FR2459358A2 - DEVICE AND METHOD FOR ISOLATING A UNDERGROUND AREA CONTAINING A FLUID, IN PARTICULAR FOR RECONDITIONING AN OIL WELL - Google Patents

Abstract

THE INVENTION CONCERNS A DEVICE AND A PROCESS FOR INSULATING AN UNDERGROUND ZONE, IN PARTICULAR FOR THE RECONDITIONING OF A WELL. THE DEVICE INCLUDES A PACKER INTENDED TO BE ANCHORED IN A WATERPROOF AND REMOVABLE WAY IN THE WELL ABOVE THE PRODUCTION AREA, A VALVE FIXED TO THE PACKER AND HYDRAULIC CONTROL MEANS FOR OPENING AND CLOSING THE VALVE, CONNECTED TO REMOVABLE BY THE VALVE AND WHICH CAN BE FIXED TO THE LOWER PART OF A ROD TRAIN OR THE PRODUCTION COLUMN, THE HYDRAULIC CONTROL MEANS OF THE VALVE BEING OPERATED FROM THE SURFACE AND BEING SENSITIVE TO THE PRESSURE EXERCISED BY THE COLUMN OF LIQUID FILLING THE ROD TRAIN OR THE PRODUCTION COLUMN. APPLICATION TO THE RECONDITIONING OF OIL WELLS INCLUDING AN ELECTRIC PUMP IN THE WELL.

Description

The invention relates to a device and a method for isolating a

  underground zone producing a fluid such as oil, natural gas

  or a mixture of both. The invention is particularly applicable to the recondi-

  oil well in that it allows the withdrawal of the production column or the repackaging of the well without having to kill it. For oil wells whose natural production is insufficient or unstable (so-called "semi-eruptive" wells), an electric pump placed near and above the production area is used to

  move the fluid up to the surface. The pump is placed at the lower end

  of the production column and is supplied with electrical power by means of an electrical cable connecting the pump to the source of electrical energy

located on the surface.

  In case of malfunction or failure of the pumping system of the pump, the motor or the electric supply cable, it is necessary to reassemble the pump for verification and repair if necessary, thus removing the entire production column. To do this, you must first

  to kill the well, that is to say, to exert on the producing zone a hydro-

  static above the pressure of this zone to prevent any eruption. This operation is accompanied by a loss of production of the fluid throughout the duration of the operation, which can be long, and also a decline in productivity of the well due to the inevitable damage suffered

by the producing area.

  The invention described in the main patent application overcomes these disadvantages in that it allows to isolate the producing zone by arranging in the casing, between the producing zone and the pump, closure means whose closure and the opening are hydraulically controlled from the surface. This hydraulic control is effected by appropriately varying the pressure difference, at the bottom of the production column, exerted by the filling liquid of the production column and by the liquid filling the annular space between the casing and the production column. This method works satisfactorily when the annular space is closed by a double packer (reference 4 in the main patent application) located near the producing zone. On the other hand, when this packer is removed from the producing zone, the annular space is generally not completely filled with liquid, since the upper part of the annular space can be occupied by gas. This space is even sometimes used to separate the gas from the liquid, when the reservoir rock produces both liquid and gas. It is then understood that the solution described in the main patent application is no longer applicable. Indeed, we can not

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  more act directly from the surface on the hydrostatic pressure of the annular space at the valve shutter. Nor can one use a hydraulic control line (which would be too long) extending from the control means of the valve to the top of the double packer, since the latter is too far from the valve. For exemple,

  this distance may be greater than 1000 m.

  The invention provides a method and a device for eliminating the disadvantage stated above. The invention makes it possible in particular to isolate the production area by arranging closure means in the casing, between the production area and the pump, whose closing and opening are controlled hydraulically from the surface by acting solely on the

  hydrostatic pressure of the filling fluid of the production column.

  To this end, the invention proposes a device for isolating a subterranean zone containing a fluid and communicating with the ground surface by a well comprising: a packer intended to be anchored in a waterproof and removable manner in the well above of said zone, said packer having an orifice for the passage of fluid through said packer; a valve fixed to said packer in a sealed manner and provided with a shutter, said valve being able to be opened or closed to respectively allow or prohibit the flow of the fluid to the surface through said orifice, and hydraulic control means for the opening and closing of said valve, connectable removably to said valve and can be attached to the lower part of a drill string extending from the surface, said hydraulic control means of said valve being implemented from the surface and being sensitive to the pressure exerted by the column

  of liquid filling said drill string.

