EQUIPMENT FOR INSTALLATION OF MODULES ON FIXED UNDERWATER BASES, SPECIALLY FOR UNDERSEA PETROLEUM WELLS

Abstract: An equipment for installation of modules (5) on underwater bases (1) that have guide posts (3) for the alignment of a set to be connected, composed of a connecting rod (4), a module (5) and a retrievable tool (6) and which has guide funnels (7) that fit to said guide posts (3) of the bases (1). The purposes of the invention are to provide an equipment of this type that reduces requirements with regard to the precision of mutual positioning between funnels (7) and set (4, 5, 6) during assembly and that reduces the costs of its manufacture. This is attained by the fact that the guide funnels (7) will be built into a rigid structure (8, 10) rotatory in relation to the set (4, 5, 6) and by the fact of this structure being modulated on the tool (6).

Description: Title; "EQUIPMENT FOR INSTALLATION OF MODULES ON FIXED UNDER¬ WATER BASES> SPECIALLY FOR UNDERSEA PETROLEUM WELLS". This invention refers to an equipment for installa¬ tion of modules on fixed underwater bases, specially for under sea petroleum wells, consisting of a connecting rod, a module built into the connecting rod and a retrievable tool, built into a rigid column and connectable to said module, a set of guide funnels being provided, distributed in a rigid geometry corresponding to that of the guide posts of the fixed base to which the connecting rod-module set has to be connected. In the exploitation of offsore oil wells, during boring, a permanent guide base is installed over the well in the mud line at the sea bottom. This base contains four guide posts and a well head on which is connected, afterwards and through a hydraulic connecting rod, a valve module, better known as a "wet Christmas tree". From a platform or vessel on the surface, the tree is lowered to the bottom connected to a retrievable tool, with remote hydralic drive and connected to a rigid column. This tool is connected to the upper part of the wet Christmas tree, and in the lower part of the latter is the referred hydraulic connecting rod, which in turn is fitted with four guide funnels suitable for slipping over the guide posts of the base that contains the well head. The entire set formed by the tool, tree and connect¬ ing rod is guided during the descent by four steel cables stretching from the surface to the bottom, each of which has its lower end connected to one of the guide posts of the base, and each cable passes through one of the guide funnels. In this way it is possible to carry out a speedy and safe connection, without the aid of divers, even at great depths. Conventionally., the guide posts of the permanent base have a tubular shape of standardized dimensions, and are distributed on the apexes of an imaginary square and turned upwards. The already mentioned guide funnels are, essentially, metallic tubes with a tapered widening of their lower ends and whose internal diameters are greater than the external diameter of the guide posts, in order that the funnels may freely slip onto the posts, when the connecting rod is connected to the head of the well. The connection between the guide funnels and the connecting rod is rigid, the former being disposed around the connecting rod in an identical geometr to that of the guide posts of the base. Once the tree is connected to the head of the well, the hydraulic connecting rod is locked and the tool is raised by means of the rigid column, remaining on the bottom the tree and the connecting rod together with the guide funnels built into it. This known system has the disadvantage that, after the funnels being to be guided on to the posts, the freedom of rotary angular movement between the tree-connecting rod set and the base is limited to the radial clearance existing between the posts and the funnels, normally resulting in a degree of freedom, of about 2 . Since the well head generally has two eccentrically located openings - one of larger diameter for the extraction of oil and the other of smaller diameter for the injection of gas - a .certain precision becomes necessary in the angular disposition rod from which leave the ducts that have to be fitted into the referred openings. These ducts are rigidly disposed in the tree-connecting rod set, by virtue of the fact that an incorrect disposition of the set of guide funnels can make, inclusively, the coupling impossible when the error in said disposition is superior to the freedom of angular movement already mentioned. The purpose of this invention is to provide a system for the installation of valve modules in submerged bases, by which great concern becomes unnecessary with regard to the precision of mutual positioning between the set formed by the connecting rod, the tree and the tool. This purpose is attained, according to the invention, by the fact that the set of guide funnels is built into a rigid structure that is mounted rotatably on one of the parts of the connecting rod-tree-tool set. Another purpose of this invention is to provide a system of the type described that is of lower cost than that of the conventional systems. This purpose is attained by the fact that the set of guide funnels is mounted on the tool. By means of the measures recommended by the inventicn it is possible to reduce the requirements relating to precision of assembly, since the connecting rod-tree tool set can be rotated in relation to the set of guide funnels, and the fact that this latter set is mounted on the tool - instead of being mounted on the connecting rod, as is usual - makes it possible also to recover the set of funnels when the tool is unlocked from the tree and raised to the surface by means of the rigid column. The reuse of this set of funnels in other operations reduces, consequently, the manufacturing costs of the tree, which passes to do without a built-in set funnels. In order to prevent the connecting rod-tree-tool set during descent from being twisted by marine currents, giving a torque to the rigid column that is fixed to the tool, an interlocking plunger can be provided between the set of funnels and said first set, in such a manner that the freedom of turn between both sets only exists when this plunger undoes the interlocking between the parts. In this way, the sets can be lowered to the guide base blocked between themselves and, only in the case of the position between the ducts of the tree connecting rod and the openings of the well head being incorrect, the interlocking plunger is freed at a distance - after the fitting of the funnels on the guide posts of the base - and the connecting rod-tree-tool set is turned, by means of the rigid column, until the correct coupling position is obtained. In a preferred embodiment of the invention, four equidistant arms of equal length are radially extended outwards from a band just fitted on the tool , and the ends of such arms the guide funnels being, built in. A preferred embodiment of the present invention will now be described with reference to the drawings which show: Figure 1 : a schematic frontal view of the system in accordance with the invention, already, connected to the permanent base; and Figure 2: a schematic view, partially in cut-off, of a variation of the tool. Figure 1 represents the phase in which the wet Christmas tree 5 has already been connected to the well head 2 of the permanent base guide 1 , by means of hydraulic connect ing rod 4, base 1 being located at mud line on the sea bottom. Here, in substitution of the known system, in which the guide funnels were built into connecting-rod 4, the funnels 7 are interconnected to a band 10, by means of inclin¬ ed arms 8. This band 10 is fitted on the hydraulic tool 6 in a rotary fashion, in such a manner that even with the set of funnels 7 being guided initially by the steel cables 11 - which are fixed to the upper ends of the guide posts 3 of the base 1 - and, in the final phase, by the guide posts 3 themselves, a rotary mobility of the set 4, 5, 6 is still possible by means of the rigid column 9. In lines traced on well head 2 are represented open¬ ings 2a, 2b respectively destined to receiving the ducts 12a, 12b that are built into the connecting-rod and tree. Duct 12a, of greater diameter, serves for extraction of oil, while the smaller duct 12b is for the injection of gas. The nominal diameters of these ducts are generally 4" and 2" (10.16 cm and 5.08 cm), respectively. In this case, the connecting rod-tree-tool 4, 5, 6 is lowered to the bottom, suspended by the rigid column 9 which, as also for the steel cables 11, extends to theplatform or ship. The cables 11 give permanent guidance to the set 4, 5, 6, until the guide funnels 7 slip on to the guide posts 3 of base 1. If the fitting of ducts 12a, 12b inside the open¬ ings 2a, 2b is not immediate, the set 4, 5, 6 can be turned round by means of twisting the rigid column 9, until the fit position is reached. The connecting rod and tree 4, * 5 being connected to base 1 , tool 6 is freed, which is retrieved together with the structure of the guide f nnels 7, 8, 10, and these elements can be reused in other operations. A second realization of tool 6 is represented in figure 2. While in figure 1 the arms 8 have a downward inclination as from band 10, in figure 2 the arms 8 protrude horizontally from said band 10. This type of configuration is applicable in the case of the wet tree (or any other device to be connected to the base) having a height H (see figure 1) - more reduced, so that it is not necessary to have the arms with a corresponding inclination. From figure 2 it is observed that the band 10 is only supported on an annular projection, of the- tool 6, a hydraulic or pneumatic cylinder 11 being provided next to the band 10, inside which there is a plunger that can cross band 10. Cylinder 11 being subjected to pressure for exemple, the plunger is compressed against the tool 6, impeding the relative rotation between the band 10 and the tool 6. In order to free the plunger, it is only necessary to reduce the pressure on cylinder 11. The ways of making the structure of, the guide funnels according to the invention are innumerable, it being essential only that it is disposed in a rotary manner either on the connecting rod or on the tool , or even that it is connected in rigid fashion to the tool, in which case its advantage lies in that the structure of the funnels becomes retrievable, while in the case in which it isrotatory there is the advantage that requirements are reduced with regard to the precision of assembly between the structure of the funnels and the part on which it is mounted.

