WO1987001159A1

WO1987001159A1 - Valve module, specially for undersea petroleum wells

Info

Publication number: WO1987001159A1
Application number: PCT/BR1986/000012
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: BR6501116U; EP0232335A1; AU6194086A

Abstract

A valve module, specially for undersea petroleum wells, consisting of a central block inside which are first and second flow lines fitted with valves; from the first line 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 also fitted with a valve, which is characterized by the fact that the first and second lines (L1 and L2) of the central block (B) are each fitted with a single valve (2, 1); under each valve (2, 1) of these lines (L1 and L2) emerge the production (LP) and control (LC) lines, respectively, the production and control lines being fitted with two valves (3, 8; 5, 6) each, outside the central block (B), and the interconnecting line (LI) emerges from the production (LP) and control (LC) lines from a stretch between the two valves (3, 8; 5, 6) of these lines.

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 comes out of the block, and from the second line derives, also to outside block, a control line fitted with a valve, the production and control lines being interconnected by a connecting line outside of 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. The wet 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) .

The 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 (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 outside 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 the present invention is to improve the known valve module in such a way that its^" manufacturing cost is reduced, its dimensions being reduced, and making it more suitable for undersea operations. This purpose is attained by the present invention, due to the fact that each of the first and second lines of the central block is fitted with a single valve; under each valve of these lines leave the production line and the control line, respectively, said production and control lines being fitted with two valves each, outside the central block, and the inter connecting line leaves the production and control lines from a section located between the two valves of these lines.

The invention will how 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 conven¬ tional wet Christmas tree;

Figures 1a to 1e: the various operating methods of the system in 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: pruduction 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

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 arranged along a first line, L1 , inside block B, and vlaves 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, contain¬ ing valve 6, branches off from line L2. The production line, LP, and the control line, LC, are communicable between themselves by means of an interconnecting line, LI, or cross¬ over, that valve 7 has. This latter line LI is only schemati¬ cally represented above block B, since in reality itgoes 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.

The operating modes, also applicable to this system, are the following: a) Normal production flow: the oil flows along lines

L1 and LP, valves 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 flow 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 this standardization for carrying out the intervention, which also applies to valves 1 and 5. According to the invention, these disadvantages are minimized by the layout shown in figure 2.

The differences between the tree proposed herein and the conventional one are that valve 4 (figure 1 ) has been eliminated and valves 3 and 5 transferred to the exterior of central block B. Elimination of one of the production master valves (3,4) is possible due to the fact of there being a sub¬ surface valve in the underwater production string, that can be closed in case of need, guaranteeing together with valve 3 - in this invention - double safety in case of need. By means of these measures it is possible to reduce the size of central block B, whose height becomes substantial¬ ly less than that of the block in figure 1 , making the use of smaller-sized raw material possible and simplifying the entire process during manufacture thereof. Apart from this, not only do valves 3 and 5 make standardization unnecessary with regard to the nominal diameter of the well piping, but also are no longer subject to occasional damage by tools introduced by means of lines L1 and L2 of the block, in the case of intervention of the well (mode e) .

With the proposed embodiment as represented in figure 2, all possibilities already described of operating modes are maintained, and in mode e, corresponding to the intervention, valves 3 and 5 remain closed, since only valves 1 , 2, which are in the interior of the block, need to be open for letting tools through.

In the case that it is advisable to increase the strength of the unit in order to provide against possible damage from impacts from foreign elements to the equipment, such as ships' anchors, the valves 5,6 and 3,8 can be disposed in the interior of two individual blocks, respectively.

Whatever the final arrangement of the new Christmas tree or module may be, the result is a unit whose dimensions are smaller than those up to the present time,- which in itself makes the unit less prone to damage by foreign elements.

One embodiment based on purely schematic drawings having been described, merely by way of exemple, it should be understood that the invention is limited only by the following claims.

Claims

Claims :

1. Valve module, specially for undersea petroleum wells, consisting of a central block inside which there are provided first and second flow lines fitted with valves; from the first line derives a production line fitted with a valve and which comes oil of 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 outside of the block, which is also fitted with a valve, characterized by the fact that each of the first and second lines (L1 and L2) of the central block (B) is fitted with a single valve (2, 1); under each valve (2, 1) of these lines (L1 , L2) leave the production line (LP) and the control line (LC) , respectively, said production and control line being fitted with two valves (3,8; 5,6) each, outside the central block (B) , and the interconnecting line (LI) leaves the production (LP) and control (LC) lines from a section located between the two valves (3,8; 5,6) of these lines.

2. Valve module, in accordance with claim 1 , characterized by the fact that the two valves (3,8; 5,6) of each of the production (LP) and control (LC) lines are housed inside an individual block.