RO126048A2 - Improved process for hydrocarbon extraction employing in-situ combustion - Google Patents

Abstract

The invention relates to a process for hydrocarbons recovery from an underground deposit by underground combustion, during which the oxidation gas is injected through a vertical bore hole while the fluid extraction is made through a bore hole in the shape of a reversed L. According to the invention, the process consists in injecting an oxidation gas through at least one vertical bore hole within or in the vicinity of the vertical section of a production well bore hole having the shape of a reversed L, creating a vertical combustion front which advances to the top of a horizontal section of the production well which makes the hydrocarbons in the deposit, above the horizontal portion, run up and liquefy, further on they running down to the permeable horizontal portion wherefrom the said hydrocarbons are extracted through a pipe string placed within the production bore hole where a pipe string for the injection of a non-oxidating gas into the bottom area of the horizontal portion is also placed, the injection and production wells being adjacent in front of the vertical portion of the production well.

Description

This invention relates to a modified process for the recovery of hydrocarbons from an underground deposit by in situ combustion and the use of a horizontal extraction well.

BACKGROUND OF THE TECHNIQUE

US patent no. 5,626,191, assigned, issued on May 6, 1997 (hereafter, '191), describes in-situ combustion processes for the extraction of hydrocarbons from an underground hydrocarbon reservoir by using: (i) the a little injection well, located relatively high in an oil field, for injecting an oxidizing gas into the hydrocarbon deposit, and (ii) an extraction well, for the extraction of liquefied or gasified hydrocarbons from the hydrocarbon deposit. The extraction well has a vertical section which is in communication with a horizontal foot, which extends effectively perpendicularly outside the vertical section and which has a "peak" part and a "heel" part. The horizontal leg ends relatively low in the deposit, and at its "heel" side it is in communication with the vertical section. Air or other oxidizing gas, such as oxygen-enriched air, is injected through the injection well into the hydrocarbon reservoir, usually through the perforations at the top of a vertical injection well, located in the vicinity of the "heel" of the horizontal foot of the well. of extraction. The horizontal foot of the extraction well is generally oriented perpendicular to a generally quasi-vertical combustion front of the combustion hydrocarbons, which are produced after igniting a portion of the hydrocarbons in the deposit near the injection well. This combustion front is supplied with an oxidizing gas through the injection well. The "tip" of the part of the horizontal leg is positioned on the path of the combustion front. The resulting combustion front propagates from the "tip" of the horizontal leg, along the horizontal foot, in the direction of the "heel" part. During this process, hydrocarbons heated from the deposit, in advance of the combustion front moving, become liquefied or gasified and circulate in the horizontal foot, and from this foot are then brought to the surface through the vertical section of the extraction well. This process from US patent no. 5,626,191 is called "THAI ™", an acronym for "toe-to-heel air injectiofr ^ LfiSt ^ xo mark [f P ^ TTnet -1 ltn / _r ^M · OFF £ £ -2 -2 1 1 0 - 0 07 3 5 -2 3 -01- 2009 registered by Archon Technologies Ltd., a subsidiary of Petrobank Energy and Resources Ltd., Calgary, Alberta, Canada.

U.S. Patent no. No. 6,412,557, also disclosed, describes a similar, but modified, process that has the additional step of placing a hydrocarbon uptake catalyst along, within or around the horizontal foot, for the effective reduction of hydrocarbon viscosity, for improving the quality of the hydrocarbons and increasing the flow of hydrocarbons from the deposit into the horizontal foot of the extraction well, for subsequent removal to the surface. This modified process is known in the industry as CAPRI ™, also a registered trademark of Archon Technologies Ltd.

W02005121504 (PCT / CA2005 / 000833), published on December 12, 2005, assigned, discloses a process similar to the THAI ™ process, which further comprises an additional step of providing an injection pipe in the extraction well, in the interior of the vertical section and effectively along the length of the horizontal foot, at a position near its "tip", for the purpose of injecting through said tubing, in the region of the "peak" of said horizontal foot, a non-oxidizing environment, comprising steam, water or a neoxidizing gas. The injection of this non-oxidizing medium into the "tip" region of the horizontal foot, has the effect of displacing any oxidizing gas from such a zone and, thus, preventing the combustion of the ennobled hydrocarbons, which entered through the horizontal foot, further increasing the ambient pressure. from the horizontal foot, so as to prevent or further reduce the influx of oxidizing gas from the injection well which is the oxidizing gas injected into the hydrocarbon tank.

The disadvantage is that in each of the above techniques for recovering liquefied and / or gasified hydrocarbons from a hydrocarbon reservoir, the oxidizing gas must be injected near the horizontal foot tip and away from the vertical section of the extraction well. This place of injection of the oxidizing gas is far from the vertical section of the extraction well, the surface of the extraction well being the place where the oxidizing gas is in the way

commonly generated. Injection and vertical section of wells separated by one (1) kilometer or more. consequently, it obeys either

The prior art thus requires the transport of oxidizing gas to the injection well site, through the extraction well pipes, or, alternatively, requires installation. of equipment at the injection well site to allow the generation of oxidizing gases for subsequent injection. This requires free access, by grinding, and / or increased space at the injection well site, to accommodate additional distribution and / or generation and compression gas oxidation facilities, thereby increasing the environmental 'footprint'. and the impact of drilling operations on the environment, which also leads to high costs.

Thus, there is a need for a modified THAI ™ and CAPRI ™ process, in which these disadvantages are eliminated.

SUMMARY OF THE INVENTION

The process of the present invention relates to a modified process for recovering in situ hydrocarbons, which, instead of injecting the oxidizing gas close to the "tip" side of the horizontal foot, injects the oxidizing gas into or near the vertical section of the extraction well (that is, at the “heel” portion). The modified process eliminates the need for a separate drilling / extraction platform for the injection of oxidizing gas, thereby reducing the cost and reducing the environmental impact of in situ recovery processes.

