EP2886793A1 - Method for introducing an inductor loop into a rock formation - Google Patents

Abstract

The invention relates to a method for introducing an inductor loop (90) into a rock formation (100) for heating an oil reservoir (110) in the rock formation (100) for oil production, comprising the following steps: drilling a first inductor bore (120) for the Inserting a first inductor arm (20); Drilling a second inductor bore (130) for insertion of a second inductor arm (30); Drilling at least one cut bore (140) to create a first cut area (150) having the first inductor bore (120) and a second cut area (150) with the second inductor bore (130); Inserting the first inductor arm (20) into the first inductor bore (120) and the second inductor arm (30) into the second inductor bore (130); Introducing at least one connecting arm (40) into the cutting bore (140) for electrically conductive connection to the two inductor arms (20, 30) in the two cutting regions (150) for forming the inductor loop (90). The invention further relates to an induction device for carrying out this method.

Description

The present invention relates to a method for introducing an inductor loop into a rock formation for heating an oil reservoir and to a corresponding induction device.

It is well known that new methods should be used to extract from difficult oil deposits. For example, oil reservoirs are present in rock formations in which the oil is present in sand in a bound manner. In order to facilitate the promotion of the thus bound oil, it is necessary that the oil is heated and receives a reduced viscosity. Only in this way is it possible to pump the oil flowable from such an oil reservoir. To facilitate this heating, different techniques are known. Thus, for example, the steam injection method can be used, which is able by the introduction of superheated steam in the oil reservoir to heat it and thus to reduce the viscosity of the oil to be pumped. Furthermore, it is known that inductor cables are introduced, which cause the same by the generation of electromagnetic eddy currents in the oil reservoir heating.

A disadvantage of using the superheated steam method is that the heat distribution within the oil reservoir is difficult or impossible to predetermine. With regard to the known induction heating for the oil reservoir, the introduction of the inductor cable is particularly difficult. So it is imperative for the induction heating to form a so-called inductor loop. In other words, an annular or otherwise closed form of Induktorkabels must be introduced into the oil reservoir. This is done, for example, in flat bores in the area of about 40 m below the surface of the rock formation. In this case, the so-called Bananaloopverfahren can be used, in which along a curved path two substantially parallel holes are performed. Each of these bores has an inlet opening and an outlet opening, so that the two outlet openings on the surface of the rock formation can serve to connect the two ends of the two inductor arms together again to the inductor loop on the surface. However, such a method can only be used in areas near the surface for the oil reservoir. For deep drilling in areas up to 800 m or 1000 m below the surface of the rock formation, such a drilling method is not possible. This is particularly due to the fact that when drilling a hole, the weight of the drill pipe itself is supportive. If it were now necessary, for example in the case of the bananaloop method, to drill this section upwards again from a depth of about 1000 m, the corresponding drill pipe would no longer act together with the drilling pressure on the drill head, but instead would relieve it. A corresponding feed would accordingly be ensured in such a case only to a small extent that the cost of such a deep banana bore would be incredibly large in terms of cost, time and complexity. Accordingly, the use of inductor loops for heating in oil reservoirs present in deeper regions in rock formations has not been possible.

It is an object of the present invention to at least partially overcome the disadvantages described above. In particular, it is an object of the present invention, in an inexpensive and simple way to make an induction heater for deep drilling used.

The above object is achieved by a method having the features of claim 1 and an induction device having the features of claim 10. Further features and details The invention will become apparent from the dependent claims, the description and the drawings. In this case, features and details that are described in connection with the inventive method, of course, also in connection with the induction device according to the invention and in each case vice versa, so that with respect to the disclosure of the individual aspects of the invention always reciprocal reference is or may be.

• Bohren einer ersten Induktorbohrung für das Einbringen eines ersten Induktorarms,
• Bohren einer zweiten Induktorbohrung für das Einbringen eines zweiten Induktorarms,
• Bohren wenigstens einer Schnittbohrung unter Erzeugung eines ersten Schnittbereichs mit der ersten Induktorbohrung und eines zweiten Schnittbereichs mit der zweiten Induktorbohrung,
• Einbringen des ersten Induktorarms in die erste Induktorbohrung und des zweiten Induktorarms in die zweite Induktorbohrung,
• Einbringen wenigstens eines Verbindungsarms in die Schnittbohrung zur elektrisch leitenden Verbindung mit den beiden Induktorarmen in den beiden Schnittbereichen zur Ausbildung der Induktorschleife.

