EP0533526A1 - Device for monitoring deposits for a production well - Google Patents

Abstract

In a well (1) which is to be equipped for production from an underground deposit, a lining tube or casing (2) is lowered, which casing comprises a set of tubular sections connected in succession to each other by means of tubular connectors (3), at least some of which are modified, and it is cemented once installed in the well. These special connectors (3) comprise housings (5, 7) for one or more sensors (6) and others possibly for electronic acquisition and transmission circuits (8). The various connectors (3) of the device are interconnected to each other by cables (18) and to a surface installation by a multi-conductor cable (13) for the electrical power supply to the electronic modules and the transmission of the acquired data. This arrangement enables the various connectors to be prewired, which simplifies the installation of the device during the manipulation of well equipment. <??>Application to the monitoring of oil production wells for example. <IMAGE>

Description

The invention relates to an improved device for monitoring an underground deposit, which is permanently installed in a cased well.

Such a device finds its applications for example in wells equipped for the production of an underground deposit and in particular of an oil deposit. In applications of this kind, a monitoring device makes it possible to make different types of measurement: checking the state of the well, monitoring the equipment in the well, making statements of the acoustic emissions produced by the area during production, carrying out seismic surveys to know the evolution over time of the monitored underground area etc. By the published French patent applications Nos. 2,593,292 and 2,642,849, methods are known for installing a set of sensors in a well which, for the needs of the production of petroleum fluids, is equipped with a casing tube sealed in a well by cementing. The sensors are installed outside the casing tube and once it has been placed in the well, they are embedded in the cement which is injected to couple it with the walls of the well. In the aforementioned patent application 2 642 849, a device is described to facilitate the installation of well monitoring equipment. It comprises protective elements fixed externally to certain sections of the casing tube, delimiting housings where reception assemblies can be fitted. Each of these sets includes a support with cavities for acoustic or seismic sensors and electronic circuits to amplify and correct the signals picked up before their transmission by a transmission line going up the length of the tube to a central control and monitoring station. 'recording installed on the surface. The device is designed to effectively protect the monitoring equipment placed outside the casing tube against the shocks and settlements which generally occur during lowering operations and positioning of the latter in the drilled wells.

The installation in a well of the prior device makes it necessary to use modified tube sections with welding of thick ribs and anchoring elements, in order to delimit the housings for the boxes containing the sensors and the electronic equipment. acquisition and transmission. The addition of these protective elements must often be carried out by modifying the sections of tube available on the same well equipment site. In addition, the elements which are attached to the outside of the casing tube come in extra thickness and the total section is very significantly increased, which is often penalizing in relatively narrow wells.

The improved device according to the invention allows the simplified integration of equipment for monitoring casing tubes intended to be cemented once placed in wells, using elements which can be manufactured in the workshop and brought to a construction site. well equipment to be directly connected to sections of the casing tube when assembled.

The improved deposit monitoring device according to the invention is intended to be installed in a well provided with a casing tube comprising a plurality of sections interconnected to each other by tubular connections, this casing being held in place by injection of cement in the annular space between it and the well. The device according to the invention is characterized in that it comprises at least one tubular connection between two successive sections of the casing tube, modified to contain a main monitoring module including sensitive sensors and possibly an electronic unit, said monitoring module being connected to a surface installation by connecting means.

The device may for example include at least one second modified tubular connector containing a secondary monitoring module including sensitive sensors and sealed connection means for the interconnection of each second monitoring module to the first.

Each secondary monitoring module can include electronic means for amplifying and filtering the signals received by the sensors of the same module.

The device comprises for example at least one secondary monitoring module connected to the main module by analog transmission means.

The device can also include at least one secondary monitoring module provided with means for acquiring signals received by sensitive sensors from at least one other secondary monitoring module.

The electronic unit of the main monitoring module comprises for example digital transmission means for communications between them and said surface installation.

The device can also include at least one secondary monitoring module including digital connection means with the main monitoring module.

According to one embodiment, the device comprises asymmetrical tubular connections provided with a thicker wall on a part of its periphery, this thicker wall being provided with several housings, for elements of the monitoring module, these housings being closed by a cover fixed against said wall.

According to one embodiment, the device comprises connecting cables arranged outside the casing tube.

According to another embodiment, the device comprises connecting means arranged at least partially inside the different sections of the casing tube.

With the device according to the invention, the installation of the casing tube can be carried out more easily by interconnection of sections by means of fittings pre-equipped with sensitive sensors and in electronic modules, which are joined to each other as they are put in place by cables which are connected by waterproof connectors. Well equipment operations are therefore greatly facilitated.

• la Fig. 1 montre schématiquement un tube de cuvelage ou casing avec des raccords pour l'interconnexion de ses différentes sections;
• la Fig.2 montre schématiquement un module de surveillance principal installé dans un raccord intermédiaire;
• les fig.3 à 6 montrent des vues en coupe du même raccord suivant plusieurs plans de coupe;
• la Fig.7 montre schématiquement le raccordement de lignes conductrices d'un câble de transmission extérieur au tube de cuvelage avec des conducteurs intérieurs à un module de surveillance;

Other characteristics and advantages of the device according to the invention will appear better on reading the following description of embodiments described by way of nonlimiting examples, with reference to the appended drawings where:

• Fig. 1 schematically shows a casing or casing tube with fittings for the interconnection of its different sections;
• Fig.2 schematically shows a main monitoring module installed in an intermediate connection;
• fig.3 to 6 show sectional views of the same fitting along several cutting planes;
• Fig.7 schematically shows the connection of conductive lines of an external transmission cable to the casing tube with internal conductors to a monitoring module;

A well 1 having been drilled in order to put an underground deposit into production, a casing or casing tube 2 is generally installed there (Fig. 1) constituted by the end-to-end interconnection of a set of sections by means of fittings 3 and it is held in place by an injection of cement into the annular space between it and the well 1.