  The invention also relates to a system for the reconditioning of an oil well of the type comprising a production column, a pumping assembly attached to the lower part of the column, an electric supply cable for connecting said pump assembly to an electrical energy source located at the surface, a double packer being anchored in the well and having two sealed passages, one for holding said production column and the other for passing said power cable, said repackaging system comprising the device for isolating an underground zone as defined in the preceding paragraph, said hydraulic control means of the valve being fixed under said pumping assembly.

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  The invention also proposes a process for reconditioning a well according to which the production of the fluid is carried out through a production column, characterized by the following steps: isolating the producing zone by means of a production device; isolation comprising a packer and an isolating valve provided with a shutter slidable in a direction substantially parallel to the axis of the well and previously placed in the closed position, said isolation device being placed in the well at above the production zone using a setting tool, fixing, at the lower end of the production column, hydraulic control means of the isolation valve, said means comprising two hydraulic lines connected to two fittings of the production column, said means being sensitive to the hydrostatic pressure prevailing in said production column and thus being operable from the

  surface through the liquid filling said column of

  duction., - setting up said production column in the well, said means

  hydraulic control unit which secures in a removable manner to said ob-

  slider, and - operating the hydraulic control means from the surface to move

  said shutter in the open position of the valve.

  The invention will be better understood on reading the description which

  follows of an embodiment of the invention given as an explanatory example

  but not limiting. The description refers to the accompanying drawings,

  in which: FIG. 1A diagrammatically represents the essential elements of the production column provided with the zone isolation device according to FIG.

  the invention, this device being in the open position, the column of

  duct and the annular space being open at their upper end, and - Figure lB shows only the closure means, in the closed position, the production column and the annular space to their

upper parts.

  The production column 150 is concentrically placed in the casing 2. The lower end of the production column is located near and above the producing zone 102. The production column

  comprises a pumping assembly 5 consisting mainly of an electric motor

  that actuating blades. This engine is powered by energy using a

  6 electric cable through a double packer 152 located not far from the sur-

face.

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  This double packer holds the production column inside the casing. It is located below a ball valve 154 for closing the production column from the surface. The control device of the valve 154 also controls the displacement of a liner 156 for communicating the annular space 158 with the production column when the ball valve 154 is closed. This communication is illustrated in Figure 1B in which the passage 160 allows the circulation in closed circuit of the filling liquid of the production column. This

  allows not to damage the electric pump when the valve 154 is closed.

  The double valve-packer assembly 152 is commercially available and can be

provided by Otis.

  The lower end of the production column, under the pump 5, is connected to the isolation means of the producing zone as indicated in the main patent application. These isolation means comprise a single packer 12 and a valve. with sliding sleeve It whose shutter is operated using a hydraulic cylinder 10. The packer 12 and the valve It are

  identical to those already described in detail in the main patent application.

  The hydraulic cylinder comprises a piston 14 connected by a rod 36 to the shutter sleeve of the valve. This piston delimits two chambers 15 and 16 located

on both sides of the piston.

  The two chambers 15 and 16 are connected, respectively, by hydraulic lines 17 and 18 at two distinct locations of the production column, above the pump assembly 5, with the respective couplings

  162 and 164. These connections can be closed by means of closure folders.

  placed in the fittings from the surface by the cable working technique. When the connections are closed, the communication between the hydraulic cylinder and the production column is closed. It should be noted that these connections may be non-closable. In this case, the communication between the hydraulic cylinder and the production column is closed with a plug

  that we place above the connection that we want to close.

  According to one of the features of the invention, the piston 14 is "differential", instead of being balanced as in the embodiment described in the main patent application. This means that its two faces on which the hydraulic fluid act have different sections. It is noted in fact that the rod 36 connecting the piston to the jacket closing the

  sliding sleeve valve has no equivalent on the opposite side of the piston.

  As a result, the hydraulic fluid acts on a section of the piston in

  the chamber 15 which is larger than the section of the piston in the chamber.