An inventive method is used to introduce an inductor loop in a rock formation for heating an oil reservoir in the rock formation for oil extraction. For this purpose, the method comprises the following steps:

• Drilling a first inductor bore for the introduction of a first inductor arm,
• Drilling a second inductor bore for insertion of a second inductor arm,
• Drilling at least one cut bore to create a first cut region with the first inductor bore and a second cut region with the second inductor bore;
• Inserting the first inductor arm into the first inductor bore and the second inductor arm into the second inductor bore,
• Introducing at least one connecting arm into the cutting bore for electrically conductive connection with the two inductor arms in the two cutting regions for forming the inductor loop.

According to the invention, a total of three holes are now carried out. On the one hand, an inductor bore is carried out in each case for the first inductor arm and the second inductor arm. Of course, with more complex geometries of the oil reservoir, three or more inductor arms can also be used. It is crucial that according to the invention a separate inductor bore is generated for each Induktorarm. However, it is possible that the inductor holes in sections overlap with each other. In other words, it may be that the inductor bores are all created by a common inductor bore so that all or some of the inductor bores are coextensive in the initial region of the respective bore. However, at the latest within the oil reservoir, the individual inductor bores run apart and in particular parallel to one another, in order to open up an area in which the inductively generated eddy currents can carry out the heating of the oil reservoir.

In addition to the necessary Induktorbohrungen for the introduction of the inductor according to the invention at least one cut hole is provided. This cut hole now serves to hit or substantially hit the ends of the inductor bores designed as blind holes. By this is meant that the cutting bore is drilled as close as possible to the ends of the individual inductor bores. For this purpose, in addition to conventional drilling mechanisms in particular a finding means can be used to detect the respective ends of the inductor arms during drilling can also.

For the operation of the present invention, it is necessary that a cutting area is created between the cutting bore and the respective inductor bore. For the purposes of the present invention, a cut area is to be understood as an area which is preferably less than or equal to approximately 1 m. This means that in this section region the distance between the cutting bore and the inductor bore, preferably the end of the inductor bore, is less than or equal to approximately 1 m. Preferably, even a real intersection or a real overlap between the cutting bore and the respective Induktorarm exists. However, it is sufficient for the electrical closing of the inductor loop by the connecting arm when the cutting area has a size as described above with less than about 1 m.

If the described holes for the inductor arms and for the connecting arm in the form of the cut hole have been carried out, the introduction of the individual arms can be done. About the inductor holes, the inductor arms are used. These are now in their fullest possible extent within the oil reservoir and up to the corresponding control unit or control unit on the surface of the rock formation. In the cut hole now one or more connecting arms are used. Thus, with two inductor arms, one connecting arm and, with four inductor arms, two connecting arms, etc. become necessary. The connecting arms now do not extend over the entire length of the cut hole, but extend only over sections of this cut bore. The connecting arms thus have a length which corresponds to the length of the cutting bore between the two corresponding or correlating cutting areas with the two inductor arms. The introduction takes place in such a way that an electrically conductive connection between the respective ends or at other locations of the inductor arms takes place in the respective inductor bore. This can be done, for example, in a mechanically contacting manner. Thus, devices can be introduced, which enable a mechanical contact for the electrically conductive connection between the connecting arm and the end of the respective Induktorarms when actually overlapping the cutting bore and the respective inductor bore in the cutting area.

However, in principle it is also sufficient if an electrical conductivity of the rock formation or of the oil reservoir in the cutting area, although low, is used. This means that the inductor loop is formed by the inductor arms, the connecting arm and the cutting area in the form of the rock formation and the rock present there.

Depending on the rock, however, it may be that the electrical conductivity is insufficient. Thus, in the event that there is no actual overlap between the cut hole and the inductor arm, the conductivity of the cut area can be deliberately increased. This will be explained later as a possibility with respect to the introduction of an electrically conductive fluid.

According to the invention, a simple bore for each inductor bore and the cutting bore is now possible. It is crucial that all of these holes exclusively downwards (ie in the vertical direction) or horizontally aligned within the oil reservoir. Contrary to the known Bananaloopverfahren no up-hole must now be made, so that can be used on simple, inexpensive and above all in a relatively short time feasible drilling techniques. As a result, it is only through a method according to the invention that the possibility of induction heating of the oil reservoir is also available at any depth within the rock formation. In particular, in this way oil reservoirs can be provided with an induction heating of the inductor loop, which are also arranged in deep well areas of approximately 1000 m or more below the surface of the rock formation.

