MXPA98002095A - Single well vapor extraction process - Google Patents

Abstract

A method of producing hydrocarbons from a subterranean formation comprising the steps of:forming a well having a horizontal section located between the midpoint and the bottom of the formation and having a raised end;and continuously injecting a fluid through said raised end to induce hydrocarbons to flow towards the horizontal section in response to gravity drainage while continuously producing hydrocarbons through the horizontal section of the well-bore, so that the injection of fluids occurs simultaneously with the production of hydrocarbons.

Description

PROCESS OF EXTRACTION OF VAPOR OF A WELL Technical Field This invention relates to the general subject of methods and devices for recovering hydrocarbons from underground formations, and, in particular, to processes and apparatus for recovering heavy oils by means of injection fluids within the formation.

Background of the Invention It is well known that liquid hydrocarbons, commonly known as crude oils, found in underground formations vary considerably according to specific viscosity and density. Crude oils with an API density of twenty-two degrees or less are generally considered to be heavy crude oils. As heavy crude oils are more difficult to treat, transport and refine than light crude oils, the market value of heavy crude oils has historically been lower than the value of light crude oils.

It is also known that the composition, thickness and conditions of the underground formations in which the crude oils are found vary widely. The REF: 26984 Formations that contain hydrocarbons can vary in physical composition of consolidated rocks to unconsolidated sands, which could affect permeability and porosity. These formations could also vary in thickness from several hundred feet to less than six feet. Stratification and natural mixing of a variety of natural impermeable materials within an underground formation can also be presented. The presence of diagenetic clay, or partially impermeable barriers (such as sediment or sediment rock laminations), calcite crystals within an underground formation could affect the ability of the fluids to flow into the formation.

In the underground formations of optimum compositions and characteristics, due to the higher viscosity of heavy crude oils, the application of primary, secondary and tertiary production techniques and technologies could not allow the economic recovery of heavy crude oils. Where the heavy crude oil contained within an underground formation will initially flow at economical speeds into and into the bore hole of a well under natural reserve conditions, only a small fraction of the oil contained within the formation can be produced by conventional The speeds and recovery volumes achieved from an underground formation containing heavy crude oil, comparable to a similar formation containing light crude oil, can in general be carried out at a higher only at a higher production cost.

To improve the production economy of crude heavy oils, it has been well understood that the introduction of heat, solvents or artificial pressure into an underground reservoir containing heavy crude oil can significantly increase the amount of heavy crude oil recovered and the Recovery speed of such training. See Redford, D.A. and Luhning, R.W. "In Situ Recovery from the Athabasca Oil Sands - Past Experience and Potential Future, Part II," Paper 95-24 published and presented at the 46th Annual Meeting of the Petroleum Society of CIM, May 14 - 17, 1995.

The current state of the art reflects an evolution of technology through the general innovative improvement in addition to the innovation to establish the specific conditions found in the heavy crude oils that contain the underground formations. There are many methods proposed in the art to produce heavy crude oils. The use of horizontal wells for the injection and production of fluids is preferred in most art and is indicated by means of the present invention. See: Nasr, T.N., "Analysis of Thermal Horizontal Well Recovery and Horizontal Well Bibliography," November 1990, Report # 9091-12, Oil Sands and Hydrocarbon Recovery Department, Alberta Research Council; and G.S. Sawhney, "Steam-Assisted Gravity Drainage with Vertical Steam Injection Wells," Thesis for University of Calgary, National Library of Canada, TN 871 S29, 1993.

Many methods show the recovery of heavy crude oils through the use of multiple well horizontal drilling arrangements, excavated from the surface, into the underground formation containing the heavy crude oil ("the reserve"). For example, see: U.S. 3,572,436 for Riehl, U.S. 4,067,391 for Dewell, U.S. 4,257,650 for Alien, U.S. 4,296,969 for Willman, U.S. 4,344,485 for Butler, U.S. 4,385,662 for Mullins et al., U.S. 4,410,216 for Alien, U.S. 4,510,997 for Fitch et al., U.S. 4,577,691 to Huang et al., U.S. 4,598,770 for Shu et al., U.S. 4,633,948 for Closmann et al., U.S. 4,850,429 for Mims et al., U.S. 5,033,546 for Combe, U.S. 5,244,041 for Renard et al., U.S. 5,273,111 for Brannan et al., U.S. 5,318,124 to Ong et al., U.S. 5,407,009 for Butler et al., Canadian 1,304,287 for Edmunds et al.

