EP0134734B1 - Oil well logging method and apparatus - Google Patents

Description

The invention relates generally to the exploitation of oil wells, and more particularly to the measurements which are carried out there with a view to determining the characteristics of the deposit.

A conventional method for determining the characteristics of a deposit consists in causing it to flow through the drill string or the production column, then interrupting the flow using a valve, and observing the pressure evolution upstream of the valve.

In certain situations, this process is implemented using a valve located on the surface. This proven technical solution has the drawback, however, that the pressure measurement made at the surface, just upstream of the valve, only reflects the true response of the reservoir itself to the interruption of the flow far enough. The disturbing phenomena are quite numerous. The most important are the height of the column of fluid present between the wellhead and the deep layer where the deposit is located, as well as the possible exchanges, thermal or other, between this column of fluid and the intermediate underground formations.

In other situations, a bottom valve, remote controlled from the surface, is used. It is mounted in the production column, near a seal (or packer) isolating the producing layer from hydrostatic pressure. This arrangement will hereinafter be called "conventional test apparatus". To record the test, a pressure gauge-recorder assembly sensitive to the pressure upstream of the valve is provided in depth. The measurements are then only available after raising the drill string.

Various means have already been proposed tending to allow measurements with a valve and a pressure gauge located in depth (see for example French patent application no. 81 13810, published under no. 2 509 366). These newly proposed means are not entirely satisfactory and have not yet undergone substantial development.

• a. soit utiliser un câble de descente qui soit à la fois porteur et électriquement conducteur, de façon à envoyer les données immédiatement en surface, ce qui permet le contrôle en direct des essais; soit utiliser un câble non conducteur et enregistrer les données au fond dans des mémoires, ce qui se fait maintenant de manière classique;
• b. prévoir une vanne qui laisse un passage aussi large et dégagé que possible, aussi bien sur le plan hydraulique que mécanique, à l'intérieur de la colonne de production, de façon à permettre des interventions éventuelles sous la vanne;
• c. éviter que plusieurs descentes ne soient nécessaires pour la mise en place de la vanne et de son dispositif de commande, avec le manomètre. La présente invention vient apporter une solution à ce problème.

The problem to be solved has been analyzed as follows by the plaintiff; it is necessary

• at. either use a descent cable which is both load-bearing and electrically conductive, so as to send the data immediately to the surface, which allows direct control of the tests; either use a non-conductive cable and save the data in the background in memories, which is now done in a conventional manner;
• b. provide a valve that leaves a passage as wide and clear as possible, both hydraulically and mechanically, inside the production column, so as to allow possible interventions under the valve;
• vs. avoid that several descents are necessary for the installation of the valve and its control device, with the pressure gauge. The present invention provides a solution to this problem.

US-A-4,278,130 and US-A-4,108,243 each describe a method of measuring in an oil well and a device for carrying out this method, the device comprising a tubular body forming part of a train of drilling rods, and a control unit comprising a pressure gauge, suspended on a cable and capable of being inserted and anchored in the tubular body.

The tubular body includes a valve operable by the control crew to interrupt or release the flow of fluid from the underground layers in the drill string. The control of the valve is obtained by means of a motor arranged in the control equipment, without traction on the cable.

In US-A-4 278 130, the valve is normally closed, and its opening puts the pressure gauge in communication with the fluid of the underground layers. A bypass passage is provided around the control crew, in parallel with the valve.

In US-A-4,108,243, a bypass passage is also provided around the control crew, the valve being interposed on this bypass passage.

The invention relates to a method according to claim 1, and a device according to claim 7. Optional features of the invention are defined in the dependent claims.

• -la figure 1 illustre, sous forme d'une vue en coupe schématique, un puits muni du dispositif de la présente invention;
• -la figure 2 illustre, sous la forme d'une vue en coupe plus précise, un cuvelage de puits et la partie "corps" du dispositif selon l'invention, incorporée à une colonne de production;
• -la figure 3 est une vue schématique en demi- coupe longitudinale (coupe partielle) de l'équipage de commande qui viendra coopérer avec le corps de vanne de la figure 2, tandis que les figures 3A à 3E en sont des vues partielles détaillées complémentaires;
• -les figures 4 à 6 illustrent l'état du dispositif de la présente invention en différentes phases de la mise en oeuvre du procédé; et
• -la figure 7 est un diagramme schématique montrant mieux un chemin de came intervenant dans l'équipage de commande de la figure 3.