It may be advantageous if, in a method according to the invention, the first inductor bore and the second inductor bore are drilled through a common inductor bore. As has already been indicated, it is sufficient if the individual inductor bores run separately within the oil reservoir. They thus clamp the induction field or the heating field in the oil reservoir. The implementation of a common Induktorbohröffnung, so that subsequent to this Induktorbohröffnung the inductor bores together along a common Induktorbohrachse, leads to a reduction of the drilling effort. These preferably have an enlarged one over the common sections of the inductor bores Drill cross-section in order to accommodate the total number of all passing through this common inductor bore inductor can. Another advantage is that in this embodiment, as little heating power as possible takes place within the vertical drilling direction of the inductor bores. The heating power depends on the distance between the individual inductor arms. The greater the distance between the Induktorarmen, the greater the heating power is formed. If the inductor arms in their vertical sections as close as possible to each other, for example, in a common vertical inductor bore, this leads to a low or very low heat output in these sections. Only after splitting into the individual separate inductor bores the inductor arms bring a distance between them, so that now the heating power is provided to a greater extent and exactly at the desired location within the oil reservoir. The branching for separating the individual inductor bores from each other can take place, for example, at different heights within the rock formation. Even at different positions on a common height or even in different radial directions, a separation of the individual inductor bores from each other is conceivable.

A further advantage is achieved if, in a method according to the invention, the inductor bores have at least one deflection point, in particular exactly one deflection point. In other words, the inductor bores are formed substantially with a vertical and with a substantially horizontal or inclined portion. The vertical sections mean that the inductor arms can be introduced as vertically as possible into the rock formation. Vertical holes are particularly cost effective, quick and easy to execute. The use of at least one deflection point means that now a horizontal or angled section can be provided for the respective inductor bore. These horizontal or angled Portions of the inductor bores now preferably extend into the oil reservoir. The actual orientation of the respective deflection point preferably depends on the respective geometric design of the oil reservoir within the rock formation. This deflection is preferably designed such that a deflection into the horizontal or at an angle downwards from the horizontal takes place. This avoids that drilling upwards with the disadvantages already described would be necessary.

It is also advantageous if, in a method according to the invention, the cutting bore has at least one deflection point, in particular is drilled in sections along a curved path. A deflection point for the cutting bore brings about the same advantages as have already been explained with regard to the deflection point for the inductor bores. A curved path, that is to say a continuous deflection point, preferably in an angled or horizontal plane, results in that a network of inductor arms or inductor bores distributed in a radially star-shaped manner can be achieved with a single cutting bore. This results in that a particularly homogeneous heating of a substantially radially formed oil reservoir with only a few holes in accordance with the invention is possible.

It is likewise advantageous if, in a method according to the invention, a locating means is arranged at the bore end of at least one of the inductor bores for a detection of this borehole end during the boring of the cutting bore. For example, such a detection means can emit radiation in the form of radioactive radiation or electromagnetic radiation. Also, acoustic signaling, for example in the form of ultrasound, may be provided for the finder. A magnetic training of the finder is conceivable. It is crucial that the shape of the signals emitted by the finder be transportable through the rock. In this way makes it possible, when drilling the cutting hole, for example by means of a detection device, to perceive the actual location of the respective finding means. Thus, the control or the orientation of the drill bit for the cutting bore can be aligned with this drill end, so that the cutting area is hit with a higher probability. In particular, it is possible in this way, with high probability to achieve an actual overlap between the cutting bore and the respective Induktorarm.

It is likewise advantageous if, in a method according to the invention, the cutting bore is closed, in particular cast, adjacent to the at least one connecting arm. This preferably takes place when parts in the cutting area are provided with electrically conductive liquids or fluids. By completing and thus sealing the connecting arm, it is ensured that such an electrically conductive fluid also remains at the desired location in the cutting area. By closing and potting, for example using concrete material, in addition, the positioning of the connecting arm within the cutting bore for a long time can be determined. Undesirable shifting or slippage, which would possibly be accompanied by the loss of the electrically conductive connection to the inductor arm, is effectively avoided in this way.

