Classifications

• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B37/00—Methods or apparatus for cleaning boreholes or wells

Definitions

• the present invention relates to a method for cleaning an underground well and to a device for implementing such a method.
• a first method consists in reconditioning by means of a drilling device the production conduit at the level of the layer.
• the application of this method is very expensive because it is necessary to dismantle the equipment in place and after cleaning carry out a new completion.
• a first drawback resides in the fact that the circulation of the cleaning fluid exerts a back pressure on the often brittle and very sensitive layer (loss, emulsion, precipitate, etc.)
• a second drawback resides in the fact that the process requires an operation beforehand. to the cable whose length, load and deflection limitations are known.
• a third drawback relates to training in a sub-hydrostatic or depleted regime: the system by the back pressure that it develops requires the use of fluids produced with low specific weight and compatible with the training; this can become prohibitive.
• the significant development of deflected, highly deflected wells and horizontal drains poses many new cleaning problems by the very fact that the direction and speed of the flow of fluid for discharging solid matter by known and conventional methods and devices does not can oppose the forces which tend to disintegrate the layer.
• the tube train is injected into the well after dismantling the existing completion.
• the device cannot operate continuously over a large range of sediment accumulation without heavy intervention, such as the addition of additional concentric tubes. The implementation of this process disrupts the completion, which is a major drawback.
• the present invention provides a cleaning method according to which a small diameter maintenance tube called "coiled tubing" is lowered inside the production column, comprising at its end a cleaning head for the suction of the sediments to be extracted, a hydraulic separation of the annular space between the maintenance tube and the production column is carried out, at a certain level above the part of the well to be cleaned, the maintenance tube being able to slide axially in said hydraulic separation over a length at least equal to the total length of the well part to be cleaned, and a driving fluid is injected into said annular for the operation of a hydro-ejector, which hydro-ejector causes the suction by the tube maintenance of the sediments to be extracted, the hydraulic separation isolating the annular in overpressure from the bottom of the well in depression.
• said hydraulic separation is carried out by means of a cable gland mounted, with the possibility of sliding in the cleaning position of the device, on the maintenance tube, which cable gland cooperates with a polished connection (in English: "landing nipple") of the production column to achieve a watertight and sliding separation.
• a polished connection in English: "landing nipple"
• the maintenance tube is a so-called “coiled tubing” tube with a diameter less than or equal to 38 mm.
• the "coiled tubing” is flexible and by this means the process applies equally to vertical wells, deviated wells, strongly deviated wells, or horizontal drains.
• the “coiled tubing” is remarkable in that it comes into perfect contact with the low generatrix of the highly deviated or horizontal drain.
• the cable gland includes a set of seals on its internal diameter to allow leaktight sliding of the maintenance tube on said cable gland.
• the cable gland is shaped to be immobilized in abutment against a shoulder of the polished fitting, and also includes external seals applying to the internal surface of said polished fitting. It is the overpressure in operation that keeps it in this position.
• the cleaning is then done, in one or more progressive passes, by moving the cleaning head in the part of the well to be cleaned by sliding the maintenance tube through the hydraulic separation, that is to say by sliding the tube to through the cable gland.
• the cleaning device comprises a cleaning head mounted at the end of an extension of the maintenance tube, a cable gland mounted sliding on said extension above said cleaning head, a hydro-ejector mounted at the other end of said extension, the outlet of the hydro-ejector being connected to the surface by the maintenance tube.
• the cleaning head has an outer diameter less than the internal passage diameter of the polished fitting while the cable gland has an outside diameter greater than the internal passage diameter of the polished fitting, so as to come to a stop in translation on said polished fitting .
• the cable gland is temporarily immobilized in translation on the cleaning head by means of a pin or any other equivalent means, the rupture of which can be caused by hydraulic overpressure or mechanical support to the 'arrival in the polished fitting.
• the cleaning head has an ejectable plug for closing the external fluid inlet to the maintenance tube, the ejection of the plug being caused by an overpressure in the maintenance tube.
• a well-known and widely used intervention technique such as the so-called "coiled tubing” technique is an important advantage.
• the present invention does not relate to this technique per se, which is known to require surface devices, known per se, such as a well shutter block (BOP), an airlock, a coiled tubing storage reel “, an injector and pumping means, all not described in detail and not shown in the context of the present patent application. It is also another object of the present invention to propose a cleaning method comprising the complete lowering of the maintenance tube according to which:
• - Figure 1 shows the device for cleaning a well bottom when descending into the well
• - Figure 2 shows the same device in the cleaning position in the well
• FIG. 3 represents the cable gland of the device in FIGS. 1 and 2
• FIG. 4 represents an exemplary embodiment of the cleaning head, with its ejectable plug
• FIG. 4a represents an exemplary embodiment of the external face of this cleaning head which can be rotated by the suctioned fluid
• FIG. 5 shows an embodiment of the plug connector used for the removal of the hydro-ejector after cleaning operation.
• the reference 1 represents a continuous tube of relatively small diameter, less than or equal to 38 mm (l "l / 2).
• This tube is that of a tool used for intervention operations under pressure in production wells, known as the "coiled tubing” technique, a technique in which a flexible and continuous tube stored on a drum is injected into a pressure well.
• This technique adapts to any head configuration well and offers a rapid maneuver.