Other characteristics and advantages of the present invention will appear on examining the detailed description below, and the appended drawings, in which:

• FIG. 1 illustrates, in the form of a schematic sectional view, a well provided with the device of the present invention;
• FIG. 2 illustrates, in the form of a more precise sectional view, a casing of wells and the "body" part of the device according to the invention, incorporated in a production column;
• FIG. 3 is a schematic view in longitudinal half-section (partial section) of the control unit which will come to cooperate with the valve body of FIG. 2, while FIGS. 3A to 3E are partial detailed views thereof ;
• FIGS. 4 to 6 illustrate the state of the device of the present invention in different phases of the implementation of the method; and
• FIG. 7 is a schematic diagram better showing a cam path intervening in the control equipment of FIG. 3.

Given the complexity of the forms of the device according to the invention, the drawings are to be considered as an integral part of the description, to contribute as much as necessary to the definition of the invention.

In FIG. 1, the reference 10 designates a well casing.

The reference 100 designates as a whole the valve body part of the device according to the present invention. This body 100, of generally tubular shape, is inserted into a drill string or into a production column. It will be assumed hereinafter that it is a production column, having end caps 101 and 102 to which the body 100 is screwed.

Between the casing 10 and the end piece 102, a packing or "packer" P is put in place. The end piece 102 is provided with a deep valve VP, controlled from the surface, at the opening as well as 'at closing. When the VP valve is open, the zone to be tested flows into the nozzle 102.

As will be seen below in detail, the body 100 comprises a flap valve 121, actuated by a jacket 130, itself controlled by a crew 200 lowered at the end of an electric cable and carrier 199. The crew comprises a internal rod 251, with a manometer 252 at the head, as well as an external tube 201 in which the rod 251 slides. The tube 201 is engaged on the body 100, and the rod 251 on the liner 130. A wide passage 140 bypasses the two anchor points. A thin, tubular passage 150 enables the upstream connection of the flap valve 121 to the rod 251, and thereby to the pressure gauge.

Reference will be made to FIG. 2 for the description of the body 100.

It is materially composed of several parts, referenced 103 to 109. Its structure is defined by two main parts 103 and 105 screwed one on the other. The upper part 103 is screwed onto the end piece 101 and the other 105 onto the end piece 102. Peripherally, the parts 103 and 105 are hollow machined, with a double recess over part of their length. The first step receives a thin cylinder or jacket 104, below which is defined an annular passage 142. The part 103 is provided with a series of through orifices such as 143, making the annular passage 142 communicate with the interior of the part 103. At the other end, the part 105 is likewise provided with a series of through orifices such as 141, making the annular passage 142 communicate with the interior of the part 105. The elements 141, 142 and 143 together define a first derivative passage 140.

At its lower end, the part 105 is provided with a series of radial outward recesses 118 and 119. The lower recess 119 houses a cylindrical sleeve 109, completed by a part 108. This has a radial shoulder inward, and at the same time serves as a point of articulation for a flap valve 121, pivotally movable about the axis 120, against an elastic return not shown (spiral spring for example). It is then threaded to receive the end piece 102.

Higher than these recesses 118 and 119, the internal bore 117 of the part 105 slidingly receives a jacket 130, provided with a radial shoulder towards the outside 131, which normally abuts against the homologous shoulder of the part 108, and this under the effect of the elastic return of the spring 132, which bears between the shoulder 131 and one of the internal recesses of the part 105.

In its rest position, where the stop 131 rests on the part 108, the jacket 130 maintains the flap valve 121 in the open position, fully retracted in its housing. It is noted that the free passage inside the jacket 130 corresponds substantially to the diameter of the end piece 102.

It is also noted that the low orifices such as 141 of the branch passage 140 terminate, in the bore 117, in an area which is in line with the liner 130. In this exemplary embodiment, the liner 130 naturally comprises a series of orifices such as 134, counterparts of the inputs of the various orifices such as 141. The jacket 130 is immobilized in rotation so that the orifices 134 correspond to the orifices 141.