The injection of ethane, propane or butane in the form of vapor is known by the art: R.M. Butler & I.J. Mokrys, "Solvent Analog Model of Steam-Assisted Gravity Drainage," AOSTRA Journal of Research, vol. 5, No. 1, Winter 1989, pp. 17-32; R.M. Butler & I.J. Mokrys, "A New Process (VAPEX) for Recovering Heavy Oils Using Hot Water and Hydrocarbon Vapor, "The Journal of Canadian Petroleum Technology, January-February 1991, vol 30, No. 1, pp. 97-106; I.J. Mokrys & R.M. Butler, "The Rise of Interfering Solvent Chambers: Solvent Analog Model of Steam-Assisted Gravity Drainage," The Journal of Canadian Petroleum Technology, March 1993, vol. 32, No. 3, pp. 26-36; I.J. Mokrys & R.M. Butler, University of Calgary, "In-Situ Upgrading of Heavy Oils and Bitumen by Propane Deasphaulting: The Vapex Process," Society of Petroleum Engineers Inc., paper No. SPE 25452, March 21-23, 1993, Oklahoma City, Oklahoma, USA, pp. 409-424; S. K. Das. & R. M. Butler, "Further Studies of the 'Vapex' Process Using a Hele-Shaw Cell," Petroleum Society of CIM, paper No. CIM 93-50, May 9-13, 1993, Calgary, Alberta, Canada, 15 pages; R.M. Butler & I.J. Mokrys. "Recovery of Heavy Oils Using Vaporized Hydrocarbon Solvents: Further Development of the Vapex Process, "The Journal of Canadian Petroleum Technology, June, 1993, vol.32, No. 6, pp. 56-63; J. H. Duerksen & A. Eloyan, "Evaluation of Solvent-Based In Situ Processes for Upgrading and Recovery of Heavy Oil and Bitumen," Proceedings from the UNITAR International Conference on Heavy Crude and Tar Sands, WITH F-9502114, February 12-17, 1995, Houston , Texas, USA, pp. 353-361; R.M. Butler & I.J. Mokrys, University of Calgary, "The Solvent Requirements for Vapex Recovery, "The Society of Petroleum Engineers, paper No. SPE 30293, June 19-21, 1995, Calgary, Alberta, Canada, pp. 465-474; US 5,407,009 to Butler, et al.

The prior art indicates the use of multiple well drilling arrangements to facilitate the application of various thermal or solvent processes under specific reserve conditions. An invention that would allow the application of the same process without the requirement of a multiple well drilling arrangement would be a significant improvement over the prior art cited above.

For this purpose, several methods prescribed in the art for recovering crude heavy oils from an underground reserve indicate the use of a horizontal wellbore. For example see: U.S. 4,116,275 for Butler et al., U.S. 4,508,172 for Mims et al., U.S. 4,565,245 for Mims et al., U.S. 4,640,359 to Livesey et al., U.S. 5,148,869 for Sánchez, and U.S. 5,289,881 for Schuh U.S. 5,511,616 for Bert Thus, the use of a horizontal wellbore as an injector and simultaneous producer of reserve fluids is known to those skilled in the art.

A major drawback of many of the well processes shown in the art (See US 5,289,881), is the difficulty of maintaining a fluid level around the horizontal section of the perforated well, while preventing percolation of the fluid through the fluid that is produced from the reserve.

In processes involving the use of heated injection fluids, percolation of the injection fluid through the fluid produced from the reservoir often results in the overheating of the fluid produced from the reservoir and a reduction in thermal efficiency and quality of the injection fluid. The overheating of the fluid that is produced from the reserve could lead to wear and premature failure of the pumping equipment used to drive fluids from the reservoir through the horizontal well.

In processes that involve the use of non-thermal injection fluids, the percolation of the injection fluid through the fluids that are produced from the reservoir often results in a loss of fluid quality through the humidification or condensation of the fluid. injection fluid, where the fluid is a condensable gas.

In the processes involving the use of a single horizontal well for fluids produced and injected simultaneously, the failure to maintain a sufficient fluid level around the horizontal section of the well drilled, can result in the interruption of the injection fluid through the fluids that are produced from the well and that are preferentially produced for hydrocarbons within the reserve. In addition to making the process inefficient, the primary injection fluid or the advance can also cause damage and premature wear or failure to the pumping and production equipment. For example, the use of an injection pump (see U.S. 5,289,881 for Schuh) would suffer from such problems. The method shown by Schuh is difficult to apply because the tendency for the steam has a preference to occur and cause an enclosed vapor to be present in the pump. The overheating of the fluid that is produced from the reserve through the combination of the percolation of the injection fluid and the production fluid can also cause instantaneous vaporization of some liquids contained in the production fluid, when such fluids pass through the Venturi. or of the injection pump.

Multiple well drilling arrangements (See U.S. 4,344,485 and Canadian Patent 1,304,287) aim to overcome these problems by using separate wells for the injection and production of fluids. Of course, two wells are more expensive than one.

To avoid the cost and operational complexity of using multiple well drilling arrangements, some methods (See US 5,148,869) are intended to address and resolve the problems associated with maintaining a fluid level in processes involving the use of a well. horizontally injecting and continuously producing fluids from the reserve. However, these methods have their own shortcomings. For example, the method of U.S. Pat. 5,148,869 requires the use and guidance of specialized production equipment.

