Pipeline abandonment methods and apparatus

Abstract

A method of abandoning a section of a subterranean pipeline is disclosed. The method comprises forming an exterior passage from the surface to the pipeline at a position exterior and adjacent each end of the section of pipeline to be abandoned; forming an interior passage from the surface to the pipeline at each end of the section of pipeline to be abandoned; cutting a hole in the pipeline at a position corresponding to each of the passages; inserting a plug into the pipeline via each of the exterior passages; and inputting a filler material into the section of pipeline to be abandoned via one of the interior passages.

Description

Pipeline Abandonment Methods and Apparatus Technical Field The invention relates to methods for carrying out pipeline abandonment and more specifically to methods of pipeline abandonment on subterranean pipelines which may optionally be under a rail, river, road or other crossing. Background When a pipeline is no longer used various segments of it may be properly abandoned to avoid long term impact on the surrounding environment. Segments of the pipeline that are underground may be filled and sealed to ensure that when the discarded pipeline breaks down and collapses the ground above it will not be left with a void causing possible cave-in or indentation in the ground. Although this applies to all terrain proximate the pipeline, this is especially important is areas where the pipeline passes under a crossing as it can cause related issues if a road, rail line, river or the like is above the collapsed pipeline or is in an area of higher traffic or use. Often, the pipeline segment that is desired to be abandoned is located on farmland or other land that must be excavated to access the pipeline segment to be sealed. The excavation process can be very intrusive and cause damage to the land to around the segment. Typically, once permission is obtained from the landowner to grant access, the top soil is stripped and a hydrovac process is used to find the pipeline. Once located, a large hole is excavated on both sides of the crossing of the bridge, rail, rivers or other at a location where the pipeline is to be cut and filled with concrete or other suitable filler material. A portion of the pipe is cut on each side of the crossing where it has been excavated and a section is cut out of the pipeline. This can involve the cutting of a section sufficiently large to grant access to machinery suitable to cap and weld each side and insert an inlet valve onto which a cement truck is connected and cement is pumped into the section to be abandoned. A vent is added, typically to the opposite end of the section to be abandoned to allow air to escape while the cement is pumped in the section. The section to be cut out may be up to ten feet in length requiring a suitable sized excavation hole to be dug. Once pumped full of cement, the valves are shut and the area is backfilled and may be compacted, top soil added, seeded and a fence may be added surrounded the area if needed. The prior methods are typically time consuming, expensive and can have a significant impact on the area as, depending on the grade of the area, 50-70 feet of land may need to be excavated. This also generally upsets the land owner as well. In addition, it has been observed that in the long term, there can be sink holes or cave-ins in the area which must be dealt with. A need therefore exists for a method of abandoning a pipeline as well as apparatuses to aid in doing so which helps to mitigate one or more of the deficiencies observed in the prior methods. Summary The current invention provides for a method of abandoning a section of subterranean pipeline which has a decreased impact on the surrounding terrain relative prior state of the art methods. Using the methods of the inventions requires less excavation to expose the pipeline by using, for example, a minimally invasive technique such as a hydro excavation process, to form a passage from the surface to the pipeline into which a cutting device may be passed to cut a hole in the pipeline to receive filler material for forming a plug, filling the pipeline section to be abandoned and optionally other devices, such as an optional airbag. The passages may then be backfilled with suitable material. Heavy machinery may be avoided as can significant excavation. In one embodiment of the invention a method of abandoning a section of a subterranean pipeline is provided, the method comprising: forming an exterior passage from the surface to the pipeline at a position exterior and adjacent each end of the section of pipeline to be abandoned; forming an interior passage from the surface to the pipeline at each end of the section of pipeline to be abandoned; cutting a hole in the pipeline at a position corresponding to each of the passages; inserting a plug into the pipeline via each of the exterior passages; and inputting a filler material into the section of pipeline to be abandoned via one of the interior passages. In a further embodiment of the method or methods described above, the method further comprises: adding an anti-slip device to each of the plugs to reduce or prevent slipping of the plug when the filler material is input. In a further embodiment of the method or methods described above, the anti-slip device comprising a friction fit of the plug and / or an element imbedded into the plug and protruding therefrom to cause friction against the pipeline or protruding through the hole in the pipeline and into the