Method for initiating circulation for steam assisted gravity drainage.

(54) Title: METHOD TO INITIATE GRAVITY ASSISTED STEAM DRAIN CIRCULATION. (54) Title: METHOD FOR INITIATING CIRCULATION FOR STEAM ASSISTED GRAVITY DRAINAGE.

(57) Summary

A method of initiating mobilization and recovery of hydrocarbons by steam assisted gravity drainage (SAGD) in a hydrocarbon formation is described that initially includes forming a circulation path by connecting a SAGD injection well and a circulation well. The circulation well may be a SAGD extraction well or a completed separate well adjacent to the tip of the injection well. Initially, a thermal carrier such as steam or discharge gases is circulated, forming a thermal chamber around the injection well. Once the initial start-up is complete, the circulation path is decoupled for further propagation of the thermal chamber and establishing steady state SAGD operations.

(57) Abstract

A method for initiating steam assisted gravity drainage (SAGD) mobilization and recovery of hydrocarbons in a hydrocarbon-bearing formation ineludes initially forming a circulation path by connecting SAGD injection well and a circulation well. The circulation well can be a SAGD production well or a separate well completed adjacent to toe of the injection well. Initially, a thermal carrier such as steam or flue gases, is circulated, forming a thermal chamber about the injection well. One initial start-up is complete, the circulation path is decoupled for further propagating the thermal chamber and establishing steady-state SAGD operations.

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Institute

Mexican Property

Industrial _SE_

MCMreWM K

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PATENT TITLE NO. 343261

Owner (s): RII · NORTH AMERICA INC.

Address: Suite 2200, 777-8th Avenue SW, Calgary, Alberta T2P 3R5, CANADA

Name: METHOD TO INITIATE GRAVITY-ASSISTED STEAM DRAIN CIRCULATION.

Classification: IC 8: E21B43 / 24

Inventor (s):

NÚWMMNR

MXZa / 2012/01 '^ 308

FRED SCHNEIDER; GREG KURAN; LYNN P. TESSIER

SBOUM WWW

Presentation date:

November 2012

PRIORITY

<img file="MX343261B_D0003.tif" />

Country:

US

Date:

November 2011

Number:

61/560,367

Validity: Vein e arog ^

Venfcimiejjlto date: November 15, 2032. ''

8 5

Ma patent of reference granted by the articles 1, 2, V, 6, f-accon Hi. and δβ from u $ &lt;e Jb Proplead Industrial.

For example, in accordance with "Article 23 of the Industrial Property Law, this patent will be tijsjrtá w □ ntada as of the date of filing of the application and will be subject to the payment of the tar Λ pm TUt

ΙοΒο does on the basis of the presentation by the artteufet β ·

Industrial Property (D rio Oficie de la Federaciórr ^ fe ^ f) 27 / OeMWI, reforma® et “

01/16/2004, 06/16/2005 g25 / 01 / 2CÍ6, 06/05 / 2009,06 / 01 -------------- ----- • Diso a), 4 ° and 12 ° sections I «II of the In!

»07/01/2002, 07/15/2004 (07/28/2002 and 07/09/2007); 1st articles,⁶ fractions I and III and 30 of the E | the Mexican Institute of Industrial PropAad (DOF 27/12/1999, amended on 10/1/2002, 07/29/2004, 08/04/2004 and 13,

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Inte years (these rights are non-extendable,

II and 7 ° bis 2 the Law of 0/1996, 12/26/19 7, 05/17/1999, [04/01/2012); articles', 3rd section V ústrial (DOF 12/14/199, amended Organic Institute 9/2007); 1st, 3rd of the

Regional Offices, Divisional Deputy Directors, Departmental Coordinators and other subordinates of the Mexican Institute of Industrial Property. (DOF 12/15/1999, amended on 02/04/2000, 07/29/2004, 08/04/2004 and 09/13/2007).

Issue Date: October 31, 2016

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METHOD TO INITIATE DRAINAGE CIRCULATION

BY GRAVITY

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FIELD OF THE INVENTION

The modalities described herein relate to methods and systems for initiating vapor circulation between horizontally extending, generally parallel, and adjacent wells such as those for a pair of steam-assisted gravity drainage (SAGD) wells. English).

