The present invention describes a fracturing tube system comprising a plurality of tube lines for being introduced into a bore hole in order to carry out a hydraulic and/or pneumatic fracturing process, as well as the utilization of at least one traction cable, multiple coupling devices that can be removably attached to the at least one traction cable and multiple separate tube sections in the form of corrugated metal tubing with a braiding, which can be coupled to the coupling devices in a pressure-tight fashion and collectively form the tube lines, for assembling a fracturing tube system.
Hydraulic fracturing (hydraulic fracturing) and/or pneumatic fracturing, which is generally also referred to as fracking, is used for extracting hydrocarbons, natural gas or crude oil from corresponding subterranean natural gas or oil formations. Among other things, hydraulic and/or pneumatic fracturing also makes it possible to reactivate abandoned natural gas or oil formations and to thereby extract residual amounts of liquid and gaseous fossil fuels that were previously inaccessible, wherein this process is also referred to as intervention.
Natural gas or oil formations usually are subterraneously fractured with the aid of a fracturing fluid in order to create artificial flow channels for the hydrocarbons to be extracted and to thereby simplify the process of pumping off the hydrocarbons. To this end, a multi-lumen tubing has to be purposefully lowered into an existing bore hole for the hydraulic and/or pneumatic fracturing process, wherein this is also referred to as coiled tubing. The multi-lumen tubing is unwound from a drum on-site with a suitable device and lowered into the bore hole to a depth between a few meters and a few kilometers. In this case, the fixed length of the multi-lumen tubing has to be adapted to the desired lowering depth or bore hole depth, respectively. A corresponding system for carrying out hydraulic and/or pneumatic fracturing processes is illustrated in
Subsequently, the fracturing fluid is hydraulically pumped into the bore hole in a controlled fashion by means of tube lines of the multi-lumen tubing. Since the fracturing fluid not only contains water, but also supporting particles and/or additives that preserve the fractures being produced, the enlarged flow channels leading to the bore hole remain open such that an increased amount of hydrocarbons can be pumped off.
Nowadays, preassembled multi-lumen tubing, which comprises a plurality of prefabricated tube lines in the form of metal tubes that typically have diameters between one inch and 3.25 inches, are used for hydraulic and/or pneumatic fracturing processes. The tube lines are completely encased in a plastic covering and form a flexible, compact tube line cluster. The thusly realized multi-lumen tubing is protected from external influences by the plastic covering, as well as an optional covering of steel cables and another optional plastic covering, wherein the individual tube lines are clustered in an encapsulated fashion at a distance from one another and enclosed by plastic. Such compact and integrally designed multi-lumen tubing can be introduced into a bore hole and is designed for being vertically and horizontally advanced therein.
A preassembled multi-lumen tubing according to the prior art is illustrated in
The individual tube lines serve for pumping in or pumping out fracturing fluids and/or for supplying supporting particles and/or additives, as well as for pumping off hydrocarbons. Since an electronically controlled pump device or control device (so-called packer) usually is subterraneously arranged on the multi-lumen tubing, this multi-lumen tubing also features optional electrical wiring that is likewise encased in the plastic covering along the entire length of the preassembled multi-lumen tubing. The fracturing tube system is manufactured with a constant outside diameter and a fixed length and wound on a drum. Since pressures up to 200 bar and temperatures within the bore hole of a few hundred degrees Celsius occur during hydraulic fracturing, the individual tube lines are realized in the form of metal tubes that are able to withstand these conditions.
The manufacture of preassembled multi-lumen tubing known from the prior art is elaborate and expensive. The individual tube lines in the form of metal tubes have to be encased in the plastic covering at a distance from one another over the entire desired length of the multi-lumen tubing and the steel cable-reinforced outer covering also has to be arranged over the entire length of the multi-lumen tubing such that the preassembled fracturing tube system can be wound up on a drum in one piece for its transport and intended use.
During the intended use of the fracturing tube system, this drum, which may have an enormous mass depending on the overall length of the wound-up fracturing tube system, has to be unwound in an exactly controlled fashion by means of a suitable device in order to introduce the fracturing tube system into the bore hole in a controlled fashion.
The present invention is based on the objective of developing a fracturing tube system that can be manufactured in a simpler and more cost-efficient fashion, as well as introduced into a bore hole with a variable overall length and with reduced effort.