corresponding passage. In a further embodiment of the method or methods described above, the element is a steel element. In a further embodiment of the method or methods described above, the steel element is rebar. In a further embodiment of the method or methods described above, the element comprising a bend or hook for catching the hole in the event the plug slips. In a further embodiment of the method or methods described above, the method further comprises: forming a third set of passages from the surface to the pipeline at a position between the exterior and interior passages; cutting a hole in the pipeline at a position corresponding to each of the third set of passages; inserting an airbag into the pipeline for positioning against the adjacent plug between the section of pipeline to be abandoned. In a further embodiment of the method or methods described above, the passages are formed using a hydro excavation process. In a further embodiment of the method or methods described above, each of the holes are cut using a high pressure hydraulic cutting tool inserted into the passage. In a further embodiment of the method or methods described above, the passage is formed with a diameter no larger than that required to accommodate and operate a cutting tool for cutting the holes in the pipeline. In a further embodiment of the method or methods described above, the method further comprises backfilling the passages. In an even further embodiment of the invention, there is a provided a method of abandoning a section of a subterranean pipeline spanning a crossing thereabove, the method comprising: forming an exterior passage from the surface to the pipeline at a position exterior and adjacent each end of the section of pipeline to be abandoned outside each edge of the crossing; forming an interior passage from the surface to the pipeline at a position at each end of the section of pipeline to be abandoned outside each edge of the crossing; cutting a hole in the pipeline at a position corresponding to each of the passages; inserting a plug into the pipeline via each of the exterior passages; and inputting a filler material into the section of pipeline to be abandoned via one of the interior passages. In a further embodiment of the method or methods described above, the passages are formed using a hydro excavation process. In a further embodiment of the method or methods described above, each of the holes are cut using a high pressure hydraulic cutting tool inserted into the passage. In a further embodiment of the method or methods described above, the method further comprises: adding an anti-slip device to each of the plugs to reduce or prevent slipping of the plug when the filler material is input. In a further embodiment of the method or methods described above, the anti-slip device comprising a friction fit of the plug and / or an element imbedded into the plug and protruding therefrom to cause friction against the pipeline or protruding through the hole in the pipeline and into the corresponding passage. In a further embodiment of the method or methods described above, the element is rebar. In a further embodiment of the method or methods described above, the rebar comprises a bend or hook for catching the hole in the event the plug slips. In a further embodiment of the method or methods described above, the method further comprises: forming a third set of passages from the surface to the pipeline at a position between the exterior and interior passages; cutting a hole in the pipeline at a position corresponding to each of the third set of passages; inserting an airbag into the pipeline for positioning against the adjacent plug between the section of pipeline to be abandoned. In a further embodiment of the method or methods described above, the filler material is concrete. Brief Description of the Drawings Figure 1 is an illustrative embodiment of an example of a pipeline abandoned using one method of the current invention; Figure 2 is an illustrative embodiment of an example of a pipeline abandoned and backfilled using one method of the current invention; and Figure 3 is a flowchart outlining steps of one method of the invention for abandonment of a pipeline. Detailed Description The embodiments and examples referred to herein are intended to be illustrative of the invention and are not intended to be limiting. All embodiments and examples are non-limiting embodiments and examples. All reference to dimensions are for illustrative purposes. It will be appreciated that the methods and apparatus referred to herein may be applied to any suitable subterranean pipeline for carrying out abandonment of a section or section(s) of that suitable pipeline. The invention is not limited to those sections which pass below a crossing and may be applied to any subterranean section of a pipeline to be abandoned. Figure 1 shows an illustrative example of a cross-section of a crossing 100 under which a pipeline 105 has been abandoned using a method of the present invention. On each side of the crossing 100, in this case a road crossing 170, a passage from the surface 180 to the pipeline 105 is formed. The passages 110 and 125 may be formed using any suitable method, but a hydro excavation technique is ideal as it can be done with little impact on the surrounding terrain and allows for a narrow passage to be formed which can accommodate a cutting tool to cut a hole in the pipeline 105. The passages 110 and 125 on each side can be referred to as exterior passages as they are used to insert a plug on each side of the