EP2447462A1 - Method for subterranean insertion of a conduit - Google Patents

Abstract

The method involves creating a pilot borehole (16) on the starting side (2) to the destination side (4), where a drilling head is advanced by a drilling string (12), and increasing the pilot borehole in one or multiple steps by moving a reamer (30) of a diameter of the borehole using the drilling string from the destination side to the starting side. The reamer and the pipeline (20) are moved from the destination side to the starting side.

Description

The invention relates to a method for the underground introduction of a pipeline, which is particularly suitable for pipeline construction.

In the previously known HDD method ("Horizontal Directional Drilling"), a pilot bore with a drill string is created from a start page to a target side. After reaching the landing page a so-called reamer is mounted on the drill head or the drill bit. This reamer is now pulled to the starting side in a rotating manner, whereby a suitable drilling fluid (for example bentonite) escapes from the boom tip under pressure, which on the one hand releases the existing soil and on the other hand supports the resulting borehole against collapse. The clearances are repeated with larger and larger scrapers until the hole is made in the desired size. The created drill hole diameter is considerably larger than the diameter of the product tubing to be introduced later. The considerable excess diameter is necessary to reduce the frictional forces during Einbringvorgang. The lubricating action of a bentonite suspension, on the one hand, and the floating of the product tubing with low skin friction on the borehole wall, on the other hand, require a spacious distance from the pipe wall to the borehole wall.

The success of the HDD process depends on certain geological conditions and the final well size. For a 56 "(1.42 m) diameter product pipe, a 1.80 m diameter hole will be made, and in case of failure, the hole will need to be abandoned.

At the in EP 1 802 844 B1 The method described ("EasyLong") is a micro-tunneling process for pipeline construction, in which steel support pipes are propelled in a microtunnelling process from a start page to a target side. After this the support pipe string has reached the target side, the product pipe string (ie the pipeline) prepared in the area of the target side is connected to the support pipe string and pulled or pushed into the supported borehole. This method is safe in any geology because the borehole wall can not collapse because of the support tubes, but because of the microtunnelling it is slower and more expensive than the HDD method. The created hole has a slightly larger diameter than the product tube to be installed. Less soil is mined and less bentonite is consumed than HDD. The process "EasyLong" is thus more ecological than the HDD process.

It is an object of the invention to provide a method for underground insertion of a pipeline, which can be performed similarly fast as the HDD method, but is fundamentally safer and more ecological.

This object is achieved by a method for underground introduction of a pipeline with the features of claim 1. Advantageous embodiments of the invention will become apparent from the dependent claims.

In the method according to the invention, a pipeline with a predetermined diameter is introduced underground between a starting side and a target side. First, similar to the HDD method, a pilot hole is created, with a drill bit (preferably with a drill bit) being advanced from the start page to the landing page by means of a drill string. To drive the drill pipe a so-called HDD rig can be used, as it is known from HDD methods and which is built on the start page. The HDD rig can be used to rotate the drill pipe, propel it towards the landing page, and move it back toward the home page as needed.

The next steps are optional, if the pilot hole is not in a single step to the desired final diameter (which is at least as large as the diameter of the pipeline) to be expanded. In these optional process steps, the pilot well is increased in one or more steps by means of a scraper moving from the target side to the home using the drill string to a diameter of the well that is smaller than the final diameter of the well, as further explained below.

After creating the pilot hole or after performing the optional process steps, the drill string extends to the target side. At the target side, a reamer designed for the final diameter of the borehole is now mounted, e.g. at the drill head or at the end of the drill string. At the reamer or the end of the drill string or the drill head, the previously prepared or parallel to the previous process steps on the target side pipe is coupled. The purpose of a coupling device between the reamer and the end of the pipeline. Then the scraper and the pipeline are moved from the landing page to the home page. The reamer enlarges the wellbore to the final diameter and the tubing comes to rest in the wellbore.

Scavengers are also used in HDD processes. A scraper can be used to clear a not too hard ground. Preferably, the scraper is rotated when moving from the target side to the home using the drill string. Furthermore, the process flow is usually greatly facilitated if, when moving the reamer from the target side to the home, a drilling fluid is introduced into the wellbore, e.g. via arranged on the reamer nozzles. The drilling fluid preferably has a bentonite suspension.

