METHOD FOR CONFIGURING WELLBORES IN A GEOLOGIC FORMATION

Abstract

Closed loop wellbore configurations with unrestricted geometry for accommodating irregular or challenging thermal gradients within a thermally productive formation are disclosed. A working fluid is utilized in the loop for extraction of thermal energy there from. The loop and the unrestricted geometry are achieved using magnetic ranging of independent drilling operations which intersect from an inlet well and outlet well to form an interconnecting segment. In conjunction with the directional drilling, conditioning operations are incorporated to condition the rock face, cool the entire system, activate the wellbore for treatment to optimize thermal transfer inter alia. The significant degree of freedom in wellbore configuration is further optimized by the absence of mechanical impediments such as casing or liners in the heat transfer areas.

Claims

1. A method for configuring wellbores in a thermally productive geologic formation, comprising: drilling independently in said formation a well having an inlet well and an outlet well; signalling between said inlet well and said outlet well during drilling to intersect to form a continuous well having an interconnecting segment between said inlet well and said outlet well, said interconnecting segment having a predetermined angular configuration relative to said inlet well and said outlet well within said formation; conditioning at least said interconnecting segment to facilitate thermal recovery by working fluid flow therethrough without casing or liner material in said interconnecting segment.

2. The method as set forth in claim 1, wherein conditioning is effected by at least one of continuously, discontinuously, during, after and in sequenced combinations of drilling of at least one of drilling said inlet well and said outlet well.

3. The method as set forth in claim 1, wherein conditioning includes introducing at least one of a composition not native to said formation and a unit operation and combinations thereof.

4. The method as set forth in claim 1, further including the step of dynamically modifying said conditioning responsive to signalling data from at least one of the drilling operations of said inlet well and said outlet well.

5. The method as set forth in claim 3, wherein said unit operation includes controlling the temperature of drilling fluid, pre-cooling a rock face in said formation being, drilled, modifying pore space of wellbores formed from drilling in said formation.

6. The method as set forth in claim 5, wherein modification of said pore space comprises at least one of activating said pore space for subsequent treatment to render said pore space impermeable to formation fluid ingress into said interconnecting, segment or egress of said working fluid into said formation, sealing said pore space during drilling in a continuous operation, sealing said pore space during drilling in a discontinuous operation and combinations thereof.

7. The method as set forth in claim 5, further including the step of selecting a modification based on signalling data from signalling between said inlet well and said outlet well.

8. The method as set forth in claim 5, wherein said unit operation includes forming conduits in said formation relative to a longitudinal axis of said interconnecting segment and in fluid communication therewith for augmenting thermal recovery with said working fluid.

9. The method as set forth in claim 8, wherein said conduits have a terminal end.

10. The method of claim 9, wherein said conduits comprise radial bore segments, induced fractures, induced cracks, induced fissures and combinations thereof.

11. The method as set forth in claim 9,further including the step of augmenting thermal recovery with said conduits by containing buoyancy driven convection cells.

12. The method as set forth in claim 10, further including the step of positioning radial bore segments of an interconnecting segment in thermal contact with the adjacent radial bore segments of an adjacent interconnecting segment of another well.

13. The method as set forth in claim 10, further including the step of connecting radial bore segments of an interconnecting segment for fluid communication with the adjacent radial bore segments of an adjacent interconnecting segment of another well.

14. The method as set forth in claim 1, further including positioning said interconnecting segment relative to a plane of said inlet well arid a plane of said outlet well within said formation where the plane of said interconnecting segment is in a plane that is selected from the group comprising: an orthogonal plane, an acute plane, an obtuse plane, coplanar and a parallel plane relative the plane of at least one of the inlet well and outlet well.

15. A well configuration suitable for recovering thermal energy from a thermally productive geologic formation through circulation of fluid there through, comprising: an inlet well; an outlet well; an interconnecting segment in fluid communication with said inlet well and said outlet well and disposed within a thermally productive area of said formation; a selectively operable auxiliary segment in fluid circulation communication with said interconnecting segment for storing heated fluid; a detritus segment in fluid communication with at least one of said inlet well, said outlet well and said interconnecting segment for collecting well detritus; said outlet well being at least one of concentric with said inlet well and between 5° and 175° relative to said inlet well; the interconnecting segment being between 5° and 355° relative to said inlet well; and a conversion device connected with the wells to form a dosed loop and collect recovered thermal energy from said fluid for conversion.

