EP0404669A1 - Method and apparatus for conducting perforating operations in a well - Google Patents

Abstract

Method and apparatus making it possible to obtain a perforation of the wall of a well by the action of a tool, such as an explosive gun. Lowered into the well is a working assembly comprising a perforation tool (4) associated with a measurement housing (5), such as a logging probe and temperature and pressure sensors. The assembly (4, 5) is suspended by means of a connecting cable on a supporting element (8) capable of being locked on the inside of and on the base of a column (1). The column is lowered as far as the working zone and blocked by means of a packer (2). The supporting element (8) and the assembly (4, 5) are displaced by means of a control cable lowered from the surface, and the best locations of the well for carrying out the blasts are determined by means of measurements. Sensors contained in the housing (5) make is possible to monitor the results. After the work has been carried out, the gun (4) is left in the well, and the supporting element (8) and housing (5) are raised in order to open up the interior of the column. The invention is used, for example, for oil-producing wells. <IMAGE>

Description

The subject of the present invention is a method and a device for carrying out perforation operations in a well and in particular a well intended for the production of petroleum.

According to a method well known to drilling specialists, the production of an oil well is carried out by lowering into a cemented well a production column (or tubing) of section smaller than that of the well. A perforation tool such as a barrel containing one or more explosive charges, is fixed to its base by detachable connection means. The column is fitted towards its lower part, with a packer type shutter block whose expansion controlled from a surface installation, makes it possible to close the annular space between the wall of the well and the production column and d '' immobilize it when the barrel has reached the chosen depth. The triggering of the barrel is ensured by the descent into the column of a percussion bar adapted to strike a detonator at the top of the barrel, by opening a valve allowing the application of a hydraulic overpressure which is imposed in the column or alternatively by electric firing by lowering a female electrical connector to a complementary connector disposed at the top of the barrel. When the well begins to produce, due to the perforations made, the entire lower part of the column is detached below the block or pack so as to clear the passage to the surface and this part falls to the bottom of the well. Specialists often refer to these perforation systems as TCP (for Tubing Conveyed Perforating) systems.

Various systems of this type are described, among other examples, in US patents No. 4,633,945 or 4,756,371 or also in European patent application No. 288239.

In such a perforation system, the distance between the obturation block or packer and the barrel is often several tens of meters due to rigid tubular sections interposed between the two. It is therefore necessary to drill an additional portion of well (called "rathole" by specialists) well beyond the depth where the perforations will take place, so that the perforation system can fall into it and clear the end bottom of the column. In addition, if several perforations are to be carried out in the same area of the well after blocking of the sealing member or packer, a perforation device with several stages must be used spaced from each other by sections of tube. The spacing must be chosen so that the perforations occur at the desired depths. This complicates the mounting operations of the device at the bottom of the column. In addition, due to the greater elongation of the perforating device, the length of additional well to be drilled to allow the barrel to fall after use is greater.

By French patent No. 2,544,013, there is also known a device for bringing an intervention tool (such as a measurement probe or a perforation gun) to the bottom of a drilled well comprising a column or casing provided towards its lower end of an expandable or packer sealing member, a support element for the tool, disposed in the vicinity of the lower end of the column, a flexible connection element comprising an electric cable to connect the tool to its support element and remote control means comprising a cable provided with an electrical connector which can be lowered all along the column until it comes to be plugged into a complementary connector carried by the support element, so as to transmit signals electric control and / or tensile forces to ensure the movement of the tool.