Another method (see US 5,511,616) shows the formation of an inverted section at the end of the horizontal well, with such an inverted section having an angle shape about ninety degrees, and termination near the top of the reservoir containing the oil heavy crude. U.S. 5,511,616 indicates the injection of heated fluids through the inverted end of the horizontal well, to prevent the formation of a steam vessel or chamber that brings the horizontal section of the well into contact. However, as this portion of the well ends near the top of the reservoir, this would result in premature vapor contacting the upper part of the reservoir containing the heavy crude oil, without creating an acceptable level of mobility with respect to to the heavy crude oil located between the base of the steam chamber and the horizontal section of the well.

In addition, U.S. 5,511,616 does not indicate the use of unheated injection fluids (such as propane, butane, ethane or other solvents). However, even if such fluids were used, injecting such fluids into the terminal end of the inverted section of the well would not facilitate the efficient mobilization of heavy crude oil located near the horizontal section of that well. As the oils used to mobilize heavy crude oil have a higher specific gravity than the oil they intend to mobilize, the solvents injected in the upper part of the reserve will preferentially form a chamber that extends horizontally along the upper part of the reserve, passing the oil that falls under such chamber.

Thus, although much progress has been made in the use of a horizontal well to produce heavy crude oil simultaneously injecting fluids that mobilize and produce mobilized oil, there are still deficiencies. These deficiencies show that additional improvement is needed.

Description of the Invention In accordance with the present invention, a method is provided for producing hydrocarbons from an underground formation. The method comprises the steps of: forming a well bore having a horizontal section that is located within the formation, between the midpoint and the base of the formation, and near the base of the formation; forming one end of the horizontal section of the well bore to be above the highest point of the rest of the horizontal section of the borehole; completion of the well bore so that the fluids can be injected into the formation through the horizontal section of the borehole at the point generally located adjacent to the high end of the horizontal section of the borehole and for the fluids can be produced from the formation through the horizontal section of the well bore along at least one position that is located below the high end of the horizontal section of the borehole; mobilization of a portion of the hydrocarbons within the formation and inducing such hydrocarbons to move toward the horizontal section of the well bore in response to gravity drainage by injecting a fluid through the horizontal section and into the formation using the high end of the horizontal section of the well drilled; and production of associated hydrocarbons and fluids from the formation through at least one position of the horizontal section of the perforated well, such that the production of hydrocarbons occurs simultaneously with the injection of said fluid into the function.

The preferred embodiment of the present invention indicates the use of an unheated hydrocarbon solvent as the injection fluid, which could or could not be a hydrocarbon but which has to be able to reduce the viscosity of the hydrocarbons residing in a reservoir through the action of the solvent in such hydrocarbons in the reserve. While various fluids or combinations of fluid, in the form of vapor or liquid, could qualify and be used for this purpose in the practice of this invention, the preferred fluids are ethane, propane, or butane injected in vapor form. In a preferred embodiment of the present invention, these fluids are injected as a saturated vapor. The practice of the present invention in this way maximizes the benefits of the invention: (i) less losses are used that relate to thermal losses, as are heated injection fluids, such as steam; (ii) there is some improvement of the crude oil within the reserve, separating and leaving in the reserve a significant fraction of the asphaltenes and heavier hydrocarbons contained within the crude oil; and (iii) it is under the cost of recycling the preferred injection fluids, when compared to the cost of recycling other possible injection fluids known in the art.

The present invention could be practiced using: (i) a heated injection fluid, in vapor or liquid form, such as steam or hot water, (ii) unheated solvents apart from the preferred solvents, (iii) a combination of fluids, such as propane or steam, or (iv) the injection of different fluids or different combinations in an alternative form. However, when using heated injection fluids, the use of an uninsulated injection tube in a horizontal section of the well (as indicated by US 5,289,881, for example) is not recommended due to heat loss and thermal quality of the injection fluid as it passes through such a tube. The present invention also indicates the retention and maintenance of the quality of the injection fluid through the injection point within the formation.

The choice of fluids or combination of fluids used will depend on the nature, thickness, depth and composition of the reservoir containing the hydrocarbons, and on the composition and nature of such hydrocarbons. However, the objective that governs any selection and use of injection fluids in the practice of this invention, is to reduce the viscosity of the hydrocarbons found within the reserve and to maximize the flow thereof, under drainage by gravity, for horizontal well drilling which, as indicated by the present invention, is used to inject and produce fluids from the reservoir. For environmental and economic reasons the present invention indicates the recovery and recycling of the injection fluid, where possible, through means known in the art.