  Due to this difference in section, the piston is subjected to a force pushing it downwards, which keeps the valve in the open position as shown in FIG. 1A (the distance between the two hydraulic line connections 162 and 164 being relatively small, the hydrostatic pressures of the fluids in the chambers 15 and 16 are virtually identical). To move the piston upwards, it suffices to first place a plug 166 between the lateral connectors 162 and 164, then to increase the pressure of the liquid in the hydraulic line 18 and the chamber 16 by pumping from the surface of the piston. liquid in the production column. The piston then moves upwardly driving the shutter sleeve of the valve, which closes. The liquid of the chamber 15 is driven into the annular space by the hydraulic line 17 and through the orifices 122 of the pump 5. According to one embodiment (not shown) of the hydraulic cylinder, the piston 14 may be provided with means which make it either "differential" or balanced. The face of the piston, in the chamber 15,

  then includes a threaded hole in which the lower part can be screwed

  rod, similar to the rod 36, the upper part sliding in a sealed manner in a hole made in the upper wall of the

  chamber 15. This hole can be closed in a sealed manner by a plug.

  Due to the long length of the production column, which is fixed at two points by the double packer 152 not far from the surface and by the single packer 12 near the production zone, the flow of the hot liquid from the producing zone 102 in the production column induces an increase in the temperature of the column and therefore in its length. This elongation could cause buckling of the production column as well as serious damage to the pump 5 by subjecting the pump to compressive forces. To overcome this drawback, the described embodiment comprises a telescopic seal 168 placed above the side connectors 162 and 164. This telescopic seal 168 is located not far from the pumping assembly 5 so as to reduce the weight

  exercising on the pump. Such a type of seal is commercially available.

  Assuming that the piston, placed in the up position, does not move when increasing the pressure in the hydraulic line 17, so in the

  chamber 15, (piston blocked for one reason or another), the resulting force

  aunt acting on the upper part of the chamber 15 could have the effect of lifting the portion of the production column between the chamber 15 and the telescopic seal 168. The valve could then no longer be maneuvered and the safety of the system of isolation of the producing area would be jeopardized. In order to avoid this disadvantage, weights, such as drill collars

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  , are interposed between the pump 5 and the hydraulic cylinder 10. For example, seven meters of mass-rods weigh one ton. Besides these weights,

  it is also necessary to take into account the weight of the part of the column of pro-

  duction located between the pump 5 and the telescopic seal 168.

  Note that the isolation valve is held in the open position

  by the hydrostatic pressure of the liquid of the production column.

  In FIG. 1A, the lower part of the annular space is filled with liquid while its upper part is filled with gas. The annular space can thus be used to separate the gas from the liquid when the producing zone 102 produces gas and liquid or liquid containing dissolved gases. As for the production column, it is filled with liquid since the assembly 5 pumps the liquid from the annular space through the orifices 122 in the production column to the surface. It may also be noted that the embodiment shown in FIG. 1A also functions when the annular space is completely filled with liquid between the two packers.

  and 12. This embodiment can therefore be used in all cases.

  With regard to the laying of means of isolation of the production area,

  trice, that is to say the installation of the isolation valve 11, the packer 12 and the hydraulic cylinder, the procedure is the same as that described with reference to Figures 3 of the main patent application. It can be noted that the isolation means of the producing zone can be placed indifferently

  with a drill string or with the production column.

  The isolation valve It has come down in the closed position.

  To open it, simply increase the pressure in the production column by pumping liquid in this column from the surface. The piston 14 goes down and the valve opens. After checking that the valve is open,

  the pumping assembly 5 can then be started.

  To remove the production column, it is necessary first to close the isolation valve It so as to isolate the producing zone 102. To do this, the plug 166 is installed under the lateral connection 164 by cable work. The pressure in the production column is increased, which has the effect of increasing the pressure in the hydraulic line 18 and thus moving the piston upwards. The valve 11 is then closed. Pressure

  in this hydraulic line 18 is maintained by installing an obturating sleeve

  The plunger 14 then remains locked in the up position corresponding to the closure of the valve. We check that the valve is

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  well closed by pumping liquid into the annular space. Then, equalize the pressures between the production column and the annular space, above the lateral connection 164, by opening a sliding sleeve valve 172, called a flow valve. The production column can then be removed with the mass-sheets 170 and the hydraulic cylinder 10. The valve 11 and the packer 12

  remain in place so as to isolate the producing area.