BACKGROUND OF THE INVENTION

Referring to Figure 1 and as it is commonly known in the industry, Steam Assisted Gravity Drainage (SAGD) uses a pair of closely coupled, horizontally extending wells, generally parallel wells comprising a first steam injection well. (injection well) and a second extraction well (extraction well) separated and placed under the injection well. SAGD is typically initiated in a start-up phase by simultaneously and independently circulating steam through both the injection well and the extraction well. Steam is injected through a chain of tubing which extends to the base of each of the injection well and the extraction well. The injected steam condenses in each well, releasing heat and creating

REF: 237262 Mexican institute .Z.

a liquid phase which is extracted to_; travIsNuáet ^ L jacket-pipe in the opposite direction _________

The released heat is transmitted initially through an intermediate portion of the formation between the injection well and the extraction well (interstellar region) and then through the formation to heat enough or otherwise mobilize bitumen in the same to cause the heated bitumen to flow by gravity drainage to the extraction well. In this initial phase, a thermal chamber is generated between the injection well and the extraction well as the mobilized bitumen drains by gravity into the extraction well.

After a well-to-well steam communication is established, the steam is continuously injected into the injection well. upper and condenses and the heated oil is extracted from the lower extraction well.

This SAGD startup has so far been enhanced by several known techniques including cold water expansion, steam expansion, solvent soaking, and electrical heating to reduce the time required to establish communication between the injection well and the extraction well. . In the expansion with cold water and steam, the cold water returns in case they inject in the region between the wells to create a vertical expansion zone and increase the porosity, permeability and water saturation of the region between the wells. '^NDum,* L

In solvent soaking, lUj / iLuta dissolves within the area between the wells and is allowed to soak prior to steam application. The solvent mixes with the bitumen in it and reduces the viscosity of the bitumen allowing the bitumen to be mobilized at a lower temperature.

In electric heating techniques, an electric heater is placed in the wells to conduct heat within the region between the wells to reduce the viscosity of the bitumen therebetween.

As the mobilized bitumen drains into the extraction well, the interstitial space emptied by the mobilized bitumen forms a vapor chamber which continues to grow horizontally and vertically. Simultaneous steam circulation in both the injection well and the extraction well (or start of SAGD) ceases when the steam chamber reaches the extraction well and the gradual increase in SAGD can be started.

During the gradual increase, steam is injected into the injection well only at a constant pressure to move heavy oil above the injection well for continuous gravity drainage and recovery in the extraction well.

The factors that determine success or timing - · - _____ _ fori ^ á ^ lon

<img file="MX343261B_D0008.tif" />

Recovery of improved oil from hydrocarbons includes the transport of oil fASCaiilsupu¹»'Thermal or impulse within the enhanced oil recovery (EOR) formation. Frequently, primary hydrocarbon extraction leaves areas of voids, wormholes, or other highly transmissive areas conductive to introduce EOR mechanisms.

In formations that are generally considered suitable for SAGD, such as previously unused formations, initial transport conditions for steam, solvent, or other transmission media are slow to initiate and may retard the development of a thermal mobilization chamber. Additionally, hitherto, each well pair in a well pair field is treated independently without consideration or advantage of adjacent well pairs.

Regardless of the mechanism, there is an opportunity to improve the onset of circulation for steam-assisted gravity drainage and inter-well communication between injection and extraction wells.

SUMMARY OF THE INVENTION

In general, the modalities described here, the initial formation of a SAGD thermal chamber is accelerated by establishing a circulation path of '^^^ ανο one-way thermal stimulation between inSuZSKai injection and a circulation well, already —τγ. τ¹¹ toe or toe to heel.

In modalities, communication between a pair of wells is established to initiate the one-way thermal stimulation circulation path from the heel of the injection well to the tip for return via a circulation well, such as the extraction well, for thermal stimulation and rapid initial formation of the solvent-solvent vapor chamber before transitioning to a more conventional pair of SAGD injection and extraction wells. Communication between the wells is established in one or more places along the length, for example through one or more processes that include fracturing, intersection of the pair of wells during drilling, and re-reaming from the tip of each well with overlapping reamed tides. A connection between wells, between the injection well and the extraction well, adjacent to their respective tips of the well pair maximizes the circulation path.

Alternative modalities establish toe-to-heel circulation upon initial completion of a circulation well, such as a completed thermal well adjacent to the tip of the SAGD injection well, to initially establish the stimulation circulation path.

<img file="MX343261B_D0009.tif" />

For example, between the thermal well and the industrial SAGD injection well towards the surface ^ lewSSSSKol ^

Once a one-way thermal stimulation circulation path has been developed, the thermal energy applied to the initial circulation can be provided by means of a thermal carrier such as steam, vapor-solvent, or other thermal mechanisms.

In addition to steam-based thermal mechanisms, other thermal sources may include a downhole steam generator, a burner or a form thereof that includes the applicant's co-pending patent application titled for a Bottom Well Vapor Generation Apparatus and Methods and Enhanced Oil Recovery (EOR) (filed Jan. 14, 2010 in Canada with serial number 2,690,105 and in the United States published on July 22, 2010 as US document 2010/0181069 Al, the entirety of both documents which are incorporated herein by reference). The applicant also refers to the downhole generation process as STRIP^mr, a trademark of Resource Innovations Inc., Calgary, Canada.