Thus, those skilled in the art will note that the present invention has many advantages over the prior art. Three important advantages are: reduced environmental impact, low capital cost, and low operating cost. In particular, the use of a horizontal well having a raised end for injecting fluids provides a number of benefits over the prior art. Where unheated hydrocarbon solvents are used as injection fluids, the solvent value of such injection fluids is maximized, preventing the percolation of such injection fluids through fluids being produced from the reservoir. In the same way, where heated injection fluids are used in the practice of the invention, the heat loss of such injection fluids to the fluids being produced from the reservoir (and the potential for overheating of the fluid that is being produced) is minimized. occurs from the reservation). In some cases, the injection of the fluids through the high end of the horizontal well reduces the potential for the eliminated injection fluid and premature wear from the pumping equipment in the orifice.

Numerous other advantages and features of the present invention will become readily apparent from the following detailed description of the invention, the embodiments described herein, the claims, and the accompanying drawings.

Brief Description of the Drawing FIG. 1 shows, from the side view, the approximate geometry of a horizontal well formed in accordance with the present invention.

Detailed Description of the Invention While this invention is susceptible to the embodiment in many different forms, it is shown in the drawings, and will be described herein in detail, a specific embodiment of the invention. It should be understood, however, that the present disclosure is to be considered an exemplification of the principles of the invention and is not intended to limit the invention in any specific manner so described.

Referring to FIG. 1 a horizontal well 4 formed in an underground reservoir 1 is illustrated. Reserve 1 is bounded by the relatively impermeable upper and lower borders 2 and 3 and is composed of a waterproof coating containing heavy crude oil. Reserve 1 shown is exemplary for this process. Not all reservations will have this exact structure. Those skilled in the art know that reserves containing heavy crude oil can vary significantly in depth, location, nature, composition and structure.

The well 4 is formed from the surface using means known in the art. The vertical depth and horizontal le of the well is dependent on the depth, location, composition and nature of reservoir 1 containing heavy crude oil. However, a horizontal le of 300 feet is preferred. The vertical depth of the well 4 should be sufficient to allow the location of the horizontal portion of the well borehole as described below. Well 4 is formed so that horizontal section 4a of well 4 is located above, but as close to base 5 of the reserve as possible. This well is formed so that the protruding or far end 6 of the horizontal section 4a of the well is formed and ultimately falls above the highest point of the rest of the horizontal section of the well bore. The vertical and horizontal reach of the high end and the upward trajectory of the horizontal section 4a of the well borehole is determined by observation of the field and simulation of the reserve, based on the nature, structure and composition of the reserve and the heavy oil of the reserve. Raw content here. The orientation of the horizontal section 4a of the well will be determined by factors such as the direction of the fracture trend and the reserve moisture. Horizontal multiple wells could be drilled within the reserve in the manner described above, however, each well will operate as a separate injection / production unit. The communication of the fluid and the pressure between the wells could be of benefit in the improvement of the process. However, locating the wells too closely together could inhibit the operation of the process indicated by this invention. The location of new wells too close to the existing wells, which have been subjected to the process shown by this invention for some time, could make the application of such processes ineffective through such a new well. The spacing between the horizontal wells (formed as indicated by this invention) should consider the nature of the reservoir, the type of heavy crude oil contained in it, and the production history of that reservoir.

Referring again to FIG. 1, once the section 4a of the well bore has been formed within the reserve 1, the well has to be "completed" using means known in the art. While the horizontal section of the wellbore 4 is being completed 7, the injection pipe 8 is installed from the surface. The injection tube substantially crosses the total length of the well. The production pipe 9 is installed from and connects to the surface. The production pipe 9 runs to the low point (if possible to the lowest point) in the horizontal section 4a of the well bore. The completion of such a well could require the installation of artificial lifting equipment known in the art, such as a down-hole pump 10. Although the inventors recommend the completion of the horizontal section 4a of the well bore using a slotted liner , a wire mesh or perforated lining 7, where the nature and composition of the reserve will allow the completion of the well without a coating within the horizontal section of the well bore, this feature could be eliminated. On the surface, the equipment for the injection of the fluid and the production of heavy crude oil and associated liquids is installed and connected to the well 4. The nature and installation of such equipment is determined and carried out through known means in art. If a steam hydrocarbon solvent or water is used as the injection fluid, such equipment will preferably include devices for the recovery and recycling of such an injection fluid. However, where steam or water is used as the injection fluid, the use of such devices could be eliminated and devices for the disposal of produced water could be used instead.