Advantageously, the process of the present invention, in a third special embodiment, described below, further eliminates the need for a separate oxidizing gas injection well because, by this enhancement, the vertical section of the extraction well serves as well. injection, thus reducing well drilling costs and also reducing investment costs.

Specifically, instead of being a "toe-to-heel" process, the process of the present invention is a "heel-to-toe" process. The injection point of the oxidizing gas is modified to be at "heels" as opposed to

A-201Q-OO735 - 2 3 -01- 2009

"Peak".

In the present invention, three regions of the deposit are developed, in relation to the position of the combustion zone. Near the "heels" and after crossing the combustion front of "heels" is the burnt area, depleted by crude oil, an area that results after the injection of oxidizing gas and after the combustion front has advanced a while outside and away from the injection well. and the "heel" part of the horizontal leg. This burned area is effectively filled with oxidizing gas. Nearby is the coking area, which is essentially the area inside the deposit that the oxidizing gas could then penetrate into the deposit and, in essence, is the area where the combustion front exists (the combustion that takes place is that of the remaining coke representing the hydrocarbons which then remain after the lighter hydrocarbons in this deposit and before this combustion front have been liquefied or gassed and have run in the horizontal foot and, afterwards, have been brought to the surface. The "tip" of the horizontal well is the region of the deposit containing the hydrocarbons to which the combustion front advances.

At higher injection rates, the pressure in the deposit increases, and the oxidizing gas in the burned area, which contains residual oxygen, can be forced into the horizontal foot of the extraction well. This is prevented in the process of the present invention by injecting, for a limited or continuous period, a medium, for example, a non-oxidizing gas, such as carbon dioxide, and / or steam or water, for magnification. pressure inside the horizontal leg of the extraction well.

Accordingly, in a broad aspect of the process of the present invention, in order to realize the advantage of being able to inject oxidizing gas near or in the vertical section of the extraction well, a modified process for recovering liquefied or gasified hydrocarbons from gas is described. an underground hydrocarbon deposit, comprising the steps of:

(a) providing at least one extraction well having an effective horizontal foot, positioned relatively low in the said deposit, the horizons leg having, at its extremity, at least one heel, and at the ends ^;

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^ -2 0 1 0 - 0 0 7 3 5 -2 3 -01- 2009 a peak portion, said horizontal foot being adapted to allow the inflow of hydrocarbons within said horizontal foot, said extraction well having an effectively vertical section , connected to said horizontal leg near said mentioned portion of heel;

(b) providing an extraction pipe in said extraction well, which extends within said vertical section and within at least a portion of said horizontal foot, for collecting said hydrocarbons, circulating in said horizontal foot;

(c) periodic or continuous injection of a medium into the horizontal leg, near its heel portion, wherein said medium is selected from the medium group comprising, alone or in combination, a non-oxidizing gas, such as carbon dioxide , steam or water;

(d) supplying an oxidizing gas to said underground deposit, at least initially, at a site of, or near, said vertical section of said extraction well;

(e) ignition of hydrocarbons within the hydrocarbon deposit near said vertical section of the extraction well to cause combustion of a portion of said hydrocarbon in said hydrocarbon deposit near said vertical section, thereby creating, combustion front advancing, outward and away from said injection well, in at least one direction, along said horizontal leg and to said peak portion thereof;

(f) challenge of heated hydrocarbons from said deposit to flow from its upper regions and to collect in said horizontal foot; And (g) extraction of hydrocarbons from the extraction well through the extraction pipe

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Referring to step (g) above, removing the hydrocarbons from the extraction well through the extraction pipe is typically without pumping, but may require pumping to remove them from the horizontal foot if sufficient quantities of inert gas, such as be gas hydrocarbons, carbon dioxide or nitrogen, do not circulate in the horizontal foot and thus the extraction pipe is under significant ambient pressure of the hydrocarbon formation, as it may occur during the commissioning period. The normal mechanism of extraction of crude oil by reducing the density of the mixture of gas fluids is called 'artificial eruption' ('gas lift').

In a first refinement / embodiment of the above process, from the present invention, the injection of oxidation gas near the vertical section of the extraction well is accomplished by drilling a separate injection well near the vertical section of the extraction well, for allow the oxidizing gas to be injected into the formation through this injection well near the extraction well. In this way, and advantageously, the same drilling rig can then be used to drill both the extraction well and the injection well, thus saving the costs and costs of drilling wells.

in addition, and advantageous, because the injection well is located near the extraction well, which typically has energy generating equipment, used for extraction, oxidizing gas can usually and much more easily be obtained and immediately injected into the injection well, which otherwise could not have been done if the injection well had been positioned away from the vertical section of the extraction well, as in the previous technique.

In a second embodiment of the invention, the injection well is a lateral inlet well within the vertical section of the operating well, which, again, allows the injection well to be located near the injection well to the above advantages were realized, as well as the additional advantage, in that the upper part of the vertical section of the operating well can be used when drilling the lateral inlet well, thereby reducing drilling costs further.