A further advantage can be achieved if, in a method according to the invention, the inductor bores within the oil reservoir are drilled at a uniform or essentially uniform distance of, in particular, more than approximately 50 m. These are, in particular, the horizontal or angled sections of the inductor bores within the oil reservoir. A distance that is uniformly leads to uniform heating power within the oil reservoir. Unwanted heat islands in parts of the oil reservoir are avoided in this way. Distances of about 50 m and more lead to a particularly advantageous and strong heating power for a sufficient reduction of the viscosity of the oil in the oil reservoir.

In addition, it is advantageous if, in a method according to the invention, an electrically conductive fluid is introduced into at least one of the intersecting regions for the electrically conductive connection of the connecting arm and of the adjacent inductor arm. As has already been explained, it is sufficient if the cutting areas have a sufficient proximity between the cutting bore and the respective inductor bore. The cutting regions preferably have a spacing of the cutting bore from the respective inductor bore, which is smaller or equal to approximately 1 m. Now, if a rock is present in the rock formation, which has a high electrical resistance or a low electrical conductivity, then this can be improved to the effect that now an electrically conductive fluid is introduced into this cutting area. The introduction takes place for example in the form of pressure, which presses the fluid into the cutting area. As the electrically conductive fluid, for example, an aqueous or liquid suspension of electrically conductive particles can be used. The solid powder in such a suspension may be, for example, graphite, chromium oxide or a similar material. Also, ionic liquids or salt solutions can be used as electrically conductive fluids. In particular, the electrically conductive fluid is an electrically conductive fluid. In sum, the intersection region and also the electrically conductive fluid thus become part of the induction device since it forms part of the inductor loop in the electrical chain between inductor arm, electrically conductive fluid, connection arm, electrically conductive fluid and to the second inductor arm.

The method according to the preceding paragraph can be further developed such that at least one transverse bore is introduced into the cutting regions of the cutting bore for the introduction of the electrically conductive fluid. In order to be able to carry out the distribution of the electrically conductive fluid in an even more targeted manner, bores can be made transversely, in particular perpendicular to the drilling axis of the cutting bore, in order to provide an opening in the cutting area. Preferably, it is even possible to provide a complete transverse bore to an overlap and thus a passage between the cutting bore and adjacent inductor bore available. This area is filled up with the electrically conductive fluid or the surrounding rock is impregnated with the electrically conductive fluid. Thus, the already described electrically conductive connection between connecting arm and Induktorarm is made.

Likewise provided by the present invention is an induction device for heating an oil reservoir in a rock formation for oil production. This induction device is in particular formed by a method according to the invention and has a first inductor arm in a first inductor bore and a second inductor arm in a second inductor bore. An induction device according to the invention is characterized in that at least one connecting arm is arranged in a cutting bore, which forms cutting areas with the two inductor bores. In this case, the connecting arm connects the two inductor arms in an electrically conductive manner with each other. The inventive design of the induction device, in particular by means of a method according to the invention, the induction device according to the invention brings about the same advantages as have been explained in detail with reference to a method according to the invention.

Preferably, a frequency generator can be provided in a method according to the invention, which feeds the inductor loop with a frequency between 1 kHz and 500 kHz.

The inductor loop, in particular in the form of an electrical conductor, can be designed as an induction line, so that it can carry the high-frequency current, operated with little loss as a resonant circuit. Since both ends are preferably connected to the frequency generator, the induction line forms an inductor loop. The technical realization of the electrical line is performed as a resonant circuit.

The frequency generator can be designed as a frequency converter, which converts a voltage having a frequency of 50 Hz or 60 Hz from the mains into a voltage with a frequency in the range of 1 kHz to 500 kHz. The frequency converter can be installed on a day-to-day basis.

Furthermore, at least one production well may preferably be drilled into the storage zone zone heated by the inductor loop, that is to say the oil reservoir.

After installation of the inductor loop in at least two holes and the connection of the inductor loop to the frequency generator, the energization of the conductor, thus the inductive heating underground and the oil reservoir begins with the resulting formation of a heating zone, which is characterized by an elevated temperature.

A conductor of an inductor loop may have a longitudinal inductance of 1.0 to 2.7 μH / m (micro Henry per meter length). The cross-capacitance coating is, for example, 10 to 100 pF / m (pico Farad per meter length). The characteristic frequency of the array is due to the loop length and shape and the transverse capacitance across the inductor loop.