Until the formation and completion of the perforation of the well 4, a process begins with the injection of the selected injection fluid, using the injection tube 8 through means known in the art. In a preferred embodiment of the present invention, ethane, propane or butane are used in the form of vapor as the injection fluid. To mobilize a portion of the heavy crude oil within reservoir 1 and cause such associated hydrocarbons and fluids to flow into the horizontal section 4a of the well bore in response to gravity drainage, these fluids are injected into the vapor phase at or just below the saturation point, within the reservoir at the end 6 of the well bore, through the injection tube 8, using the means known in the art. For example, U.S. 5,407,009 for Butler et al. indicates that the injection pressure should be selected and maintained in such a way that the injection fluid remains in the vapor phase as close to the saturation point as possible. This will increase the percentage of oil mobilized and the asphaltenes precipitated from the oil. The speed of injection of the solvent should be controlled to avoid the formation of a very high concentration of solvent within the reserve that could cause the localized packing of the reserve by excessive precipitation of asphaltenes. Also, the fluid injection pressure should be kept below the reserve separation pressure. It is not possible to predict a precise range of desirable concentration of solvent, since the injection speed and the desired concentration will depend on the nature and composition of the reserve and the fluids contained therein. Nuclei and samples of the fluid within the pool could be taken and analyzed before starting the injection of the solvent to determine the preferred rate of injection and level of reception or concentration range of the solvent. The pressure and temperature within the reserve could also be taken into account in this evaluation. It is known that once the injection of the solvent begins, the fluid produced from the reserve should be analyzed from time to time and the speed of injection of the solvent adjusted to ensure therefore the range of reception of the concentration of the solvent (as determined by the analysis performed before the start of the solvent injection). The pressure and temperature changes of the reserve should also be monitored and taken into account in the adjustment of injection speeds, once the solvent injection begins.

The elevation of the crude oil and associated fluids of the reserve could be accomplished by any means known in the art. The selection of a lifting method will depend on the selection of the injection fluid, the nature of the fluids to be produced from the reservoir, the nature of the reservoir itself and other factors known to those skilled in the art. Of course, the pump intake should be below the range of fluid level elevation around the horizontal section of the well borehole.

Referring to Fig. 1, as the solvent or injection fluid 11 is injected into reservoir 1, it increases, diluting and reducing the amount of asphaltenes and heavy parts contained in the heavy crude oil native to reservoir 1, eventually forming a chamber 12. The mixture of 13 high-grade diluted oil and condensed solvent fluid flows down through the formation in response to gravity, where it accumulates around the horizontal portion of the wellborehole 4. There it is collected , through the production tube 9, and it is stirred towards the surface. The chamber 12 formed as a result of the injection of the solvent 11 into the reservoir 1 gradually expands horizontally as well as vertically along the length of the horizontal section 4a of the perforation of the well 4 as a result of the production of the fluids 13 of the reserve. Since the preferred embodiment of the present invention indicates the use of an unheated solvent to produce heavy crude oil from a reservoir, those skilled in the art will recognize the value of creating and using a raised section at the end of the horizontal section of horizontal well drilling to inject hot and unheated fluids to produce light crude oil and heavy crude oil from a reserve. Thus, by means of injecting a fluid at or near the raised end or end 6 of the well borehole, a fluid level 14 is developed. This fluid is composed of a mixture of diluted and high grade oil and fluid of condensed injection 13. A greater part of the horizontal section 4a of the well borehole is formed and maintained up and around. This fluid level is below the raised end 6 of the horizontal section 4a. The creation and maintenance of this fluid level 14 tends to avoid the injection fluid vapor by counteracting the process and breaking the mixture 13 of the produced fluids. Such breaking can result in the production of such non-condensed steam, causing premature wear or failure of the artificial lifting equipment 10, as well as reduction in the efficiency of the process. Those skilled in the art will recognize that this embodiment appears to be of equal value and utility, wherein this invention is practiced using a variety of injection fluids or injection fluid mixtures, including without vapor limitation.

Although a variety of fluids or mixture of fluids could be used in the practice of this invention, in all cases such fluids should be injected through the horizontal section 4a of the well bore at a point located at or near the 6th end of the well. well drilling. Where the recoverable fluids are used as the injection fluid, such fluids could be separated and recovered on the surface of the fluid mixture 13 produced in a well, by means known in the art. Regardless of the fluid used as the injection fluid, simultaneous injection of the injection fluid 11 and production of the mixture 13 of high-grade diluted oil and reservoir injection fluid is preferred.

The present invention will operate with greater efficiency in reserves characterized by high permeability (1 darcy or more), as is typically found in reserves that have heavy oils composed of unconsolidated material. However, where the conditions of the reserve are less than ideal, (eg, fracture, acidification of the reserve, etc.) means known in the art can be used to improve the permeability of the reserve and facilitate efficient development. of the process of the invention.

Where the initial conditions within the reservoir 1 initially do not provide sufficient "injectability" to allow the start of simultaneous production and injection of fluids, other processes known in the art (such as cyclic injection and fluid production, primary production, or fracture of the reserve) could be applied using such a well until such injectability is created. Until sufficient injectability is created / increased, the process of simultaneous injection and production of fluids from the reservoir, as indicated in this invention, could be started.