ίΧ-2 această 10 - ο 07 3 5 - 2 3 -01-2009 Specifically, in this second preferred embodiment, the present invention comprises a process for recovering liquefied or gaseous hydrocarbons from an underground hydrocarbon formation, which contains the steps of:

(a) providing at least one extraction well having an effective horizontal leg, positioned relatively low in said deposit, said horizontal leg having, at one end thereof, at least one heel and, at its opposite end, a top portion, located in the formation slightly lower, in level, than said heel portion, said horizontal foot being adapted to allow the inflow of liquefied hydrocarbons within said horizontal foot, said extraction well having an effectively vertical section, said horizontal close to said heel portion thereof;

(b) providing an extraction pipe in said extraction well, which extends downwards, in said vertical section and along said horizontal leg, to the top portion, for collecting said hydrocarbons, which circulates in the horizontal foot mentioned;

(c) providing an injection pipe in said extraction well, said injection pipe extending downwardly in said vertical section to said heel portion;

(d) injecting a medium into said extraction well, through said injection pipe, wherein said medium is selected from the medium group comprising, alone or in combination, a non-oxidizing gas, steam, water or carbon dioxide;

(e) providing an injection well as a reintroduction in the form of a side channel, from said vertical section of said extraction well, injection well extending into the hydrocarbon formation;

(f) supplying an oxidizing gas to said hydrocarbon portion through said injection well;

Section

de ^ -201 Ο- 0 0 7 5 5 -2 3 -01- 2009 (g) ignition of said hydrocarbons, from said hydrocarbon formation, near said vertical section, in order to cause combustion of a part of said hydrocarbons of said formation of said hydrocarbons, thereby creating a combustion front that advances, outward and away from said vertical section, in at least one direction, along said horizontal leg and toward its tip portion; and (h) removing from the extraction well, through said extraction pipe, the hydrocarbons which have circulated in said horizontal leg.

A third preferred embodiment of the present invention comprises a process for producing hydrocarbons from a hydrocarbon reservoir which completely eliminates the need for an injection well for injecting an oxidizing gas, thereby reducing the costs of implementing the process. in situ of the present invention.

Specifically, in the third and preferred embodiment of the present invention, the vertical section of the extraction well is perforated to allow an oxidizing gas (which is provided in this vertical section) to penetrate the hydrocarbon formation near the vertical section. . In this way, the need to bypass a separate injection well is eliminated.

Again, as part of the process of the present invention, a medium in the form of a non-oxidizing gas, such as carbon dioxide, steam or water is injected either continuously or intermittently into the extraction well through the injection pipe, which extends to the heel portion of the extraction well. A series of "gaskets" may be provided, located in the extraction well, to isolate the oxidizing gas, fed into the vertical section of the extraction well, by the heel portion of the horizontal foot of the extraction well, in which the non-oxidizing medium is fed.

Thus, in this third preferred embodiment, the process of the present invention comprises a process for recovering liquefied or gaseous hydrocarbons from an underground hydrocarbon deposit, which contains

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(a) providing at least one extraction well, having an effective horizontal foot, positioned relatively low in said deposit, said horizontal leg having, at one end, a heel portion and, at its opposite end, a portion top, said horizontal foot being adapted to allow the inflow of liquefied hydrocarbons within said horizontal foot, said extraction well having an effective vertical section, connected to said horizontal foot near said said heel portion;

(b) providing an extraction pipe in said extraction well, which extends from the surface of said extraction well to at least the heel portion of said extraction well, for collecting said hydrocarbons, circulating in said horizontal foot;

(c) providing an injection pipe in said extraction well, said injection pipe extending downwardly in said vertical section to a position extending at least in said heel portion of said horizontal leg;

(d) injecting a medium into the extraction well, wherein said medium is selected from the group of media comprising, alone or in combination, a non-oxidizing gas, such as aryl carbon dioxide, steam or water;

(e) drilling in said vertical section of said extraction shaft, at a position above said heel portion;

(f) supplying an oxidizing gas to said vertical section and thus to a portion of said hydrocarbon deposit, through said perforations in said vertical section;

(g) ignition of said hydrocarbons in said hydrocarbon deposit, near said vertical section, in order to cause said combustion, to a portion of said hydrocarbons in the hydrocarbon deposit;

* - ²⁰¹ OT & outward and away from said vertical section, in at least one direction, along said horizontal leg and to said top portion thereof; and (h) causing the heated hydrocarbons, from said deposit, to flow from its upper regions and to collect them in said horizontal foot; And (i) removing from said extraction well, through said extraction pipe, said hydrocarbons, which circulated in said horizontal leg.

Advantageously, the third embodiment of the present invention also eliminates the need, as in the prior art, to "close (by using a cement plug or the like) the horizontal leg of each extraction well, when in a series of extraction wells are located end-to-end and when the vertical section of a first extraction well is subsequently transformed into an injection well (see US '191, col 6, row 47-col 7, row 9 and FIG. 14D-F thereof). The in situ process of the present invention, in particular the third embodiment, is a process for further reducing the recovery costs in situ, by reducing the number of steps, which includes and not only eliminates the need to drill injection wells, but it also eliminates the need to "close" other wells, as required in the prior art in situ procedures, as exemplified in US Ί91 above.

BRIEF DESCRIPTION OF THE DRAWINGS in the accompanying drawings, which illustrate a number of exemplary embodiments of the invention:

Figure 1A is a schematic perspective view of an assembly of the previous technique of in situ recovery, in a hydrocarbon deposit, which shows the air injection wells, located at the top of each of the corresponding horizontal legs of the associated extraction wells;

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Figure 1B represents a cross section through a well of} qj ^ âare__ and prî

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CK-2010-00735-2 3 -01- 2009 associated extraction, shown in Figure 1 A;

Figure 2A represents a schematic cross-section (not on a scale) through an injection well and the associated extraction well from a first embodiment of the present invention, which uses the process of the present invention to cause a combustion front to propagate. in the direction of the "tip" of the horizontal foot from the extraction well, at a point in time close to the time of ignition of the hydrocarbons and of the initial propagation of the combustion front;

Figure 2B represents a cross-section, similar to that of Figure 2A, also not to scale, at a later point in time, when the combustion front propagated for a time and moved closer to the "peak" portion of the horizontal foot from the extraction well;