Accordingly, in another embodiment, the combustion products are circulated along at least the injection well. A combustion source can be located to access the injection well, flow

<img file="MX343261B_D0010.tif" />

the combustion products heated to the ^ iarw'ísíclil?

í «TOUSTRIAL injection from the heel to the toe or from_the toe to the heel.

Similarly, as in other circulation strategies described above, the combustion products can be injected through generation thereof in the injection well itself or from an adjacent completed thermal well at the tip thereof. Non-condensable products of combustion are vented from the other of the injection well or the extraction well that does not have the source of combustion. Ventilation may include pressure control.

In the case of a field of two or more adjacent and generally parallel SAGD well pairs, the additional thermal energy through injection of combustion products can alter and mobilize a more significant portion of the well pairs between the reservoir. In modalities that use a thermal well, a thermal well can be completed to service or establish inter-well communication with multiple pairs of SAGD wells.

In a broad aspect, a method of initiating the mobilization and recovery of hydrocarbons by SAGD in a hydrocarbon formation involves drilling a pair of SAGD wells comprising an injection well having a first bead, a first tip, and a first portion that is extends horizontally between them, an extraction well that has a second heel, a second tip and, ΌΙ ^ ·&gt; ^ 'INSTITUTOMSXICaWC' t- 'To a second portion that extends horizontally ^^^^ n ^ e same, initially establishing a thermal circulation path along at least a portion of the horizontally extending portion of the injection wells during the start-up phase; and subsequently establish either a gradual increase or a conventional SAGD operation.

In another aspect, one method of initiating SAGD mobilization and oil recovery in an hydrocarbon formation involves completing a pair of SAGD wells within the formation, the pair of wells having an injection well placed generally parallel to and separated above an extraction well, the injection well and, once completed, establishes a one-way thermal stimulation circulation along the injection well by connecting the injection well to a circulation well. After the thermal carrier circulates between the injection well and the circulation well, an initial thermal chamber is formed along at least a portion of the injection well. The thermal chamber mobilizes the hydrocarbons for recovery from the extraction well.

In various respects, initially establishing thermal circulation comprises one or more of: forming a unidirectional thermal flow path along the tip of a portion path that extends horizontally. CS'J '^ iíl ^ i ^;'

J INOUtfklAL injection, in one modality from heel to toe, in another from toe to heel, or to form a thermal circulation path between wells, between the first and second horizontally extending portions to establish an initial thermal chamber between the first and second portions that extend horizontally in the communication path between wells, establish steady-state thermal energy injection to grow the initial thermal chamber or complete and communicate with a thermal well adjacent to the first tip to establish a thermal flow path along the first portion extending horizontally in any direction and subsequently interrupt the circulation flow path; and mobilize the hydrocarbons and recover the hydrocarbons from the extraction well in a SAGD operation.

In other aspects, the source of thermal energy to transfer along the thermal flow path is steam, combustion products of steam formed from the boundary of combustion products, and injected water. Combustion products such as downhole combustion exhaust gases can be generated using a downhole burner located in the injection well or in a thermal well adjacent to the first tip

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with recovery of at least part

INDUSTRIAL non-condensable combustion of the thermal well or the injection well, respectively.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is a representative figure of a steam assisted gravity drainage (SAGD) system known in the prior art;

Figure 2 illustrates a direct inter-well connection of a pair of SAGD wells created by directionally drilling a tip of an injection well downward to a tip of a corresponding extraction well;

Figure 3 illustrates a direct connection between wells of a pair of SAGD wells created by fracturing a region between wells between a tip of an injection well and a tip of an extraction well;

Figure 4 illustrates a direct well-to-well connection path of a pair of SAGD wells created by directionally drilling a tip of an extraction well upward to intercept a tip of a corresponding injection well;

Figure 5 illustrates a downhole burner positioned at the heel of the injection well and the formation of an initial thermal chamber created by the circulation of the thermal carrier from the injection well to the extraction well, the thermal chamber performs the connection between the wells;

<img file="MX343261B_D0014.tif" />

Figure 6 illustrates the connection between wells of Figure 5 subsequently cemented or otherwise blocked to propagate the growth of a thermal chamber in steady state SAGD operations;

Figure 7 illustrates a downhole burner placed in a new thermal well adjacent to a pre-drilled injection well tip;

Figure 8 illustrates a thermal chamber created by a burner at the bottom of the well in the embodiment of Figure 7, the thermal camera is in communication with the bottom of the well and intersects the extraction well;