In the practice of this invention, the fluids produced from the well formed and used as indicated by this invention are, until reaching the surface, handled, processed, treated, stored, recycled or disposed, as the case may be, using methods known in art. Where the injection fluid produced with the fluids withdrawn from the reserve is recycled, it will be reinjected in the manner described above.

When the reserve has been producing to the point of maximum economic recovery of the heavy crude oil found in the reserve through the horizontal drilling of the well 4a indicated by this invention, a portion of the injection fluid injected into the reserve through such perforation of the well and maintained within the reservoir could be recovered to a large extent by means of ceasing further injection, and producing such fluid through the horizontal well used to inject such fluid by means known in the art. The amount of residual injection fluid recovered will depend on the method used and the nature of the reserve. Those skilled in the art will realize that the injection fluid remaining in the reserve will recover when the recovered fluid has sufficient economic value to justify the cost of production and recover such fluid.

Although multiple horizontal wells could be formed and operated as indicated in the present invention, within and in respect of the same stock, each well will operate as a separate injection / production unit. However, those skilled in the art will recognize that, in certain reservations, it may be possible to form and operate multiple horizontal wells (in the manner indicated by the present invention), such that the simultaneous injection and production of fluids by any well can have a positive benefit in adjacent wells. Similarly, a well formed in accordance with the present invention could benefit from the injection and production of fluids from adjacent wells. The operation of individual production injection units in this way is demonstrated by U.S. 5,318,124 for Ong et al.

With respect to any single well formed as indicated in the present invention, the recovery of injection fluids from within the reserve will usually be made as soon as possible after the point of maximum economic recovery of heavy crude oil has been reached. the reserve for such a well. However, such recovery could be delayed where the removal of the injected fluid remaining in the reserve could negatively affect the production of reserve fluids through any offset well.

From the above description, it will be noted that numerous variations, alternatives and modifications will be apparent to those skilled in the art. Therefore, this description is to be construed as illustrative only and is for the purpose of indicating to those skilled in the art the manner of carrying out the invention. Several changes could be made in the form, materials, size and arrangement of the parts. In addition, techniques and equivalent steps (taken individually or together) could be substituted for the illustrated and described.

Also certain features of the invention could be used independently of other features of the invention. For example, the present invention is not limited to the use of propane, butane or ethane as injection fluids. The reference to the use of propane, butane, ethane and methane, in the above description, since they are preferred for a variety of reasons known to those skilled in the art, is exemplary only. Those skilled in the art will understand from the foregoing description that this invention could be practiced using a variety of injection fluids or injection fluid mixtures. Such injection fluids include, without limitation, steam, water, hydrocarbon solvents (either in a liquid or gaseous state), or any combination or combinations thereof. Applying the process of the invention, the nature, type and composition of the injection fluid should be considered in relation to the arrangement in which it is used. By "nature" is indicated the manner in which the substance acts to reduce the viscosity of the oil (eg, hydrocarbon solvents vs. steam / water). By "type" the characteristics of the substance are indicated (eg, water and steam and inert are relatively benign compared to a hydrocarbon solvent). By "composition" is indicated the chemical or molecular composition of the injected substance or mixture thereof. Thus, the present invention should not be limited by the specified details or by the specific embodiments chosen to illustrate the invention or the drawings appended thereto. Accordingly, it will be appreciated that such modifications, alternatives, variations, and changes could be made without departing from the spirit and scope of the invention as defined in the appended claims. It is intended, of course, to cover all the modifications involved within the scope of the claims by means of the appended claims.

It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects to which it relates. Having described the invention as above, the content of the following is claimed as property.

Claims (50)

1. A method of producing associated hydrocarbons and fluids from an underground formation containing such hydrocarbons and fluids, characterized in that it comprises the steps of: a) forming a well bore having a horizontal section that is located within the formation, between the midpoint and the bottom of the formation, and near the bottom of the formation; b) forming one end of said horizontal section of the well bore to be above the highest point of the remainder of said horizontal section of the borehole; c) completing the well bore such that the fluids can be injected into the formation through said horizontal section of the well bore, and such that the fluids can be produced from the formation by means of said horizontal section of said well bore. together with at least one position that is located below said raised end of said horizontal section of said well bore; d) mobilization of a portion of the hydrocarbons from the formation and induction of such hydrocarbons to move toward said horizontal section of said well bore in response to gravity drainage by injecting a fluid through said horizontal section and into the formation using said elevated end of said horizontal section of the well borehole; and e) production of associated hydrocarbons and fluids from the formation by at least one position of said horizontal section of the well bore, such that the production of said hydrocarbons occurs simultaneously with the injection of said fluid into the formation.

2. The method as set forth in claim 1, characterized in that in the step of embodiment (b) said end of said horizontal section of said borehole of the well is formed and rests the latter at least a few meters above said highest point of said rest of said horizontal section of the well drilling.