Figure 2C represents a cross-section similar to that of Figure 2B, also not to scale, at another point in the next following time, when the combustion front propagated and moved further, and closer to the "peak" portion of the horizontal leg of the extraction shaft;

Figure 3 represents a partially schematic cross-section through a hydrocarbon deposit, comprising a formation containing hydrocarbons, which has a second embodiment of the process of the present invention, namely an extraction well and the associated lateral inlet injection well. (not on the scale) and which further describes the process of the present invention for causing a combustion front to propagate in the direction of the "tip" of the horizontal foot from the extraction well, at a point in time near the time of ignition of the hydrocarbons and initial propagation of the combustion front;

Figure 4 represents a partially schematic cross-section through a hydrocarbon deposit, comprising a hydrocarbon-containing formation, which has a third preferred embodiment of the present invention, namely a cross-section through an extraction well (not at scale) which uses the process of the present invention to cause a combustion front to propagate (

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the horizontal foot of the extraction well, at a point in time close to the time of ignition of the hydrocarbons and initial propagation of the combustion front; and

Figure 5 is a schematic perspective view of the in situ recovery process of Figure 4, which shows a third and preferred embodiment of the process of the present invention for recovering hydrocarbons from a hydrocarbon deposit.

DESCRIPTION OF THE PREFERRED EMBODIMENT FORM

Figure 1A shows a schematic, semi-transparent view of a well arrangement used in the prior art for the in situ recovery of hydrocarbons from a reservoir or hydrocarbon formation 10.

Specifically, Figure 1A schematically describes the process from the previous technique for the in situ recovery of hydrocarbons, disclosed in US patent no. 5,626,191, comprising the placement of a series of extraction shafts 12, each comprising an effective vertical section 16 and an effective horizontal foot 16, which has a portion of "tip 18 and a portion of" heels "20. The horizontal foot 16 of The extraction well 12 is located in a lower region of the hydrocarbon formation 10, and is effectively porous to allow fluid to enter. A series of injection wells 22 are located, located in a region close to the "peak" and extending downwards, in the formation 10, with perforations in the upper part that reaches the oil field.

Figure 1B shows a schematic cross-section through an injection well 22 and the associated extraction well 12, Figure 1 A.

In the process of in situ recovery, from the prior art, described in Figures 1A and B, an oxidizing gas 24, such as air (containing oxygen), oxygen or oxygen-enhanced air, is injected into the formation 10 through each of the wells. injection 22, to allow a portion of the hydrocarbons in the formation 10 to be burned. Specifically, the ignition and combustion of a portion of the hydrocarbons in the hydrocarbon formation 10 in the region of the well <^ has 22, when it is supplied with oxidizing gas 26, in this way / thus / / N / E 2

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Inside the formation 10, a combustion front 26, effectively vertical and extending laterally. This combustion front 26, by thermal conduction and the creation of heated flue gas inside the formation 10, heats the hydrocarbons of the formation 10 directly in front of and before the combustion front 26, causing the more volatile compounds of the hydrocarbons of the formation 10 to gas and cause, in further, concentrating part of the hydrocarbon solids or bitumen in the formation, simultaneously increasing their viscosity, to create mobile liquefied hydrocarbons 30. Heavier, remaining hydrocarbons, especially bituminous coal, remain, providing fuel for the advancing combustion front 26 and which supports the advancement of the combustion front 26 and in situ combustion and the hydrocarbon concentration process. Then, the mobile liquefied hydrocarbons 30 and the gasified components (of which one can subsequently condense in the form of liquids 30), circulate downwards, through the action of gravity, through the formation and are collected in the lower region of the formation 10 by circulating in the horizontal foot. 16, which extends horizontally, of the extraction well 12. The horizontal foot 16 of the extraction well 12 generally has, at least for a limited period, a gas pressure inside it less than that of the formation 10 (due to removal of collected liquid hydrocarbons 30 and gaseous hydrocarbons thereof). This reduced pressure of the gas from the horizontal foot 16, as opposed to that of the inside of the formation 10, in advance of the combustion front 26, participates in the influx of liquid and gaseous hydrocarbons from the hydrocarbon formation 10 into the horizontal foot 16. at other times, Due to the injection of the environment 52, through the injection pipe 50 (analyzed below), in the horizontal foot 16, the horizontal foot 16 may have, over time, a gas pressure close to the gas pressure inside the formation 10, or even in excess.

In the process of the prior in situ recovery technique, as shown in Figures 1A and B and described above, it is important that the injection wells 22 are located near the "tip" of the horizontal foot 16, and the oxidizing gas was injected. in formation in these places, through the injection wells 22. The combustion front 26, which receives the oxidizing gas 24, is thus caused to advance outward from the injection well 22, and perpendicular to and along the wells.

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What is disadvantageous in this process from the prior art is not only the need to create a drilling rig 32 for the operating well 12, but also the need to create an additional and separate drilling rig for the injection well 22, and the need for this separate injection well 22 to be drilled in this formation. in addition, oxygen creation and injection equipment (not shown) must be transported and installed on the surface of this injection well 22, so that the injection well is far from the surface of the extraction well 12. Both requirements add significantly to the costs of carrying out the procedures from the previous technique of in situ recovery of hydrocarbons.

Figures 2A-2C hereinafter show a (first) modified in situ recovery process, which is expressly adapted to eliminate at least one of the costs of prior hydrocarbon recovery techniques, namely the expense of creating a separate drilling rigs for injection well 22.

