between the central block (B) and the take-off from the interconnecting line (LI) of the control and production lines.