16. The well configuration as set forth in claim 15, wherein said auxiliary segment includes a selectively operable valve for allowing stored heated fluid circulation access to said interconnecting segment.

17. The well configuration as set forth in claim 15, wherein said auxiliary segment includes a selectively operable outlet in fluid communication with at least one of said conversion device and an adjacent well configuration.

18. The well configuration as set forth in claim 15, wherein said auxiliary segment augments thermal recovery by containing buoyancy driven convection cells.

19. The well configuration as set forth in claim 15, wherein said configuration comprises a plurality of said well configurations.

20. The well configuration as set forth in claim 19, wherein said configuration comprises a plurality of said well configurations in at least one of a concentric and spaced relation, a spaced laterally offset parallel planar relation, including a common inlet well and a common outlet well and combinations thereof.

21. The well configuration as set forth in claim 14, wherein said configuration includes a plurality of interconnecting segments in fluid communication with said inlet well and said outlet well, said configuration having a plurality of spaced apart arrays of said interconnecting segments in a predetermined pattern.

22. The well configuration as set forth in claim 21, wherein said plurality of interconnecting segments include at least one of a common inlet well and a common outlet well.

23. The well configuration as set forth in claim 21, wherein said plurality of interconnecting segments each have an inlet well and are collectively connected to a common outlet well.

24. The well configuration as set forth in claim 15, wherein said detritus segment includes a sensor for sensing collected detritus in said segment.

25. A method of forming a well configuration suitable for recovering thermal energy from a thermally productive geologic formation through circulation of fluid there through, comprising: independently drilling an inlet well and an outlet well in a predetermined location in said formation; intersecting drilling from said inlet well and said outlet well to form an interconnecting segment between said inlet well and said outlet well in a predetermined thermally productive area of said formation position in said formation, said outlet well being at least one of concentric with said inlet well and between 5° and 175° relative to said inlet well, said interconnecting segment being between 5° and 355° relative to said inlet well; forming a selectively operable auxiliary segment in selective fluid circulation communication with said interconnecting segment for storing heated fluid; forming a detritus segment in fluid communication with at least one of said inlet well, said outlet well and said interconnecting segment for collecting welt detritus; and providing a conversion device connected with the wells to form a closed loop and collect recovered thermal energy from said fluid for conversion.

26. The method as set forth in claim 25, wherein intersecting drilling from said inlet well and said outlet well to form an interconnecting segment between said inlet well and said outlet is conducted by electromagnetic signalling.

27. The method as set forth in claim 26, further including selectively positioning electromagnetic signalling devices in predetermined combinations of said inlet well, said outlet well, said detritus segment and said interconnecting segment.

28. The method as set forth in claim 27, further including the step of operating said electromagnetic signalling devices in, a predetermined sequence.

29. The method as set forth in claim 28, further including the step of signalling a well in progress with signalling from a previously formed adjacent well.

30. The method as set forth in claim 25, further including the step of positioning a sensor in said detritus segment.

31. The method as set forth in claim 30, further including the step of altering the chemical composition of said working fluid in response to a sensed signal from said detritus segment.

32. The method as set forth in claim 25, wherein said formation is a geothermal formation.

33. The method as set forth in claim 25, further including the step of circulating fluid within said interconnecting segment in the absence of casing and liners.

34. The method as set forth in claim 32, wherein said geothermal formation has a temperature of not less than 40° C.

35. The method as set forth 25, further including the step of providing a plurality of interconnecting segments in fluid communication with said inlet well and said outlet well, said configuration having a plurality of spaced apart arrays of said interconnecting segments in a predetermined pattern.

36. The method as set forth 35, further including the step of selectively circulating said fluid from one array as a slipstream to an inlet point of a spaced second array prior to discharge at said outlet well common to all arrays.

37. The method as set forth in claim 36 wherein said slipstream preheats fluid from said inlet well prior to circulation in said spaced second array.