We will now give an overall description of the central passage, generally designated by 110, formed inside the body 100. This passage 110 begins with a wide section defined inside the end piece 101, then is extended by the bore 111 of part 103, practically without modification of section. In the lower part of the bore 111 terminate the orifices 143 already mentioned. The bore 111 ends with a constriction at 112 followed by a bore 113 where a first anchoring zone is defined. This first anchoring zone is constituted by the succession of two radial outward recesses, or grooves, denoted respectively 114 and 115. The grooves are here of an annular shape, covering the entire periphery of the bore. One of them is however provided with a pin projecting radially inwards (not shown). It is noted that the groove 114 has a trapezoidal section, symmetrical about a radial plane. On the other hand, the groove 115 has a straight section in a rectangular trapezium, the side of which at right angles is at the top. The bore 113 extends to the right of the thread connecting the part 103 to the part 105. As an extension of said bore 113, the part 105 receives two inserts or rings 106 and 107 respectively, offering in order straight sections decreasing with respect to that of bore 113. The ring 107, intended to receive a seal as will be seen below, has a carefully polished inner face.

After this ring 107, the interior passage 110 is again defined by a bore 116 machined in the part 105 itself. Finally, a transition 116A is provided between the bore 116 and the bore 117 which receives the jacket 130 already mentioned.

It will now be noted that the upper part of the jacket 130 internally comprises a second anchoring zone, defined by a groove 133, of trapezoidal cross section, like the groove 115 mentioned above.

It now appears that the first branch passage 140 is suitable for establishing, downstream of the valve 121, a hydraulic short circuit substantially of the same section as the central passage 110 (in its polished intermediate bore 107 which represents the lower section). This short circuit is established to bypass at least the two anchoring zones (114 and 115 for one, and 133 for the other).

A second derivative passage, noted as a whole 150, is provided between the upstream of the flap valve 121 and an intermediate bore point defined by the ring 107. The passage 150 is of small section, and tubular over its entire length. It begins with the through orifice 151 formed in the part 109. This orifice 151 is connected to the fine pipe 152, which returns slightly inwards at 153 to avoid the annular passage 142 already mentioned, and finally leads to a radial orifice through 154 formed in bore 107.

The tubular body which has just been described, with reference to FIG. 2, is interesting in itself, in that it can be inserted in a drill string or in a production column, without greatly reducing the cross-section thereof. of passage.

By its anchoring means, it can receive at will a valve control unit, or another control tool, which engages on the above-mentioned anchoring zone or zones.

In the absence of a control crew, the body 100 internally provides a passage 110 with a large section, which allows both the passage of the fluid and the passage of other tools used at depth.

When, on the contrary, the control crew is put in place, mechanical passage is no longer possible. On the other hand, the first derivative passage 140 maintains a hydraulic short circuit which is substantially of the same section as the minimum section of the central passage 110 (at the level of the ring 107).

By installing a valve body as described above in the rods or the production column, the present invention makes it possible to install, above the normal test apparatus, another valve device, connected to a cable which allows, on the one hand, its actuation and, on the other hand, the immediate transmission of the pressure information recorded by a pressure gauge. The invention also makes it possible, in the event of an incident or breakdown which may occur, in particular on the pressure gauge, to go up and change or repair and to descend the control crew in place without interrupting the actual test operations, and in particular without that it is necessary to reassemble all the rods or the production column.

There will now be described with reference to FIGS. 3 and 3A to 3E the preferred embodiment of the control equipment which is inserted into the body of FIG. 2.

Figure 3 is a sectional view in its left half, and a side view in its right half. The sectional section shows in particular that the assembly 200 mainly consists of an outer tube referenced 201 and an inner rod referenced 251. It is important to note that, in the left part of the figure, the inner rod 251 n 'is no longer shown in section, but in external view, above the line 250.

The entire crew 200 can be lowered into the rods or into the production column by means of a carrying and conducting single cable (199, FIG. 1), which hangs on the head 252 of the internal rod 251 Load bars are naturally provided with sufficient mass to ensure the proper descent of the crew.

The head 252 contains an electronic pressure gauge, which may for example be of the TPT type, manufactured by Etudes et Fabrications FLOPE-TROL.

Before describing the rest of the internal rod 251, we will first look at the external tube 201.

This begins, at the top, with a short end piece 202, provided with a radial pin 203 projecting inward. The part 202 is fixed to a tubular sleeve 204. The sleeve 204 carries, in its intermediate part, a hooking member. This is defined by two outward projections, respectively denoted 293 and 294, which are homologous with the grooves 114 and 115 of the first anchoring zone, respectively. Such protrusions are commonly referred to as "keys" or "dogs" in the art. The des are retractable radially inside the sleeve 204, against an elastic return shown diagrammatically at 293A and 294A (FIG. 3C), and bearing on a tube 295.

