EP0816632B1 - Apparatus and method for information transmission by electromagnetic waves - Google Patents

Description

The present invention is in the field of well production tests drilled in a geological formation, usually for the purpose of qualitatively and quantitatively the effluents contained in the geological formation crossed by the drilling. This type of test, called "DST" for "Drill Stem Test" is generally performed in course of drilling an exploration well. We will not, however, depart from the framework of the present invention, if these tests are carried out in production wells, at the start or in during the production phase.

The present invention relates to a device for transmitting, in particular in real time, information on both sides of a test valve placed in a packing of tubes, commonly called test packing, the packing being introduced into a well drilled in the ground, according to conventional procedures.

There are different systems to know in real time and from the surface, pressures, temperatures, flow rates, etc. at a point in a well located under a test valve while this valve can be opened or closed depending on the operational phase of this test: in flow (flowing) or in pressure rise (build up).

Some systems use a hydraulic channel located in the wall of the train test, which connects the pressurized volume located under the test valve up to pressure measurement gauges located above the valve. Measures these gauges are then transmitted to the surface via an electric cable connected to a fitting with special electronic means. The connection is made by coupling by means of a mutual induction transformer or by a loop of current.

Other systems use acoustic transmission in the body of the train. test, for example according to document WO 92/06278.

The first systems have the main disadvantage of requiring a train test, and more specifically a test valve including the integration of a passage hydraulic. This type of implementation is very complex and very expensive to manufacture and maintenance. Furthermore in these systems, the connection, electrical or mutual induction, of the electric cable connecting to the surface the measurement means located above of the test valve, is very sensitive to the nature of the fluid located inside the tube production. In particular, transmission is very difficult when the fluids are conductors.

The system illustrated by document WO 92/06278, also requires a electrical connection between the receiver above the valve and the cable electric. Whether this connection is made by mutual induction or by a connector electric in a liquid environment ("wet connector"), the same results disadvantages than for other known systems.

In addition, in these solutions the transmission distance is practically limited to a length of tubes, about ten meters. Therefore the connector attached to the lower end of the electrical cable must be positioned approximately ten meters above the test valve. In the event that the well produces a effluent containing sand, this sediments after the flow corresponding to closing the test valve, thus forming a plug that can reach several tens of meters high, which can prevent the proper functioning of the connector, its anchoring or undocking.

Thus, the present invention relates to an information transmission device between the bottom of a well and the ground surface, said device comprising a set of tubes separated into a lower part and an upper part by sealing means of the interior space of said tubes, annular sealing means between said tubes and said well. In the device, said lower part comprises a first set comprising means of acquiring information and means of transmitting and reception of electromagnetic signals, a second set of transmission and reception of electromagnetic signals is placed in the interior space of the party upper tubes by maneuvering means comprising at least one line of electrical or optical communication going up to the surface and said second set comprises means of electrical contact with said tubes.

The first and second assemblies may include means for injecting a low frequency electric current along the tubes.

The first set may include a toroidal transformer substantially concentric with the axis of the tubes. The second part of the transformer can be a single turn constituted by the tubes looping through the casing or the ground.

The operating means may consist of at least one length of cable with coaxial conductors and metallic outer armor.

The upper part of the tubes may include an electrical insulation means placed between two tube elements. In this case, at least one of the means of contact between the second set and the tubes is located between the insulation means and the means shutter.

The information acquisition means may include at least one sensor and a temperature sensor.

The operating means of the second set may include means of contact with the tubes on which the electromagnetic current flows, said contacts advantageously being spaced several meters apart.

The well can be cased by metal tubing, and the portion of tubes included between said assemblies can be partially electrically isolated from said casing by centering means.

The tubes may include at least two means of electrical contact with the metal casing, the contacts being located on either side of said portion of tubes centered.

One of the means of contact with the metal casing can be constituted by said annular sealing means.

The information acquisition means can be remotely controlled from the surface through the line channel and electromagnetic transmission between said two sets.