38. The method as set forth in claim 36, further including the step of distributing said slipstream to an adjacent well configuration for thermal augmentation of said adjacent well.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0070] FIG. 1 is a schematic illustration of a closed loop energy recovery arrangement;

[0071] FIG. 2 is a coordinate system illustrating the possible positions of an interconnecting segment or segment group within the volume of a formation to have thermal energy recovered therefrom;

[0072] FIG. 3 is a flow chart delineating the steps involved in forming a wellbore configuration by drilling intersection of at least two points;

[0073] FIG. 4 is a cross section of a wellbore variation;

[0074] FIG. 5 is side view of FIG. 4;

[0075] FIG. 6 is an alternate embodiment of FIG. 5;

[0076] FIG. 7 is an, embodiment of a wellbore configuration;

[0077] FIG. 8 is an alternate embodiment of a wellbore configuration;

[0078] FIG. 9 is a further alternate embodiment of a wellbore configuration;

[0079] FIG. 10 is a further alternate embodiment of a wellbore configuration;

[0080] FIG. 11 is a further alternate embodiment of a wellbore configuration;

[0081] FIG. 12 is a further alternate embodiment of a wellbore configuration;

[0082] FIG. 13 is a schematic illustration of a system of wellbore configurations within a formation;

[0083] FIG. 14 is a schematic illustration of a network of sectored wellbore configurations;

[0084] FIG. 15 is schematic illustration of a wells system illustrating the detritus segments;

[0085] FIG. 16 is a schematic illustration of stacked wells in a modular format;

[0086] FIG. 16A is an alternate embodiment of FIG. 16;

[0087] FIG. 17 is a schematic illustration of a well system where there is interconnection between auxiliary segments; and

[0088] FIG. 18 is a schematic illustration of a network of well systems integrated with an electrical grid

[0089] Similar numerals used in the Figures denote similar elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0090] Referring to FIG. 1, shown is a schematic representation of a closed loop well system 10 disposed within a thermally productive formation 12. The system 10 includes an inlet well 14, an interconnecting well segment 16 and an outlet well 18 in closed loop fluid communication with an energy processing device 20 positioned on the surface, S. The outlet well may be co-located with the inlet well at the device 20 or located distally as shown by the dashed line 22 for alternate connection. A working fluid is circulated through the system 10 in order to absorb thermal energy from within the formation 12.

[0091] For efficiency, the interconnecting well segment 16 is not cased or lined and does not include any other pipe or related mechanical arrangements. The outlet well 18 and inlet well 16 may be cased or otherwise made to comply with accepted practices known to those skilled in the art Any detritus that evolves from use of the arrangement may be collected in segments 19.

[0092] Energy processing device 20 may process the energy for other uses broadly denoted by numeral 24, stored at 26 or passed on to an electrical grid 28 which optionally may include solar devices 30 and/or wind devices 32 in any suitable combination.

[0093] In respect of the spatial orientation of the wells within a thermally productive formation, reference may be had to FIG. 2. In the illustration, elements have been removed for clarity, however it will be understood that the illustration is to convey the disposition of the interconnecting segment 16 may have relative to at least one of the plane of the inlet well 14 and outlet well 18.

[0094] In the Figure, the interconnecting well segment 16 may be positioned at any angle within any of the planes (X-Y), (X-(-Y)) ((X)-Y) ((-X)-(-Y)), (X-Z), (X-(-Z)), (Z-(-X)), ((X)-(-Z)), (Z-Y), (Z-(-Y)), ((-Z)-(-Y)) and ((-Z)-Y) and may also be disposed to have an X, Y and Z coordinate for cross plane disposition. For purposes of explanation the positive x axis will represent the inlet well 14. The well may be disposed at any angle alpha or beta in a range which does not impede operation of the well 14. This is equally true for outlet well 18. The inlet wells 14 and outlet wells 18 communicate with the surface, S, as referenced in respect of FIG. 1.

[0095] Any number of interconnecting segmentsl6 may be disposed within the space discussed. Other well configurations will be discussed in the advancing Figures. The quantity and spatial positioning will depend on the thermal gradient of the formation 12.

[0096] Advantageously, the observation of the drilling by intersection between the inlet well 14 and outlet well 16 by independent drilling operations to form the interconnecting segment 18, the absence of liners, casing, etc. within the interconnecting segment with conditioning of the drilling operation, results in configuration freedom to maximally recover thermal energy.