The sleeve 204 is fixed at its other end to the end piece 206, which ends in an inward radial recess on which the seals 207 are housed.

During the descent of the mobile assembly, the linings 207 will come into place on the bore 107, ensuring a seal, while allowing communication between the outlet 154 of the second branch passage 150 (FIG. 2) and an orifice through 208 formed in said linings 207 and the part 206.

We will now return to the inner tube 251.

After its head 252 (in two parts in FIG. 3A), this comprises a rod of smaller section 253, provided with a longitudinal groove 254 in which the pin 203 already mentioned is housed. The internal rod 251 is therefore movable to slide inside the external tube 201. The cooperation of the pin 203 and the groove 254 ensures their immobilization with relative pivoting.

The rod 253 is followed by a barrel 255, provided with J-slots (J-slots), which form a circuit closed by its periphery, and cooperate with a pin 205, as will be seen below. After the barrel 255, the internal rod again comprises a tube of small section 256, provided with an axial passage which communicates with the pressure gauge housed in the head 252. The tube 256 passes inside the tube 259 already mentioned.

The bottom of the tube 256 is associated with a part forming a first bulge 257, which externally houses an annular seal 261. The bulge 257 is followed by a zone of reduced section 258 in which the central passage of the tube 256 terminates. second bulge 259 houses a second annular seal 262.

After that, the internal rod 251 is continued by a solid tube 270, provided with an end stop 271, consisting of an attached nut. On the solid tube 270 is movable axially sliding a key holder made in two parts 272 and 273. The keys 274 and 275, integral with each other, define a second gripping member. The second key 275 is suitable for cooperating with the anchoring groove 133 of the jacket 130 (FIG. 2) and has a shape homologous to that of the groove 133. The key 274 located above is suitable for coming into cooperation with the shrunk 116A provided between the bores 117 and 116, to allow the erasure of this second gripping member, as will be seen below.

The keychain, made of parts 272 and 273, is normally biased in abutment towards the shoulder 271 by an elastic return 276. The latter bears at its other end on a sleeve 230, which is also movable by sliding on the tube 270. The sleeve 230 has, turned upwards, an internal shape suitable for housing the bulge 259 which carries the second annular seal 262. It is therefore prevented from moving axially upwards, either by this widening 259, or by the fact that it abuts against the lower end 209 of the outer tube 201. In this abutment position, the second annular seal 262 can move smoothly from its position housed inside the cap 230 to a higher position, sliding inside the tube 206 (Figure 3D).

Preferably, the moving assembly 200 comprises, between the external tube 201 and the internal rod 251, a device for converting reciprocating movement into unidirectional movement, and means suitable for disengaging one of the two gripping members (here the first gripping device) after a predetermined number of pulls / releases of the descent cable.

More specifically, the barrel 255 already mentioned has grooves whose shape is better illustrated in Figure 7. This figure is a developed view of the outer contour of the barrel, with its slots in J.

The pin 205 mentioned above is mounted on a jacket 290, movable in rotation inside the external type 201. In the lower part, the jacket 290 comprises a part 290A (FIG. 3B) of reduced diameter, externally provided with a thread , which cooperates with a homologous thread of another jacket 291. This comprises openings allowing the keys 293 and 294 to pass. These same openings ensure the immobility of the jacket 291 in rotation. On the other hand, it can move in translation under the effect of the thread which connects it to the first jacket 290. In the lower part, the jacket 291 has an internal conical shape 292, widening upwards. When the jacket 291 has sufficiently risen, this wedge 292 will engage the keys 293 and 294, and ensure the retraction of these inside the external tube 201.

It will be seen below that the operation of the mobile assembly supposes an alternating translation of the rod 251 inside the tube 201. It is assumed that at the start of such an alternating translation movement, the pin 205 is in position 280 of FIG. 7. During a traction exerted on the rod 251, this pin will come to abut at 281, then take the slot path 282, to complete its movement at 283. During the relaxation which will then intervene, the pin will now take the slot path 284, to come back to 285 a position which is in fact (taking into account the development of 360 °) the same position as 280.

We will now describe the implementation of the method according to the invention.

It will be recalled that, in the preferred application, the method is applied to a well in which a test of productive zones is carried out.

The first step of the process, carried out in advance, consists in inserting into the drill string or the production column of the well, a tubular body as described above with reference to FIGS. 1 and 2.