If the pilot hole is increased in the optional process steps to a hole diameter that is still below the final diameter, the intermediate steps already indicated can be performed. For this purpose, a reamer is drawn from the target side to the start page by means of the drill string, the reamer enlarges the pilot hole. This reamer provides a hole diameter that is smaller than the final diameter. If the well needs to be further incrementally increased, eg because of the size of the final diameter or soil condition, the drill string is again advanced to the target side and then an enlarged scraper is pulled from the target side to the start by the drill string, the enlarged scraper being the one created so far Bore further enlarged. If appropriate, this step is repeated once or several times with increasingly enlarged scrapers. Finally, the drill string is advanced again to the target side to assume the home position required for the previously discussed steps of creating the final diameter of the wellbore and for introducing the tubing into the wellbore.

To enlarge the reamer, a larger reamer is preferably mounted each time. In principle, it is also conceivable to use an adjustable reamer, which can possibly even be adjusted so far that it is designed for the final diameter. If a reamer is designed for a specific diameter, it does not necessarily mean that he himself must have that diameter. The reamer may also be smaller because of the effect of the drilling fluid.

Typically, the borehole will have a smaller diameter than the tubing prior to use of the final diameter scraper. In principle, however, applications are also conceivable in which the borehole is widened so far that its diameter is already greater.

In preferred embodiments of the method according to the invention, the pipeline is advanced from the target side to the starting side using a sliding device arranged on the target side. For such a purpose suitable sliding devices (eg "Pipethruster") are known and can basically exert high shear forces, for example when a hydraulic device by means of a coat-like sleeve on the outer wall of the prepared pipeline attacks. However, if the pipeline is tension resistant and relatively easy to move through the well, it is also conceivable to pull the pipeline from the target side to the home using the drill string.

When a pusher is used, it is preferable to synchronize the movement of the end diameter raker with the drill string and the operation of the pusher so that the movements are made at as basic ground speeds as possible and not by forces transmitted from the pipe and drill string need to be aligned.

The coupling device preferably has a rotary coupling and also means for engaging the end of the pipeline. The tubing should not rotate about its longitudinal axis when it is inserted into the ground while the reamer is rotating. To compensate, the rotary joint is used.

Since the distance between the reamer and the end of the pipeline is low when introducing the pipeline, the borehole usually does not fall. However, depending on the upcoming geology, when moving the reamer and tubing from the target side to the home, a support shell may be carried in the space between the reamer and the end of the tubing to prevent a drilled hole. The diameter of the support jacket is adapted to the diameter of the pipeline, e.g. the same size or slightly larger.

As already mentioned, the pipeline is prepared at the target side before moving into the wellbore. For this purpose, it can already be completely prepared, for example, welded together from individual tubes and if necessary provided with a corrosion protection, and also be tested. The pipeline can be stored on the destination side eg on a roller conveyor. The pipe can be used for the transport of media, but also designed as a conduit, eg for later retraction of cables.

The method according to the invention, which can be called HDJ ("Horizontal Directional Jacking") method, combines the advantages of the HDD method and the "EasyLong" method. The diameter of the borehole needs only to be slightly larger than the diameter of the pipeline to be introduced, since a lubricating film (for example of bentonite suspension) is generally sufficient to reduce skin friction. The HDJ process is more economical than the "EasyLong" process and safer and more ecological than the HDD process.

• Figur 1: einen schematischen Längsschnitt durch eine Baustelle, bei der das erfindungsgemäße Verfahren verwendet wird, in einer ersten Phase,
• Figur 2: einen schematischen Längsschnitt durch die Baustelle gemäß Figur 1 in einer zweiten Phase,
• Figur 3: einen schematischen Längsschnitt durch die Baustelle gemäß Figur 1 in einer dritten Phase und
• Figur 4: einen schematischen Längsschnitt durch eine Ausführungsform eines an einem Bohrgestänge angebrachten Räumers, an den mittels einer Kopplungseinrichtung das Ende einer Rohrleitung angekoppelt ist, während der Bauphase gemäß Figur 3.

In the following the invention will be further explained by means of exemplary embodiments. The drawings show in

• FIG. 1 FIG. 2: a schematic longitudinal section through a construction site using the method according to the invention, in a first phase, FIG.
• FIG. 2 : a schematic longitudinal section through the site according to FIG. 1 in a second phase,
• FIG. 3 : a schematic longitudinal section through the site according to FIG. 1 in a third phase and
• FIG. 4 FIG. 2: shows a schematic longitudinal section through an embodiment of a reamer attached to a drill pipe, to which the end of a pipeline is coupled by means of a coupling device, during the construction phase according to FIG FIG. 3 ,

In the FIGS. 1 to 3 different phases are shown in the implementation of an embodiment of a method for underground insertion of a pipeline in a schematic longitudinal section.