The invention also relates to a method of transmitting information between the bottom of a well and the soil surface, said device comprising a set of tubes separated into a lower part and an upper part by means for closing off the interior space of said tubes, annular sealing means between said tubes and said well, means for acquiring information. In the method, we pass a electromagnetic current carrying said information from the lower part to the upper by a first assembly placed under said closure means and a second set placed in the interior space of the upper part, and said information is transmitted to the surface by an electrical or optical communication line connecting said second set on the ground surface.

Information acquisition can be remotely controlled from the surface by the channel of said line and of the second and first sets.

Said second assembly can be maneuvered above the shutter means by by means of a coaxial cable of the "logging" type.

It is possible to communicate bi-directionally between said two sets by injecting a sinusoidal electric current of programmable intensity and frequency, the frequency preferably being between 1 and 200 Hz.

• La figure 1 illustre un schéma de principe du dispositif selon l'invention.
• La figure 2 illustre une autre mise en oeuvre du dispositif.
• La figure 3 est un schéma d'un ensemble du dispositif.
• La figure 4 montre le principe de l'émetteur/récepteur du type transformateur.

The present invention will be better understood and its advantages will appear more clearly on reading the examples which follow, in no way limitative, and illustrated by the appended figures, among which:

• Figure 1 illustrates a block diagram of the device according to the invention.
• Figure 2 illustrates another implementation of the device.
• Figure 3 is a diagram of an assembly of the device.
• Figure 4 shows the principle of the transformer type transmitter / receiver.

In FIG. 1, the device which is the subject of the present invention comprises a first communication set 1 equipped with transmitter / receiver means and various means measurement, including pressure and temperature sensors. The device includes also a second communication set 2 called shuttle, and equipped with additional transmitter / receiver means of the first set 1 and means of bidirectional digital telemetry with the surface via a cable 3 (type logging) comprising electrical conductors or optical fibers. Cable 3 is operated in tubes 4 using a surface installation known to technicians concerned, i.e. a winch and a control, recording and processing of signals passing through the communication lines integrated into the cable 3.

The tubes 4 are lowered into a well 5 drilled through a geological layer whose effluents that may be contained in the pores of the layer. For this, at the end of the tubes 4, a so-called test lining is assembled. comprising the assemblies 1 and 2, a sealing means of the “packer” type 6 for performing an annular seal around the tubes, a strainer 7 placed below the packer and intended to allow access of the effluent to the interior space of the tubes 4, a sliding joint 8 and / or a threshing slide ("jar") to allow installation and facilitate removal of the packer, a test valve 9 which can be opened or closed several times in order to open or to close the communication between the geological layer and the interior space of the tubes 4 in communication with the surface. Other conventional equipment, not shown here, can complete the test train: circulation fitting, safety seal, etc.

In the situation shown in Figure 1, the well 5 is cased by a tube in steel 16, usually cemented in the drilled hole. The link between the producing layer and the hole is made either by perforations through the casing tube, or by a borehole 17 extending to the beyond the shoe of column 16. In this configuration, the test lining includes preferably contacts 10 and 11, for example in the form of blade centralizers metallic, packer or natural contacts provided by a set of tubes offset in a well. We arrange for the contact points 10 and 11 to be the most spaced possible along the lining, on either side of the valve 9 and at least separated more than one tube segment, i.e. at least 10 meters.

In this example, namely transmission during a DST or any other equivalent configuration, from one side to the other of a test valve, it is preferable to take a number of precautions so that the two bonds of the first set 1, constituting a transformer type transmitter / receiver, with contacts 10 and 11 constituting the poles, are not electrically interrupted. We make sure, for example, that no equipment such as a slip joint or a jar is sandwiched between the two contact points 10 and 11. If it cannot be otherwise, we check and if necessary, electrical continuity is carried out using an appropriate device integrated into the equipment in question: "slip joint" or "jar". In addition, these precautions allow the use of the "packer" 6 as the lower pole insofar as it practically always has anchor dogs ensuring electrical contact on column 16. In the event that assembly 1 is of the insulating junction type and not of the transformer type, there will be a electrical interruption substantially to the right of the transmission / reception dipole of the assembly 2 and of assembly 1, according to the very principle of the transmission of the insulating junction type.