pipeline that will be abandoned and filled with filler material, such as concrete. A plug on each side of the section to be filled is preferred to ensure that the filler material stays in place when input into the pipeline and to ensure that the filler material generally completely fills the pipeline section to be abandoned. If the pipeline section is not generally completely filled it can still somewhat collapse over time as the pipeline deteriorates. Once each of the exterior passages 110 and 125 is formed, for example by hydro excavation, a cutting tool is inserted into the passage to cut a hole in the pipeline to receive the filler material to generate a plug 155 in the pipeline. To further ensure the plug 155 does not move as the pressure of the filler material pushes against it, the plug 155 can have an optional further anti- slip device added thereto. This may comprise of a friction fit of the plug 155 within the pipeline or may comprise of an additional component 130 embedded into the plug 155 and protruding therefrom against the wall of the pipeline or through the hole cut into the top of the pipeline and into the passage 110 thereabove. Each plug 155 and 160 may have a one or more anti-slip devices 130 and 135. The anti-slip device may be any suitable element such as a piece of steel, such as rebar, inserted through the hole in the top of the pipeline and embedded into the plug 155. To further strengthen the plug 155 and reduce the chance the plug 155 may slip, the element, such as rebar, may have a hook or bend formed into it to catch on the passage 110 and / or the hole in the top of the pipeline. For example, a 90 degree bend may be made in the rebar 130. It will be appreciated that a plurality of anti-slip devices, such as rebar, may be embedded into each plug 155 and 160. To form the plug, any suitable filler material may be used, such as concrete. Any suitable filler material may be used including concrete of various mixes. In one embodiment, the filler material used to form the plug is formulated to have a quicker set time to help maintain the form of the plug as it sets. To allow for the filler material to be input into the pipeline section to be abandoned, such as that section that passes beneath the crossing 100, an interior passage is formed on at each end of the pipeline section to be filled and interior the passages formed to make the plugs. Again, any suitable method for forming the passages may be used, and ideally a method is used that minimizes or reduces impact on the surrounding terrain, such as hydro excavation. The passages should have a diameter sufficient to accommodate the cutting device that will be used to cut a hole in the top of the pipeline for input of the filler material. One of the interior passages will be used for input of the filler material, such as interior passage 115, while the other interior passage is used as an air vent passage 120 to allow escape of air that would otherwise be trapped in the pipeline when the filler material is input. Once the plugs 155 and 160 are set at each end of the pipeline section to be filled, a filler material may be input into the interior input passage 115 as represented by arrow 140 and pipeline section 105 is filled with filler material such as concrete. In one embodiment, the filler material used to fill the pipeline section to be abandoned has a formulation that provides for a filler material that is suitably flowable so that pumping and filling the section of pipeline to be abandoned is aided. For example, the filler material used for filling the pipeline section to be abandoned may be more flowable than the filler material used to form the plugs and may have a longer setting time than the filler material used to form the plugs. Air escapes through the air vent passage 120 as shown by arrow 145. Once set the filler material 105 is set in the pipeline section, the pipeline is abandoned. By using relatively narrow passages to accommodate a pipe cutter to form holes in the pipeline and then inputting filler material via the passages and holes into the pipeline to form plugs and then filling the pipeline section to be abandoned, the impact on the surrounding terrain is reduced as compared to previous methods. The inventive methods may also be carried out more quickly and can result in a decrease in the erosion of the terrain and / or soil in the vicinity of the project. It will be appreciated that any suitable cutting tool may be used to cut the holes in the top of the pipeline. Ideally, the tool is relatively narrow so that the passages can be narrow in diameter to accommodate the cutting tool without requiring a large passage to be formed. For example a drill or a hole saw may be used or the hole may be formed by machining. In one embodiment a high pressure hydraulic cutting tool may be used, such as that described in Canadian patent no.: 2,757,675. It will also be appreciated that in a further optional embodiment, methods of the current invention include the formation of an additional passage positioned between the exterior 110 and 125 and interior passages 115 and 120. The additional passage is used to allow a further hole to be made in the pipeline and for the insertion of an airbag into the pipeline between the plugs and are to be filled. The airbags further aids to prevent the plugs from slipping. With reference to Figure 2, once abandoned, the exterior passages 110 and 125 for the plugs 155 and 160 and the interior passages 115 and 125 for the input of filler material 140 and the venting of air 145 may be