Specifically, as can be seen in Figures 2A-2C, a single drilling ramp 32 is created by clearing trees and removing other obstacles, and by building a single drilling platform thereon. An extraction well 12 is drilled using conventional drilling techniques, comprising a vertical section 14 and another horizontal foot 22, in communication with the vertical section 14. The horizontal foot 16 has a "peak" portion 18 and a "peak" portion. heel ”20, where it meets the vertical section 14. The extraction well 12 is completed by the usual process of lining the well 12 and, further, by inserting inside the extraction well 12 the extraction pipe 40, which extends into down, in the vertical section 14, up to that portion of heels 20 and, preferably, along the horizontal leg 16, preferably up to the top portion 18 thereof, this extraction pipe 40 having an open end 42 in the interior of said horizontal leg 16. Extraction pipe 40 is usually a helical pipe, as is conventionally used in drilling operations.

An additional injection pipe 50, as usual, a helical pipe, as is conventionally used in drilling operations, hassle-free replacement for injecting an environment 52 into the Extraction Duct / this nWBiu 52

CABINETM. OPRQIU f ^ -2010-00735-2 3 -01/2009 comprising a non-oxidizing gas, preferably carbon dioxide, due to its effect or diluent on hydrocarbons, or alternatively or in combination, steam or water or other fluid medium, non-flammable. As can be seen from Figures 2A-2C, the injection pipe 50 extends into the "heel" portion 20 of the horizontal leg 16. At least one insulation gasket 54 is provided to allow the environment 52 to be injected, if desired. , in a pressurized state, from time to time or continuously injected, to pressurize from time to time or continuously, if desired, the horizontal foot 16, to participate in forcing liquefied hydrocarbons 30 in the extraction pipe 40 and in preventing entry of oxidizing gas into the horizontal foot 16.

By using a single drilling rig 32, a new injection well 22 is drilled, which extends at least into the upper region of the hydrocarbon formation 10. The injection well 22 usually has perforations 75 at its lower end, in order to allows the infusion and injection of an oxidizing gas 24, such as air or oxygen, in the hydrocarbon-containing region of the hydrocarbon formation 10.

The process of the present invention, in the first embodiment shown in the Figures

2A-2C, works accordingly, as follows:

The oxidizing gas 24 is injected into the formation 10 through the injection well 22. Advantageously, the equipment (not shown) used to create the oxidizing gas 24 and to inject this oxidizing gas 24 should not be located far from the extraction well 12, but , on the other hand, due to the process of the present invention, it may be located near the extraction well 12 and, in particular, if desired, it may be located on or near the drilling platform 32, thereby eliminating the need to grind and create a separate drilling rig in a remote location as it would have occurred if the injection well 22 had been located to the "tip" of the horizontal well 16. Also, the operation and maintenance of the oxidizing gas supply equipment may either made conveniently at the oil treatment site, located near probe 12. The hydrocarbons near the injection well 22 are ignited and, due to the supply of oxidizing gas 24, a combustion front 26 is created, which, in the process presented in Figures 2A-2C, advances in the form of a front that extends effectively vertically and laterally (see also front), from " the heel ”20 of the horizontal foot 16 towards the“ tip ”/ t8

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generated, the viscous and very viscous hydrocarbons, including bitumen, from the hydrocarbon formation 10, in front of the advancing combustion front 26, are challenged to concentrate and become liquid, and during the process, become less viscous. Some hydrocarbons in Formation 10, in front of the front 26, will be gassed. The liquefied hydrocarbons 30 and the gaseous hydrocarbons, now being mobile, circulate downwards and in the horizontal foot 16, which is made porous (ie has holes 60 at the top of it) to allow the infusion of these hydrocarbons 30 and thus the collection of these hydrocarbons 30 .

This process continues as the combustion front 26 evolves and "sweeps" such from the "heel" portion 20 to the "tip" portion 18 of the horizontal leg 16.

It is worth noting that, prior to generating the combustion front 26, the hydrocarbon formation 10 is preferably initially heated by injecting a non-oxidizing medium, heated 52, such as steam, which is injected into the horizontal foot 16 of the extraction well 12, through the injection pipe 40, and which is removed through the extraction pipe 50 or, alternatively, through the annular space 80 of the vertical section 16, if the insulation gaskets 54 are not present. The pre-injection of a heated environment has the advantage of heating the extraction well 12 and its extraction component elements, thereby increasing the fluidity of the liquefied hydrocarbons 30, which circulates in the horizontal foot 16 of the extraction well 12. This procedure is useful in bituminous deposits. , because the cold oil that can enter the horizontal foot 16 will be very viscous and will flow very hard, possibly blocking the horizontal foot 16. For the formation 10 with mobile oil, extensive pre-ignition treatment with steam is not necessary for the purpose of heating the oil, for it to flow, however, it may be useful for reducing oil saturations near the oxidizing gas injection well 22 and for increasing the temperature of the hydrocarbons in order to ignite them. Other ignition processes, such as injecting lightly flammable fuels, such as flaxseed oil, or injecting a hot combustion gas, may also be used. For bituminous deposits, steam is also injected through the injector shaft 22 and may be ........ '' 10

from the region between the injector shaft 22 and the tip 18 <a ^ -2010- 0 0 7 3 5 -2 3 -01- 2009 heat the crude oil and increase its mobility before initiating the injection of oxidizing gas 24 into the reservoir formation 10.

