MX2013001364A - Systems and methods for the improved recovery, applied to reservoirs which crudes have conditions of movement at the bottom. - Google Patents

Abstract

The present invention is referred to systems and methods which uses combine alternate and continuous injection of vapour for increasing the recovery factor, particularly of heavy crudes and extra heavy crudes, in reservoirs where the crudes have conditions of mobility at the bottom, in new wells and current wells in soft sandstone; in calcarenite and limestone which need to be fractured; in naturally fractured calcarenite and limestone; and current wells. The methods comprise in a first step the injection of a vapour cycle to at least a producer well, and a second step comprising the continuous injection of vapour through at least an injector well, where at least a producer well and an injector well form the arrangement of wells.

Description

SYSTEMS AND METHODS FOR IMPROVED RECOVERY APPLIED TO DEPOSITS WHOSE RAW SHOWS MOBILITY TO FUND CONDITIONS FIELD OF THE INVENTION The present invention relates to various methods for improved recovery applied to reservoirs, particularly of heavy and extra heavy oils, which show mobility to bottom conditions, and systems comprising novel modular well arrangements.

BACKGROUND OF THE INVENTION In closed reservoirs, which are not in contact with large aquifers that perform pressure maintenance, subjected to primary exploitation, the production of each well declines or decreases, to the extent that the reservoir pressure decreases due to accumulated oil production, water and gas. In heavy and extra heavy crude deposits, the reduction of the production rate per well per accumulated production is very notable, due to the high viscosities shown by these crude oils. Of course, all those high viscosities are very temperature dependent; so in this area of application, thermal recovery is advisable, since the injection of hot fluids has the double effect of recharging the reservoir and drastically reducing viscosities. For the thermal recovery of this type of deposit, the following 4 technologies are known: ? Cyclic steam injection, also known by the denomination "Alternative Steam Injection" and by the expression in English language "HUFF &PUFF".

? Continuous steam injection.

? Steam assisted gravity drainage, better known by the expression, also in the English language "STEAM ASSISTED GRAVITY DRAINAGE" or by its initials SADG.

? Combustion in Site or IN SITU.

In an oilfield, mineral oil is found between pores and fractures in the rock. These small spaces are usually shared by fossil water, mineral oil, free gas and gas in solution. Steam injection positively affects the behavior of these deposits. The steam heats everything with what comes in contact: thus, it heats the rock and the fluids that it contains, behaving like a gas, the steam always rides on the viscous oils that it fluidizes, and in the sector of a deposit reached by steam , a hybrid scenario is formed; that is, a chamber in the upper part that contains water vapor and natural gas and an area of fluids mobilized by gravity, towards the lower part, composed essentially of condensed water from the steam and the waters and oils secreted from the pores of the rock.

The cyclic steam injection does not affect the recovery factor of the deposit but it does improve the production rate per well. For example, to a well that is producing cold at a rate of 20 barrels of oil per day, if you inject an adequate dose of steam and let it soak for a few days, it is most likely that when new in production, its flow rate is above 100 barrels of crude oil and these production levels decline to the initial values of cold production, in a period of a few months. Here, the energy supplied to the reservoir is drained along with the hot production.

While for cyclic steam injection it is only necessary consider the condition of each well in particular and its drainage area, for continuous injection is considered a whole deposit or a good portion of it, since it requires at least one. arrangement of wells where one or more injector wells serve several producing wells located nearby. The injection wells perform the filling or recharging of the deposit, while the producing wells perform the emptying of the same; although in the balance, the volume of steam injected must be greater than the total volume extracted from the deposit; so that the steam chamber keeps growing, since a retraction of it would mean re-saturating the area already devoid of crude. With continuous injection also forms a chamber filled with steam and natural gas, which rises to be located at the top of the producing sand and widens in all directions and as this technology contemplates long periods of injection, the steam chamber manages to reach the wells producers, after which the latter must be produced at controlled rates, to avoid wasting energy from said camera ...

The technology "Drainage by Gravity Assisted by Vapor", better known as SAGD, is applied through pairs of wells, in deposit whose hydrocarbons do not present mobility to bottom conditions, its more generalized form of application consists of pairs of parallel horizontal wells , drilled in the same vertical plane, the injector on top of the producer, spaced about 5 meters from each other and placed the producer well very close to the bottom of the horizon to be exploited. The technique consists in using a double string completion in the injector well; a long string to inject hot water at the far end of the horizontal section and a short string with its lower end placed near the point where the horizontal well penetrates the producing formation, to produce the already warm water after traversing the horizontal section of the injector well. All this operation that can take several weeks, to be heating the environment of the producer well and to manifest the mobilization of fluids in the second of the wells, start the injection of steam through the injector well and the production of the fluids mobilized by the well producer. Figure 2 shows schematically how the steam chamber is developed in a SAGD pair.