Monitoring the production area requires the installation in the well of a set of sensitive sensors adapted to the type of measurements to be made. This installation is ensured with the device according to the invention, by replacing the conventional fittings used to connect the sections of the casing tube with the special fittings 3 described below in relation to FIGS. 2 to 7.

The connections 3 are tubular and eccentric with, at each end, a nozzle 4 where one comes to fit and screw one end of a section of the casing tube. On part of their periphery, the sleeves 3 have an extra thickness 4 of their wall. In each of these extra thicknesses 4, are provided different housings 5 for suitable sensor elements 6 such as for example three geophones Gx, Gy, Gz whose axes are oriented in three orthogonal directions, so as to determine the amplitude and the direction of arrival of the received waves. Other housings 7 are provided for an electronic unit E. Depending on the case, the electronic unit may include one or more circuits or cards 8 adapted to process the signals received by the various sensors 6. Electrical conductors 9 (Fig. 7 ) associated with the various sensors 7 and / or with the cards 8, are connected by waterproof connectors 10, in a lateral cavity 11 of the upper part of the sleeve 3, with different conductive lines 12 of a multi-conductor cable 13. The cable 13 crosses the wall of the connector (Fig.7) and opens into the lateral cavity 11. Its outer sheath 14 is held in place relative to it by means of a locking cone 15. Once the connections established between the lines 12 and the waterproof connectors 10, the cavity 11 is filled with insulating grease and closed by an outer plate 16. The cable 13 is placed, for example, outside the casing tube and goes up to one hundred unit control and recording line C on the surface (Fig. 1).

In the lower part of each connector 3, waterproof connectors 17 allow the connection to the electronic unit, of several external cables 18.

This type of connection 3 allows different organizations of the monitoring device. According to the invention, this comprises at least one main module in an interconnection connector 3 such as that of FIGS. 2 to 7. This main module comprises an electrical supply circuit 8A supplied from the surface installation C by conductors 12 of the multi-conductor cable 13 and producing the regulated voltages necessary for the operation of at least the main module, several circuits d acquisition 8B, 8C, 8D suitable for amplifying, filtering and digitizing and possibly multiplexing the signals received by sensors, and a coding circuit 8E for the transmission of the signals acquired to the central unit C at the surface.

The monitoring device according to the invention can also comprise at least one secondary module in another connection at a different depth with housings for at least one or more sensors 6. These sensors can be connected directly by cables 18 with the main module and the signals they pick up are acquired by its electronic circuits.

According to another embodiment, the secondary module can also include local electronic circuits for amplification and filtering of the signals received locally before their transmission in analog form to the main module.

In another two-stage arrangement, a secondary module without electronic circuits can directly transmit the analog signals produced by local sensors to a secondary relay module where amplification and filtering circuits have been included, and this relay module transmits all amplified signals to a main module via an analog or digital type link.

The monitoring device may include a large set of various sensors distributed in a plurality of fittings at different depths of the casing tube, with secondary modules without electronic circuits, one or more secondary relay modules provided with electronic circuits for collecting received signals to one or more lower levels and transmit them amplified to a main module provided with coding, multiplexing and data transmission circuits collected towards the central unit C at the surface.

The passive (sensors) and active (electronic circuits) elements being grouped together in the fittings and pre-wired, the installation of the device at the time of the construction of the casing tube 2, essentially consists in establishing the electrical connections of the cables 13 and 18 which connect them all to the surface installation.

In the embodiments described, the cables (13, 18) for the interconnection of the various monitoring modules and the connection of a main module are arranged outside the casing tube. It would not, however, depart from the scope of the invention to establish connections included at least in part inside the casing tube 42.

Claims (10)

1) An improved device for monitoring an underground deposit intended to be installed in a well provided with a casing tube (2) comprising a plurality of sections interconnected to each other by tubular connections (3), said casing tube being held in place by injecting cement into the annular space between it and the well, characterized in that it comprises at least one tubular connection (3) disposed between two successive sections of the casing tube, provided with at least one sealed housing to contain a main monitoring module including sensitive sensors (6), said main monitoring module being connected by connecting means (13) to a central control and recording unit (C). 2) Device according to claim 1, characterized in that it comprises at least a second modified tubular connection containing a secondary monitoring module including sensitive sensors (6) and sealed connection means (17, 18) for interconnection from each second monitoring module to the first module. 3) Device according to claim 2, characterized in that the main monitoring module and each secondary monitoring module comprises electronic amplification and filtering means (8) of the signals received by the sensors of the same module. 4) Device according to claim 2 or 3, characterized in that it comprises at least one secondary monitoring module connected to the main module by analog transmission means (18). 5) Device according to claim 2 or 3, characterized in that it comprises at least one secondary-relay module provided with means for acquiring signals received by sensitive sensors included in at least one other secondary monitoring module. 6) Device according to one of the preceding claims, characterized in that the electronic unit E of the main monitoring module comprises digital transmission means (8E) for communications between it and said control and recording unit (C) at the surface. 7) Device according to claim 6, characterized in that at least one secondary monitoring module comprises digital type connection means with the main monitoring module. 8) Device according to one of the preceding claims, characterized in that each tubular connection is asymmetrical and has a thicker wall on a part of its periphery, this thicker wall being provided with several housings (5, 7), for elements of the monitoring module, said housings being closed by a cover (16) fixed against said wall. 9) Device according to one of the preceding claims, characterized in that it comprises connecting cables (13, 18) arranged outside the casing tube (2). 10) Device according to one of the preceding claims, characterized in that it comprises connecting means arranged at least partially inside the different sections of the casing tube (2).

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