EP0533526B1 - Device for monitoring deposits for a production well - Google Patents

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 measurements: check the state of the well, monitor the equipment in the well, make statements of the acoustic emissions produced by the area during production, carry 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 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, constituting the prior art corresponding to the preamble of claim 1, there is described a device for facilitating 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 assemblies 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 added 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.

By patent application GB-A-2 196 410, a method of monitoring the interior space of a tubular column in a well is known, consisting essentially of including parameters measurement devices in housings formed in connections between the sections of the column, these housings communicating or not with the interior of each fitting and adjacent tubular sections, to measure different parameters related to the circulation of fluids inside: pressures, temperatures, acoustic, nuclear, electromagnetic activity .

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 device for monitoring an underground deposit which is the subject of appended claim 1, is intended to be installed in a well provided with a casing tube comprising a plurality of sections interconnected to one another by connection means, this casing tube being held in place by injecting cement into the annular space between it and the well. The device includes sensors for monitoring and it is characterized in that it comprises at least one tubular connection disposed between two successive sections of the casing tube, provided with a first cavity separated from the outside of the casing tube by a plate containing a main monitoring module including surveillance sensors, this main surveillance module being connected by means of waterproof connectors and connection means, to a central control and recording unit. At least one second tubular connection between two other sections of casing tube is also provided with a cavity separated from the outside of the tube by another plate, containing a secondary monitoring module including monitoring sensors and sealed connection means. for the interconnection of each second monitoring module to the first module.

Because the cavities in the fittings are separated from the outside of the tube and the formations surrounding the well by a plate, acoustic or seismic equipment can be placed there to monitor an underground deposit.

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

The device may also include at least one secondary relay module provided with means for acquiring signals received by monitoring 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 cavities isolated from the outside of the casing tube by plates, for elements of the monitoring module.

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.

The invention also relates to a method for monitoring a deposit according to claim 8 appended.

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 with the aim of bringing 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 positioning 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 fittings 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 can 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 have been established between the lines 12 and the waterproof connectors 10, the cavity 11 is filled with insulating grease and closed by an external 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 adapted to amplify, filter and digitize and optionally multiplex 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 at 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 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 partly inside the casing tube 42.

Claims (8)

1. Improved device for monitoring an underground deposit designed to be installed in a well fitted with a lining tube or casing (2) having a plurality of sections inter-connected with one another by connector means, the said casing being retained in position by injecting cement into the annular space between it and the well, this device having monitoring sensors and being characterised in that it has at least one tubular connector (3) arranged between two successive sections of casing tube, this connector being provided with a first cavity separated from the outside of the casing tube (2) by a plate (16) and containing a main monitoring module incorporating monitoring sensors which is linked by means of sealed connectors (10) and linking means (13) to a central control and recording unit (C), the device having in addition at least one second tubular connector between two other sections of casing tube also provided with a cavity separated from the outside of the casing by another plate (16), containing a secondary monitoring module incorporating monitoring sensors (6) and sealed linking means (17, 18) for inter-connecting each second monitoring module to the first module.
2. Device as claimed in claim 1, characterised in that it has at least one secondary monitoring module linked to the main module by analogue transmission means (18).
3. Device as claimed in claim 1, characterised in that it has at least one secondary relay module provided with means for acquiring signals received by monitoring sensors (6) incorporated in at least one other secondary monitoring module.
4. Device as claimed in one of the previous claims, characterised in that the electronic unit (E) of the main monitoring module has digital transmission means (8E) for communications between it and the said control and recording unit (C) at the surface.
5. Device as claimed in claim 4, characterised in that at least one secondary monitoring module has means for providing a link of the digital type to the main monitoring module.
6. Device as claimed in one of the previous claims, characterised in that each tubular connector is non-symmetrical and has a wall that is thicker over a part of its circumference, this thicker wall section being provided with several housings (5, 7) for the elements of the monitoring module, isolated from the outside of the tube by a cover (16) fixed against the said wall.
7. Device as claimed in one of the previous claims, characterised in that it has linking means arranged at least partially inside the different sections of casing tube (2).
8. Method for permanently monitoring an underground deposit consisting in installing modules in a fixed position in a well, each of which incorporates one or several monitoring receivers behind a lining tube or casing (2) made up of a plurality of tubular sections connected to each other, this tube being designed so as to be cemented in the well once it has been positioned, the method being characterised in that the monitoring receivers are inserted in cavities arranged in several connectors (3) inserted between two consecutive tubular sections at different depths along the casing (2), the cavities being separated from the outside of the casing by plates (16) and being linked to one another and to a central control and recording unit (C) by means of sealed linking means.

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