Claims: Claims ; 1. Equipment for installation of modules on fixed underwater bases, specially for undersea petroleum wells, consisting of a connecting rod, a module buil into the connect ing rod and a retrievable tool, built into a rigid column and connectable to said module, a set of guide funnels being provided distributed in a rigid geometry corresponding to that of guide posts of the fixed base to which the connecting rod- module set has to be connected, characterized by the fact that the set of guide funnels (7) is built into a rigid structure (8,10) which is mounted rotatory on one of the parts of the connecting rod-tree-tool set (4,5,6). 2. Equipment, in accordance with claim 1 , characteri. zed by the fact that said rigid structure (8, 10) is rigidly joined to a cylinder (11) containing an interlocking plunger being movable at least between two terminal positions, in one of which it makes an interlocking by friction with the part (4,5,6) on which the structure (8, 10) is mounted. 3. Equipment for installation of modules on fixed underwater bases, specially for undersea petroleum wells, consisting of a connecting rod, a module builtinto the connecting rod and a retrievable tool, built into a rigid column and connected to said module, a set of guide funnels being provided distributed in a rigid geometry corresponding to that of guide posts of the fixed base to which the connect¬ ing rod-module set has to be connected, characterized by the fact that the set of guide funnels (7) is mounted on the tool (6). 4. Equipment, according to any of claims 1 to 3, characterized by the fact that the set of guide funnels (7) is built into a rigid structure (8, 10) including a band (10) mounted rotatory on the tool (6) from which arms (8) extend, radially outwards in whose ends the guide funnels (7) are fixed. 5. Equipment, in accordance with * claim 4, characteri zed by the fact that the band (10) is supported on an annular projection (6a) of the tool (6) . 6. Equipment, in accordance with claim 4, characteri. zed by the fact that the arms (8) are protruding radially with a downward inclination from the band (10).

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: E21B33
IPC codes: E21B33