The test device installed in depth, with its own valve, is therefore installed at the level of the seal (or packer) delimiting the layer which it is desired to test.

Note that the insertion of the body leaves a large hydraulic and mechanical passage for access to said test device. It is especially possible to pass a wide variety of useful tools for the test.

The method of the invention installs above the conventional test apparatus (without pressure gauge or recorder) another valve system, which involves the flap valve 121 incorporated in the body, and its control jacket 130, and will be used for the test.

To be able to implement this other valve system, the method of the invention has as a second step the descent into the well, at the end of the carrier and conductor monocable, of the control equipment illustrated in FIG. 3, and described with reference to this.

At the end of this descent, the keys 293, 294 of the crew 200 arrive on the constriction 112, while the keys 274, 275 of the lower part were able to pass this constriction, then avoid, given their smaller diameter outside, the attachment in the grooves 114 and 115, and subsequently retract to cross the zones of smaller section at 113, 106 and 107 as well as 116. They therefore arrived at 117, above the liner 130.

The load bars added to the mobile assembly are chosen to be of sufficient mass to fit the keys 293, 294 into the grooves 114 and 115, respectively. A finger (not shown) ensures, by abutment on the keys, that the tube 201 cannot (or only slightly) rotate relative to the body 100. The crew 200 lands on the upper part of the part 107, the diameter of which is lower than that of the part 206 of the crew 200. This ensures a deep positioning of the crew 200 relative to the body 100 (No-Go function = does not fit). The establishment of these keys is naturally accompanied by that of the seal 207 on the polished bore 107. The central passage is now completely closed.

For their part, under the effect of both the aforementioned load bars and the spring 270, the key 275 engages on the groove 133 of the liner 130. The mobile assembly is then put in place. The situation is that of figure 4.

The flap valve 121 is open, and the fluid can pass through the passage 140 to bypass the moving element, and go up towards the head of the well. It was previously indicated that this passage 140 has in all points a section substantially equal to the section of the main passage 110 (or more exactly at its minimum value available here at the bore of the ring 107). It is also noted that the upper part of the passage 110, inside the end piece 101 and the body 103, has been provided much wider. This makes it possible to continue to benefit from a cross section equivalent to that of bore 107, even when the mobile assembly is located in the upper part of passage 110.

The well flow therefore passes normally.

Next to that, the sleeve 230 is separated from the outer tube 201. The fluid pressure can therefore enter there through the central tube of the internal rod 251_, to go up to the pressure gauge housed in the head 252. The latter can thus deliver pressure information which is transmitted to the surface by the carrying and conducting cable.

The next phase of the process occurs when it is desired to close the flap valve 121.

A traction is then exerted on the cable, which comes to pull the internal rod 251 upward relative to the external tube 201. The stop 271 then pulls the lower keys 274, 275, as shown in FIG. 5, and these drive the jacket 130 with them, against the effect of the spring 132. Sufficient raising of the jacket allows the flap valve 121 to close under the effect of both its spiral spring and its drive by the movement of fluid.

After closing the valve, the well no longer flows. On the other hand, the rising pressure of the valve is transmitted by the fine tube 150 to the homologous orifices 154 and 208. The sleeve 230 has now come into abutment on the lower end of the tube 201, and the pair of seals 261 and 262 frames the outlet of the orifice 208 inside the tube, isolating the latter from any other pressure. The pressure upstream of the valve is thereby transmitted to the central pipe formed in the tube 251, thereby reaching the pressure gauge, which transmits the measurement to the surface as before.

When pulling up, the J-groove device illustrated in Figure 7 rotated the jacket 290 by half a turn.

It will then be necessary to reopen the well. This can be done by opening the flap valve 121, but it will only open when the pressures it feels on both sides are substantially equalized.

To this end, the opening operations of the flap valve 121 begin with a loosening of the cable fixed to the central rod 251. The latter then descends, as illustrated in FIG. 6. On the other hand, the key ring 273 does not not follow, since it is fixed on the jacket, and the movement of the latter downward is prohibited by the pressure of the fluid under the flap valve. The bulge 259 has again come to be housed, with the seal 262, in the sleeve 230, which, in a downward movement, is detached from the outer tube 201. The passage 150 then allows the fluid located upstream of the valve 121 to come, through orifice 208, to escape downwards in the annular pipe formed between the two seals 261 and 262, and thereby join the downstream face of the flap valve as well as the entire volume of the casing by the first bypass passage 140. After a certain time, the difference in pressures on either side of the valve has decreased enough for the elastic return exerted on the jacket by the spring 132, and the force due to the spring 276 (taking into account the low position of the cap 230) again become sufficient to ensure the opening of the valve. Equalization can be accelerated by closing the deep valve and / or injecting pressurized fluid into the tubing.