3. The method as set forth in claim 1, characterized in that in the embodiment (d) said injected fluid is a solvent.

4. The method as set forth in claim 1, characterized in that in step of embodiment (d) said injected fluid is a hydrocarbon solvent; and wherein said solvent is injected into its vapor phase at or just below its saturation point.

5. The method as set forth in claim 1, characterized in that in the step of embodiment (d) said injected fluid is selected from the group consisting of propane, butane, methane and ethane; and wherein said injected fluid is injected into its vapor phase at or just below its saturation point.

6. The method as set forth in claim 1, characterized in that in step of embodiment (d) said injected fluid is a dry vapor.

7. The method as set forth in claim 1, characterized in that in the embodiment (d) said injected fluid is a condensable gas.

8. The method as set forth in claim 1, characterized in that in the embodiment (d) said injected fluid is heated to a temperature higher than the temperature of the hydrocarbons in the formation for the purpose of heating and mobilizing the hydrocarbons.

9. The method as set forth in claim 1, characterized in that in the embodiment (d) said injected fluid is selected from the group consisting of steam and hot water.

10. The method as set forth in claim 1, characterized in that in step of embodiment (d) said injected fluid comprises a mixture of fluids.

11. The method as set forth in claim 10, characterized in that said injected fluid comprises methane and propane in vapor phase.

12. The method as set forth in claim 10, characterized in that said injected fluid comprises a mixture of vapor and a solvent.

13. The method as set forth in claim 10, characterized in that said injected fluid comprises a mixture of steam and hot water.

14. The method as set forth in claim 10, characterized in that said injected fluid comprises a mixture of hot water and a solvent.

15. The method as set forth in claim 10, characterized in that said injected fluid comprises a mixture of steam, hot water and a solvent.

16. The method as set forth in claim 1, characterized in that in the embodiment (d) in at least one of nature, type and composition of said injected fluid is changed over time, such that at least more than one fluid is used injected or mixed injected fluids.

17. The method as set forth in claim 1, characterized in that before the implementation step (d) the following step is carried out: increasing the injectability of the formation.

18. The method as set forth in claim 1, characterized in that it also includes the step of improving the permeability of the reserve.

19. The method as set forth in claim 1, characterized in that it also includes the step of recovering the injected fluid that is produced from the reserve in conjunction with the hydrocarbons and associated fluids produced in the formation.

20. The method as set forth in claim 19, characterized in that in the embodiment (d), said recovered fluid is injected into the formation by said high end of said horizontal section of said well bore.

21. The method as set forth in claim 1, characterized in that in step of embodiment (d) said injected fluid is selected from at least one of the group consisting of propane, butane, methane, ethane and mixtures thereof; and wherein at least one of the fluids of propane, butane, methane and ethane is produced in the reserve in conjunction with the hydrocarbons and associated fluids produced in the reserve; and further includes the steps of recovering and reinjecting said at least one fluid into the formation as a saturated or nearly saturated vapor using said elevated end of said horizontal section of said well bore.

22. The method as set forth in claim 1, characterized in that, after the additional recovery of hydrocarbons by the injection of fluids by means of the horizontal section of the wellbore is not economical, the production of hydrocarbons ceases without the recovery of hydrocarbons. the injected fluids.

23. The method as set forth in claim 1, characterized in that, at the point where the additional recovery of hydrocarbons from the introduction or injection of fluids by means of the horizontal section of the well drilling is not economical, the step (d) ) is discontinued, and the production of associated hydrocarbons and fluids, including any of said injected fluid remaining in the reserve, continues until it is no more economical to continue such production.

24. A method of producing hydrocarbons and associated fluids from an underground formation containing such hydrocarbons, characterized in that it comprises the steps of: (1) forming, between the midpoint and the bottom of the formation and as close to the bottom of the formation as possible, a predominantly horizontal well bore having an opening that remains substantially above the remainder of said predominantly horizontal section of said well drilling; (2) completing the drilling of the well for the production of hydrocarbons from the formation using at least one point which is located intermediate to the ends of said predominantly horizontal section of said well bore and which is below said open end; (3) injection of a fluid into the formation through said predominantly horizontal section of the well bore using said open end of the well bore to mobilize at least a portion of the hydrocarbons within the formation for movement toward said well. predominantly horizontal section of said well bore in response to drainage by gravity, and the simultaneous production of hydrocarbons and said injected fluid by means of said predominantly horizontal section of said well borehole; and (4) recovering said injected fluid produced in step (3) and reinjection of such injected fluid recovered earlier within the formation by repeatedly performing step (3).

25. The method as set forth in claim 24, characterized in that said injected fluid is a solvent that mobilizes the associated hydrocarbons and fluids within the formation.

26. The method as set forth in claim 24, characterized in that said injected fluid comprises a hydrocarbon solvent.

27. The method as set forth in claim 26, characterized in that said hydrocarbon solvent is selected from the group consisting of propane, butane, methane and ethane; and wherein said hydrocarbon solvent is injected as a vapor at or just below its saturation point.