[0097] FIG. 3 illustrates an example of the steps involved in sensor ranging the inlet well and outlet well in a formation for intersection through the formed interconnecting segment. Although the example references an interconnecting segment, it will be understood that the methodology relates to multiple interconnecting segments formation in any pattern as discussed in respect of FIG. 2. The individual interconnecting segments are fully utilizable to have sensor communication there between to guide the drilling of subsequent interconnecting segments with a given well system or those being formed in a proximate system within the formation. By providing the cross communication between the wells, the inlets, the outlets and interconnecting segments, trajectory drift is minimized to facilitate accurate intersection of the wells being drilled. Sensors may also be utilized in the detritus capture segments 19, not shown and discussed in greater detail herein after.

[0098] Referring now to FIG. 4, a cross section of an interconnecting segment 16 is shown disposed with formation 12. Extending from the segment 16 are or conduits 34 extending into the formation 12. Conduits 34 may be voids either in fluid communication with the interior 36 of segment 16 or sealed without fluid communication with the interior 36. It has been found that the conduits 34 are useful to enhance the thermal recovery capacity of the interconnecting segment when working fluid is circulated there though as well in periods of quiescence. Positioning and quantity of the radially extensions will be dictated by formation characteristics to maximize thermal recovery without structural/mechanical compromise of the segment 16. Where adequate, if pre-existing fissures, cracks, fractures or contained areas of permeability are encountered, they may be used to function as conduits. Theses may also occur during drilling of the segment 16.

[0099] FIG. 5 illustrates an example where the conduits 34 are arranged in a generally helical pattern with the dotted points representing those extending outwardly from the plane and those crossed points being representative of the extensions on the opposed surface extending away from the plane. This is exemplary; the pattern with be ascertained from gradient data amongst other germane parameters.

[0100] FIG. 6 illustrates a further example where a plurality of segments 16 are disposed within formation 12. In the example, the extensions 34 of adjacent segments may be arrange in close proximity to fill a given area 38 with extensions to effectively increase the volume of the gradient from which thermal energy may be recovered. The conduits 34 act as a convection cell of buoyancy driven flow which direct thermal energy into the interior 34 of segments 16. The extensions can be arranged for adjacent positioning or interdigitated with other conduits 34.

[0101] As a further embodiment, the individual segments 16 may be connected by the conduits 34, the connection being generally denoted by numeral 40. In this manner, the arrangement has the appearance of a ladder when viewed perspectively.

[0102] Turning now to the well configuration possibilities, FIG. 7 illustrates a generally toroidal well configuration generally denoted by numeral 42 disposed within formation 12.

[0103] In this arrangement, inlet well 14 is in fluid communication with a main inlet hub well 44 which is connected to each of the interconnecting segments 16. Suitable valve devices (not shown, but generally represented by numeral 46) may be incorporate in some or all of the looped segments 16 for fluid flow redirection and other control. The arrangement 42 also includes a main outlet hub well 48 connected in a similar manner as that indicated for main inlet hub well 46 with a similar valving feature (not shown).

[0104] Within the structure, each looped segment 16 may be operated as a single unit to recover thermal energy.

[0105] As an operational alternative, the flow of working fluid within arrangement 42 may be circulated in a generally helical pattern through the whole arrangement with sequencing of periods of quiescence to allow for maximum thermal recovery. Such flexibility allows for connection to, for example the energy processing device 20. This facilitates on demand power when the energy is converted to electricity and overcomes the limitations associated with baseload power peak delivery issues.

[0106] FIG. 8 illustrates a further embodiment of a well configuration denoted by numeral 50. The general shape is that of a saddle where the interconnecting looped segments are adjacent one another with an arcuate presentation. The inlet well 14 may be connected to each of the looped segments 16 in a hub or manifold arrangement 52 or valved at 54 for selective operation. In a similar manner, outlet 18 may connected in the same fashion.

[0107] FIG. 9 illustrates yet another possible variation generally in the form of an inverted parabola.

[0108] FIG. 10 illustrates another well system configuration where the inlets 14 may be singular from distant points in the configuration or joined at 56. Similarly, outlets 18 may be combined at 58. For coloration, the outlets 58 and inlets 56 may be extended for geographic proximity.

[0109] FIG. 11 illustrates a general cone shaped configuration where the outlet well 18 may be at the bottom portion of the configuration or the top as shown in dashed line. The lower parts of the looped segments 16 may be connected together or independent.