The method according to the invention makes it possible to conduct operations for perforating a well such as an oil well for example, under conditions which facilitate in-situ measurements before and after the perforation operations and clearing the well. for its production. It includes the descent into the well to the zone to be perforated by a column of section smaller than that of the well provided towards its lower part with an external expandable sealing member making it possible to close the annular space between the well and the column and immobilize it, with a perforation tool connected by a connecting element to a movable support assembly inside said column, which assembly is provided with connection means making it possible to establish a connection electrical connection between said connecting element and an electrical connector lowered from a surface installation at the end of a control cable. The method is characterized in that it comprises:
the addition of a measuring assembly permanently connected to the connecting element and movable with the perforating tool, and of fixing means detachable by remote control, allowing the separation between said connecting element and the perforation,
the displacement of the measuring assembly in the well below said column by action on the connecting element and the carrying out of measuring cycles allowing the determination of at least one location where the perforation tool must be operated,
- triggering of the perforation tool at each determined location,
- the separation between the connecting element and the perforation tool, and
- Clearance of the column by raising the support assembly and the connecting element which is attached to it.

The method according to the invention may also include a step of measuring state parameters by said measuring assembly after the triggering of said perforation tool.

The device according to the invention comprises a column of section smaller than that of the well provided towards its end bottom of an external expandable sealing member making it possible to close the annular space between the well and the column and to immobilize the latter, motor means for lowering the column into the zone to be perforated, a perforation tool, a support assembly movable inside said column, a connecting element connecting the perforation tool to said support assembly, a control cable which can be unwound from a surface installation up to said support assembly, connection means allowing , at the determined depth, the interconnection of the control cable to the perforation tool via said connecting element. It is characterized in that it further comprises
a logging assembly connected to said connecting cable, making it possible, by displacement of the support assembly, to determine at least one location to be perforated, and
- Removable fixing means for detaching the perforation tool from the connecting element at the end of the perforation operations.

The device according to the invention comprises for example removable locking means by remote control from the surface installation, for immobilizing in translation the support element relative to the column in at least one location thereof. This location can be above the sealing member or even between the location of the sealing member and the lower end of the column. A low stop can optionally be combined with it.

The device can also include both removable locking means of the support element with respect to the column, in a high position and a stop integral with the column serving to support the support element in a low position from that -ci, the support element being movable in the column between these two positions.

According to a preferred embodiment, the device comprises means for measuring the conditions prevailing in the part of the well below the sealing member, such as the temperature and pressure.

According to another embodiment, the device may include means for intermittently isolating from one another the parts of the column on either side of the support element, so as to benefit during the perforation operations , the difference in pressure prevailing on both sides.

The device according to the invention and its method of implementation have numerous advantages:

The perforation tool being movable relative to the column at the end of a connecting cable, the portion of additional well to be drilled below its lowest position to allow its fall and the release of the lower end of the column is shorter than with previous systems. It is also possible to use a perforation tool with several selectively triggerable loads and thus by moving the tool, successively make several perforations at different depths. The implementation of perforation operations is much more flexible than with cannons with stepped charges at fixed intervals from each other.

This advantage is further increased by the fact that it is possible to carry out preliminary measurements such as correlation logs, by means of which the depths are precisely located or the tool must be triggered. Its positioning is then obtained simply by moving the support assembly relative to the column immobilized in the well.

The measurement system attached to the connecting element also makes it possible to make production logs (temperature and pressure measurements for example) along the part of the well under the column.

In addition, the insulation of the parts of the column on either side of the support element makes it possible to benefit from the generally lower pressure prevailing in the column, to clean the perforations obtained by the triggering of the tool.

• - la Fig.1 montre schématiquement un premier mode de réalisation du dispositif ou l'instrument de perforation ou canon est connecté à l'ensemble de support correspondant par un câble de liaison;
• - la fig.2 montre schématiquement un deuxième mode de réalisation ou le même canon est relié à son ensemble de support par un élément de liaison tubulaire;
• - la Fig.3 montre une première étape de la mise en place et de l'ancrage dans un puits de la colonne avec le canon à sa base;
• - la Fig.4 montre une deuxième étape ou le canon est connecté à l'installation de surface par un câble de commande;
• - la Fig.5 montre une troisième étape ou le canon est descendu dans le puits au-dessous de la colonne;
• - la Fig.6 montre un troisième mode de réalisation ou l'élément de support du canon est verrouillé à la colonne au-dessous du l'organe d'étanchéité et peut sortir de celle-ci lorsque le canon est descendu vers la base du puits, et
• - la Fig .7 montre un quatrième mode de réalisation ou l'élément support est simplement retenu par une butée basse vers l'extrémité de la colonne.