The In Situ Combustion technique is very similar to the continuous injection of steam since it comprises arrays of injectors and producers wells and normally includes a period of continuous injection of steam, except that once the steam chamber is developed, the change is made to injection of air, which causes the chamber vapor to condense and the new air-natural gas mixture, in contact with the interface of liquid hydrocarbons and under controlled conditions, to spontaneously combust and develop a front in said interface of combustion, which constitutes a source of energy supply to the deposit.

On the other hand, Russian Patent Application No. RU2446280 (C1) describes a method of extracting crude oil comprising the arrangement of , J Q minus two vertical wells with a secondary opening in them and the pumping of cyclic steam; however, said document does not teach the alternate use of cyclic and continuous steam to improve the recovery of crude oils.

Russian Patent Application No. RU2232263 discloses methods for extracting oil comprising, inter alia, drilling vertical wells and injecting a hot vehicle into said well. This document does not teach the alternate use of cyclic and continuous steam to improve the recovery of crude oil.

Russian Patent Application No. RU2307242 (C1) is directed to the production of high density petroleum, through the use of a system of vertical and horizontal wells and a thermal treatment. Again, this document does not refer to the alternate and continuous application of steam for improved oil recovery.

Finally, the patent publications RU2149266 (C1), RU2431744 (C1), RU2446278,,; RU2425969, CN101871339, US2007175638 (A1), 20 US2003000711 (A1) US6318464 (B1) and MX9802095 (A) claims various technologies for the recovery of crude oils that comprise the application of cyclic or continuous steam, but none of them teaches or suggests the combination of both techniques, in modular well arrangements such as those of the present invention.

Despite the various methodologies that are known in the art, there is a need for more efficient methods that present high yields in thermal oil recovery at affordable costs.

BRIEF SUMMARY OF THE INVENTION In a first aspect, the present invention refers to a method that allows, by means of the combined injection (alternate and continuous) of steam, to increase the recovery factor of oil, particularly of heavy and extra heavy oils, in deposits where the crude they present mobility to background conditions.

In a second aspect, the present invention relates to the systems for improved recovery of heavy and extra-heavy oil in reservoirs, which comprise modular arrays of wells, where in each case there is at least one producing well and one injector well.

In a third aspect, the present invention relates to the methods comprising in a first step the injection of a steam cycle to at least one producing well, and a second stage comprising the continuous injection of steam through at least one injector well. , where at least one producing well and one injector well make up a well arrangement.

In a further aspect, the present invention is also directed to the methods for the realization of the systems that allow the application of improved recovery to heavy and extra heavy oil deposits.

In a further aspect of the invention, at least one producing well and one injection well correspond to wells drilled, or to be drilled, in poorly consolidated sandstones.

In a further aspect of the invention, at least one producing well and one injection well correspond to drilled wells, or which will be drilled, in calcarenites and limestones that require to be fractured.

In a further aspect of the invention, at least one producing well and one injection well correspond to wells drilled, or to be drilled, in calcarenites and naturally fractured limestones.

In a further aspect of the invention, at least one producing well and one injection well correspond to existing wells.

The systems and methods of the present invention advantageously allow to increase the rate of production per well and the recovery factor per reservoir considerably compared to the recovery factor of heavy and extra heavy crudes that show mobility to background conditions obtained with the use of the available energy in the deposit, which is approximately 10%.

DESCRIPTION OF THE FIGURES Figure 1. Shows in schematic form three aspects of the area of influence of a vertical well steam injector, where 1 represents the vertical well, 2 to the steam chamber, 3 to the area of mobilized fluids composed basically of condensed water from the chamber of steam, fossil water and mineral oil and 4 to the production formation not yet affected by the injection of steam.

Figure 2. Illustrates four scenarios of the exploitation of a reservoir drainage area through a SAGD pair. It is appreciated that the steam injected by the injector well always opens upwards and that the steam chamber 2 first grows to the sides and then downwards and that both the water condensed by the chamber 2 and the fluids mobilized by the heat make up the band. 3, which is produced through well 6, while 4 corresponds to the part not affected by thermal stimulation.

Figure 3. It is a cross-sectional view of an arrangement of wells, exemplary of the present invention, comprising a module of fifteen wells, fourteen parallel horizontal producing wells grouped into two macropears of seven wells each and a steam injector well, also horizontal , but placed in an intermediate position and perpendicular to the producing wells, where7 represents a seven-hole macro well, 8 the drainage area of one of the 14 producing horizontal wells and 9 the corresponding horizontal section, 10 the pear or corresponding location to the horizontal injector well and 11 the horizontal section of said injector well. Figure 4. It is a perspective view of the fifteen-well module described in Figure 3.

Figure 5. Shows a vertical well (1), drilled in a calcarenite or limestone that needs to be fractured, said sand has a train or fracture tendency (13), each fracture has an area of influence (12) and the well has an assigned drainage area (14).

Figure 6. Shows three views of a multiple-fractured horizontal well, drilled in the bottom of a calcarenite or limestone.

Figure 7. Illustrates a fractured vertical well (1), with an effective drainage area (12) and an assigned drainage area (14), a train or the fracture trend (13) of the limestone calcarenite and a macropera (15) ) of five multi-fractured horizontal wells.