Figure 9A is a cross-sectional view of laterally spaced thermal chambers created from conventional SAGD operation;

FIG. 9B is a cross-sectional view of laterally separated thermal chambers created from a conventional steam-solvent SAGD operation;

Figure 9C is a cross-sectional view of the laterally separated thermal cameras created by the various embodiments described herein;

Figure 10 is a perspective view of a formation having multiple thermal wells, each of which is generally positioned between a pair of SAGD well pairs of a field of SAGD well pairs;

IMPIOUS;

Figure 11 is a vist4 &lt;?^andW^to

IXTRIAL

INDUSTRIAL modality of a formation that has a thermal well placed generally between the tips of pairs of facing SAGD wells;

Figure 12 illustrates a thermal well placed at the tip of an injection well of a pair of SADG wells that have previously been produced and depleted;

Figure 13 illustrates an alternative distribution of the injection well and the extraction well in a carbonate formation, a horizontally extending portion of the injection well being positioned closest to the ceiling of a useful-overload zone boundary;

Figure 14 illustrates a gas powered gravity drain procedure as applied to carbonate formations;

Figure 15 illustrates a thermal siphon process as applied in conventional SAGD formation; and Figure 16 illustrates fractures within the usable zone of a carbonate deposit to increase the permeability and mobilization of hydrocarbons around a downhole burner.

DETAILED DESCRIPTION OF THE INVENTION

The modalities herein increase the initiation phase of prior art SAGD operations and establish a stimulation circulation path P

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Μ- ΡI one-way thermal along the pcFaiCgl '^ w ^^ eC ^ .óílí ^ an INDUSTRIAL circulation well, either by creating a substantially direct connection between wells to the extraction well or by introducing a new thermal well adjacent to the tip of the injection well for communication with it. The unidirectional thermal stimulation circulation path P to extract the liquid phase, condensate or emulsion created by the steam as the bitumen heats up in the formation. Thermal energy can be applied by means of steam, or a burner at the bottom of the well. A downhole burner can further increase extraction from even depleted SAGD formations.

During or after completion of a pair of SAGD wells, the injection well may be connected to a circulation well to form a one-way thermal stimulation circulation flow path through them. The circulation well is either proportional to the introduction of a thermal carrier or the extraction of its products. The products of the introduction of a thermal carrier may include condensate, emulsion and non-condensable components.

Referring to Figure 2, one embodiment may comprise establishing a substantially direct connection between a pair of wells in an injection well 10 and a well 20

Vip. 1 extraction, as the circulation well ^ 5 ^ OÍ &amp; A0l&gt; T ^ 3? £ ae

INIM.FSTAIAI can develop an initial thermal camera.

A pair of SAGD wells is completed, as shown, by drilling the injection well 10 comprising a first bead 40, a first tip 50, and a first portion 60 extending horizontally therebetween from the surface within a formation 70 with hydrocarbons. Similarly, extraction well 20 comprises a second bead 80, a second tip 90 and a second portion 100 extending horizontally therebetween, which is drilled so that the second portion 100 extending horizontally is substantially parallel and spaced below the first horizontally extending portion 60.

In one embodiment, a direct connection 120 can be formed between the horizontally extending portions 60, 100 of the well pair to rapidly establish communication between wells, between injection well 10 and extraction well 20 and the path P of thermal stimulation circumcision to allow direct circulation of thermal energy between at least a portion of the horizontally extending portions of the injector well 10 and a circulation well, in this case, extraction well 20. Although Figure 2 illustrates the substantially direct connection 120 between wells that is formed

IMP i approximately at points 50, 90 de'i ^ np ^ iPiMi ^ e, * NDUSTHML injection-extraction, the applicant notes that the substantially direct connection 120 between wells is located somewhere along and between the portions that they extend horizontally 60, 100 from the respective injection well 10 and the extraction well 20. For purposes of this application, connection 120 between wells will be illustrated positioned adjacent to tips 50, 90 of horizontally extending portions 60, 100 of injection and extraction wells 10, 20, maximizing effective length of portion 60 extending horizontally from injection well 10.

Referring to FIG. 3, and in one embodiment, the direct inter-well connection 120 can be formed by fracturing a region between wells or an intermediate portion 130 of formation 70 between horizontally extending portions 60, 100 of the pair of wells . In one embodiment, and as shown, the fracture can be performed at at least one of tips 50 or 90 of the pair of horizontal wells to the other. The Applicant considers that, due to the close proximity of well spacing in SAGD well pairs, typically on the order of 5 meters, fracture preferentially occurs between injection well 10 and extraction well 20 of each pair of wells which generates a substantially direct 120 connection, connections or pathways P

IMP pariTiao «tocare ot la rnomoAtj INDUXTglAL

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for the formation thermal mechanism 70.