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

• - Fig.1 shows schematically a first embodiment of the device or the perforation instrument or barrel is connected to the corresponding support assembly by a connecting cable;
• - Fig.2 shows schematically a second embodiment or the same barrel is connected to its support assembly by a tubular connecting element;
• - Fig.3 shows a first step of the establishment and anchoring in a well of the column with the barrel at its base;
• - Fig.4 shows a second step where the gun is connected to the surface installation by a control cable;
• - Fig.5 shows a third step where the barrel is lowered into the well below the column;
• - Fig.6 shows a third embodiment where the barrel support element is locked to the column below the sealing member and can come out of it when the barrel is lowered towards the base of the well, and
• - Fig .7 shows a fourth embodiment where the support element is simply retained by a low stop towards the end of the column.

To carry out operations for perforating a well (P), a tubular column or tubing 1 is lowered there, provided at its lower end with an expandable sealing member 2 such as a packer of known type. On order, it can be expanded until it locks against the wall of the well and immobilizes the column 1. At the lower end of the column is adapted an intervention set 3 comprising a perforation instrument or barrel 4 of a known type surmounted by a box 5 containing a measuring assembly. The section of the housing 5 is chosen so that it can pass through the opening at the base of the column.

Cannon 4 has one or more charges of explosives which can be triggered selectively by application of a signal electric control.

The measurement assembly in the housing 5 includes signal transmission-reception means making it possible, for example, to make correlation logs capable of being compared with records obtained beforehand in the well. These means include for example a gamma probe. The measuring system also advantageously includes means for making so-called production logs making it possible to measure the values of parameters such as the temperature and the pressure of the fluids from the surrounding formations. The housing 5 is connected to the barrel by detachable connection means 6. For example, anchoring fingers (not shown) are used which move apart by the action of an electric motor and disconnect the barrel 4 from the housing 5. It is possible to also use equivalent means such as explosive bolts.

In the embodiment of Fig.1, the housing is fixed to a first end of an electrically-carrying cable 7. The opposite end of the cable 7 is connected, inside the column 1, to an element support 8 of section smaller than that of the column. Anchoring fingers 9 are pivotally mounted relative to the support element 8. Under the action of a motor not shown, they can be moved apart to an open position where they come to lock in a groove 10 formed in the inner wall of the column 1. The support element comprises, on the side opposite to the cable 7, a tubular extension 11 terminated by a flared flange 12. In the center of the tubular extension 11 and along its axis, a male plug is arranged multi-contact 13. The flange 12 is used to guide the plug 13 of a suitable socket 14. This is connected to the various conductors of a control cable 15 connected to a surface installation 16 (Fig.3) comprising maneuvering means 17 and an assembly 18 for controlling and recording the data captured by the measurement assembly in the housing 5. The socket 14 is surmounted by a tubular ballasting bar 19 of substantially equal section. The socket 14 also includes anchoring fingers 20 of a known type which can be moved apart by the action of means electromagnetic or electric motor. Notches 21 for the fingers 20 are formed in the inner wall of the tubular extension 11. The fingers can engage there when the male plug 13 is in the correct insertion position. The locking of the fingers 20 allows the translation of the support element 8 by traction on the cable 15 exerted by the surface lifting means. Inside the support element, conductors (not shown) ensure the electrical interconnection of cables 7 and 15.

Examples of electrical connectors using this type of multi-contact male plug and suitable female socket are described for example in US Pat. No. 4,500,155.