Figure 8. Illustrates two modalities of exemplary arrangements of four and seven wells according to the present invention: on the left a modality with three diversion producing wells of low angle (16) and one injector of vertical completion (1) without drainage area assigned and to the right another modality with six producers diverted, three of low angle (16), three of medium angle (17) and one vertical injector (1), both arrangements inscribed in? equilateral triangles, whose shape facilitates the massification of the same, while reducing to the maximum expression the areas without assigned well.

Figure 9. Illustrates one embodiment of the invention with an arrangement of seven wells, six producers and one injector. It shows what by placing six modules together, an additional injector can be added in the central part of the array.

Figure 10. Shows an embodiment of the invention with an arrangement of nineteen wells, eighteen producers, three low angle (16), three medium or angle deviation (17), twelve high angle deviation (18) and one injector vertical (1).

Figure 11. Illustrates one embodiment of the invention with six modules, in where each module comprises an arrangement of nineteen wells. In the central part of the six-module arrangement, a seven-hole macro well is opened, preferably six producing wells and one injector.

Figure 12. Shows in schematic form a macroover of vertical completion wells according to the present invention where 1 represents the vertical injector well, without assigned drainage area, 19 the vertical section of all the wells, 20 the KOP or point where it begins the diversion of the deviated wells, 21 to the production formation and 16, 17, and 18 to the maximum lateral displacements corresponding to the arrangements of 3 diverted wells of low angle, 6 diverted wells of medium angle and 12 diverted wells of high angle.

Figure 13. It shows a small sector of the map of an unconsolidated sandstone, being exploited by vertical, deviated and horizontal wells, to which a probable drainage area is pointed out, only to facilitate the search of possible exploitation areas through the realization of improved recovery with existing wells.

Figure 14. Shows a cross-sectional view of a steam injector completion diagram of a horizontal well drilled in a poorly consolidated sandstone according to the present invention, where conventional pipe 22, Nitrogen as thermal insulator 23, a thermal pack injection 24, an expansion joint converted into a mechanical jacket 25 and a string of perforated tail pipe 26, with its occluded lower end. The perforated glue pipe facilitates the formation on the well of a temporary steam chamber of elongated shape, which can then be fed by a continuous injection well located nearby.

Figure 15. Shows the profile of three neighboring wells, one horizontal6, one vertical1 and one deviated, 16 being used for improved recovery applied through existing wells. In the figure, 2 represents the steam chamber, 3a the fluid belt mobilized with steam injection and 4 to the formation producer not yet affected by the injection of steam.

DETAILED DESCRIPTION OF ASSOCIATED TERMS AND EXPRESSIONS TO THE INVENTION The present invention must be understood according to the following definitions and descriptions: Improved recovery: It is related to the injection of fluids to an oil field in order to increase its recovery factor.

Recovery factor: It is defined as the percentage of original oil on site that can be recovered through the application of technologies available for this purpose.

Macropera: It is the locality or space where the drilling of several wells can be carried out.

Approximately: Refers to the range of ± 10% with respect to the established amount. By way of example, by indicating approximately 50%, it ranges from 45% to 55%.

Hot production: This method consists of putting into production a well to which a steam cycle has been injected.

Service drill: Serves to replace the removable iron that make up the completion of the well; that is, remove existing completion and put new completion, without interacting with the production arena as it would be: stimulate, cement, cannon, extend, seal, etc.

Drill hole: A medium capacity drill hole allows the drilling of horizontal wells of short sections, while large capacity drills allow drilling wells with very long horizontal sections.

Water viscosity: 1 Centipoise.

Viscosity of extra heavy crudes: from 200 to 300 thousand centipoises.

Portable steam injection equipment: This equipment consists basically of 2 trailers (TRAILES), one with the water treatment plant and the other with the steam generator, all this with a series of connections and electricity supply lines, water , air, gas or diesel.

Vertical well (1): It is drilled in a straight line.

Deviated well (16): It is drilled in 5 sections, first a vertical straight section, which is followed by a curved section, then comes a straight section cocked, then another curved section and finally a vertical straight section.

Horizontal well (6): It is drilled in 3 sections, first a vertical straight section, then a curved section where the well is progressively diverted in such a way that when starting to penetrate the target sand, it already has an accumulated deviation close to 80 °. The 90 ° of deviation is reached within the target arena and it is from this point of deviation that the third section begins, which is horizontal.

The 3 well geometries referred to above are shown in Figure 15.

The methods of the present invention have application only in reservoirs whose crudes present mobility to background conditions, a fact that can be evidenced if the corresponding exploratory wells have shown capacity to contribute production in a consistent manner, without the need of a previous thermal stimulation.

The methods and systems of the present invention have four preferred embodiments: • Wells drilled, or to be drilled, in poorly consolidated sandstones.

• Wells drilled, or to be drilled, in calcarenites and limestones that need to be fractured.

· Wells drilled, or to be drilled. In calcarenites and naturally fractured limestones.

• Existing wells, drilled in any type of producing sand.