Sets 1 and 2 communicate with each other by means of currents electromagnetic guided by the casing 16 and / or the test train. In general, we use frequencies between a few Hertz and a few hundred Hertz. These waves are modulated by phase jump (PSK in English), in order to transport information. The sets 1 and 2 being located most often inside a casing 16, it is very advantageous to constitute the widest possible injection dipole in order to create behind casing as large a propagation signal as possible. Such a dipole is described in the document US-A-5394141 cited here for reference. In the event that it is not possible to constitute a large dipole, the operation of this transmission device is always possible. But in this case, the transmission distance between set 1 and assembly 2 and / or the information rate can be reduced in order to reduce the energy of the noise according to well-known principles for improving the signal-to-noise ratio.

In the case of a large dipole, it is advantageous to avoid contact between the test train and the casing 16. Standard tube protectors can be used in rubber or any other insulating ring 13 and 14 mounted on a tube element and inserted in the test train at adequate distances. Note that whatever the nature of the fluid in the annular test lining / well, including brines, difference in conductivity between the fluid and the packing tubes constitutes a dipole apparent more than 10 meters, which is generally sufficient for this transmission.

The transmitter / receiver of each set 1 and 2 of this device used to inject, or receive the carrier frequency propagating along the test train, may be realized using one of the well known techniques, namely either an insulating junction such as described in document US-A-5163714, either an extended dipole, or else a transformer whose toroidal magnetic circuit surrounds the assembly 1. The winding primary with a number of turns adapted to the power supply, while the secondary has a single turn formed by the test train closing on the casing via contacts 10 and 11.

The second transmitter / receiver assembly 2 called shuttle, includes a link insulator 21 and a lower electrical contact means 18 with the inside of the tube 4, said means that can be achieved, either by dogs anchored in a corresponding groove machined in a screw connection on the tubes 4 or by extractable pads remotely controlled from the surface via the electrical connection used for data transfer measured.

The second pole, or upper pole, of the receive / transmit dipole is constituted by the metal reinforcement of the coaxial cable 3 (for example, of the logging type). This cable being sufficiently centered in the tubes up to a height where there is a point of contact 15, it can only be in contact with the wall of the tubes at a sufficient distance large allowing to realize a long transmitter / receiver dipole. Of preferably, the contact 11 is located below the point of contact 15, or in the vicinity. However, in the case where this large dipole could not be produced, we would obtain equivalent results using a fitting with an insulating junction 12 located above contact means 18 and below contact 15 of the armature of the coaxial cable with the casing. The use of a fitting comprising an insulating junction 12 therefore requires to the shuttle a position relative to the junction, since the contact 18 must be under the insulating fitting 12 and the contact 15 above the fitting 12. In fact, in this case, will have to decide on the position of the insulating junction before the surface formation of the test pad to be lowered into the well. It will however be possible to install it several tens of meters above the test valve.

FIG. 2 represents the configuration where the well 20 is not cased by a steel casing. The test lining comprises at least one strainer 7, one packer 6, one test valve 9 assembled to tubes 4. The first assembly 1 includes means for measures, electronic and electromagnetic means to ensure communication by electromagnetic waves with shuttle 2. Shuttle 2 descended into space inside the tubes, above the test valve 9, by means of a cable 3 comprising at least one electrical or optical communication line. Set 2 or shuttle comprises electrical contact means 18, preferably in the form of fingers remotely controlled or wipers. The shuttle has an insulating connection 21 so as to constitute a first lower pole thanks to contact 18 and a second pole with the cable frame 3. To prevent the contact of the cable frame with the tubes 4 too close to the lower pole, you can if necessary surround the cable with insulating elements 22 or centering on a sufficient height. It is clear that this configuration does not impose precise position of the shuttle relative to the test pad, unless a fitting insulation similar to that 12 described in Figure 1 is used for the needs of a even more efficient transmission.