In another embodiment, the direct connection 120 may be formed by directional drilling through the intermediate portion 130 of the formation 70 between two horizontally extending portions 60, 100 such that the horizontally extending portions 60, 100 intersect between yes. Referring again to Figure 2, the first tip 50 of the first horizontally extending portion 60 may be tilted down during drilling to

<td>to extend</td><td>and intercept</td><td>to</td><td>second</td><td>serving 100 c</td><td>Thu</td><td>I know</td>

<td>extends</td><td>horizontally.</td><td></td><td></td><td></td><td></td><td></td>

<td></td><td>With reference</td><td colspan="2">to figure 4,</td><td colspan="2">similarly,</td><td>in</td>

<td colspan="2">another modality, the tip</td><td>90 of</td><td colspan="2">the second portion 100</td><td>than</td><td>I know</td>

<td>extends</td><td>horizontally</td><td>can</td><td colspan="2">be leaning towards</td><td colspan="2">above</td>

<td>during</td><td>drilling</td><td>for</td><td>to extend</td><td>and intercept</td><td>to</td><td>the</td>

first portion 60 extending horizontally.

The intersection of the injection well 10 and the extraction well establishes a direct or substantially direct connection 120 and the circulation path P.

Referring to Figure 5, once the connection 120 between wells is established, an initial thermal chamber 140 is generated by the circulation of a thermal carrier. In one embodiment, thermal energy can be injected or conveyed to the bottom in injection well 10

1Μ Ρ ϊ by injection of the carrier ténroii ^ pp ^^^ c

INDUÍTRIAL or, as shown in an alternative modality, through the discharge of the hot discharge gases from a burner 150 at the bottom of the well placed approximately in the first bead 40 of the injection well 10. The heat carrier, commonly in the form of steam, either from the surface or from an on-site steam generator, hot discharge gases from a burner, either located above the surface or placed at the bottom of the well can be circulated through, from injection well 10 through thermal chamber 14 0 and into extraction well 20. During the circulation of the thermal carrier, the steam condenses and the water and the emulsion are pumped from the extraction well 20. In the case of a burner, the non-condensable materials and exhaust gases can be vented through the extraction well 20 simply as part of the circulation path by thermal stimulation.

In one embodiment, and as shown, a burner 150 may be placed at the bottom of the well in a vertical position 160 adjacent to the first bead 40 of injection well 10 to generate hot discharge gases which can be circulated through the path P of circulation by thermal stimulation created between a pair of wells to heat, dissolve or mobilize some other

ΙΜΡΙ injtttut · mu, CAN », Munom» »,, INtwST» · »¹

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way surrounding oil in the well pair.

Additionally, as shown in Figure 5, and in one embodiment using a steam generator, such as the applicants generator described in the published US patent application serial number 2010/0181069, at least the hot discharge gases, and the associated heat in the formation, can be placed approximately on the first bead 40 of the injection well 10 and can be operated in a stable state to drive so less thermal energy and hot discharge gases downward from the first horizontally extending portion 60 to supply the hot discharge gases and heat formation 70. Thermal energy from the heat and hot discharge gases can be transferred to the intermediate portion 130 of the formation 70 while the resulting excess non-condensable gases can be circulated and extracted through the bottom extraction well 20. The heat from the processes also converts water with cream or additional injected water to steam, adding a thermal steam mechanism. The heavy oil mobilized by oil flows down to the extraction well 20 and can also be mixed with the excess discharge gases which can provide an upward hydraulic force of gas to transport the mobilized oil to the surface.

Referring to Figure 6, once startup is complete and in accordance with

<img file="MX343261B_D0017.tif" />

Í&gt; E LA MOriFDAÚ 'Í'V-'

INDUSTRIAL gqK, hydrocarbon receives an increasing amount of thermal energy for heating the bitumen, and as the thermal chamber 140 grows or spreads, the method is adjusted to focus more this way on the matrix oil above the extraction well 20 and around injection well 10. Consequently, the circulation path P formed by the two wells 10, 20 is decoupled for transition in a more conventional SAGD scenario or in steady state operations by blocking connections 120 between wells.