The sandstones little consolidated have permeabilities in the order of the 2 Darcies and present very good conditions to be exploited by horizontal wells, with long sections of horizontal navigation, each well completed with LINER SLOTTED (SLOTTED LINER) placed 5 in bare hollow, except when they are on a water-oil contact, in which case it is advisable to look for some type of technology that offers to exploit the deposit in a balanced or balanced form, without realizing in the drainage, despond or DRAWDOWN points of consideration, which promotes the channeling of water from the nearby aquifer.

In a first embodiment of the invention, the system applied through wells drilled, or to be drilled, in poorly consolidated sandstones, , | Q comprises at least one modular well arrangement, where each module comprises producing wells grouped into at least 2 macropears, with a common steam injector well, the producing wells being horizontal and parallel to each other, located very close to the bottom of the producing sand and at least one injector well being also horizontal and being positioned in a direction perpendicular to the producing wells. The number of producing wells that make up each macro is made up of odd numbers, starting with three, followed by, five, seven, nine, and so on. The number of fifteen wells depends on a set of sensitivities and simulations performed, among which are the money that will be invested and the time in which the project will be exhausted, taking into account the depth and other parameters of the deposit, the drilling rig's capabilities, etc. .

Figures 3 and 4 illustrate, by way of example, a module of nine wells, where fourteen of the wells are producers. Distributed in two macropears of seven and a steam injector well.

In a second embodiment of the invention, the method for forming the aforementioned system comprises the following steps: A. A horizontal producing well (6) is placed at the bottom of a long narrow strip of sand that is not well consolidated, to form, along with its drainage area (8) and a horizontal section (9), a magnificent well-sand interconnection . By injecting steam it is possible to heat the drainage area with extreme ease and the flow of fluids into the well, both cold and hot, must travel relatively short distances.

B. In each horizontal producer well (6), the artificial lifting equipment 5 is always placed inside the production casing (not shown), very close to the point of entry from the well to the deposit. This makes the horizontal section ordinarily much more drained on that side than on the other. Place the well for continuous injection of steam (5), with its horizontal section (11), in an intermediate area common to the set of horizontal wells producers (6) grouped in the two macrocrops (7), to achieve matching the contribution of the horizontal section , since one end, | Q produced by high drainage and the other by being warmer and being pushed up close by the steam chamber (not shown), created and being fed by the horizontal injector well (5), drilled from the pear (10).

C. The first stage of the recovering method in poorly consolidated sandstones of the invention comprises the injection of a steam cycle to each producing well (6), which is followed by a second stage comprising the continuous injection of steam through the well injector (5). The initial steam injection significantly increases the production capacity per well and the continuous injection of steam ensures that these initial benefits remain relatively high during the life of the improved recovery project, resulting in high and stable levels of production and factors of recovery up to approximately fifty %.

In a second embodiment, the system of the present invention is applied through perforated wells, or drilled in calcarenites and limestones that need to be fractured. The calcarenites and limestones that need to be fractured have permeabilities in the range of 0.10-0.15 Darcy. They are not usually associated with aquifers or accumulations of bottom water and when they are exploited by vertical completion producing wells, these are deflated with very little accumulated production; for example, they go from an initial production rate of 100 barrels of oil per day, to producing only 20 barrels of oil per day, in a period of just 4 months, which is an indication of a very low well-deposit connectivity. The vertical completion well only allows to perform a fracturing work by producing sand lens, with which it is possible to contact only a small fraction, about 1/7, of the drainage area assigned by well, as exemplified in Figure 5 .

The method applied through wells to be drilled in calcarenites and limestones that need to be fractured, includes the modular drilling in macro-holes of parallel multiple-fractured wells, with long and narrow drainage areas; long to be able to make many fractures by well and narrow to ensure the necessary interference between wells, which allow the corresponding works of steam injection. Figure 6 shows 3 views of the type of well suitable for the exploitation of calcarenites and limestones that need to be fractured and Figure 7 shows a macroperformance of five horizontal wells multiply fractured, placed perpendicular to the fracture train of the reservoir and graphically compare the rectangular drainage areas of the multiphase wells, with the assigned square or circular drainage area corresponding to a vertical well (1). As it happens in the first modality, the number of wells that make up each module is an odd number such as: three, five, seven, nine, etc., and depends on a set of sensitivities and simulations that have to be done, with the depth and other parameters of the deposit, the effective linear extension estimated by fracture, the capacities of the drilling rig available and the estimated time in which it is planned to recover the remaining oil reserves.

The application of this method in calcarenites and limestones that need to be fractured, begins with the injection of a steam cycle to each well producer, which is followed by the start of the continuous injection of steam through the injector well, which in this case is one of the multiple-fractured parallel wells of the module, chosen according to its position in the array. It is known that steam injected into a well drilled in the bottom of a producing sand lens, first makes its way upwards until it reaches the above-mentioned sealing sand and then accumulates under that ceiling if the reservoir is horizontal or continues its journey of rise dip above if the deposit has a slope in its roof. If the deposit does not have an inclination, the well of intermediate position is chosen as the injector well in the modular arrangement of wells in question and in the case of an inclined deposit, the injector well must be located at the end of the greater relative depth in said module.