• la mesure au moins de la pression et de la température sous la vanne de test 9,
• la transmission de ces données vers le second ensemble 2 situé au-dessus de la vanne de test,
• la réception et l'interprétation d'un signal émis par la navette 2.

FIG. 3 illustrates in section an embodiment of the assembly 1, the latter having at least three functions:

• measuring at least the pressure and the temperature under the test valve 9,
• the transmission of this data to the second set 2 located above the test valve,
• receiving and interpreting a signal from the shuttle 2.

The pressure and temperature measurement is ensured by three standard 30 gauges, say by memory, powered by three independent energy sources. The measurements are stored in non-volatile memory with a programmed sampling frequency on the surface by an operator. Each gauge measures, as desired, the internal pressure in the channel 31 via conduit 32 or the pressure in the ring finger, that is to say outside of the assembly 1. The gauges 30 are connected to an electronic cartridge 33 by via an electrical connection 34. The electronic cartridge 33 collects the data measured by one of the three gauges and injects a signal in the preferential form a representative low frequency phase modulated electromagnetic current (PSK) of this data to the torus 35. FIG. 4 represents the principle of an embodiment and of operation of a toroidal transformer whose primary circuit 40 is connected to the transmitter / receiver 33 while the secondary circuit has a single turn 41 constituted by the inner shaft 42 of the assembly 1. The shaft 42 is mechanically linked and electrically to the trim of DST and allows to convey the electric current up to assembly 2, thus ensuring bi-directional communication between assemblies 1 and 2. A cover 36 integral with the assembly 1 is electrically insulated at least on one of its ends 37 while protecting the torus 35 and the electronic cartridge 33.

• un mode dit "Temps Réel" par lequel les données fournies par une ou plusieurs jauges sont transmises en temps réel à la navette, puis à la surface par l'intermédiaire du câble,
• un mode dit "Play-Back" par lequel il y a émission de type multiplexée des données en temps réel et des données mesurées précédemment. Ce mode permet de connaítre l'ensemble des données mesurées depuis la mise sous tension des jauges jusqu'à l'instant présent. Il permet en particulier d'avoir accès, alors que le test est en cours, aux données correspondantes à la phase dite de débit ("flowing") alors que l'ensemble 2 est généralement descendu pendant la phase de fermeture de la vanne ("build-up") qui se déroule après la phase de débit du puits.

In the mode of transmission of a signal from the surface to the assembly 1, via the shuttle 2, a low frequency signal modulated in phase is emitted by the shuttle. It is received by the torus 35 and processed by the electronic cartridge 33. This signal allows, for example, to modify the operating mode of assembly 1. The two main operating modes can be:

• a so-called "Real Time" mode by which the data supplied by one or more gauges are transmitted in real time to the shuttle, then to the surface via the cable,
• a mode called "Play-Back" by which there is transmission of multiplexed type of real-time data and previously measured data. This mode allows you to know all the data measured from the power up of the gauges until the present time. It allows in particular to have access, while the test is in progress, to the data corresponding to the so-called flow phase ("flowing") while the assembly 2 is generally lowered during the valve closing phase (" build-up ") which takes place after the well flow phase.

The operating command signal, emitted from the surface, also makes it possible to choose the gauge which will be read by the electronic cartridge.

It should be noted that the data is also stored in each gauge 30 and can also be read on the surface at the end of the test.

The second set 2 or shuttle (Figure 1 and Figure 2) is connected to the surface by a coaxial cable 3. The cable provides power to the electronic compartment included in the shuttle and the bidirectional dialogue between the shuttle and the surface.

The electronic compartment mainly consists of: a electromagnetic transmitter / receiver and a two-way electrical transmitter allowing dialogue with the surface via the cable conductors.