Steady state operations are reminiscent of conventional SAGD operations. In the case of discharge gases supplied by a burner, there is also a CO₂ non-condensible that collects at the bottom of the initial thermal chamber 140. The hot discharge gases released in this chamber are superimposed on the CO cooler₂ in discharge gases which have lost thermal energy when they come into contact with an upper portion of the chamber walls. This procedure heats and dissolves the contact bitumen, the mobilized liquid drains down from the chamber walls for collection at the bottom of the chamber. Both liquid and excess non-condensable vapors are produced from the bottom of this chamber.

iwymvro M rX! CAN&gt; ¿'v · -;

In preparation for stable operation, the thermal injection process is temporarily suspended to allow for cement removal or blocking of some other type of any one of either injection well 10 or extraction well 20 at approximately connection 120 between wells. In one embodiment, and as shown in FIG. 6, the tip 90 of the extraction well 20 can be blocked by cementing and sealed adjacent to its tip 90. The extraction well 20 can be plugged by pressing and cementing to minimize the preferential flow of thermal injection between the pair of wells. In another embodiment, cemented and plugged blocking may occur in injection well 10 around connection 120 between wells. Additionally, in order to mitigate the preferential flow around the plugged well, cementitious compression can be used in the formation by avoiding the preferential flow of thermal injection between the pair of wells through the gap between the jacket and the formation.

As a result of the decoupling of the injection well 10 and the extraction well 20, and the gravity drainage of oil mobilized within the lower extraction well 20, the growth of the thermal chamber 140 is generally expected to be radial in nature, from approximately the location of a connection 120 between wells substantially directly to heels 40, 80 of the py

MEXICAN INSTITUTE&gt;. · 7. '-y Λ, OF THE PROPERTY' ¿'r. . ; J-: '2i INDUSTRIAL pair of wells.

In an alternative embodiment, and as shown in Figure 7, a new circulation well, such as thermal well 15, can be drilled to place burner 120 at the bottom of the well at approximately the first tip 50 of injection well 10 . As shown in this embodiment, the thermal well 15 is vertical.

As shown, thermal well 15 is produced and a burner 150 can be installed at the bottom of the well at approximately the first tip 50 of an injection well 10. Thermal well 15 can be placed close enough to upper injection well 10 to allow steam and / or solvent to decompose and flow into formation 70 via first portion 60 extending horizontally to create circulation path P by thermal stimulation. Heat and / or solvent can be displaced downward from the first horizontally extending portion 60 of injection well 10, during which time heat and / or solvent can propagate into the surrounding formation 70. The combined effect mobilizes the bitumen around injection well 10. As a result, injection well 10 can provide a dual function, firstly to create heat stimulation circulation path P and secondly as a vent for excess

IM

PJ &lt;Λ ·

------. you .i nwfTUTO M «X ICAN&gt;

D «LA F« t »'f?;? A) · &lt;

INDUSTRIAL non-condensable gases.

Referring to Figure 8, the hot discharge gases produced by the downhole burner 150 can be injected into formation 70 and heated from them can propagate through formation 70 surrounding upper injection well 10 to mobilize the bitumen therein and allow drainage by gravity and produced via the bottom extraction well 20.

The burner 150 at the bottom of the well additionally generates a thermal chamber 200 around the upper injection well 10 and the steady state operation of the burner 150 causes the thermal chamber 200 to grow until it reaches the lower extraction well 20.

Over time, the thermal chamber 200 grows to intersect the extraction well 2 0 and the area around the pair of wells evolves into a conventional thermal chamber. The non-condensable gases preferentially flow from the first tip 50 to the first bead 40 of the upper injection well 10.

Steady state operation of the downhole burner 150 generates hot discharge gases in approximately thermal chamber 200 and enters formation 70 of approximately first tip 50 to permeate therethrough. As described in the applicant's published US patent application

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... L u -&gt; ·. . '' sL

2010/0181069 (published on July 22, ^^^ "eusfRut steam within formation 70 as gravity drains water injected into it hot discharge gases. Steam formed within formation 70 surrounding chamber 200 Thermal will likely follow the path of least resistance and accordingly will likely flow into the first tip 50 of top injection well 10. This vapor transports and conducts heat into formation 70 around injection well 10 while non-condensable gases are then produced at the surface through injection well 10.

Ventilation of the discharge gases allows the mass flow of the thermal carrier along the injection well 10. To maintain pressure and prevent hot exhaust gases from venting immediately through injection well 10, a pressure valve 210 may be placed in injection well 10 at the surface. An excess of non-condensable gases are released at the surface through the circulation path P, the temperatures between the steam and the bitumen can be controlled allowing the pressure management of the system. This pressure management control allows the operator to control and manage thermal energy flows within the formation preferentially for areas that have not been taken into account o! Π&gt; Κ n »'T» TUT0&gt;'

Dt THE PROPERTY í „„ »IC _&gt;

industrial

Alternatively, the thermal well 15 may be virgin.

forming the ventilation portion of the circulation path P and the burner located in the injection well 10, as illustrated above in figure 5. The additional part of the thermal well replaces the connection 120 between wells, between the injection well 10 and extraction well 20 allowing an alternative improved start-up operation. Manipulating the reservoir pressure also controls the thermal spread of the thermal chamber

200.

