FR2877989A1 - WELL SHAPING METHOD - Google Patents

Abstract

- The object of the invention is a method of lining a well (1) comprising an old tube (A), characterized in that one brings vertically to the inlet of the well a first segment of tube (S1 ), the lower end of a second tube segment (S2) is welded to the upper end of the first tube segment, the tube segments welded to each other are lowered into the well, leaving l 'end of the second tube segment from the upper end of the well, the operation is repeated, with respectively a third (S3) and the second tube segments (S2), the third tube segment taking the place of the second and thus immediately with tube segments (S1, ..., Sn) successively brought until the well (1) is completely lined with a new tube, and, in a complementary step, the complete new tube is crimped on the old tube (A) in the well by a succession of positioning, inflation and movement of a crimping tool (3).

Description

WELL SHAPING METHOD

  The present invention relates to a method of lining wells.

  Wells such as water wells are drilled into the ground and have a continuous tube liner made from segments connected over the entire height of the well to double the natural well wall and provide a watertight seal. the height of the well.

  The walls of the tubes must in particular be sealed to prevent any contamination of the water captured by water infiltration of the layers of land above the capture point, particularly in the case of a drinking water collection.

  It is known to make the walls of the wells using tubes descended by drilling machines.

  This technique is cumbersome to implement and the few drilling machines are extremely expensive to use.

  In the case of old wells in particular made with steel tubes, the corrosion of the tubes causes the appearance of leaks internal to the well which must be plugged. In addition, when they are very deteriorated, the tubes, likely to have a cumulative height of several hundred meters may collapse on themselves.

  Finally, old wells are made with corrosion-resistant steel tubes while the current demand is for stainless steel tubes 20 reduced maintenance.

  To repair or re-condition the walls of the wells, it is known to double the old walls by an internal liner and the injection of concrete between the pre-existing tube and the new tube. This prior method has the disadvantage of reducing the diameter of the borehole, thus limiting the flow capacity of the well not only by the simple section reduction but also by reducing the diameter of the downhole pump that can be lowered into the borehole.

  In the case of boreholes for water collection for growing local communities the repair of a well is an expensive operation whose outcome is uncertain since the well repaired may be insufficient for drinking water needs.

  Another method is to insert sleeves at the corroded portions and, using an expansion tool having either rollers or an inflatable cylindrical bladder lowered into the well below the portion on which the sleeve is to be crimped, crimp these inner sleeves inside the tube in the deteriorated areas. Such a method, complex to implement and unusable in the case of heavily damaged wells, is described for example in US 3,477,506 or WO 00/37768 A1.

  In the case of a bore whose walls are heavily corroded, the application of the sleeve can cause a rupture of the tube at the junction between one end of the sleeve and the tube which irreparably damages the well, the laying of a second sleeve on the first sleeve and the original tube becoming impossible ..

  The present invention relates to a simple lining method to be implemented for the re-conditioning of an already existing well whose walls are deteriorated and ensuring a good seal over the complete height of the well without causing an excessive reduction of the section of the well. well.

  To do this, the present invention mainly relates to a method for lining a well comprising an old tube, characterized in that a first tube segment is brought vertically to the well inlet, the lower end of the tube is welded. a second tube segment at the upper end of the first tube segment, the welded pipe segments are lowered into the well, leaving the end of the second tube segment of the upper end of the tube well, the operation is repeated, with respectively a third and the second tube segments, the third tube segment taking the place of the second and so on with tube segments successively brought to complete lining of the well by a tube nine, and in a complementary step, the entire new tube is crimped on the old tube in the well by a succession of positioning, inflation and displacement of a crimping tool.

  According to an advantageous embodiment of the process according to the invention, the tube is crimped from the top of the well to the bottom of the well.

  Advantageously, during crimping, air is blown between the new tube and the internal section of the old tube in such a way as to drive down the water infiltrated between the new tube and the internal section of the old tube before crimping the new tube. on the old tube.

  Other aspects and advantages of the invention will be better understood on reading the following description of a nonlimiting exemplary embodiment of the invention accompanied by the figures which represent: in FIG. 1: a schematic view of a well being lined according to the method of the invention; in FIG. 2: a detail of the crimping operation of the method according to the invention with an inflatable bladder crimping device and an air injector device according to the invention; in FIG. 3: a detail of a crimping defect that the method according to the invention makes it possible to avoid; in FIG. 4: a detail of a section of tube crimped according to the process of the invention; in FIG. 5: a detail of a tube segment used in the process according to the invention; in Figure 6: a detail of the weld between two segments of tubes of the invention according to the method of the invention.