Around the support element 8 is disposed a set of elastic cups 22. The column section 1 where the locking groove 10 is hollowed out, is provided with a rectified wall portion 23. In the blocking position of the support element 8 shown in FIG. 1, the set of cups 22 is in contact with this rectified portion 23 and separates the column parts in leaktight manner on either side. Inside the support element 8 is provided a bypass channel 24 closed by a valve 25, the opening of which can be remote-controlled from the control assembly 18 (FIG. 3). The channel 24 connects the two opposite sides of the cup assembly 22. Pressure sensors can be included in the support element to measure the pressures prevailing on either side of the cup assembly 22.

In the embodiment of Fig.1, the end section of the column 1 is too narrow to allow the passage of the support element 8. The travel of the latter is therefore made entirely in the column from the high position shown up to a low position delimited by a low stop 26. This stroke is adapted to the latitude of movement that we want to give to the intervention unit 3.

In the embodiment of Fig.2, the section of the well and / or the packer 2 used, allow the use of a column without restriction of terminal diameter. In this case, the support element 8 can freely exit from column 1 to follow the descent of the intervention unit 3 towards the base of the well P. The connection between the housing 5 and the support element 8 can be ensured by a rigid connection such as a tube 27 (case shown in Fig.2) or even by a cable as before.

The operations for perforating a well with the device described above take place as follows:
- The connecting element (cable 7 or tube 27) associated with the intervention unit 3 consisting of the barrel 4 and the logging box 5, is introduced into the terminal section of the column 1 provided with a packer 2 and mechanically and electrically connected to the base of the support element 8. The latter is positioned in the column so as to be able to engage the fingers 9 in the groove 10 and to place the cup assembly 22 in contact with the rectified portion 23 The valve 25 is closed.
- The intervention assembly 3 with its support element 8 locked in column 1, is lowered into the well and column sections are gradually added to bring it to the well area where operations must take place . Packer 2 is then anchored by expansion against the wall of the well (Fig. 3).
- The socket 14 surmounted by its load bar 19, is then lowered into the well at the end of the control cable 15 until it is plugged into the multi-contact plug 13. The locking of the fingers is then controlled 20 in their notches 21. The socket 14 descends into the column by gravity or else propelled by a stream of fluid as indicated in French patent No. 2,547,861.
- The well is most often filled with water while column 1 is partially empty. Therefore, the pressures prevailing towards its base on either side of the cup assembly 22 are uneven. We can also adjust this difference by filling the column more or less with water and the operation is facilitated if we have incorporated sensors in the support element 8 to measure the pressures prevailing on either side of the set of cups 22. The base of the well being isolated by blocking the packer 2, the valve 25 is opened so as to equalize the pressures on both sides.
- The fingers 9 are then unlocked, which block the support element 8 in the high position, and the operating means 17 are actuated to lower the intervention assembly towards the bottom of the well P.
- The intervention assembly 3 is then gradually reassembled and the operation from the assembly 18 at the surface, the operation of the logging probe contained in the housing 5. The records obtained are compared at the surface with other recordings previously made in the same area. By correlation, one can find the position or positions most suitable for performing the perforations.
- The barrel 4 is brought to the desired depth and the explosion of a charge is triggered electrically. The pressure and temperature sensors advantageously included in the housing 5 make it possible to monitor the results of the explosion. The depression of the lower zone of the well following the opening of the valve 24 (Fig. 1) makes it possible to clear the perforations made by suction of the cuttings out of the underground formations.

When several perforations must be carried out, the barrel is brought successively to the depths identified by correlation and explosions are triggered there.

When the perforation operations are completed, the column is released. To this end, the barrel 4 is detached from the instrument casing 5 and the operating means 18 are actuated on the surface to reassemble it with the support element 8. The barrel falls to the bottom of the well.

According to the embodiment of Fig.6, the end section of the column 1 containing the locking means 9,10 of the support element 8, is added below the section carrying the anchor packer 2 and l The chosen connecting element (cable 7 or tube 27) is adapted to the section of the column at the level of packer 2.