backfilled with any suitable material depending on the terrain. For example, the passages may be backfilled with sand 200. The passages may then be covered with a different covering material 205 based on the surrounding terrain, such as top soil. The top soil may be covered in or include seed or may be covered in sod 210 to complete the finish of the surrounding terrain. Figure 3 is a flow chart illustrating an embodiment of a method of abandoning a subterranean pipeline section. The pipeline section may optionally be beneath a crossing such as a road, rail, river or other crossing. In step 300, passages are formed above the pipeline to be abandoned stretching from the surface to the top of the pipeline. The passages include exterior passages which are used to input a plug on each side of the pipeline section to be abandoned and interior passages, one of which may be used for inputting the filler material into the pipeline section and the other of which may be used to vent air from the section of pipeline which will be filled. The passages may be formed using any suitable hole drilling technique such as by digging, auger or by hydro excavation. Preferably the passages are formed with reduced impact on the surrounding terrain and are formed with a diameter sufficient only to accommodate the cutting tool that will be used to cut the holes in the tops of the pipeline. Optionally, a third set of passages may be formed between the exterior and interior passages and may be used to allow for the insertion of an airbag between each of the plugs and the section of pipeline to be filled and abandoned. In step 310, a hole is made in the top of the pipeline corresponding to each passage to allow for input of the filler material, such as concrete, to form the plugs, fill the pipeline section to be abandoned and, optionally, to allow insertion of the airbags into the pipeline. The holes should be of sufficient diameter to accommodate a nozzle for inputting the filler material or to at least accommodate a flow of filler material. The optional third set of holes should be of sufficient diameter to accommodate the insertion of airbag into the pipeline. The holes may be formed using any suitable method, but preferable, the holes are formed using a narrow cutting device such as a drill, a hole saw or a machining tool. In one embodiment a high pressure hydraulic cutting tool such as that described herein may be used. In step 320 a plug in formed at each end of the pipeline section to be abandoned. Filler material is input through the exterior passages and into the pipeline. Any suitable filler material may be used including concrete. In step 330 an anti-slip device may optionally be inserted into the plugs to prevent or reduce sliding of the plugs when pressure in placed on them from the filler material that is used to abandon the pipeline. The anti-slip device may simply be a friction fit or may alternatively or additionally include an element such as a steel insert such as one or more sections of rebar embedded into the plugs and protruding from the plug against the pipeline or through the hole above the plug and into the passage. The element may include a hook or bend to further reduce sliding of the plug. In step 340, an optional airbag is inserted into the pipeline interior of each plug to aid in reducing sliding of the plugs when pressure is increased on the plugs as a result of the input of the filler material into the section of pipeline to be abandoned. In step 350, the pipeline section to be abandoned is filled with filler material, such as concrete, via one of the interior passages while the other passage is used to vent air that would otherwise have been trapped in the pipeline section. The allows for the pipeline section to be more easily and completely filled with the filler material. Finally, in step 360, the passages may be backfilled with suitable material and the area may be covered with suitable material based on the surrounding terrain. This can include sand, gravel, top soil or other earth as desired. The area may be seeded or have sod covering put down. It will be appreciated that all embodiments defined herein are non-limiting embodiments intended to illustrate the nature of the invention and that any modifications, adaptations and substitutions are intended to be within the scope of the invention.

Claims

<pat:Claims com:id="claims"> <pat:Claim com:id="CLM-00001"> <pat:ClaimNumber>1< / pat:ClaimNumber> <pat:ClaimText>1. A method of abandoning a section of a subterranean pipeline, the method comprising: forming an exterior passage from a surface to the pipeline at a position exterior and adjacent each end of the section of pipeline to be abandoned; forming an interior passage from the surface to the pipeline at each end of the section of pipeline to be abandoned; cutting a hole in the pipeline at a position corresponding to each of the interior and exterior passages; inserting a plug into the pipeline via each of the exterior passages; and inputting a filler material into the section of pipeline to be abandoned via one of the interior passages. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00002"> <pat:ClaimNumber>2< / pat:ClaimNumber> <pat:ClaimText>2. The method of claim 1, further comprising: adding an anti-slip device to each of the plugs to reduce or prevent slipping of the plug when the filler material is input. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00003"> <pat:ClaimNumber>3< / pat:ClaimNumber> <pat:ClaimText>3. The method of claim 2, wherein the anti-slip device comprising a friction fit of the plug and / or an element imbedded into the plug and protruding therefrom to cause friction against the pipeline or protruding through the hole in the pipeline and into the corresponding passage. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00004"> <pat:ClaimNumber>4< / pat:ClaimNumber> <pat:ClaimText>4. The method of claim 3, wherein the element is a steel element. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00005"> <pat:ClaimNumber>5< / pat:ClaimNumber> <pat:ClaimText>5. The method of claim 4, wherein the steel element is rebar. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00006"> <pat:ClaimNumber>6< / pat:ClaimNumber> <pat:ClaimText>6. The method of any one of claims 3 to 5, wherein the element comprising a bend or hook for catching the hole in the event the plug slips. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00007"> <pat:ClaimNumber>7< / pat:ClaimNumber> <pat:ClaimText>7. The method of any one of claims 1 to 6, further comprising: forming a third set of passages from the surface to the pipeline at a position between the exterior and interior passages; cutting a hole in the pipeline at a position corresponding to each of the third set of passages; inserting an airbag into the pipeline for positioning against the adjacent plug between the section of pipeline to be abandoned. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00008"> <pat:ClaimNumber>8< / pat:ClaimNumber> <pat:ClaimText>8. The method of any one of claims 1 to 7, wherein the passages are formed using a hydro excavation process. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00009"> <pat:ClaimNumber>9< / pat:ClaimNumber> <pat:ClaimText>9. The method of any one of claims 1 to 8, wherein each of the holes are cut using a high pressure hydraulic cutting tool inserted into the passage. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00010"> <pat:ClaimNumber>10< / pat:ClaimNumber> <pat:ClaimText>10. The method of any one of claims 1 to 9, wherein the passage is formed with a diameter no larger than that required to accommodate and operate a cutting tool for cutting the holes in the pipeline. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00011"> <pat:ClaimNumber>11< / pat:ClaimNumber> <pat:ClaimText>11. The method of any one of claims 1 to 10, further comprising backfilling the passages. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00012"> <pat:ClaimNumber>12< / pat:ClaimNumber> <pat:ClaimText>12. A method of abandoning a section of a subterranean pipeline spanning a crossing thereabove, the method comprising: forming an exterior passage from a surface to the pipeline at a position exterior and adjacent each end of the section of pipeline to be abandoned outside each edge of the crossing; forming an interior passage from the surface to the pipeline at a position at each end of the section of pipeline to be abandoned outside each edge of the crossing; cutting a hole in the pipeline at a position corresponding to each of the exterior and interior passages; inserting a plug into the pipeline via each of the exterior passages; and inputting a filler material into the section of pipeline to be abandoned via one of the interior passages. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00013"> <pat:ClaimNumber>13< / pat:ClaimNumber> <pat:ClaimText>13. The method of claim 12, wherein the passages are formed using a hydro excavation process. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00014"> <pat:ClaimNumber>14< / pat:ClaimNumber> <pat:ClaimText>14. The method of claim 12 or 13, wherein each of the holes are cut using a high pressure hydraulic cutting tool inserted into the passage. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00015"> <pat:ClaimNumber>15< / pat:ClaimNumber> <pat:ClaimText>15. The method of any one of claims 12 to 14, further comprising: adding an anti-slip device to each of the plugs to reduce or prevent slipping of the plug when the filler material is input. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00016"> <pat:ClaimNumber>16< / pat:ClaimNumber> <pat:ClaimText>16. The method of claim 15, wherein the anti-slip device comprising a friction fit of the plug and / or an element imbedded into the plug and protruding therefrom to cause friction against the pipeline or protruding through the hole in the pipeline and into the corresponding passage. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00017"> <pat:ClaimNumber>17< / pat:ClaimNumber> <pat:ClaimText>17. The method of claim 16, wherein the element is rebar. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00018"> <pat:ClaimNumber>18< / pat:ClaimNumber> <pat:ClaimText>18. The method of claim 17, wherein the rebar comprises a bend or hook for catching the hole in the event the plug slips. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00019"> <pat:ClaimNumber>19< / pat:ClaimNumber> <pat:ClaimText>19. The method of any one of claims 12 to 18, further comprising: forming a third set of passages from the surface to the pipeline at a position between the exterior and interior passages; cutting a hole in the pipeline at a position corresponding to each of the third set of passages; inserting an airbag into the pipeline for positioning against the adjacent plug between the section of pipeline to be abandoned. < / pat:ClaimText> < / pat:Claim> <pat:Claim com:id="CLM-00020"> <pat:ClaimNumber>20< / pat:ClaimNumber> <pat:ClaimText>20. The method of any one of claims 1 to 19, wherein the filler material is concrete. < / pat:ClaimText> < / pat:Claim> < / pat:Claims>