VALVE MODULE, SPECIALLY FOR UNDERSEA PETROLEUM WELLS

Abstract: A valve module, specially for undersea petroleum wells, of the type consisting of a central block, in the interior of which are first and second flow lines; from the first line, a production line fitted with a valve comes out of the block, and from the second line, also to outside the block, leaves a control line fitted with a valve, the first line (L1) of the central block (B) is fitted with only one valve (3) and is sealed at its upper end by a removable cap (9); the production line (LP), fitted with a valve (8), leaves from a stretch of the first line (L1) located above the valve (3) of this line (L1), the control line (LC) being fitted with at least one valve (5).

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; 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 the block, a control line 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 usually has 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 tree 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,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 ines, outside the block. Although very efficient for the purpose for which it is intended, this module or conventional tree represents a simple adaptation of the equipment used in completion work done on shore. The purpose of this invention is to improve the known valve module in such a that its manufacturing cost is reduced, its dimensions being reduced, and making it more suitable for underwater operations. By the invention, this purpose is attained by the fact that the first line of the central block is fitted that the first line of the central block is fitted with only one valve and is sealed at its upper end by a removable cap; the production line, fitted with a valve, leaves fjrom a section of the first line located above the valve of this line, the control line being fitted at least with one valve. A preferred embodiment of the present invention will now be described in more detail, with reference to the drawings which show: Figure 1 : the valve distribution system in a conven¬ tional wet Christmas tree; Figures 1a to 1e: the various operating modes of the system in figure 1 ; and Figure 2: the distribution system of the 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, Lt", 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 methods, also applicable to this invention, 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 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 milling difficult, apart from not being a raw material of low cost. Iii 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 certai 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. According to the present invention, these disadvant ges are minimized by the layout shown in figure 2. In comparison with the conventional tree or module (figura 1), three valves have been eliminated, while in figure 2 the reference numbers of figure 1 are maintained, which identify the valves and elements whose purposes coincide in both cases. One of the valves - production master - has been eliminated, as the fact of the underwater production string having a valve below the surface guarantees additional safety in case of need, due to the fact that only valve 3 has been maintained on the first line L1 of the central block B. In conventional installations, before the placing of the tree on the head of the underwater well, there is a closing plug (Baker), sealing the annular space. This p.lug is withdrawn through the second line L2 of block by means of a tool introduced from above as in mode e already described, this tool raising the plug, freeing the passage for control and possible injection of gas in the annular space. Meanwhile, it is possible to replace the conventional ly used plug with a double-retaining -valve that can be opened mechanically, simultaneously with the coupling of the tree at the head of the well. Utilizing this alternative, the doublά- retaining valve is automatically opened during the coupling of the tree, and there is no need for extracting, any sealing element. In this way, provision of a passage for tools through the second line L2 of the central block B is not required, due to the fact that in the invention the annulus swab valve of the conventional (valve 1 in figure 1) has been eliminated. Apart from this, the production swab valve of figure 1 (valve 2) has also been substituted by a blank flange, placed by a diver. In this way, central block B passes to contain only one valve, whereby its dimensions are substantially reduced, simplifying the manufacturing process of the tree and reducing its final cost. The proposed valve tree of the invention allows operations in accordance with all the modes from a to e_already listed, with the exception of intervention of the annular space, as mentioned above. An additional simplification is possible, eliminat¬ ing the interconnecting line LI that connects the control line LC to the first line L1 of block B. This interconnecting line LI being maintained, then valve 6 of the control line LC should have a diameter equivalent to valve 7. In the opposite case, that is, line L1 and valve 7 being eliminated, then valve 6 can have a quite smaller diameter, and can even be a pin valve. In this last case, the tree is specially suitable for wells of injection of water in the reservoir, i.e., for those wells in which water is injected with a view to increas¬ ing pressure in the reservoir, the oil being extracted by another well existing in the same reservoir. Only water being injected - instead of extracting oil - there is no need for carrying out the washing of the lines (mode b) , line L1 being dispensed with. The invention provides, therefore, a tree or valve module significantly more simplified than the conventional ones. 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 invention is limited only by the following claims.

Claims: Claims: 1. A valve module, specially for undersea petroleum wells, consisting of a central block inside which are provided first and second flow lines; 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 the block, a control line fitted with a valve, characterized by the fact that the first line (L1) of the central block (B) is fitted with only one valve (3) and is sealed at its upper end by a removable cap (9) ; the production line (LP) , fitted with a valve (8), leaves from a section of the first line (L1) located above the valve (3) of this line (L1 ) , the control line (LC) being fitted with at least one valve (5) . 2. A module, in accordance with claim 1 , characteri- zed by the fact that, interconnecting the first line (L1 ) of the central block (B) to the control line (LC) , an interconnect ing line (LI) fitted with a valve (7) is provided for; this interconnecting line (LI) comes out of the first line (L1) from a section above the valve (3) of this latter, and emerges from the control line (LC) at a stretch between the valve (5) of the control line (LC) and a second valve (6) also provided in this latter line. 3. A module, according to claim 1 or 2, characterized by the fact that the referred seal (9) is a blank flange.

Inventors: BELLA PINTO MARIO RUBEN, MARTINS SOBRINHO JOSE ACIEL, MELLO FACHETTI NELITO DE, BELLA PINTO, MARIO, RUBEN, MARTINS SOBRINHO, JOSE, ACIEL, MELLO FACHETTI, NELITO DE
Applicants: CBV IND MECANICA, CBV INDUSTRIA MECANICA S.A.
Application year: 1986
Main classification: E21B34
IPC codes: E21B34