The arrangement of the construction site is over FIG. 1 seen. Between a home page 2 and a landing page 4, a pipeline under a body of water 6 shall be installed. On the home page 2, a HDD rig 10 is constructed and anchored. HDD rigs are used in HDD processes and are known to the person skilled in the art. With the help of a HDD rig you can turn a drill pipe and move it forward and pull it down. In the exemplary embodiment, a pilot bore 16 is created with the aid of the HDD rig 10, a drill pipe 12 driven therefrom and a drill head 14 mounted at the end of the drill string 12, which leads to the target side 4 and determines the later course of the pipeline to be introduced. The drill head 14 is controllable so that the pilot bore 16 can be guided along a curved and predetermined path. In the in FIG. 1 As shown, the drill head 14 has arrived just below the water body 6.

While the pilot hole 16 is being prepared, the pipeline to be inserted, indicated at 20, is prepared at the target side 4. In the exemplary embodiment, the pipe 20 is welded together from steel pipe sections, the area of the welds is provided with a corrosion protection, and a leak test is performed. Through the pipe 20, a liquid or gaseous medium can later be transported. Other designs, e.g. as a conduit or other material, are also conceivable.

As in FIG. 1 can be seen, the pipe 20 is mounted on a roller conveyor 22. Furthermore, a so-called Pipethruster is already brought into position. The Pipethruster has a pipe clamp 24 which acts on the outside of the pipe 20 via a kind of sleeve and can exert large forces. The pipe clamping device 24 is via feed cylinder 26 with an in FIG. 1 Anchoring 28 shown schematically connected. By actuating the feed cylinder 26, the pipeline 20 can later be advanced in the direction of the starting side 2.

In FIG. 2 a state is shown in which the pilot hole 16 is completed and after the drill head 14 has arrived at the target side 4. The drill head 14 is then removed from the drill string 12, and instead a reamer 30 is mounted at the forward end of the drill string 12. The reamer 30 is then connected by means of a coupling device to the end of the pipeline 20. The reamer 30 and the coupling device are in FIG. 4 shown in enlarged view (wherein the coupling device is designed slightly different than according to the FIGS. 1 to 3 ).

Scavengers such as the scraper 30 are known in the art of HDD method ago. The reamer 30 has a larger diameter than the drill head 14. In the embodiment of the reamer 30 is mounted instead of the drill head 14 at the end of the drill string 12. But it is also conceivable that the drill head 14 left on the drill pipe 12 and the reamer 30 is attached to the drill head 14. With the help of an embodiment conically shaped attack side 32 of the reamer 30 can widen the borehole when it is rotated by means of the drill string 12 and pulled to the home page 2. In the embodiment, a bentonite suspension, which facilitates the widening of the borehole, solidifies the wall of the borehole and at the same time serves as a lubricating film.

The reamer 30 is connected to the pipeline 20 via the coupling device. As the FIG. 4 shows, this coupling device has a hinge part 34, a rotary coupling 36, a further hinge part 38 and a Zugaufnahme 40. The Zugaufnahme 40 is mounted at the end of the pipe 20 and is removed later, when the pipe 20 is finished laying.

The FIG. 2 Thus, the condition of the construction site immediately after the assembly of the reamer 30 and the coupling device 34, 36, 38, 40. Now the reamer 30 is pulled over the drill pipe 12 by means of the HDD rig 10 in the direction of home 2, while the Pipethruster in Action is set and simultaneously with the help of the feed cylinder 26, the pipeline 20 advances. In the exemplary embodiment, the movements of the drill string 12 and the feed cylinder 26 are synchronized to avoid unnecessary tensile or compressive forces in the drill pipe 12 and the pipe 20. The FIG. 3 shows a state in which the reamer 30 has arrived under the water 6. The area of the reamer 30 with the end of the pipeline 20 is, as already explained, in FIG. 4 shown in enlarged view.

While the reamer 30 is rotated by the drill string 12 and the drilling fluid exits the attack side 32 of the reamer 30, the reamer 30 expands the well bore 50, generally designated 50. As a result, the pilot bore 16, the wall 52 of which has a first diameter, in the exemplary embodiment increases to a borehole with a wall 54 which already has the desired final diameter. The reamer acts in particular at a transition zone 56. The rotary coupling 36 ensures that the reamer 30 can rotate easily, while the pipe 20 performs no rotational movement. The drilling fluid also passes into a gap 58 between the conduit 20 and the wall 54 of the borehole 50 and forms there a kind of lubricating film, which significantly reduces the frictional forces between the pipeline 20 and the wall 54 of the borehole 50.