The present fracturing tube system no longer has to be supplied in a preassembled fashion with a given overall length, but rather can be modularly assembled and therefore have a variable overall length such that it no longer has to be elaborately wound up on a drum in one piece.
A preferred exemplary embodiment of the object of the invention is described in greater detail below with reference to the attached drawings.
The fracturing tube system 1 presented herein comprises a plurality of tube lines 10 that can be introduced into a not-shown bore hole by means of a traction cable 11. The tube lines 10 are arranged separately and spaced apart from one another, wherein said tube lines are composed of a plurality of separate tube sections 100 that are coupled to a plurality of coupling devices 12. The tube sections 100 are provided with tube coupling means 101 that can be functionally connected to device coupling means 125 such that a pressure-tight separable connection between the tube sections 100 and feedthroughs 120 of the coupling device 12 can be produced and fluid can be conveyed in a tubeless fashion from one tube section 100 into a following tube section 100 through the feedthrough 120 in the coupling device 12.
The tube sections 100 are held on the coupling devices 12 such that the respective tube sections 100 or tube lines 10 and the coupling devices 12 are held by the traction cable 11. The preferably single traction cable 11 extending over the entire length of the fracturing tube system 1 is respectively routed through a cable feedthrough 121 in or on each coupling device 12 and removably attached to the coupling device 12 at this location. The overall length of the fracturing tube system 1 can be easily adapted.
Additional tube sections 100 with section lengths I can be respectively coupled to additional coupling devices 12 as needed and connected such that the individual tube lines 10 are extended, wherein the length of the traction cable 11 also has to be adapted. Since the transport and the costs of a traction cable 11 are respectively not elaborate or expensive, a sufficiently long traction cable 11 can be chosen before lowering of the modularly designed fracturing tube system 1 begins. This traction cable 11 is unwound from a roll and respectively attached to each coupling device 12.
Corrugated metal tubing is used for the tube sections 100. The corrugated metal tubing is made of steel, preferably of high-grade steel, and therefore extremely resistant to corrosion, wherein this corrugated metal tubing can withstand pressures up to a few hundred bar and temperatures up to 600° C. Consequently, corrugated metal tubing of this type is suitable for hydraulic and/or pneumatic fracturing processes, during which pressures up to 200 bar and occasional temperatures in excess of 200° C. occur. Increased fatigue strength is achieved due to the corrugation of the corrugated metal tubing. Corrugated metal tubing can be used for conveying liquid or gaseous mediums, as well as pumpable solids that are frequently added to the fracturing fluid as an additive.
In order to provide sufficient mechanical protection for the tube sections 100, it is advantageous to provide the tube sections 100 with a braiding 1000. Although it was determined that a single braiding 1000 delivers adequate results during the utilization of the fracturing tube system 1, it is preferred to respectively use a two or more braidings 1000 for strength reasons. The arrangement of one or multiple braidings 1000 increases the bursting pressure of the tube sections 100 and therefore of the entire tube lines 10. The braiding 1000 consists of high-grade steel wire or galvanized steel wire and is directly braided on the circumferential surface of the tube sections 100 of corrugated metal tubing. Braided tube sections 100 of this type are commercially available.
In this case, the tube coupling means 101 on both ends of the tube sections 100 are realized in the form of a flange 1011 and a union nut 1012.
The device coupling means 125 is realized in the form of a double nipple 125. The utilization of a double nipple 125 makes it possible to connect the tube section 100 and the feedthrough 120.
An externally realized thread 1251 of the double nipple 125 can be screwed into one side of the feedthrough 120 of the coupling device 12 whereas the union nut 1012 can be screwed on an additional external thread 1251. In this way, a pressure-tight connection between the tube sections 100 and the feedthroughs 120 is produced.
The partial section through a coupling device 12 illustrated in
The tube sections 100 used in this case are illustrated in a partially sectioned fashion in
The internal thread 10120 of the union nut 1012 is screwed on the external thread 1251 of the double nipple 125 manually and subsequently tightened with a wrench, wherein the flange 1011 is flanged on the double nipple 125 with or without an additional seal. In this case, the double nipple 125 features a thickening in the form of a hexagon such that the double nipple 125 also can be easily fastened in the threaded section 1201 of the feedthrough 120 in a removable fashion by means of a wrench.