  According to the method just described, the isolation valve is advantageously lowered into the well in the closed position. It could also be lowered in the open position, without leaving the frame

  of the present invention. In the same way, the packer 12 has been described and

  attached under the isolation valve 11. Other configurations are possible

  without departing from the scope of the present invention.

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Claims (12)

  1. Device for isolating an underground zone containing a fluid and communicating with the soil surface by a well according to one of   Claims 1, 7 to 13 of the main patent, characterized in that   it comprises - a packer intended to be anchored in a sealed and removable manner in the well above said zone, said packer having an orifice for the passage of fluid through said packer, - a valve attached to said packer of a sealed and shut-off manner, said valve being able to be opened or closed to, respectively, allow or prohibit the flow of fluid to the surface through said orifice, and hydraulic control means for the opening and closing of said valve, connectable removably to said valve and being attachable to the lower part of a drill string, said hydraulic means of said valve being operated from the surface and being sensitive to the pressure exerted by the liquid column filling said drill string.   2. Device according to claim 1, characterized in that said control means comprise a hydraulic jack having a displaceable piston in a chamber to define two spaces of variable volume and can be mechanically connected to said valve shutter and means of communication said spaces with two places distinct from said drill string.   3. Device according to claim 2 characterized in that said communication means comprise two hydraulic lines, each connecting one of said spaces of said chamber with one of said places. of said drill string.   4. Device according to one of claims 2 and 3, characterized in that   said cylinder can be removably connected to said shutter by   via elastic locking means. 9 2459358   5. System for reconditioning an oil well of the type comprising a production column, a pumping assembly attached to the lower part of the column, an electric supply cable for connecting said pumping assembly to a source of oil. electrical energy located on the surface, a double packer that can be anchored in the well and having two sealed passages, one to maintain said production column and the other to pass said power cable, said repackaging system being characterized in that it comprises said device as defined in one of the   of the preceding claims, said hydraulic control means   there of the valve being fixed under said pumping assembly.   6. System according to claims 3 and 5 characterized in that said column   of production comprises means for sealing each of said hydraulic lines with the inside of said column in one of said   locations above said pumping assembly.   7. System according to one of claims 5 and 6 characterized in that   has means for maintaining the fluid pressure of the fluid   in at least one of said hydraulic creepers.   8. System according to one of claims 5, 6 and 7 characterized in that la-   said production column has a sliding joint above said ; pumping set.   9: System according to claim 8, characterized in that said column comprises   further carries at least one drill collar below said pump assembly.   10. Process for reconditioning a well according to which the production of the fluid is carried out through a production column, characterized by the following steps: isolating the production zone by means of an isolation device comprising a packer and an isolating valve provided with a shutter slidable in a direction substantially parallel to the axis of the well and placed beforehand in the closed position, said isolation device being placed in the well above the zone producer using a laying tool, 2459358   - Fixing, at the lower end of the production column, hydraulic control means of the isolation valve, said means comprising two hydraulic lines connected to two connections of the production column, said means being sensitive to the pressure prevailing in said production column and thus being maneuverable from the surface via the liquid filling said production column, - setting up said production column in the well, said hydraulic control means being secured to detachable manner to said sliding shutter, and - maneuvering the hydraulic control means from the surface   to move said shutter to the open position of the valve.   11.Procédé according to claim 10 characterized in that, to remove said production column of the well, said production zone is isolated bythe following operations: - installation of a shutter in the production column between said two connections, - closing of said valve by adjusting from the surface the pressure in the production column, closing the communication of the hydraulic control means with the production column to maintain said valve in the closed position, - equalizing the pressures between the production column and the annular space, and - upstream of said production column and said control means of the valve, said zone remaining isolated by said isolation valve and said packer.   12.Procédé according to claim 11, characterized in that after the step of closing the communication of the hydraulic control means with the production column, it verifies the sealing of the isolation device of the underground area by increasing the pressure in the annular space above the isolation valve.