The description of the electrotechnical parameters of the inductive heating system based on an inductor loop is briefly explained below:

The inductor loop acts as an induction heater during operation to inject additional heat into the deposit. The active region of the inductor loop may describe a nearly closed loop (ie an oval) in the substantial horizontal direction within the reservoir. The active area may be adjoined by an end area, possibly located above ground. The above-ground portions of the inductor loop start and end regions may be electrically contacted with a power source - a frequency generator. It is preferably provided that the line inductance of the inductor loop is compensated in sections by discrete or continuously executed series capacitances. It can be provided for the inductor loop with integrated compensation that the frequency of the frequency generator is tuned to the resonant frequency of the inductor loop. The capacitance in the inductor loop may be formed by cylindrical capacitors between a tubular outer electrode of a first cable section and a tubular inner electrode of a second cable section, between which a dielectric is located. Likewise, the adjacent capacitor is formed between the following cable sections. The dielectric of the capacitor is chosen so that it meets a high dielectric strength and high temperature resistance.

Furthermore, it is conceivable to provide a nesting of several coaxial electrodes. Other conventional capacitor designs can also be integrated into the inductor loop.

Furthermore, the entire electrode may already be surrounded by an insulation. The insulation against the surrounding soil is advantageous in order to prevent resistive currents through the ground between the adjacent cable sections, in particular in the region of the capacitors. The insulation furthermore prevents a resistive current flow between the forward and return conductors.

Several tubular electrodes can be connected in parallel. Advantageously, the parallel connection of the capacitors can be used to increase the capacitance or to increase its dielectric strength.

Furthermore, a compensation of the longitudinal inductance by means of predominantly concentrated cross-capacitances can be carried out: Instead of introducing more or less short capacitors as concentrated elements in the line, and the capacitance - can be a two-wire line such. B. provide a coaxial line or multi-wire cables anyway over their entire length - are used to compensate for the Längsinduktivitäten. For this purpose, the inner and outer conductors are alternately interrupted at equal intervals, thus forcing the flow of current through the distributed transverse capacitances.

The structural design of the inductor loop can be made as a cable design or as a solid conductor design. However, the design is irrelevant to the electrical operation described above.

Further information on the design of conductors, which can also be used for the present subject of the invention, can be found below DE 10 2004 009 896 A1 and WO 2009/027305 A2 ,

A frequency generator for driving the electrical conductor of the inductor loop is preferably designed as a high-frequency generator. The frequency generator can be constructed in three phases and advantageously include a transformer coupling and power semiconductors as components. In particular, the circuit may include a voltage impressing inverter. Such a generator may require operation under resonant conditions for its intended use to achieve reactive power compensation. If necessary, the drive frequency is suitably adjusted during operation.

On the surface, the following components may be present to control the conductor of the inductor loop: Starting from the 3-phase AC mains voltage source z. B. 50Hz or 60 Hz, for example, a three-phase rectifier is controlled, which is followed by a DC link with capacitor, a three-phase inverter, which generates periodic square wave signals suitable frequency. Inductors are controlled as output via a matching network of inductors and capacitors. A waiver of the matching network is possible, however, if the inductor is designed as an inductor loop, which allows the adjustment of the required resonant frequency due to their inductance and the capacitive coating.

The described frequency generators can basically be used as voltage-impressing power converters or, accordingly, as current-impressing power converters.

The temperature in the heating zone depends on the applied electromagnetic power resulting from the geological and physical (eg electrical conductivity) parameters of the deposit, as well as the technical parameters of the electrical arrangement, in particular consisting of conductor of the inductor loop and the high-frequency generator, results. This temperature can reach up to 300 ° C and is adjustable by changing the current through the inductor loop. The regulation takes place via the frequency generator. The electrical conductivity of the reservoir may be increased by injecting additional water or another fluid, e.g. As an electrolyte can be increased.

For example, an activation of the conductor of the inductor loop can take place over a period of time, initially no removal of the heated fluids has yet taken place. The temperature development is initially due to the induction of eddy currents in the electrically conductive areas of the substrate. In the course of heating, temperature gradients, that is, places of higher temperature, than the original one Reservoir temperature. The places of higher temperature arise where eddy currents are induced. The starting point of the heat is therefore not the inductor loop or the electrical conductor, but it is the eddy currents induced by the electromagnetic field in the electrically conductive layer. Due to the temperature gradient that occurs over time, heat conduction also occurs depending on the thermal parameters such as thermal conductivity, which compensates for the temperature profile. With a greater distance to the conductor of the inductor loop, the strength of the alternating field decreases, so that only a lower heating is possible there.