In basically horizontal reservoirs, this method also contemplates, instead of a fixed injector well per module, the possibility of rotating the injector well so that when each well receives its first steam cycle, it starts by injecting the next cycle into the producer well that less is contributing production and so on. In this condition, the cyclic injection of steam carried out continuously, becomes a form of continuous injection due to the fact that one of the wells of the macropera is always receiving steam.

In a third embodiment, the system of the present invention is applied through drilled wells, or drilled in calcarenites and naturally fractured limestones. Naturally fractured limestones, normally offer double porosity, a very low one that corresponds to the rock and the other a little, higher that corresponds to the fractures, on average they present permeabilities in the order of 0.2 Darcy. Small fractures are great channels of production input and transport, but large fractures have such a high production capacity that they can endanger the good operational health of the well, by facilitating the channeling of water from bottom accumulations and aquifers, because this fluid is less viscous than extra-heavy crude oils: For this reason, in this type of deposit, instead of long horizontal wells with extensive drainage areas, deviated wells are used, grouped into macropears, which have the following characteristics: I. Entry of the well to the production formation always in vertical position, to ensure optimal conditions at the time of cementing the production casing, which must be in very good condition, when it is foreseen the possibility of performing work of stimulation by fracturing and injection of steam.

II. Naked hollow completion of thin sand and hollow tubing with selective cannonade in very thick sands, to be able in the latter case, to carry out remediation works of forced cementation of fractures with water channeling.

III. Drainage area assigned by well of cylindrical configuration and medium extension, to be able to control which part of the deposit effectively provides production as it is, which requires to be fractured, which well must be closed by high water cut or rehabilitated by work of forced cementation, et cetera.

IV. The number of producing wells that can be grouped in a macropera depends on the depth and other parameters of the reservoir, the capacity or HP (Horsepower) of the drilling rig available and the period of time in which it is desired to recover the reserves. remnants of oil.

The system of the present invention applied through perforated wells, or drilled in calcarenites and naturally fractured limestones, comprises at least one well module, where each module comprises a macropera, which has in its central part a steam injector well, without an area of assigned drainage, surrounded by a number of diverted producing wells, which may be 3, 6 or 18, depending on parameters such as the depth of the deposit, the available drilling capacity, the estimated life time of the project, etc., corresponding to the particular case.

In the calcarenites and limestones as well as in the little sandstones consolidated, the application of the method begins with the injection of a steam cycle to each producing well (16,17 and / or 18), which is followed by the start of the continuous injection of steam through the injector well (1) . This changes the production profile per well of a moderate or low production, with a high decline due to accumulated production, to a high and sustained production over time. As the volume of steam injected through the injector well (1), greater than the volume of fluids extracted from the reservoir through the producing wells (6, 7 and / p 18), the exploitation of the deposit is an over balanced process; which means that upon reaching the abandonment point of each project, the reservoir pressure must be greater than that at the beginning of it.

In a reservoir map, a vertical well is represented with a point and a well deflected by a line and two indications, one end representing the location of the well on the surface (S) and the other end representing the bottom (F) or point of entry from the well to the deposit. In Figure 8 are shown arrangements with three and six producing wells (16 and 17), inscribed within an equilateral triangle, centered by the well injectorsin assigned drainage area (1). Figure 9 shows the way to massify the arrangement of an injector well (1) and six producing wells (16 and 17), which, as illustrated, for each group of 6 macropears, has an area available as for an additional injector well ( 1). Figure 10 shows the arrangement of 19 wells. Three producers of low angle of deviation (16), three producers of medium angle of deviation (17) and 12 producers of high angle of deviation (18), also centered by an injector well (1 ) and Figure 11 exemplifies the corresponding massification arrangement, where we can also see that when closing a space with 6 macropears, in the central part opens a place for an additional macroover of seven wells, which could be six producers (6) and an injector (1). Figure 12 corresponds to a schematic representation of a macroperform formed by vertical completion wells, where 1 represents the vertical well injector, 19 the common vertical section of the 19 wells, 20 the K.O.P. or point of beginning of the deviation of the deviated wells, 21a the production formation or objective and 16, 17 and 18 to the extreme lateral displacements corresponding to the deviated wells of low, medium and high angle.

In wells producing extra-heavy crude oil fields subject to primary exploitation, the subsoil pumps are usually placed very close to the entrance of each well to the deposit, to make the most of its energy. With this technology, the K.O.P or point 20 in Figure 12, is the greatest depth at which the subsoil pump must be installed, in order to obtain the best possible operating conditions. The impossibility in these cases to install the pump deeper is not a problem because the cyclic injection followed by continuous steam injection ensures sufficient reservoir pressure, throughout the life of the project, to ensure the proper functioning of the equipment of artificial lifting used in producing wells.