After starting the combustion and combustion front 26, a non-oxidizing medium 52 is injected in the form of steam, a non-oxidizing gas, such as carbon dioxide, or water, either continuous or sporadic, through the injection pipe 50, in the horizontal foot 16 , which, due to the insulation seals 54, may be pressurized. The purpose of such a non-oxidizing environment 52 exists for a number of reasons. First, the increased pressure inside the horizontal foot 16 reduces or prevents the infusion of oxidizing gas 24 into the horizontal foot 16 of the formation 10, which could otherwise be harmful, in combination with the liquefied or gaseous hydrocarbons in the interior, forming an explosive mixture with potentially explosive consequences, or alternatively, could react with oxygen directly, to form the coke that could otherwise close the horizontal leg 16 of the extraction well 12. The consequence of having hydrocarbons (crude oil) and oxygen together. a well is represented by combustion and, potentially, an explosion with high temperatures, probably over 1000 ° C. This can cause irreparable damage to the well, including damage to sand retention grates (not shown). The presence of oxygen and wells temperatures above 425 ° C should be avoided for the safety and continuous extraction of crude oil. Secondly, the injection of a medium 52 may serve to pressurize the horizontal foot 16 and to participate in directing liquefied and gaseous hydrocarbons 30, collected in the horizontal foot 16, in the open end 42 of the extraction pipe 40, in this way taking part in lowering the level of these liquids 30 and the extraction of these hydrocarbons 30 from the extraction well 12. Thirdly, the medium 52, when injected through the injection pipe 50, may be heated. Advantageously, the means for heating this medium 52 may conveniently be located, in this process, on the surface of the extraction well 12 and on or near the drilling platform 32. Finally, when the injected medium 52 is carbon dioxide, the injection it in the horizontal well 16 serves not only as a convenient "absorbent" of carbon, to allow the removal of this greenhouse gas, but additionally, due to the diluent properties of carbon dioxide on liquid hydrocarbons 30, the carbon dioxide also reduces their viscosity, helping

thus lowering the level of liquid hydrocarbon extraction 40.

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As can be seen from Figures 2A-2C, during the advancing of the combustion front 26, the coke is deposited in the deposit 10 and serves as fuel for the in situ combustion process. Hot combustion gases 70 advance to formation 10, heating the hydrocarbons in it and any interstitial water that is present. Some of these hydrocarbons are liquefied and these liquefied hydrocarbons 30 circulate, together with the combustion gases, in the horizontal foot 16, through the perforations 60, as shown in Figures 2A-2C. The liquefied hydrocarbons 30 circulate along and at the "tip" 18 of the horizontal leg 16 and enter the open end 42 of the extraction pipe 40 and circulate back and then upward to the surface. The process is stable and continuous, with the combustion front 26 continuously advancing to the "tip" 18 of the horizontal leg 16.

Oxidising gas 24, usually air, oxygen or oxygen enriched air, is injected into the upper part of the reservoir 10. The coke, which was deposited previously, consumes oxygen so that only oxygen-free gases come in contact with the crude oil in front of the coke area. , at the combustion front 26. The temperatures of the combustion gas, usually 600 ° C and up to 1000 ° C, are obtained from the high temperature oxidation of the fuel based on coke. In the 80 zone of the mobile crude oil, in advance of the combustion front 26, these hot gases 70 and the steam heat the crude oil above 400 ° C, partially cracking the crude oil, vaporizing some components and greatly reducing the viscosity of the crude oil. The heaviest components of crude oil, such as asphaltenes, remain on the rock and will constitute the coke-fuel later, when the combustion front 26 reaches that location. In the 80 zone of the mobile crude oil, the gases and crude oil circulate downwards, in the horizontal foot 16, attracted by gravity and, sometimes, by the low pressure absorbing capacity of the horizontal foot 16, when depressurized. The coke area at the combustion front 26 and the 80 zone of the mobile crude oil move laterally in relation to the direction from the heel 20 to the tip 18 of the horizontal well 16. Section 100 of the burned area behind the combustion front is devoid of liquids (crude oil) and water) and is filled with oxidizing gas 24. The section of the horizontal well 16, opposite this burned area 100, is in danger of receiving oxygen or oxidizing gas 24, which ignites the oil present in the horizontal well 16, creating extremely high temperatures in the well shaft, which will damage the steel drill bit and, in particular, the sand grids used for combing ^ liim ^ fluid inlet 30, except for sand. If the grill grates,

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C \ -2 0 1 0 - 0 0 7 3 5 -2 3 -01- 2009 unconsolidated sand from the deposit will enter the well 16 and it will be necessary to close it for cleaning and repair with cement plugs. This operation is very difficult and dangerous because the horizontal well 16 may contain explosive levels of crude oil and oxygen.

The process of the present invention relates to a number of ways of preventing the influx of oxidizing gas 24 from formation 10 in the horizontal leg 16. A first method is to reduce the injection rate of oxidizing gas 24 to reduce the pressure of the reservoir in formation 10. A second method is to reduce the rate of discharge of the liquefied hydrocarbons 30, through the extraction pipe 40 (ie reducing the extraction speed through the extraction pipe 40), so as to increase the pressure of the well in the horizontal foot 16. Both methods lead to the reduction of hydrocarbon extraction speeds, which is economically damaging. An alternative and preferred method is the one described above, namely the injection of a non-oxidizing medium 52 into the horizontal foot 16, through the injection pipe 50, which is believed to have a small effect on the gravity drainage of liquid hydrocarbons in the horizontal well 16 In any case, this injection of the medium 52 may be carried out periodically or only for a period sufficient to reduce the oxygen concentrations within the horizontal leg 16 to less explosive concentrations. In normal operation, a thermoelectric torque may be located along the horizontal section, or indoors, and the occurrence of high temperatures will signal the penetration of oxidizing gas, so that water or steam can be added through pipe 52, as to reduce the temperatures of the well, to dilute the oxygen present and to increase the pressure in the well, to block another inlet of the oxidizing gas.