According to the embodiment of FIG. 7, the column is provided with a simple bottom stop 28 on which the element of support 8. The intervention assembly is in the low position at the end of its connecting element 7.27 during the entire descent to the intervention zone. Its vertical movement is ensured after connection and locking of the multi-contact plug 13 lowered from the surface.

It would not be departing from the scope of the invention to use the embodiment of FIG. 7 as it is without the intervention of a control cable 15 and therefore without the possibility of moving it. The support element 8 is in this case provided with a hooking head and can be recovered and raised to the surface by a hook lowered at the end of a cable.

Claims (12)

1) Method for carrying out perforation operations of a well (P) such as an oil drilling well for example, comprising the descent in the well to the zone to be perforated, of a column (51) of section smaller than that of the well provided towards its lower part and externally with an expandable sealing member (2) making it possible to close the annular space between the well and the column and to immobilize the latter, with a perforation (4) connected by a connecting element (7, 27) to a support assembly (8) movable inside said column and provided with connection means (13, 20, 21) making it possible to establish a connection between said connecting element and a connector (14) lowered from a surface installation at the end of a control cable (15), characterized in that it comprises:
- the addition of a measuring assembly (5) permanently connected to the connecting element (7, 27) and movable with the perforation tool (4), and fixing means (6) detachable by remote control , allowing the separation between said connecting element and the perforation tool,
- The displacement of the measuring assembly in the well below said column (1) by action on the connecting element and the realization of measurement cycles allowing the determination of at least one location where the tool perforation must be activated,
- triggering of the perforation tool at each determined location,
- the separation between the connecting element (7,27) and the perforation tool (4), and
- Clearance of the column by raising the support assembly (8) and the connecting element (7,27) which is attached to it. 2) Method according to claim 1, characterized in that it further comprises a step of measuring state parameters by said measuring assembly after the triggering of said tool. perforation. 3) Device for conducting perforation operations of a well (P) such as an oil well for example, comprising a column (1) of smaller section than that of the well provided towards its lower end and externally with an expandable sealing member making it possible to close the annular space between the well and the column and to immobilize the latter, operating means (17) for lowering the column into the zone to be perforated, a perforation tool ( 4), a support assembly (8) displaceable inside said column, a connecting element (7, 27) connecting the perforation tool to said support assembly, a control cable (15) which can be unwound from an installation surface (16) up to said support assembly (8), connection means (13, 14, 20, 21) allowing, at the determined depth, the interconnection of the control cable (15) to the perforation tool by means of said connecting element, characterized é in that it further comprises
a measuring assembly (5) connected to said connecting element, making it possible, by displacement of the support assembly, to determine at least one location to be perforated, and
- removable fixing means (6) allowing the perforation tool to be detached from the connecting element at the end of the perforation operations. 4) Device according to claim 3, characterized in that it comprises locking means (9, 10) removable by remote control from the surface installation, to immobilize in translation the support element relative to the column at least a location thereof. 5) Device according to claim 4, characterized in that said location is above the sealing member (2). 6) Device according to claim 4, characterized in that said location is disposed between the location of the sealing member and the lower end of the column (1). 7) Device according to claim 3, characterized in that it comprises removable locking means (9, 10) of the support element in a high position relative to the column and a stop (26) integral with the column serving to support the support element in a low position thereof, the support element being movable in the column between these two positions. 8) Device according to claim 3, characterized in that it comprises a stopper (28) for said support element. 9) Device according to one of claims 3 to 8, characterized in that it comprises means for measuring the conditions prevailing in the part of the well below the sealing member. 10) Device according to one of claims 3 to 9, characterized in that it comprises means for intermittently isolating from one another the parts of the column on either side of the support element. 11) Device according to claim 3, characterized in that said connecting element is a multi-conductor cable (7). 12) Device according to claim 3, characterized in that said connecting element comprises a rigid tube (27).

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