In a fourth embodiment, the method of the present invention is applied through existing wells. In the oil extractive industry there is also the need to apply improved recovery through existing wells, which were planned and drilled only as drainage points of a deposit and, consequently, do not keep the geometric relationships of distance and location between they are necessary to undertake an efficient process of continuous steam injection.

The method of the present invention applied to existing wells is based on the same principles applied for the case of the wells to be drilled, their associated concepts and operational practices are summarized below: 1. After taking the necessary precautions to protect the cementation, the production casing and the elements of the head, it is possible to inject steam to a reservoir through an existing well, as long as the fluids of said deposit present mobility to background conditions, fact that can be corroborated by cold production tests. 2. Injected in front of the face of the sand in a vertical well, the steam behaves as shown in the graphic sequence of Figure 1, where 1 represents the vertical well, 2 to the steam chamber, 3 to the fluid zone mobilized basically composed of condensed water from the steam chamber, fossil water and mineral oil and, 4 to the production formation not yet affected by the injection of steam. There you can see that the steam injected forms a steam chamber 2 at the top of the sand, which grows downwards and to the sides and it is that lateral growth that can be used to bring steam to one of more neighboring producing wells, which have received a preliminary steam cycle or "KICK OFF", to form an improved recovery scheme for crude oil through existing wells. In the space occupied by the steam chamber2, the removal of crude oil is total, the water condensed by the steam when yielding heat, always goes to the bottom and it is this hot water which when coming into contact with the cold formation, it stimulates it and causes a band of formation fluids 3 to form, with much greater capacity for movement, than the one in its cold condition.

The thermally stimulated training fluids and the pneumatic action exerted by the steam chamber 2 on them, considerably improves the production capacity of the well injected with steam.

To apply improved recovery through two or more existing wells, this method includes the following steps: to. In a first stage, inject a steam cycle into the well or existing wells to be used as hot producers. b. Put the well or producing wells into hot production, with appropriate lifting equipment for the expected production rate. c. In a second stage, start the continuous injection of steam through an existing well, strategically located and converted to a steam injector, with the purpose of creating a steam chamber that when expanding laterally makes contact with the chamber or cameras developed or developed in the well or producing wells, with the initial injection cycle, acting as a means of replenishment or REFILL of said or said cameras, to ensure a hot production sustainable over time, which does not decline rapidly as in the case of the cases of only cyclic steam injection. 5. If it is desired to make an improved recovery using the existing wells as much as possible, but without the limitation of drilling one or more wells, it will always be possible to form reasonably efficient arrangements by inter-spaced drilling. It is worth emphasizing that the steam chamber of refueling created with the injector well, expands ordinarily in all directions and having hot producing wells in all its perimeter of action would be desired.

Figure 13 shows, as an example, a small sector of the structural map of an unconsolidated sandstone, with a few horizontal (6), vertical (1) and deviated (16) producing wells, each with its probable marked drainage area and from where a few combinations of possible arrangements can be made for improved recovery through existing wells. Figure 14 shows a horizontal well drilled in a poorly consolidated sandstone, equipped with SLOTTED LINER, placed in a bare hole and completed with steam injector with conventional injection string 22, with Nitrogen 23 placed in the annular space as gas insulator, thermal injection pack 24, expansion joint converted into mechanical slider 25 and perforated tail pipe26. Figure 15 shows a schematic case of an improved recovery through three existing wells, where a vertical well (1) located in an intermediate position is used as an injector, to provide steam recharge service, after the injection initial, to the other two wells, one horizontal (6) and the other deviated (16).

In summary, the application of improved recovery through existing wells made with this methodology, consists of the creation of one or more temporary steam chambers, through the injection of a steam cycle into the well or the wells to be used or used as a producer or hot producers and then promote the recharging of that camera or those temporary cameras through a common injector well. This method allows high rates of hot production of wells with marginal rates of cold production and by including continuous injection of steam, definitely contributes to these high rates of hot production remain stable and that the recovery factor in the affected area of the deposit, literally doubled. In the case of existing wells, the recovery factor increases to approximately 20% and in new wells to approximately 50%.