Figure 3 schematically illustrates another, more preferred embodiment of the process of the present invention, which has components similar to those identified in Figures 2A-2C and which has a similar methodology. Again, an oxidizing gas is injected into the formation 10 through the injection well 22, and a combustion front 26 is created, which "sweeps" from the heel 20 to the tip 18 of the horizontal foot 16, causing liquefied hydrocarbons 30 and gasified hydrocarbons. to circulate in the horizontal foot 16 and to be distributed on the surface,

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However, the important and unique difference of the in situ recovery procedure, shown in Figure 3 from the previously analyzed process, as shown in Figures 2A2C, is that the injection well 22 of the process described in Figure 3 is formed in the form of a Inlet side well inside the vertical section 16 of the extraction well 12.

Advantageously, by using the process described in Figure 3, the injection well 22 is less expensive to drill, because an upper part of this injection well has already been drilled, since this is common with the vertical section 16 of the extraction well 12. .

As a result, not only can savings be made with the costs of placing the injection well 22 in place and in the immediate vicinity of the extraction well 12 and its associated equipment, without the need to create any separate drilling rig 32, but In addition, they reduce the costs of drilling the well, when drilling the injection well 22.

Figure 4 describes a third and most preferred embodiment of the process of the present invention, for achieving in situ hydrocarbon recovery. This process, like the first embodiment of the process of the present invention, depicted in Figures 2A-2C, and the same as the second embodiment of the invention, depicted in Figure 3, includes, as an integral component of the process. , the creation of a combustion front 26 which "sweeps from" the heel "20 to the" tip "18 of the horizontal foot 16, thereby causing the liquid hydrocarbons 30 to be collected in the horizontal foot 16 and then being pulled downwards. , through extraction pipe 40, and surface extracts.

Important, however, is that in this third embodiment of the process of the present invention, shown in Figure 4, there is no step of drilling an injection well 22. Instead, the perforations 110 are made in the vertical section 16 of the well. of extraction 12, and an oxidizing gas 24 is injected into this vertical section 16 and thus into formation 10. The oxidizing gas 24 is prevented from being injected into the horizontal foot 16 by the presence of the isothermal seals ~ 54. which effectively separates the liquefied hydrocarbons, produced in the horizontal foot / H6 / ae gas ^ EAxidant 24, [do A B I N E T 2]

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3 - Ο Ο 7 3 5 - 2 3 -01-2009 such as oxygen, thus blocking the formation of explosive mixtures. The injection pipe 50 still serves, as in the previous embodiments, to allow sporadic or continuous injection of a non-oxidizing gas 52 in the horizontal foot 16, to prevent the oxidizing gas 24 in the burned area 80 of the formation from entering the horizontal foot 16.

Advantageously, by using the process described in Figure 4, the drilling costs of an injection well 22 are completely eliminated. consequently, with the process described in Figure 4, not only are the costs saved, and the impact on the environment is reduced, by the fact that an injection oxidation apparatus can be had at the extraction well and only on a single drilling platform 32 at the extraction well, which, incidentally, is the case from the prior art processes, which required the creation of a separate drilling rig and additional grinding for the injection equipment (not shown) and for the creation of oxidizing gas, but in addition, savings are also made with expenses, eliminating the need to bypass any injection wells.

Figure 5 describes how the process of Figure 4 (that is, the third embodiment of the process of the present invention) can be implemented with a series of extraction wells 12 in a hydrocarbon formation 10, using a combustion front. 26, which advances from "heel" 20 to "peak" 18.

Although this disclosure describes and illustrates preferred embodiments of the process of the present invention, it is understood that the invention is not limited to these particular embodiments. For the specialized people, numerous changes and modifications can occur. For a complete definition of the invention, references will be made to the appended claims.

Claims (17)