During this maneuver, the shirt 290 has again turned a half-turn.

After a certain number of operations, the cone 292 of the shirt 291 pinches the heels of the keys 293, 294 and retract them.

The outer tube 201 is then no longer secured to the body. On the other hand, the keys 274, 275 remain engaged on the groove 133 of the shirt 130.

The traction on the cable then allows the keys 274, 275 to be raised sufficiently so that the first one (274) comes to retract on the constriction 116A formed between the bores 117 and 116, thus releasing the jacket. The valve 121 closes or remains closed during this maneuver, to reopen as soon as the pressures on either side of the valve 121 will be equalized, the deep valve being closed or not. The entire control crew can then be brought to the surface.

It will be noted that the number of closing / opening operations which are to be carried out before the tool is released can be adjusted before the control equipment is lowered, by an adequate prepositioning of the screw sleeve 290 relative to the sleeve sliding 291.

The invention is not limited to the single embodiment which has just been described. For example, we can use a ball valve instead of a flap valve, since the main thing is that the type of valve used allows access upstream of the valve with tools to perform certain operations under the valve if necessary. In addition, a non-electric cable can be used, but in this case, the pressure gauge must be connected to a set of memories which make it possible to record the pressure data. These are then read from the surface by appropriate and known means when the control unit is removed from the well.

Claims (14)

1. Method for conducting measurements in an oil well comprising the following steps:

a) inserting, previously, in the drill string or the production tubing (101, 102), a tubular body (100) comprising a large central passage (110), this passage having an intermediate bore (107) defining its smallest diameter, with, over the latter, a first anchoring zone (114, 115) and, under the intermediate bore (107), a valve (121) kept normally open by a jacket (130) mounted slidably in the central passage and loaded by an elastic return (132) toward a stop (108) and provided internally with a second anchoring zone (133), while there is provided, integrated in the tubular body, a first branch passage (140) capable of establishing a hydraulic short circuit downstream of the valve, this short circuit going around at least the two anchoring zones, and a second branch passage (150) of small section between the upstream part of the valve and a point of said intermediate bore;

b) lowering into the well at the end of a cable (199) a control unit (200) consisting of an external tube (201) equipped with first seizing elements (293, 294) capable of engaging on the first anchoring zone (114, 115) and an internal rod (251) sliding in the tube (201) and equipped with second seizing elements (274, 275) capable of engaging on the second anchoring zone (133), the external tube moreover including a seal (207) capable of cooperating with said intermediate bore (107) and, within said seal, an orifice (208) capable of establishing communication between the second passage (150) and the interior of the external tube (201); the internal rod (251) having a pair of seals (261, 262), designed to come into contact on either side of the orifice (208) with the interior of the external tube (201), and a conduit placing the space between said seals in communication with a pressure gage (252), said cable (199) being connected to the internal rod (251); and

c) pulling on the cable, thereby moving the jacket (130), closing the valve (121) and placing the upstream part of the valve in communication with the pressure gage (252).

2. Method according to claim 1, characterized in that the external tube (201) of the control unit (200) is completed by a sleeve (230) sliding on the rod (251) and capable of lodging one of the two seals of the pair (262) in the rest position, and comprising the following additional step:

d) releasing the cable (199), thereby making it possible, by the passage of fluid between the external tube (201) and the sleeve (230) to equalize the pressures on either side of the valve until the elasitc return exerted on the jacket (130) is sufficient to open the valve (121).

3. Method according to claim 2, characterized in that the steps c) and d) are repeated several times and in that there is provided, in the control unit (200), between the external tube (201) and the internal rod (251), a device capable of disengaging at least one of the seizing elements after said steps have been repeated a predetermined number of times, and further characterized in that:

e) the control unit (200) is then raised again at the end of its cable (199).

4. Method according to claim 3, characterized in that the disengagement of the other seizing element (274, 275) is achieved by the cooperation of the form between the latter and the central passage of the body (116, 116A) at the beginning of step (e).

5. Method according to any of claims 1 to 4, characterized in that the first branch passage (140) begins at a point of the body located at the level of the jacket (130), and in that the latter has one or more openings (134) coming opposite the inlet of said passage, at least in the rest position of the jacket.