  The lining method of a well 1 comprising an old tube A implemented according to the invention is described schematically in FIG. 1 after a step of successively feeding successive segments of tubes S1,..., Sn and during a step crimping the new tube formed by the segments Si, ..., Sn on the old tube.

  Prior to this step, the method comprises a step of vertically feeding and welding the segments of tubes shown schematically in FIG. 6, and according to which a lower segment Sp is kept protruding from the upper end of the well, for example by a flange 11 then that an upper segment Sp + 1 is brought vertically by a crane using ropes 13, 13 'and a flange 12 to be welded by a peripheral weld 14 to the lower segment Sp.

  Thus, according to the example of FIG. 6, the lining of the well is begun by the vertical feed of a first segment of tube S1 partially inserted into the well inside the old tube A, the supply of a second tube segment S2 above the first using a simple crane 10, the welding of the lower end of the second tube segment S2 at the upper end of the first tube segment.

  Then, the first segments of welded tubes are lowered into the well, leaving the end of the second tube segment of the upper end of the well by loosening the flange 11 and descending the segment S2 until at the height previously occupied by the first segment and by clamping the flange 11 on the second segment to retain it and be able to secure a third segment S3 with the flange 12 in the place previously occupied by the second segment.

  The operation is repeated, with respectively the third S3 and the second tube segment S2 and so on with tube segments Si ,.

  , Sn successively brought to complete lining of the well 1 by a new tube ... DTD: According to the complementary step described in Figure 1, the new tube is crimped on the old tube A in the well by a succession of positioning inflation and displacement of a crimping tool 3.

  Preferably, the crimping tool 3 is an inflatable peripheral bladder tool that allows the internal tube to be crimped in a regular manner on the outer old tube.

  This technique is particularly suitable for crimping stainless steel tubes of the order of 4 mm and over coated with a layer of external protective material prior to their supply, the use of an inflatable bladder tool not risking to injure the protective material.

  The crimping operation is preferably performed from the top of the well to the bottom of the well and the length and number of the tube segments is calculated to account for the upward shrinkage of the complete tube due to the expansion caused. by crimping. For example, for segments of welded tubes 6 m long, a shrinkage of the order of 3.5 to 6% is taken into account, which requires going deeper into the well than the final height of the tube.

  In the case where one can not go deeper, it is expected to add a terminal sleeve at the end of crimping at the bottom of the new tube.

  A problem solved by the invention is the existence of crimping defects caused by the presence of infiltration water due to the deterioration of the old tube which can cause crimping defects of the new tube as shown in FIG.

  Water being an incompressible body, if water is trapped between the old tube and the crimping tube, it will oppose the compressive force of the tool and internal bumps will appear on the wall internal well re-jacketed.

  These bumps are problematic because, first, they cause a local fragility of the tube, secondly if the water is trapped at the junction by welding two tubes, it can cause a rupture of the weld or a leak and thirdly, the bosses can block the new pump that has to be lowered into the well.

  To prevent entrapment of water between the old tube and the new one, as shown in FIG. 2, air 4 is blown along the crimping between the new tube and the internal section of the old tube A in order to drive the down the water 5 infiltrated between the new tube and the internal section of the old tube before crimping the new tube on the old tube. Indeed, crimping starting from the top of the well, the blown air can not escape from the top and therefore push water possibly trapped between the tubes down. Successive crimping operations then being done in the absence of water are thus perfectly controlled.

  The blowing of the air is carried out by means of an injector device 6 provided with peripheral nozzles and lowered into the well under the lower level of the new tube.

  Preferably, the injector device 6 is secured to a ballast 7 of the hose 16 supplying the air under pressure passing through the crimping tool 3 and on which the tool slides as shown in FIG.

  An important problem solved by the invention is the crimping of welded tubes.

  Indeed, old attempts at crimping and widening of welded tubes have been made but have led to breaks in the tubes either at the welds or near the welds. These attempts have led to consider that the crimping of welded tubes is not applicable and according to the current rules of the art, the crimping or machining of welded zones is discarded.

  To overcome this problem and overcome this prejudice, according to the invention, the tube segments S1, ..., Sp, ..., Sn are provided with an external peripheral chamfer 9 on their ends, an example of which is shown in FIG. figure 5.

  This outer chamfer preferably made about 50% of the thickness of the tube constitutes an annular receiving zone of the V-weld at the junction of the tube segments as particularly shown in Figure 6 where the tube is shown in partial section.

  Thus, during the welding operation, in particular a TIG type welding under an argon atmosphere, the tube segments are welded at the level of said outer chamfer to obtain a regular annular weld bead in the annular V-shaped groove delimited by the chamfers of butt tubes.