[0110] FIG. 12 illustrates yet another configuration in the general form of a whisk. In this embodiment, the segment loops 16 may have a concentric inlet 14 and outlet 18 with fluid flow from the inlet in the direction of arrow 62 and outlet flow at 64. This arrangement allows for a large volume of the formation to be “mined” for heat in the formation 12 outside of the configuration and in the formation volume 66 within the configuration. One of the advantages with this configuration are that all of the intersections happen with a single borehole or “mother bore” and electromagnetic signalling can be simplified, even accomplished with permanent devices placed in the mother bore or passively. Another advantage is only a single vertical bore is required to house both the inlet and outlet flow streams.

[0111] Turning to FIG. 13, a wellbore system sector is schematically depicted generally denoted by numeral 68. Sector 68 is within a thermally productive formation 12, with the positioning of different wellbore configurations positioned in predetermined zones to maximize gradient coverage. In the example, the sector 68 provides a stacked and spaced arrangement of looped segments 16 sharing a common inlet well 14 and common outlet well 18.

[0112] Depending on the parameters, fluid circulation may follow the pattern denoted A through F. In this manner, at least a portion of heated fluid from top looped segments 70 may preheat the fluid entering bottom looped segments 72. Alternatively, each of the looped segments 70 and 72 can be operated independently.

[0113] In respect of the remaining configurations, the toroidal configuration 80 may receive heated fluid from the outlet 18 of the stacked arrangement 70, 72 as denoted by the dashed lines 74 or simply have an independent inlet well 14 denoted by the chain line 76.

[0114] The whisk configuration, may have an independent inlet well 14 and a bottom positioned outlet well 18 or the inlet well may be common with that of the toroidal configuration as denoted by numeral 78.

[0115] Finally, the saddle configuration may include a common outlet well with the toroidal configuration at 80.

[0116] It will be understood that all inlet wells 14 and outlet wells 18 will extend to the surface or conversion device 20 (FIG. 1) for operation. In the FIG. 13, the wells 14, 18 are truncated for purposes of clarity in the illustration.

[0117] The sector 68 is exemplary only as are the wellbore configurations and common and independent combinations. With the intersecting directional drilling, the conditioning operations and sensor guided drilling, any pattern or configuration can be synthesized to exploit even the most irregular, disparate multizonal gradient distributions. All of these features when unified with the fact that the instant technology does not include piping liners or other mechanical arrangements within the heat recovering interconnecting segments, immediately removes geometric constraints for the configurations thus allowing the mining of any gradient in any rock formation.

[0118] FIG. 14 is another example of a well arrangement 82 to recover thermal energy from a specific volume of the formation 12. In the example, the detritus segments 19 may include sensors 84 to transmit information regarding detritus accretion. In this manner, the working fluid may be compositionally altered to incorporate chemical additives to mitigate/repair any compromised areas with the well system. The arrangement of the interconnecting segments 16 may disposed in a spaced array as shown to recover thermal energy.

[0119] Further, as illustrated in FIG. 15 auxiliary segments 86 may be in fluid communication with a respective segment 16 to which it is attached and incorporate a valve mechanism 88 to allow for selective operation. The auxiliary segments 88 may be used to store heated working fluid selectively used as a thermal driver in the arrangement for the well system in the example or used via suitable interconnection to another well system (not shown in this Figure). As illustrated, the auxiliary segments 86 may be positioned in a coplanar disposition with the segment to which it is attached or in an orthogonal plane as shown in dashed lines in the Figure. Suitable variations to this are envisioned depending on the gradient features.

[0120] FIGS. 16 and 16A illustrate grouped well systems 82 in different angular dispositions with in the formation. In the grouped configurations, the systems 82 are modularized within a specific volume of the formation 12 thus allowing for a small footprint and convenient general co-location of the inlet well 14 and outlet well 18. Within the module, inlet wells 14 and outlet wells may be common to individual well systems or common for all modules in the system 82.

[0121] FIG. 17 provides for the possibility of interconnecting auxiliary segments 86 between adjacent wells at 90 or thermal supplementation from one outlet 18 to an inlet 14 of an adjacent well.

[0122] In FIG. 18 a network is depicted and intended to convey the feature that the energy produced within any well system 82 can be taken directly for other uses through the energy producing apparatus 20 associated with that system 82, combined from one system 82 to another 82 as denoted by numeral 96 or further grouped as denoted by numeral 98 for eventual use on the electrical grid 28 to provide on demand power regardless of quantitative demand.