The reamer 30 is retracted to the home page 2 while the tubing 20 is advanced so that the tubing 20 comes to lie in the final path in the desired path.

In the exemplary embodiment, it is assumed that the soil, in particular after the action of the drilling mud, is so strong that the borehole 50 does not collapse in the area between the reamer 30 and the draw receptacle 40 of the pipeline 20. If the soil is problematic, a support shell can be arranged in this zone, whose outer diameter corresponds to the final diameter of the borehole 50 or has a slightly smaller diameter. The support jacket prevents the borehole 50 occurs in this critical area, and is moved with the pipe 20 to the home 2.

In the exemplary embodiment, the pilot bore 16 is widened by means of the reamer 30 in one step to the required for the pipeline 20 end diameter (wall 54). Depending on the nature of the soil and the diameter of the pipe to be introduced, however, intermediate steps can also be carried out. For this purpose, first a reamer with a smaller diameter than that of the reamer 30 is mounted after creating the pilot hole 16 and pulled without the pipe 20 to the home page 2, wherein the borehole 50 is widened. Subsequently, the drill pipe 12 is moved by means of the HDD rig 10 back to the landing page 4. There, if necessary, a larger reamer can be set, which is still smaller than the reamer 30, to perform a further intermediate step for widening the wellbore 50. If necessary, this process is repeated once or more, until finally the reamer 30, which produces the desired final diameter of the wellbore 50, can be mounted.

Claims (12)

Method for underground introduction of a pipe of predetermined diameter between a home page and a landing page, comprising the steps of: - creating a pilot hole (16) from the starting side (2) to the target side (4), wherein a drill head (14) is advanced by means of a drill rod (12), optionally enlarging the pilot bore (16) in one or more steps by means of a scraper moved using the drill string (12) from the target side (4) to the starting side (2) to a diameter of the wellbore (50) smaller than a final diameter wherein the final diameter is at least as large as the diameter of the pipeline (20), - mounting a final diameter scraper (30) on the target side (4) and coupling the pipeline (20) prepared at the target side (4) by means of coupling means (34, 36, 38, 40) between the scraper (30) and the end the pipeline (20), Moving the reamer (30) and the pipeline (20) from the target side (4) to the starting side (2), the reamer (30) increasing the borehole (50) to the final diameter (54) and the pipeline (20) in the borehole (50) comes to rest. A method according to claim 1, characterized in that the optional enlargement of the pilot bore (16) is carried out and comprises the following steps: Pulling a scraper from the target side (4) to the starting side (2) by means of the drill string (12), the scraper enlarging the pilot bore (16), - If necessary, again advancing the drill string (12) to the target side (4) and pulling an enlarged scraper from the target side (4) to the start (2) by means of the drill string (12), wherein the enlarged scraper further increases the previously created bore, and optionally repeating this step once or several times with ever-larger scrapers, - again advancing the drill string (12) to the target side (4). A method according to claim 1 or 2, characterized in that the scraper (30) is rotated when moving from the target side (4) to the starting side (2) using the drill string (12). Method according to one of claims 1 to 3, characterized in that when moving the reamer (30) from the target side (4) to the start (2) a drilling fluid is introduced into the wellbore (50). A method according to claim 4, characterized in that the drilling fluid is introduced into the borehole (50) via nozzles arranged on the reamer (30). A method according to claim 4 or 5, characterized in that the drilling fluid comprises bentonite. Method according to one of Claims 1 to 6, characterized in that the pipeline (20) is moved from the target side (4) to the starting side (2) by using a sliding device (24, 26, 28) arranged on the target side (4). A method as claimed in claim 7, characterized in that the movement of the raker (30) to the starting side (2) of the end diameter (54) is synchronized with each other using the drill string (12) and the action of the pusher (24, 26, 28) , Method according to one of claims 1 to 8, characterized in that the coupling device (34, 36, 38, 40) has a rotary coupling (36). Method according to one of claims 1 to 9, characterized in that when moving the reamer (30) and the pipe (20) from the target side (4) to the starting side (2) a support jacket in the space between the reamer (30) and the End of the pipe (20) is arranged, wherein the diameter of the support jacket is adapted to the diameter of the pipe (20). Method according to one of claims 1 to 10, characterized in that the pipeline (20) is completely pre-aligned and tested before moving into the borehole (50) on the target side (4). Method according to one of claims 1 to 11, characterized in that the borehole (50) has a smaller diameter than the pipeline (20) before the use of the raker (30) designed on the final diameter (54).

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