PREFERRED EMBODIMENT OF THE INVENTION Example 1: Unconsolidated sandstones As explained, the method of the present invention applied to drilled wells, or wells to be drilled, in poorly consolidated sandstones, comprises at least one modular arrangement, wherein each module comprises producing wells grouped in at least 2 macropears, with a well common steam injector, being the production wells horizontal and parallel to each other, located very close to the bottom of the producing sand and at least one injector well also horizontal and placed perpendicular to the producing wells. The number of producing wells that make up each macro is made up of odd numbers such as: three, five, seven, nine, etc., and depends on a set of sensitivities and simulations already mentioned, the depth and other parameters of the deposit, the capacities of the drilling rig and the estimated time (ranging between 10 and 25 years) to recover the remaining oil reserves. The realization of a module according to the present invention comprises the following steps: 1) Having good knowledge of the area, regional geology, static and dynamic model of the deposit and made the sensitivities and simulations According to conventional methods, both the reservoir and each well in particular are drilled producing wells and the injector well, using cements and thermal heads, suitable for wells to be injected with steam. 2) Use a well service drill to complete all the wells, including the injector, to crude oil producers and put them into production for a time 5 determined that it will be a function of the stability of the production rate, for: a) Verify that they are well connected to the deposit; since a well that produces well, also receives the injection of fluids with ease. b) Discard that during the drilling operations there has not been an open communication with an aquifer that could ^ Q propitiate the sudden invasion of water. c) Evaluate the cold wells and establish a base of comparison, for the later tests already with the thermally stimulated wells. 3) Use a well service drill to convert the well drilled for injector, from cold producer to steam injector, using a completion scheme as shown in Figure 14. This completion scheme is used both for continuous injection and for cyclic steam injection and has particular that the injection string includes a 15 tail pipe26, perforated in its trajectory and occluded at its end, which ensures a good distribution of steam throughout the horizontal section From a point of injection of steam drilled in the tail pipe26 a kind of cone is formed that rises and widens until reaching the roof of the producing sand, after which it only has to expand towards the sides, until making contact with the cones formed from the neighboring injection points, forming when connecting with them, 20 an elongated steam chamber, on the horizontal section of the steam receiver well. 4) Removing portable water conditioning and steam generation equipment to the locality of the well drilled for continuous injection of steam and to make the corresponding connections between them and with the facilities of supply of fuel, fresh water, electricity, et cetera; leaving all instrument and equipment interconnected and calibrated, ready to operate. 5) Start the continuous injection of steam through the injector well, according to the preset injection program, according to parameters of the well, reservoir and economic factors, as indicated above. 6) Proceed to Inject a steam cycle to each of the wells drilled for producers, in the two macropears that make up the module, for which we proceed as follows: i. Use a well service drill to convert the cold producer well (preliminary evaluation) to a steam cyclic injector, with the same completion scheme shown for the continuous injection well. ii. Inject steam cycle according to pre-established program. iii. Leave well in thermal soaking for a period of not less than a week. iv. Again, use well service drill to convert the cyclic steam injector well to hot producer, using a proper completion to raise the expected production.

The steam cycle injected into each producing well is a kind of initial impulse or "KICK OFF", which causes a considerable increase in the production rate of the same and the continuous injection of steam, made through the corresponding injector well, located As we know in the area near the far end of the horizontal section of each producing well, it serves as a refill or "REFILL" to the steam chambers created in each well with the initial injection cycle. The joint effects caused by the initial injection and the continuous recharge of steam cause the wells to go from modest rates in cold to high rates in hot, for example, a well that produces 20 barrels of crude oil per day, when steam is injected it goes on to produce 100 barrels per day, and if it produces 120 barrels cold, with steam injection, it produces up to 500 barrels per day. These high rates tend to to be maintained over time, since the constant supply of steam counteracts what would be the natural decline of the production rate per well, caused by accumulated production, without fluid injection.

Example 2: Calcarenites and limestones that need to be fractured: The method of the present invention applied to drilled wells, or to be drilled in calcarenites and limestones that require to be fractured, comprises the following steps: a) With good knowledge of the area, regional geology, calcarenite limestone fracture train, static and dynamic model of the deposit and made the sensitivities and simulations, both to the reservoir and to each well in particular, to drill all the wells, using thermal cements and heads for wells to be injected with steam and, of course, to carry out in each well the corresponding works of multiple fracture of the horizontal section. b) Choose for steam injector the well of the macropera that is better located, by having an intermediate position in a basically horizontal reservoir, well, because it is located deeper in an inclined deposit; this to facilitate the sweep of the deposit with the steam injected, dip up. c) Complete all the wells, including those planned for continuous steam injection, to producers and evaluate them to know their characteristics of cold production. d) Replace the completion of planned wells for producers and convert them to steam injectors and inject an alternate cycle of steam to each one. e) After the corresponding soaking period, proceed to recover in these wells the injection completions, replace them with other production ones and leave them in hot production f) Start the continuous injection of steam through the well of the macropera selected for continuous injection of steam.

If, by accumulated production, the hot producing wells decrease their production appreciably by not receiving timely energy recharge through the continuous injection well, it is necessary to resort to injecting successive alternating cycles of steam to the producing wells, until the steam recharge to said wells reaches replacement levels that ensure a stable hot production.

This method also contemplates using instead of a fixed injector well, rotating in the injector well so that it is always the producer well that has been reduced and requires a new cycle of alternate injection to stimulate its production.

Example 3: Calcarenites and naturally fractured limestones.