The shuttle's electromagnetic transmitter generates a low frequency signal modulated in phase between the armouring of the cable and the contact means 18, these two points being electrically isolated by insulating junction 21. The shuttle generates this signal on reception of an order signal from the surface via the coaxial cable. The signal generated by the shuttle is received and then decoded by set 1 to allow it to modify its operating mode. Equivalently, the shuttle can inject or receive an electromagnetic current using means comprising a transformer.

The shuttle's electromagnetic receiver receives, then decodes, the low signal frequency emitted by the assembly 1. This signal is measured between the armouring of the cable 3 and the contact 18. It is generally representative of the data measured by the gauges of the set 1.

When the data is decoded, it is transmitted to the surface by through the cable.

The contact means 18 can, in addition to ensuring electrical contact between the shuttle and the test train, ensure mechanical anchoring of the shuttle in the test train. This anchoring may be necessary if, as in the case of using an insulation fitting 12 in the test set, a specific position of the shuttle is required, or if the flow of the effluent risks creating untimely movements, or vibrations which can be troublesome for the proper functioning of the transmission.

Claims (15)

1. A device for transmitting information between the bottom of a well (5) and the ground surface, said device comprising an array of tubes (4) separated in a lower part and an upper part by sealing means (9) intended to seal the inner space of said tubes, seal assembly means (6) between said tubes and said well, said lower part comprising a first unit (1) including information acquisition means and electromagnetic signal transmission and reception means, characterized in that a second electromagnetic signal transmission and reception unit (2) is placed in the inner space of the upper part of the tubes by operating means (3) comprising at least one electric or optical communication line running up to the surface and in that said second unit comprises means (18, 15) intended for electric contact with said tubes.
2. A device as claimed in claim 1, wherein the first unit and the second unit (1, 2) comprise means for injecting a low-frequency electric current along tubes (4).
3. A device as claimed in claim 2, wherein said first unit (1) comprises a toric transformer (35) substantially concentric to the axis of said tubes (4).
4. A device as claimed in any one of the previous claims, wherein said operating means (3) consist of at least one cable length with coaxial conductors and an external metal armor.
5. A device as claimed in any one of the previous claims, wherein the upper part of the tubes comprises an electric insulation means (12) arranged between two tube elements.
6. A device as claimed in claim 5, wherein at least one (18) of the contact means between said second unit and the tubes is arranged between said insulation means (12) and said sealing means (9).
7. A device as claimed in any one of the previous claims, wherein said information acquisition means comprise at least a pressure detector and a temperature detector.
8. A device as claimed in any one of the previous claims, wherein said means (3) intended to operate second unit (2) comprise means (15) intended for contact with the tubes situated several meters away from second unit (2).
9. A device as claimed in any one of the previous claims, wherein well (5) is cased by a metal casing (16) and the tube portion contained between said units (1, 2) is substantially insulated electrically from said casing by centering means (13, 14).
10. A device as claimed in claim 9, wherein said tubes (4) comprise at least two means (6, 10, 11) intended for electric contact with the metal casing and arranged on either side of said centered tube portion.
11. A device as claimed in claim 10, wherein one of the means of contact with the metal casing consists of said seal assembly means (6).
12. A method for transmitting information between the bottom of a well (5) and the ground surface by means of a transmission device, said device comprising an array of tubes (4) separated in a lower part and an upper part by sealing means (9) intended to seal the inner space of said tubes, seal assembly means (6) between said tubes and said well, information acquisition means, characterized in that said information is transmitted through an electromagnetic current from the lower part to the upper part by a first unit (1) placed below said sealing means (9) and a second unit (2) placed in the inner space of the upper part, and in that said information is transmitted to the surface through an electric or optical communication line connecting said second unit to the ground surface.
13. A method as claimed in claim 12, wherein information acquisition is remote-controlled from the surface through the channel of said line (3) and of second and first units (1, 2).
14. A method as claimed in any one of claims 12 or 13, wherein said second unit is operated above the sealing means by means of a logging type coaxial cable.
15. A method as claimed in any one of claims 12 to 14, wherein bi-directional communication is established between said two units by injecting a sinusoidal electric current of programmable intensity and frequency.

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