  Such a weld resists perfectly the pressure exerted during crimping by the crimping tool and does not cause internal over-thickness at the junction of the pipe segments.

  As previously seen, the tube segments are coated, prior to their supply, with a layer of the order of 0.5 to 2 mm of a protective material such as an elastomer or an insulating flexible coating applied as a paint on the outer face of the tube segments and for sealing and electrical isolation of the tube.

  In order to achieve a clean and strong weld, the chamfer is devoid of protective material and, once welded, the weld area is covered with an insulating paint, insulating tape or other sealing material and electrical insulation, the entire tube being thus protected.

  The embodiment of the chamfer further avoids an edge-to-edge weld that may leave gaps between the pipe segments, through which the generally elastomeric envelope of the crimping tool may flow and break.

  The method according to the invention is simple to implement without using a specific drilling tool and, in particular, the tube segments, the crimping tool and the air blowing device 6 are lowered into the well. using a simple crane 10.

  Thus, by summarizing the method of the invention, and using tube segments provided with an external chamfer on their ends, a simple crane and means for clamping pipe segments: in a second step, the vertical line is brought up vertically. one after the other the 5 segments of tubes at the entrance of the well, - in a third step the lower end of an upper tube is welded to the upper end of a lower tube, - in a fourth step on gradually descends the welded tubes to each other, the upper tube taking the place of the lower tube, and the second, third and fourth stages are repeated until complete lining of the well.

  FIG. 1 describes various means of a particular embodiment of the method, namely an air compression unit 15 for supplying the device 6 for blowing air through a hose 16 passing through the tool crimping 3 and unwound at the compression unit, a crane 10 for lowering the tube segments in the well and down the crimping tool 3, a high pressure hydraulic unit 18 to perform the successive inflations of the crimping tool 3 connected to the crimping tool by a high-pressure hose 20, the carrier cable 8 on which the crimping tool 3 descends and a control and recording rack 18 in connection with control electronics and measuring 19 at the crimping tool 3 through an electrical cable comprising the electrical connections between the control panel and the control and measurement electronics and to which the tool 3 is attached.

  The control and recording chamber 18 in connection with the control and measurement electronics 19 in particular allows the remote control of the crimping tool, the sequential control of its descent, inflation and deflation according to the height of the pipe segments and the position of the welds to prevent the limit of a crimping being at a weld, the measurement of the depth of the well, the position of the tool 3 and the device air blowing, checking the crimping diameter of the crimping tool diameter and the air injection pressure.

  The invention is not limited to the example shown and in particular any other gas that air can be injected by the insufflation device 6.

Claims (1)

8 claims   1 - Process for lining a well (1) comprising an old tube (A), characterized in that a first tube segment (SI) is brought vertically to the inlet of the well, the lower end is welded of a second tube segment (S2) at the upper end of the first tube segment, the welded pipe segments are lowered into the well, leaving the end of the second tube segment the upper end of the well, the operation is repeated, with respectively a third (S3) and the second tube segment (S2), the third tube segment taking the place of the second and so on with tube segments ( S1, ..., Sn) successively brought to complete lining of the well (1) with a new tube, and, in a complementary step, the entire new tube is crimped onto the old tube (A) in the well by a positioning sequence, inflation and displacement of a crimping tool (3).   2 - Lining process according to claim 1 characterized in that the tube is crimped from the top of the well down well.   3 - Lining process according to claim 2 characterized in that throughout the crimping is blown air (4) between the new tube and the inner section of the old tube (A) so as to drive down the water (5) infiltrated between the new tube and the internal section of the old tube before crimping the new tube on the old tube.   4 - lining process according to claim 3 characterized in that blows air by means of an injector device (6) provided with peripheral nozzles down into the well below the lower level of the new tube.   - Lining method according to claim 4 characterized in that the injector device (6) is secured to a ballast (7) of a supply hose (16) of the injector device, passing through the crimping tool (3). ).   6 - Lining process according to any one of the preceding claims characterized in that the tube segments (Si, ..., Sp, ..., Sn) are provided with an outer chamfer (9) on their ends and in that the tube segments are welded at said outer chamfer.   7 - Lining method according to claim 6 characterized in that the tube segments are coated with a layer of a protective material prior to their supply, the protective material being removed at the chamfer (9) before soldering the tubes.   8 - Lining method according to any one of the preceding claims characterized in that the tube segments are lowered into the well using a simple crane (10).   9 - Lining method according to any one of the preceding claims characterized in that the crimping tool (3) is an inflatable peripheral bladder tool 10.