If, on the other hand, a removal of the fluids or of the fluids made of electrically conductive fluids takes place immediately as soon as they have been made fluid, then the less heated by electrical eddy currents, the more the soil with its electrical conductivity has been carried away at the vacancies. Although the electromagnetic field is still there, eddy currents can only form where there will still be conductivity. However, draining a liquid can cause other liquid to flow.

The design of the electrical arrangement is therefore preferably chosen so that the penetration depth of the electromagnetic field typically corresponds to half the distance of the horizontally formed inductor arms. This ensures that the electromagnetic field of a return conductor of the conductor is not compensated and on the other hand, the number of holes in relation to the thickness of the reservoir can be kept optimally low. In the case of the immediate removal of the fluid made electrically conductive liquids, the electromagnetic field reaches electrically conductive layers further away from the Induktorarm and induces eddy currents there. The advantage is that it is a self-penetrating effect, which means that the absolutely introduced power into the reservoir is always kept constant can be, for. In the range of a few 100kW to several mega watts, e.g. B. 1 MW. At the beginning, the highest specific power density is near the inductor arm, but as soon as the fluids are removed, the lower radius has a lower specific power density, but in a larger volume, with the result that the absolute power introduced is even remains the same, z. Eg 1MW.

This can not be achieved by other electrical methods: For example, in an immersion heater (structurally comparable to an immersion heater), the power introduced into the environment always depends on the temperature gradient and on the temperature-varying thermal conductivity, because the heating element is the starting point of Temperature is.

The number of inductor arms to be installed-which can be operated simultaneously or sequentially-depends on the size of the reservoir of the oil reservoir, and the number of simultaneously-operating inductor arms depends, for example, on the available electrical power.

During operation of the conductor of the inductor loop, the oil flows due to reduced viscosity in the production wells or in each case installed delivery pipe.

• Fig. 1 einen ersten Schritt eines erfindungsgemäßen Verfahrens,
• Fig. 2 einen zweiten Schritt eines erfindungsgemäßen Verfahrens,
• Fig. 3 einen dritten Schritt eines erfindungsgemäßen Verfahrens,
• Fig. 4 eine weitere Ausführungsform einer erfindungsgemäßen Induktionsvorrichtung,
• Fig. 5 eine Darstellung der Wirkung eines Auffindmittels,
• Fig. 6 eine Möglichkeit eines Schnittbereichs,
• Fig. 7 eine weitere Möglichkeit eines Schnittbereichs,
• Fig. 8 eine Möglichkeit der Verwendung eines elektrisch leitfähigen Fluides,
• Fig. 9 eine geometrische Anordnung der einzelnen Bohrungen,
• Fig. 10 eine weitere Möglichkeit der Anordnung der einzelnen Bohrungen,
• Fig. 11 eine weitere Möglichkeit der Anordnung der einzelnen Bohrungen und
• Fig. 12 eine weitere Möglichkeit der Anordnung der einzelnen Bohrungen.

Further features, advantages and details of the invention will become apparent from the following description in which, with reference to the drawings, embodiments of the invention are described in detail. The features mentioned in the claims and in the description may each be essential to the invention individually or in any desired combination. They show schematically:

• Fig. 1 a first step of a method according to the invention,
• Fig. 2 a second step of a method according to the invention,
• Fig. 3 a third step of a method according to the invention,
• Fig. 4 a further embodiment of an induction device according to the invention,
• Fig. 5 a representation of the effect of a finder,
• Fig. 6 a possibility of a cutting area,
• Fig. 7 another way of cutting,
• Fig. 8 a possibility of using an electrically conductive fluid,
• Fig. 9 a geometric arrangement of the individual holes,
• Fig. 10 Another possibility of arranging the individual holes,
• Fig. 11 Another way of arranging the individual holes and
• Fig. 12 another way of arranging the individual holes.