28. The method as set forth in claim 24, characterized in that said injected fluid comprises a dry vapor.

29. The method as set forth in claim 24, characterized in that said injected fluid comprises a condensable gas.

30. The method as set forth in claim 24, characterized in that in the embodiment (3) said injected fluid is heated to a temperature higher than the temperature of the hydrocarbons in the formation for the purpose of heating and mobilizing said hydrocarbons within the training.

31. The method as set forth in claim 24, characterized in that said injected fluid is selected from the group consisting of steam and hot water.

32. The method as set forth in claim 24, characterized in that said injected fluid comprises at least two fluids.

33. The method as set forth in claim 32, characterized in that said injected fluid comprises a mixture of methane and propane.

34. The method as set forth in claim 32, characterized in that said injected fluid comprises a mixture of vapor and a solvent.

35. The method as set forth in claim 32, characterized in that said injected fluid comprises a mixture of steam and hot water.

36. The method as set forth in claim 32, characterized in that said injected fluid comprises a mixture of hot water and a solvent.

37. The method as set forth in claim 24, characterized in that said injected fluid comprises a mixture of steam, hot water and a solvent.

38. The method as set forth in claim 24, characterized in that in the embodiment (3) in at least one of state, type and composition of said injected fluid is changed over time, such that at least more than one fluid is used injected or mixed injected fluids.

39. The method as set forth in claim 24, characterized in that it includes the step of creating the injectability in the formation.

40. The method as set forth in claim 24, characterized in that it further includes the step of improving the permeability of the reservoir before performing step (3).

41. The method as set forth in claim 24, characterized in that, after the additional recovery of hydrocarbons from the introduction by injection of fluids by means of said horizontal section of the wellbore is not economic, step (3) it is discontinued and the production of associated hydrocarbons and fluids, including any of said injected fluid remaining in the reserve, continues until it is no more economical to continue such production.

42. A method of producing associated hydrocarbons and fluids from an underground formation containing such hydrocarbons and associated fluids, characterized in that it comprises the steps of: (i) forming a predominantly horizontal well bore, between the midpoint and the bottom of the well; formation, and as close to the bottom of the formation as possible, said well bore having a raised end that forms and remains at least 2 meters above the rest of the predominantly horizontal section of the well bore; (ii) completing said well bore for fluids to be injected into the formation by means of said predominantly horizontal section of the well bore at an injection point located adjacent said high end of said well bore, and for hydrocarbons to be produced of the formation by means of a point of production between the ends of the well drilling and below said elevated end of said well drilling; (iii) injection of a fluid containing at least one of propane, butane, ethane, methane and mixtures thereof, in the form of a saturated vapor, into the formation through said injection point to mobilize at least one portion of the hydrocarbons within the formation for movement to said predominantly horizontal section of said well bore; (iv) simultaneously producing and associated fluids and said injected fluid by means of said predominantly horizontal section of said well bore; and (v) recovering at least a portion of said injected fluid produced in the formation of step (iv) and reinjection of such injected fluid recovered earlier within the formation in the form of a saturated vapor as in step (3).

43. The method as set forth in claim 42, characterized in that in at least one of nature, type and composition of the injected fluid is changed from time to time, such that more than one injected fluid, or mixture of injected fluids is used to perform the step (iii).

44. The method as set forth in claim 42, characterized in that before performing steps (iii) and (iv), injectability is created in the training.

45. The method as set forth in claim 42, characterized in that before carrying out step (iv) the permeability of the reserve is improved.

46. The method as set forth in claim 42, characterized in that in the step of embodiment (iii) at the point where the additional recovery of hydrocarbons by means of the additional injection of fluids by means of said predominantly horizontal section of the well borehole is not it is more economical, the injection of fluids through the perforation of the well ceases and the production of hydrocarbons and associated fluids, including any injected fluid remaining in the reserve, continues until it is not more economical to continue such production without fluid injection.

47. The method as set forth in claim 42, characterized in that in the embodiment (iii) the fluid injected is a dry vapor.

48. Apparatus for the production of hydrocarbons from an underground formation containing such hydrocarbons and associated fluids, characterized in that it comprises: a predominantly horizontal well bore located between the midpoint and the bottom of the formation and as close to the bottom of the formation as is possible, said well bore having a raised end that remains at least 2 meters above the rest of said predominantly horizontal section for the injection of fluids into the formation, and said well bore having at least one complete section that is located below said high end of said well bore to produce hydrocarbons from the formation in response to the injection of fluids through said high end.

49. The apparatus of claim 48, characterized in that it further includes means for injecting propane, butane, ethane, methane and mixtures thereof in the form of a saturated vapor through said elevated end.

50. The apparatus of claim 48, characterized in that said entire section is adapted to receive and remove from the formation the hydrocarbons mobilized by drawing thereto by means of gravity draining.