• the injection system with the well shutter block and the airlock in particular, as well as the "coiled tubing" storage system, the means fluid injection and surface pumping are not shown.
• a Venturi effect pump or hydro-ejector 3 operating in reverse pumping mode.
• valve 3a integrated in the Venturi prevents any return of liquid to the space surrounding the pump, as will be explained below.
• the pump 3 Via a sealing connection, referenced 4, with a diameter of 38 mm (l "l / 2), the pump 3 is connected to a tubular extension 5 whose diameter is equal to that of tube 1 and whose length is adjustable according to the dimensional characteristics of the well to be cleaned This length is at least equal to the distance between the level of hydraulic separation chosen (L in the drawing of FIG. 2) and the most distant part of the well to be cleaned.
• a cable gland 6 is mounted with the possibility of sliding along the tubular extension 5. It is shown in more detail in the drawing of Figure 3. it has on its inner bore 6a a set of O-rings and lip 6b and on its outer bore 6c a set of compressible resilient lip seals 6d, the seals 6b sealing the tubular extension 5 while the outer seals 6d cooperate with an element of the production column (the polished connector or "landing nipple ”) to perform the hydraulic separation as will be seen later.
• the cable gland 6 is immobilized in translation on the upper part of a cleaning head 7 by a pin 8 (see Figure 3), which can be sheared under the conditions explained below to allow the maintenance tube to slide into the internal bore of the cable gland 6.
• the end of the extension 5 is temporarily closed by an ejectable plug 7a (see FIG. 4) which has the function in the closed position of allowing the mounting of the pump 3 on the surface.
• the cleaning head 7, which extends the tubular extension 5, is designed to facilitate cleaning by turbulence and induced rotation.
• the cleaning head 7 and its mounting at the end of the tubular extension 5 are shown in the drawing in FIG. 4.
• the ejectable plug 7a is immobilized in the closed position by means of the pin 13.
• the head is rotatably mounted on a ball bearing bearing 14.
• a conventional gripping connector 18 comprising the parts 15, 16, 17 allows the attachment of the head 7 to the extension 5.
• the head is pierced with oblong grooves 19 pierced in non-radial directions, but oriented helically or almost helically, so as to impart, under the effect of the through fluids, a rotational movement to the cleaning head 7 (FIG. 4a) . It can also be provided on the outer surface of the turbulence fins 20 (FIG. 4a).
• the reference 9 schematically represents the casing of the well, which can be a vertical well, deviated, or even strongly deviated and even a horizontal drain.
• the production column is referenced 10.
• the annular space between the production column 10 and the casing 9 is closed by a seal or packer 11.
• the cleaning assembly or maintenance tube of FIG. 1 is introduced in the production column 10, which comprises a polished downhole connection 12 forming, by its shoulder 12a, seat for the cable gland 6.
• the production column 10 is of any diameter.
• the cleaning system works as follows:
• the "coiled tubing" wound on the surface on a reel is inserted without disturbing the pressure prevailing at the top of the well in a seal and maneuvering (stripper), not shown, with the addition of a lubricating grease, with the cleaning head 7 at its free end. Above the cleaning head is inserted the cable gland 6, immobilized in translation with the cleaning head 7 by the pin 8 ( Figure 3).
• the length of "coiled tubing" inserted in this way in the "stripper” depends on the distance between the most distant part of the well to be cleaned and the location (L) of the polished fitting 12 forming a sliding bearing for the maintenance and separation tube hydraulic.
• the length of the tubular extension 5 is equal to or greater than the distance indicated above.
• the "coiled tubing” is suspended in the jaws of a well shutter block (BOP) and the airlock is opened.
• BOP well shutter block
• These conventional materials of the "coiled tubing” technique are not shown in the drawing, and are not described in detail.
• the "coiled tubing" tube is cut at the surface, security being obtained by the position of the ejectable plug 7a in the cleaning head 7 which prevents any rise of fluid by the "coiled tubing" tube constituting the maintenance tube.
• the hydro-ejector 3 is inserted by means of a plugging connector 4 shown in the drawing in FIG. 5.
• This connector 4 comprises a quarter-turn valve 4a, housed in a bore 4b and can be oriented by an axis 4c.
• This type of connector also includes a plurality of seals 4d and an outer surface of curvilinear profile in the recesses from which the tubular parts of the elements to be connected are forcibly crushed (FIG. 5).
• the hydraulic separation is carried out, the part of the production column located below the hydraulic separation (referenced LB) and, therefore, also the bottom of the wells are isolated from the volume of annular pressure (LH) located at - above the hydraulic separation.
• This hydraulic separation constitutes an important characteristic of the present invention. Indeed, this separation makes it possible to set in motion and evacuate the sediments without overpressure on the layer, without contact of working fluid with the wall of the well.
• the cleaning operations take place with isolation of the part of the well to be cleaned thanks to the hydraulic separation carried out by the immobilization of the cable gland
• the ejectable plug 7a is ejected (shearing of the pin 13 or any other means known per se) and falls to the bottom of the cleaning head 7, the bottom of the well is then connected to the surface (see figure 4).
• the working fluid pumped from the surface starts the suction of the hydro-ejector 3 through the cleaning head 7 and the tubular extension 5.
• the sediments are sucked in through the orifices 19 of the cleaning head, rise up through the extension tube 5, the connector 4, the hydro-ejector 3 and the tube 1 towards the surface.
• the cleaning head 7 can be a rotary head with a cyclone effect by the conformation of the orifices along helical lines, as already mentioned.
• the working fluid is replaced by a fluid which does not pollute the tank and which stabilizes the well or not. If this fluid is gas, the well generates overhead pressure.
• the maintenance tube is closed internally, arriving at the surface by a shutter 4a housed in the connector 4 placed under the hydro-ejector 3, which allows the removal of
• any leak in the packing gland does not condemn the cleaning method, it simply results in a reduction in energy efficiency compensated by an increase in the flow of engine liquid .