The method of the present invention applied to drilled wells, or to be drilled in naturally fractured calcarenites and limestones, is done in the following manner: 1) With good knowledge of the area, regional geology, static and dynamic model of the deposit and made the corresponding sensitivities and simulations, both to the reservoir and to each well in particular, drill the producing wells in 3, 6 or 18 well arrangements and the Injector well at the center point of the arrangement, with no drainage area assigned; all the wells of vertical completion, of course using thermal cements and special heads for wells to be injected with steam. 2) Complete the production wells and evaluate them to establish cold production characteristics. 3) Convert the producing wells to steam injectors and inject each one with a steam cycle. 4) After the corresponding soaking period, convert the producing wells of steam injectors to hot producers. 5) Complete the steam injector well and start the injection

Claims (24)

continuous steam. If, by accumulated production, the hot producing wells decrease their production appreciably by not receiving timely energy recharge through the continuous injection well, it is necessary to resort to injecting successive alternating cycles of steam to the producing wells, until the steam recharge to said wells reaches replacement levels that ensure a stable hot production. As will be apparent to a person skilled in the art, any variation that does not depart from the spirit of the invention described is considered to be within the scope thereof. CLAIMS

1. - A method to increase the improved recovery of heavy and extra heavy crude oils in reservoirs that have mobility to bottom conditions, which includes the combined injection (alternate and continuous) of steam, in a well arrangement.

2. - The method according to claim 1, wherein the arrangement of wells comprises at least one producing well and at least one injector well.

3. - The method according to claim 1, wherein the wells are new or existing wells.

4. - The method according to claim 1 and 3, wherein the recovery is increased up to about 50% in new wells and up to about 20% in existing wells.

5. - A system to increase the improved recovery of heavy and extra-heavy crude oils in poorly consolidated sandstones, comprising at least one modular well arrangement, where each module comprises producing wells grouped into at least 2 macropears, with a common well steam injector .

6. - The system according to claim 5, wherein the producing wells are horizontal and parallel to each other, and the at least one injector well is also horizontal and placed perpendicular to the producing wells.

7. - The system according to claim 6, wherein the producing wells located very close to the bottom of the producing sand.

8. - The system according to claim 5, wherein the number of producing wells that make up each macro is made up of odd numbers.

9. - A method to increase the improved recovery of heavy and extra heavy crude oils in unconsolidated sandstones, comprising: A. Place the producing wells in a horizontal position at the bottom of a long narrow strip of sand that is not well consolidated, to form, together with its drainage area, a well-sand interconnection; B. Group the producing wells in at least 2 macropears; C. Place the well for continuous steam injection in an intermediate area common to the at least two macropears (7).

10. - A method to increase the improved recovery of heavy and extra heavy crude oils in sandstones poorly consolidated in new or existing wells, comprising: a first stage that begins with the injection of a steam cycle to each producing well, followed by a second stage comprising the continuous injection of steam through the injector well.

11. - The method of claim 10, wherein a recovery factor of up to about 50% is obtained in new wells and up to 20% in existing wells.

12. - A system for improved recovery of heavy and extra heavy crude oils in calcarenites and naturally fractured limestones, comprising at least one module, wherein each module comprises a macropera, which has in its central part a steam injector well, without an area of assigned drainage, surrounded by a number of diverted producing wells.

13. - The system according to claim 12, wherein the number of deviating producing wells is 3, 6 or 18.

14. - A method for improved recovery of heavy crudes and extra heavy crudes in calcarenites and naturally fractured limestones, comprising a first stage that begins with the injection of a steam cycle to each producing well, followed by a second stage that includes the continuous injection of steam through the injector well.

15. The method according to claim 14, wherein the volume of steam injected through the injector well is greater than the volume of fluids extracted from the reservoir through the producing wells.

16. - A method for improved recovery of heavy and extra-heavy crudes in existing wells, comprising the following steps: a- In a first stage, inject a steam cycle into the well or existing wells to be used as hot producers, b. Put the well or producing wells into hot production, with appropriate lifting equipment for the expected production rate. c. In a second stage start the continuous injection of steam through an existing well, strategically located and converted to injector in order to create a steam chamber that when expanding laterally makes contact with the camera or cameras developed or developed in the well or the producing wells, with the initial injection cycle, acting as means of replenishment of said or said chambers, to ensure a sustainable hot production over time.

17. - The method according to claim 16, optionally comprising inter-spaced perforation between existing wells.

18. - A system for improved recovery of heavy and extra-heavy crude oils in calcarenites and limestones that need to be fractured, comprising a modular array of parallel horizontal multi-fractured wells with long and narrow drainage areas, where the number of wells make up each module is an odd number.

19. - The system according to claim 18, wherein the odd number is three, five, seven, nine, and so on.

20. - A method for improved recovery of heavy and extra heavy crude in drilled wells, or to be drilled in calcarenites and limestones that require fracturing, which includes: a) Injection of a steam cycle to each producing well, followed by b) Start of the continuous injection of steam through the injector well, which is selected from one of the multiple-fractured parallel wells of the module, which is chosen according to the of your position in the well arrangement.

21. - The method according to claim 20, wherein the injector well is the intermediate position well.

22. The method Be according to claim 20, wherein the injector well is the well located at the end of greater relative depth in said module. 23. - The method according to claim 20, wherein the injector well is fixed.

23. - The method according to claim 20, wherein the injector well can rotate.

24. - The method according to claim 23, wherein the producing well with lower hot production is the first to receive the second steam cycle.