Referring to FIG. 9A to FIG. 9C, the Applicant believes that the process modalities described herein result in a more efficient and greater extension of the lateral growth or expansion of the thermal chamber 200 compared to those of the prior art.

As shown in Figure 9A, conventional SAGD well pairs are typically separated by approximately 50 to 200 meters, and thermal cameras 200, 200 created by adjacent SAGD well pairs are separated by approximately 20 meters at their closest point. Similarly, as shown in Figure 9B, SAGD pairs of steam-solvent wells are typically 100 to 400 meters apart, and thermal chambers 200,

200 created by each pair of esJa wells »_JT^ S5E) ^ rd4 ^ s' pbr

DELA ÍROPIEDAP t'-vil. ¿Fj} INDUSTRIAL ** »» ..

approximately 30 meters at its closest point. As shown, the thermal chambers 200, 200 of neither of the conventional SAGD well pairs (Figure 9A) nor the SAGD steam-solvent well pairs (Figure 9B) intersect each other, resulting in a portion of the Formation 70 remains intact.

Referring to Figure 9C, the pairs of wells using the modalities described here may be approximately 100 to 400 meters apart. However, thermal chambers 200, 200 created by the modalities described herein expand laterally or horizontally within formation 70 to intersect the thermal chamber created by the pair of adjacent wells. The intersection of thermal cameras 200, 200 will likely reach all portions of formation 70 for SAGD operations.

Thus, in an embodiment shown in Figure 10 and Figure 11, a single thermal well 15 can be used to sufficiently affect two or more pairs of previously drilled SAGD wells. As shown, a unique new thermal well 15 can be drilled to position burner 150 at the bottom of the well around and between the tips 50, 50 of the injection wells 10, 10 of pairs of adjacent 300 SAGD wells (see Figure 10) or pairs of

<img file="MX343261B_D0018.tif" />

ΙΜΡΙ facing wells (see figure 11).

INDUSTRIAL

Typical conventional SAGD operations are known to produce only about 30% of the original oil in place (OOIP), leaving approximately 70% of the OOIP in formation for extraction. These depleted SAGD formations contain residual oil for EOR operations.

Accordingly, referring to Figure 12, alternative embodiments of the present invention can be used to extract the remaining 70% OOIP by utilizing a thermal chamber 400 created during the previous SAGD operation and implementing a more active EOR using burner 150. at the bottom of the well.

As shown in Figure 12, a new thermal well 15 uses the upper injection well 410 to acquire thermal contact with residual heavy oil and / or bitumen that remains in formation 70. Steam and hot discharge gases such as CO₂ they are generated at the bottom 415 of the new thermal well 15, which can be directionally drilled to intersect a tip 420 of the upper injection well 410. Injection well 410 can now serve two purposes: 1) to provide strict pressure control by venting excess non-condensable gases that accumulate in thermal chamber 400 through circulation path P; and 2) provide energy

Me

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JWnWTOMEMKUíMO ¿-.b_;- 757¾ thermal, such as heat generated by the quemad®, ^; '^ 5 downhole, having access to the - .. 70 facility to mobilize heavy oil and / or residual bitumen.

The steam and hot discharge gases, generated by the burner 150 at the bottom of the well, flow through the horizontally extending portion 430 of the injection well 410 transferring heat into the surrounding formation 70. The hot discharge gases are brought into direct contact with the residual bitumen in the surrounding formation 70 to heat the residual bitumen as the steam condenses within the formation 70, releasing heat thereto to heat the residual bitumen.

The mass flow through the horizontally extending portion 430 conveys mass and convective heat propagated by the thermal chamber 400 within the surrounding formation 70 and thermal energy is absorbed within the surrounding reservoir matrix as conductive heat to increase the formation and hydrocarbon temperatures. The mobility of the bitumen is increased enough to allow gravity drainage through the interstitial space of formation 70, collecting at the bottom 435 of thermal chamber 400 and allowing extraction thereof through extraction well 440.

Temperatures at the outer end of the thermal chamber 400 gradually increase (depending on pressure) as CO₂ and he fell ^ 3 ^ i^TA ^ í / j®d! Úc ^ ife27 ^^ í iÑr&gt; í&gt; .miAL absorb in the liquid phase (oil-water-CO₂). The resulting emulsion drains down the length of the outer wells of the thermal chamber 400 and accumulates around the bottom extraction well 440 for extraction of additional oil from the exhausted SAGD formation.