6. Method according to any one of the preceding claims, characterized in that the tubular body (100) is inserted over a deep valve equipment (VP) installed at the bottom of the well.

7. Apparatus for conducting measurements in an oil well, the apparatus comprising:

-a tubular body (100) including a large central passage (110), this passage having an intermediate bore (107) defining its smallest diameter with, over the latter, a first anchoring zone (114, 115) and, under the intermediate bore, a flapper valve (121) kept normally open by a jacket (130) mounted slidably in the central passage (110) loaded by an elastic return (132) toward a stop (108), and provided internally with a second anchoring zone (133);

-integrated in the tubular body, a first branch passage (140) capable of establishing, downstream of the valve (121), a hydraulic short circuit, this short circuit going at least around the two anchoring zones (114, 115 and 133);

-also'integrated in the tubular body, a second branch passage (150) of small section between the upstream part of the plug valve (121) and a point (154) of said intermediate bore (107);

-this tubular body (100) capable of being inserted in a drill string or in a production tubing without significantly reducing the passage section, and capable of receiving if desired a valve control unit engaged on these anchoring zones, while the first branch passage maintains a hydraulic passage for the fluid when the valve is open, and the second branch passage allows hydraulic measurements upstream of the valve when the valve is closed; and

-a control unit (200) made up of an external tube (201) lodging slidably an internal rod (251) of which the head (252) is capable of being connected to a lowering cable (199);

-the external tube being provided with first seizing elements (293, 294) capable of engaging on the first anchoring zone (114, 115) of the body, and a seal (207) capable of cooperating with said intermediate bore (107) of the body as well as, in said seal, an orifice (208) designed to establish communication between said second branch passage (150) of the body and the interior of the external tube (201);

-the internal rod (251) being provided with a second seizing element (274, 275) capable of engaging on the second anchoring zone (133) of the body, and with a pair of seals (261, 262) capable of coming into contact, on either side of said orifice (208), with the interior of the external tube (201), while there is provided a conduit bringing the space between these two seals (261, 262) into communication with a pressure gage (252);

-this unit allowing the closing of the valve by pulling on the lowering cable, while the pressure gage measures the pressure upstream of the valve.

8. Apparatus according to claim 7, characterized in that the external tube (201) of the control unit (200) is completed by a sleeve (230) sliding on the rod (251) and capable of lodging one of the two seals of the pair (262) in the rest position, the passage of fluid between the external tube (201) and the sleeve (230) thereby making it possible, when the cable (199) is released, to equalize the pressures on either side of the valve until the elastic return exerted on the jacket (130) is sufficient to open the valve (121).

9. Apparatus according to claim 8, characterized in that there is provided, in the control unit (200), between the external tube (201) and the internal rod (251), a device capable of disengaging at least one of the seizing elements after the cable (199) has been pulled and released a predetermined number of times.

10. Apparatus according to claim 9, characterized in that the disengagement of the other seizing element (274, 275) is achieved by the cooperation of the form between the latter and the central passage of the body (116, 116A).

11. Apparatus according to any one of claims 7 to 10, characterized in that the mobile unit (200) has, between the external tube (201) and the internal rod (251), a device for converting alternating movement into unidirectional movement (205, 255).

12. Apparatus according to claim 11, characterized in that the internal rod (251) is held (203, 254) in a fixed radial position in relation to the external tube (201), in that said movement conversion device comprises, on the internal rod, a barrel (255) equipped with J-slots forming a closed circuit on its periphery and then, around this barrel, a jacket (190) carrying a pin which engages the J-slots, and a threading at the bottom, this threading cooperating with another jacket (291) secured against rotation, the back-and-forth movement of the internal rod in relation to the barrel (255) producing a corresponding rotation of the first jacket (190) which loads the second jacket (291) to translate it axially and, through a wedge shape (292) its second jacket disengages the first seizing element (293, 294) after the lowering cable has been pulled and released a predetermined number of times.

13. Apparatus according to any one of claims 7 to 12, characterized in that the first branch passage (140) begins at a point of the body located at the level of the jacket (130), and in that the latter has one or more openings (134) coming opposite the inlet of said passage, at least in the rest position of the jacket.

14. Apparatus according to any one of claims 7 to 13, characterized in that the tubular body (100) is inserted over a deep valve equipment (VP) installed at the bottom of the well.

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