claims 1. Process for recovering liquefied or gasified hydrocarbons from an underground hydrocarbon deposit, comprising the steps of: (a) providing at least one extraction well having an effective horizontal leg, positioned relatively low in said deposit, said horizontal leg having at least one heel at its extremity and at its opposite end; a peak portion, said horizontal foot being adapted to allow the inflow of hydrocarbons within said horizontal foot, said extraction well having an effective vertical section, connected to said horizontal foot near said heel portion; (b) providing an extraction pipe in said extraction well, extending within said vertical section and within at least a portion of said horizontal foot, for collecting said liquefied hydrocarbons, circulating in said horizontal foot; (c) injection of a medium into the extraction well, wherein said medium is selected from the medium group comprising, alone or in combination, a non-oxidizing gas, steam, water or carbon dioxide; (d) supplying an oxidizing gas to said underground deposit, at least initially, at a site of, or near, said vertical section of said extraction well; (e) ignition of the hydrocarbons within said hydrocarbon deposit near said vertical section of said extraction well to cause combustion of said hydrocarbon portion of said hydrocarbon deposit near said vertical section by said vertical section; is a combustion front that advances, outward and away from the injection well-mentioned in at least one direction, along the horizontal leg me / wriaTși> pm mentioned AabTnTt f kJM OP ROI u £ I \ r7Kt 7 ^ ίλ- 2 0 1 0 - 0 0 7 3 5 -2 3 -01- 2009 its top portion; (f) causing the heated liquefied hydrocarbons from the said deposit to flow from its upper regions and to collect it in the said horizontal foot; and (g) removing from said extraction well, through said extraction pipe, said hydrocarbons, which have circulated in said horizontal leg. 2. The process according to claim 1, wherein said step of supplying said oxidizing gas is accomplished by supplying said oxidizing gas in said hydrocarbon formation, through the perforations in an injection well. The method of claim 2, wherein said vertical section of said extraction well and said injection well are one and the same. The method according to claim 1, wherein the injection well represents a re-entry through a lateral channel in the vertical section of the extraction well, and extends into an upper region of the deposit. 5. A process according to claim, wherein the oxidizing gas supply is made by drilling an injection well near said vertical section of said extraction well and said injection well is vertical, inclined or horizontal. The process according to claim 1, wherein said vertical section of said extraction well is perforated at its top and said step of supplying an oxidizing gas is accomplished, at least in part, by supplying said oxidizing gas through said vertical section of said extraction well. said extraction well. 7. The process according to claim 1, further comprising &quot; CABINET? M. OPROIU £ 01 CD 0 7 3 5-2 3 -01- 2009 providing an injection pipe in said extraction well, said injection pipe extending downwards, in said vertical section, near the said heel portion of said horizontal leg , and said step of injecting said medium into said extraction well being accomplished by injecting said medium through said injection pipe. The method according to claim 7, wherein an open end of the extraction pipe is located in the vicinity of the top portion of the horizontal leg. The process of claim 1, wherein this medium further comprises a condensate hydrocarbon diluent. The process according to claim 1, 7 or 8, wherein said medium is injected continuously or periodically into said extraction well, to maintain a positive pressure inside the horizontal foot and thus to participate in preventing the oxidizing gas from entering the deposit in the horizontal leg of the extraction shaft. The process according to any of claims 1-8, wherein the catalyst is located in or around the horizontal foot of the extraction well. Process according to any one of claims 1-8, wherein the oxidizing gas is a mixture of oxygen and carbon dioxide. 13. Process for recovering liquefied or gasified hydrocarbons from an underground hydrocarbon deposit, comprising the steps of: (a) providing at least one extraction well having an effective horizontal foot, positioned relatively low in said deposit, said horizontal leg having, at one end, a heel portion and, at its opposite end, a portion peak, horizontal foot m ^ wn ^ Oirid adapted to allow inflow of liquefied hydrocarbons horizontally OPROIU sl v ^ · •> -2010-00735-2 3 -01- 2009 mentioned, said extraction well having an effective vertical section, connected to said horizontal leg near said mentioned heel portion; (b) providing an extraction pipe in said extraction well, which extends from the surface of said extraction well to at least said heel portion of said extraction well, for collecting said hydrocarbons, circulating in said horizontal ; (c) providing an injection pipe in said extraction well, said injection pipe extending downwardly in said vertical section to a position extending in at least said heel portion of said horizontal leg; (d) injection of a medium into the horizontal foot, wherein said medium is selected from the group of media comprising, alone or in combination, a non-oxidizing gas, steam, water or carbon dioxide; (e) providing perforations in said vertical section, of said extraction shaft, at a position above said heel portion; (f) supplying an oxidizing gas to said vertical section and thus to a portion of said hydrocarbon deposit, through said perforations, of said vertical section; (g) ignition of said hydrocarbons in said hydrocarbon deposit near said vertical section in order to cause combustion of a portion of said hydrocarbon in said hydrocarbon deposit and thereby creating an advancing combustion front; outward and away from said vertical section, in at least one direction, along said horizontal leg £ L-spx £ said top portion thereof; and in AL.oproiu î '3 * X _t V2 0 1 0-00735- 2 3 -01- 2009 (h) challenge of heated liquefied hydrocarbons from the mentioned deposit to drain from its upper regions and collect in said horizontal leg; and (i) removing from said extraction well, through said extraction pipe, said hydrocarbons, which have flowed in said horizontal leg. 14. The method of claim 12, wherein an open end of the extraction pipe is located in the vicinity of the top portion of the horizontal leg. The process according to claim 13 or 14, wherein the steam or water is injected continuously or periodically into said injection pipe, in order to maintain a positive pressure inside the horizontal foot and thus to participate in preventing said oxidizing gas from entering the reservoir. in the horizontal foot of the extraction shaft. 16. Process for recovering liquefied or gasified hydrocarbons from an underground hydrocarbon formation, comprising the steps of: (a) providing at least one extraction well having an effective horizontal foot, positioned relatively low in said formation, said horizontal leg having, at one end of it, a heel portion and, at its opposite end, a portion peak, located in the formation slightly lower, in level, than said portion of heels, said horizontal foot being adapted to allow the inflow of liquefied hydrocarbons within said horizontal foot, said extraction well having an effectively vertical section, connected to the horizontal foot mentioned close to said portion below the heel thereof; (b) providing an extraction pipe in said extraction well, which extends downwards, within said vertical section and along said horizontal leg, up to said portjujișr-cte ^ peak, for collecting said hydrocarbons, which mentioned & yn picîbMx horizontal mentioned; & ^{1 NE} T ° | cX-2 0 1 0 - 0 0 7 3 5 -2 3 -01/2009 (c) providing an injection pipe in said extraction well, said injection pipe extending downwards, in said vertical section, up to at the aforementioned portion of heels; (d) injecting a medium into said extraction well through said injection pipe, wherein said medium is selected from the media group comprising, alone or in combination, a non-oxidizing gas, steam, water or carbon dioxide; (e) providing an injection well as a side channel re-entry from said vertical section of said extraction well, injection well extending into the hydrocarbon formation; (f) supplying an oxidizing gas to a portion of said hydrocarbon formation through said injection well; (g) ignition of said hydrocarbons in said hydrocarbon formation near said vertical section in order to cause the combustion of a portion of said hydrocarbons in said hydrocarbon formation, thereby creating a combustion front which extends outward and away of said vertical section, in at least one direction, along said horizontal leg and to said peak portion thereof; and (h) removing from said extraction well, through said extraction pipe, the hydrocarbons which have circulated in said horizontal leg. The process according to claim 16, wherein the steam or water is injected continuously or periodically into the extraction well, in order to maintain an effective positive pressure inside its horizontal foot and thus to participate in preventing the oxidizing gas from entering the formation. in the horizontal foot of the extraction shaft.