EXAMPLE

The application of the modalities described here to certain hydrocarbon formations, such as carbonate deposits, may include alternative well pair distributions since well pair locations will depend on hydrocarbon formation characteristics. For example, in carbonate deposits such as Grosmont formations located in Saleski, Alberta, Canada, and in one embodiment, injection well 10 may be installed closer to the existing 170 seal rock or overburden to facilitate drainage. EOR from top to bottom through vertical fractures (see Figure 13).

The separation between injection well 10 and extraction well 20 can be increased to facilitate the exploitation of carbonate on specific deposits that have a seal rock matrix. The goal of mobilizing bitumen from top to bottom, or gas-powered gravity drainage, may represent certain

INSTITUTO MexiCANc thermal efficiency problems with an inc ^ S ^ Yes) X: o '* », ^^,'ⁱ’^J‘'^rithermal loss to overload. No nW = nt-o ra can_ produce a high pressure zone at the injection site above the production well 20 which can result in downward mobilized oil drainage in the form of a scenario gas drive.

Referring to Fig. 14 and Fig. 15, the separation between the first horizontally extending portion 60 of injection well 10 and the second horizontally extending portion 100 of extraction well 20 may result in a displacement in the mechanisms for mobilized oil recovery.

As shown in greater detail in Figure 14, EOR from top to bottom or gas-powered gravity drain, the first horizontally extending portion 60 of injection well 10 is separated away from the second portion 100 extending horizontally from extraction well 20, near an upper part 180 of useful zone 130 and adjacent to seal rock 170. The applicant considers that the vertical fractures within the useful zone 130 provide conduits for the mobilized oil to drain down, which generates the gas impulse, towards the second horizontally extending portion 100 of the extraction well 20. Locating the first portion 60 that extends horizontally from the well

IMPR-10 injection around the upper part AOfiCruid ^ useful adjacent to the seal rock 170 a high pressure zone is generated above the extraction well 20. The method is considered to propagate near the boundary of the seal-usable zone rock with CO2 (a major component of hot discharge gases), solvent, and convective heat. The hot exhaust gases are in direct contact with the sterile seal rock zone and tend to flow preferentially downward through exhausted fractures within useful zone 130.

As shown in greater detail in Figure 15, the EOR from bottom to top, or a thermal siphon, the first horizontally extending portion 60 of injection well 10 is spaced closer to the second portion 100 that is horizontally extends from extraction well 20 near the middle part of useful zone 130 and the bottom of the well from seal rock 170.

The applicant considers that with the injection well 10 positioned lower in the formation 70 with hydrocarbons, the thermal losses of the overload are reduced to a certain extent and the process will depend on the thermal siphon, so that the hot discharge gases flow upwards , through the vertical fractures that have occurred and generate a cycle back down through τ

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of the fractures moving away from the source of'ca ^^ V $ u iNixmp the heating process and drain into the lower vapor-solvent chamber.

Vertical fractures within useful zone 130 are considered to provide conduits for hot discharge gases to flow upward and mobilized oil to drain downward, causing a movement of thermal siphon gravity drainage fluids. The method is considered to propagate useful zone 130 with CO₂(hot discharge gases), solvent and convective heat. As discharge gases pass through usable zone 130, conductive heat transfer increases oil and rock temperatures while CO gas₂cooled forms an emulsion with hydrocarbons or acts as a substitute for emptying within useful zone 130.

Figure 16 illustrates a particular light oil recovery methodology for 200 carbonate deposits and the use of thermal EOR burner implementations. Similar to the gravity boost from top to bottom of Figure 14 and increased by the interaction of discharge gases and carbonates, a usable area 210 in a carbonate reservoir 200 with permeability channels 220 can be positively affected higher that are generated. As stated, burner thermal processes, such as STRIP, can promote porosity

IMPIory

JfOTWrTti - .V a greater within the carbonat deposits ^ w &amp; w ^^ si ^ aWjgXie when calcium bicarbonate contacts H₂0 saturated with C0₂ reacts to form soluble calcium carbonate [CaCO₃ + C0₂ + H₂0 - »Ca (HCO₃)₂]. Over time, this reaction will cause the carbonate component of the structure to erode. This chemistry will expand and cause the growth of existing fractures while generating high permeability channels 220 through useful zone 210. The thermal component generates an option to subject 10 portions of a carbonate deposit in close proximity to an injection well to high temperatures.

Although not shown in figure 16, a C0 gas cap₂ Growing in injection well 10 provides a harnessing mechanism to drive 15 gas to move oil down to the extraction well. Mobilized oil is swept down through fractures, such as reef fractures, with steam and C0₂. The mobilized oil is collected at the bottom of the useful zone where it is extracted through the extraction well.

It is noted that in relation to this date, the best method known by the applicant to put the aforementioned invention into practice, is the one that is clear from the present description of the invention.