The Fig. 1 to 3 describe a method according to the invention. Thus, two inductor bores 120 and 130 are separately introduced here via two inductor bores 160. After a first vertical course, the two inductor bores 120 and 130 are deflected in a horizontal plane at different heights into the oil reservoir 110 in the rock formation 100 via a deflection point 170. These are both inductor holes 120 and 130 to blind holes, which each have a bore end 122 and 132. The distance A within the oil reservoir 110 is preferably constant and greater than about 50 m.

Subsequent to the drilling of the inductor bores 120 and 130, at least one, in this embodiment exactly one, cutting bore 140 is performed here. This takes place here purely vertically, since the two inductor bores 120 and 130 are arranged at different heights in a vertically oriented plane. The cutting bore 140 thereby generates cutting regions 150 in the region of the respective bore end 122 and 132.

After all bores 120, 130 and 140 have been created, the two inductor arms 20 and 30 are inserted into the two inductor bores 120 and 130. At the respective bore end 122 and 132, a connecting arm 40 is now arranged, which closes the inductor loop 90 and thus forms the induction device 10. On the upper side of the rock formation 100, it is of course also possible to form a control unit which provides the corresponding energization for the heating process for the inductor loop 90.

Fig. 4 shows a variant of the embodiment of Fig. 1 to 3 in which the two inductor arms 20 and 30 do not run at different heights but laterally spaced from each other at an equal height within the oil reservoir 110. This makes it necessary that now also the cutting bore 140 is deflected around a deflection point 170. The other features of this embodiment correspond to the embodiment of Fig. 1 to 3 ,

In Fig. 5 the drilling process for the cutting bore 140 is shown. In this embodiment, located at the bore end 122 of this first inductor bore 120 is a locator 50 having signals, for example, in a magnetic or radiation-like form. The drill head 200, which generates the cutting bore 140 has a detection device 210 for receiving these signals. Through this so-called tracer process is likely to achieve a situation as they Fig. 6 shows. Here, the cutting region 150 between the cutting bore 140 and the inductor bore 120 is formed as an overlapping cutting region 150. Here, a mechanical contact for the electrically conductive connection between the connecting arm 40 and the respective Induktorarm 20 and 30 can now take place.

The FIGS. 7 and 8 show a situation that is achievable without a finder 50, for example. Here, the cutting region 150 is formed as an approximation or as a minimum distance between the cutting bore 140 and the inductor bore 120. This minimum distance is preferably less than or equal to about 1 m. Thus, in this section region 150, the rock formation 100 itself can form the electrically conductive connection. In order not to hinder the conductivity in the case of low-conductivity types of rock, an electrically conductive fluid 60 can be introduced, for example, by means of transverse bores 142. This may be, for example, an electrically conductive liquid, in particular in the form of a suspension of electrically conductive particles.

In the Fig. 9 to 12 different geometries for the arrangement of the individual bores 120, 130 and 140 are shown. Fig. 9 shows a variant with a radial distribution of a total of three first Induktorarmen 120 and three second Induktorarmen 130. To close the respective arms 120 and 130 to a respective Induktorschleife 90, here is a cutting bore 140 is provided which extends to the deflection point 170 on a circular path 152 , In Fig. 10 a variant is shown, which has a radial spreading of two inductor arms 120 and 130 after the deflection point 170. This is, similar to Fig. 4 , a distribution on a common horizontal plane possible. However, that became here, just like the Fig. 9 and 11 Also, a common Induktorbohröffnung 160 used so that the Induktorarme 120 and 130 in the vertical section through a common bore.

Again Fig. 9 Circular path 152 meets all ends of the plurality of inductor arms 120 and 130. However, it is preferable to insert a plurality of connecting arms into the circular path so that only two adjacent arms of inductor arms 120 and 130 are always connected together. The remaining portions of the circular path 152 contain no conductive portions. A respective connecting arm is thus only a circle segment, according to the example of Fig. 9 For example, a circle segment over an angle of about 60 °. According to the example of Fig. 9 Preferably, three conductive sections are arranged in the circular path 152. Between the conductive sections, the bore of the circular path 152 may remain empty or be filled by a non-conductive portion.

Fig. 11 shows a variant in which the inductor arms 120 and 130 are distributed via deflection points 170 to different heights within the rock formation 100. Again, a common Induktorbohröffnung 160 could find again use. Here it is even sufficient to perform a simple vertical bore as a cutting bore 140. For particularly extensive oil reservoirs 110, an embodiment according to the Fig. 12 which provides a separate inductor bore 160 for each inductor bore 120 and 130, with a common cutting bore 140 providing the desired electrical conductivity interconnect for closing the inductor loops 90.