Landscapes

• Geology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Mining & Mineral Resources (AREA)
• Geochemistry & Mineralogy (AREA)
• Fluid Mechanics (AREA)
• Environmental & Geological Engineering (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Physics & Mathematics (AREA)
• Cleaning In General (AREA)
• Cleaning By Liquid Or Steam (AREA)
• Sewage (AREA)
• Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
• Vehicle Cleaning, Maintenance, Repair, Refitting, And Outriggers (AREA)
• Refuse Collection And Transfer (AREA)
• Vending Machines For Individual Products (AREA)
• Processing Of Solid Wastes (AREA)
• Excavating Of Shafts Or Tunnels (AREA)
• Earth Drilling (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=9388362

Family Applications (1)

Country Status (9)

Families Citing this family (18)

Family Cites Families (9)

• 1989
  • 1989-12-11 FR FR8916346A patent/FR2655684B1/fr not_active Expired - Fee Related
• 1990
  • 1990-12-10 DK DK91900837.5T patent/DK0457879T3/da active
  • 1990-12-10 US US07/768,435 patent/US5158140A/en not_active Expired - Fee Related
  • 1990-12-10 EP EP91900837A patent/EP0457879B1/de not_active Expired - Lifetime
  • 1990-12-10 AT AT91900837T patent/ATE110438T1/de not_active IP Right Cessation
  • 1990-12-10 WO PCT/FR1990/000895 patent/WO1991009205A1/fr not_active Ceased
  • 1990-12-10 DE DE69011850T patent/DE69011850D1/de not_active Expired - Lifetime
• 1991
  • 1991-08-09 OA OA60061A patent/OA09390A/xx unknown
  • 1991-08-09 NO NO913111A patent/NO301728B1/no unknown

Non-Patent Citations (1)

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