The exemplary coupling option shown, in which a double nipple 125 is used as device coupling means 125, may also be realized differently. It would be possible, for example, use coupling sleeves or the coupling device 12 may feature rigid connecting pieces, on which the tube coupling means 101 can be positively and/or non-positively fastened in a removable fashion. These connecting pieces may be integrally formed or welded on and thereby integrally connected to the coupling device 12. A simple and quick coupling should be achieved, wherein it is advantageous to forgo device coupling means 125, tube coupling means 101 and additional seals of plastic because plastics are negatively affected by the temperatures occurring during hydraulic and/or pneumatic fracturing.
Cable fastening means 1211 are provided for attaching the traction cable 11. The cable fastening means shown consist of a recess 1211″′, through which a threaded pin 1211″ can be inserted.
Since significant tensile forces act upon the coupling device 12 when the traction cable 11 is inserted and attached and the tube sections 10 are in the coupled state, a slot safety 124 is provided in order to absorb forces acting upon the insertion slot 123 or the slotted coupling device 12 in the region of the insertion slot 123 and to thereby protect the coupling device 12 against distortion. Furthermore, the slot safety 124 additionally secures an attached traction cable 11 from sliding out of the coupling device 12.
In this case, the slot safety 124 features a bore 124″ and a safety screw 124′ that can be screwed through the slot safety 124; see
In the side view of a coupling device 12 illustrated in
The fracturing tube system 1 described herein can be assembled by lowering a first coupling device 12 with first tube sections 100 coupled thereto and the traction cable 11 fastened thereon into a bore hole. The ends of the first tube sections 100 on the introduction side are coupled to a second coupling device 12 and the traction cable 11 is inserted through the insertion slot 123 of the second coupling device 12 and removably attached to the cable feedthrough 121. Subsequently, second tube sections 100 can be attached to the second coupling device 12 such that the second coupling device 12, as well as the second tube sections 100, can be lowered into the bore hole with the aid of the traction cable 11. If the base of the bore hole is not yet reached, the fracturing tube system 1 can be extended to the desired overall length by connecting additional coupling devices 12 and tube sections 100 to one another and to a traction cable 11.
The fracturing tube system 1 preferably features a continuous one-piece traction cable 11. However, it would also be conceivable to divide the traction cable 11 into cable sections such that it can be extended to a desired overall length of the fracturing tube system 1. However, this would reduce the stability of the traction cable 11 and could potentially lead to undesirable twisting, which cannot be readily prevented.
In this case, the traction cable 11 used consists of a steel cable or high-grade steel cable with a diameter of at least ten millimeters. Such a traction cable 11 is capable of absorbing the tensile forces of four tube sections 100 with a respective length of about one hundred meters.
In order to additionally protect the individual tube sections 100 against abrasion, a protective helix of steel or high-right steel may furthermore be wound over the circumference of the tube sections 100. This spirally wound protective helix can be fastened in the coupling part of the tube sections 100. In addition to the use of a protective helix, a person skilled in the art is familiar with other suitable protection options.
The tube sections 100 may furthermore consist of multilayer plastic tubes that are resistant to hydrocarbons. Plastic tubes of this type are familiar to a person skilled in the art and can be used with or without braiding.
Instead of the functional connection between the tube sections 100 and the coupling device 12 described herein, it would also be possible to produce the connection by means of hydraulic rapid-action coupling. Since the tensile force acting upon the tube sections 100 is absorbed by the traction cable 11 in this case, it is also possible to use hydraulic rapid-action couplings that cannot be subjected to tensile loads.
Number | Date | Country | Kind |
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1487/13 | Sep 2013 | CH | national |
0332/14 | Mar 2014 | CH | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2014/068269 | 8/28/2014 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2015/028554 | 3/5/2015 | WO | A |
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Entry |
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International Search Report dated Nov. 4, 2014 for PCT/EP2014/068269. |
Written Opinion of the International Searching Authority published Mar. 5, 2015 for PCT/EP2014/068269. |
English translation of International Preliminary Report of Patentability published Mar. 8, 2016 for PCT/EP2014/068269. |
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Number | Date | Country | |
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20160208560 A1 | Jul 2016 | US |