Concerning. FIGS. 11 and 12 It should be noted that each two adjacent inductor arms 120 and 130 are conductively connected to each other. For this purpose, it is possible for a plurality of connecting arms to be introduced into the cutting bore 140, in this case that always only two adjacent arms of Induktorarmen 120 and 130 are connected to each other. The remaining portions of the cut bore 140 contain no conductive portions. A respective connecting arm is thus only a tubular conductor of limited length. According to the example of Fig. 11 two conductive sections are arranged in the cut bore 140. In Fig. 12 three conductive sections are disposed in the cut bore 140, between each pair of inductor arms 120, 130. Between the conductive sections, the bore of the cut bore 140 may be left empty or filled by a nonconducting section.

It is particularly an advantage of the invention that a conductor loop can be easily closed, which can be operated by a frequency converter in operation. The inductor arms 120, 130 have means which, during operation, generate an electromagnetic field which extends into the oil reservoir and which, in turn, acts inductively on the oil or on hydrocarbons in the oil reservoir. The electrically closed part of the conductor loop, which consists of the electrically conductive connecting arm in the cutting bore, does not necessarily contain means which in a special way produce a pronounced electromagnetic field. This is also not necessary, since the connecting arm is essentially intended to complete the conductor loop. This results in a continuous conductor loop consisting of two inductor arms 120, 130 and the connecting arm for connecting these two inductor arms 120, 130.

The above explanation of the embodiments describes the present invention solely by way of example. Of course, individual features of the embodiments, if technically feasible, can be combined freely with one another without departing from the scope of the present invention.

Claims (10)

A method of introducing an inductor loop (90) into a rock formation (100) for heating an oil reservoir (110) in the rock formation (100) for oil production, comprising the following steps: Drilling a first inductor bore (120) for introducing a first inductor arm (20), Drilling a second inductor bore (130) for insertion of a second inductor arm (30), Drilling at least one cutting bore (140) to form a first cutting region (150) with the first inductor bore (120) and a second cutting region (150) with the second inductor bore (130), Inserting the first inductor arm (20) into the first inductor bore (120) and the second inductor arm (30) into the second inductor bore (130), - Introducing at least one connecting arm (40) in the cutting bore (140) for electrically conductive connection with the two inductor arms (20, 30) in the two cutting regions (150) for forming the inductor loop (90). Method according to claim 1,
characterized,
in that the first inductor bore (120) and the second inductor bore (130) are drilled through a common inductor bore (160). Method according to one of the preceding claims,
characterized,
that the Induktorbohrungen (120, 130) having at least one deflection point (170), in particular exactly one turning point (170). Method according to one of the preceding claims,
characterized,
in that the cutting bore (140) has at least one deflection point (170), in particular is drilled in sections along a curved path (152). Method according to one of the preceding claims,
characterized,
in that a locating means (50) is arranged at the bore end (122, 132) of at least one of the inductor bores (120, 130) for detection of this boring end (122, 132) when drilling the cutting bore (140). Method according to one of the preceding claims,
characterized,
that the average bore (140) terminated adjacent to the at least one connecting arm (40), in particular is cast. Method according to one of the preceding claims,
characterized,
in that the inductor bores (120, 130) are bored within the oil reservoir (110) at a uniform or substantially uniform distance (A), in particular greater than approximately 50 m. Method according to one of the preceding claims,
characterized,
in that in at least one of the cut regions (150) an electrically conductive fluid (60) is introduced for the electrically conductive connection of the connecting arm (40) and the adjacent inductor arm (20, 30). Method according to claim 8,
characterized,
in that at least one transverse bore (142) is introduced into the cutting regions (150) of the cutting bore (140) for the introduction of the electrically conductive fluid (60). Induction device (10) for heating an oil reservoir (110) in a rock formation (100) for oil production, in particular formed by a method having the features of one of claims 1 to 9, comprising a first inductor arm (20) in a first inductor bore (120) and a second inductor arm (30) in a second inductor bore (130).
characterized,
in that at least one connecting arm (40) is arranged in a cutting bore (140) which forms cutting regions (150) with the two inductor bores (120, 130), wherein the connecting arm (40) electrically conductively connects the two inductor arms (20, 30) ,

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