Improving the well performance of geothermal systems

Abstract

A method and system for extracting thermal energy from a conventional geothermal reservoir is provided. One embodiment includes drilling or accessing a production well intersecting a conventional geothermal reservoir and detonating at least one shaped blast line to enlarge or widen a naturally occurring crack in the conventional geothermal reservoir at the intersection of the naturally occurring crack and the production well, thereby reducing the pressure loss of the fluid flowing from the naturally occurring crack to the production well. By reducing the pressure loss, the fluid flow to the production well can be increased, and the amount of heat obtained can be increased. Detonation of the shaped blast line(s) can enlarge the opening size of at least one naturally occurring crack on the borehole surface.

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This disclosure claims priority to U.S. Provisional Patent Application No. 63 / 504,797, titled "BOOSTING WELL PERFORMANCE IN GEOHMMAL SYSTEMS," filed on May 30, 2023, the entire content of which is incorporated herein by reference.

[0002] [Technical Field] This disclosure relates to geothermal systems for extracting thermal energy (heat) from geothermal reservoirs.

Background Art

[0003] Geothermal systems for extracting thermal energy (heat) from geothermal reservoirs have received considerable attention. Conventional geothermal reservoirs are underground rock storage spaces that contain natural sources of pressurized hot water or brine used as a source of thermal energy (heat). One or more production wells are drilled from the surface towards and through a conventional geothermal reservoir, intersecting one or more naturally occurring fractures (commonly also called cracks) in the underground rock of the conventional geothermal reservoir. These naturally occurring fractures provide a flow path for pressurized hot water or brine to flow into the production well(s) and through the production well(s) to the surface. Thermal energy (heat) from the high - temperature fluid flowing to the surface can be extracted and used by an energy conversion plant for power generation, large - scale heating or cooling, industrial / agricultural processes, or other geothermal applications.

[0004] Figure 1 shows an exemplary geothermal system 101 including a conventional geothermal reservoir 109. A production well 103 is drilled from the surface 105 towards and through the conventional geothermal reservoir 109, intersecting a naturally occurring fault 111 in the subsurface rock of the conventional geothermal reservoir 109. The naturally occurring crack 111 provides a channel for pressurized hot water or brine to flow into the production well(s) and out through the production well 103 to the surface 105, as indicated by arrow 113. The thermal energy (heat) from the hot fluid flowing to the surface 105 can be extracted and used by an energy conversion plant for power generation, large-scale heating or cooling, industrial / agricultural processes, or other geothermal applications. The borehole of the production well 103 can be completed with a drilling casing 115 perforated at the intervals of the production well 103 intersecting the naturally occurring crack 111. Alternatively, the borehole of the production well 103 may be completed with a drilling liner or as an open wellbore in at least the section of the production well 103 that intersects with the naturally occurring crack 111.

[0005] Significant fluid pressure losses can occur where naturally occurring cracks 111 intersect with production wells 103 and fluid coupling occurs. Specifically, the opening of a naturally occurring crack 111 at the intersection with production well 103 can act as a flow limiter, restricting the flow of fluid into production well 103 through the naturally occurring crack 111. This can limit the amount of heat acquired by the system and delivered to the surface, potentially reducing the system's productivity. [Overview of the project]

[0006] This abstract is provided to introduce a set of concepts further described in the embodiments for carrying out the invention described below. This summary is not intended to identify the main or essential features of the subject matter described in the claims, nor is it intended to be used to help limit the scope of the subject matter described in the claims.

[0007] A method and system for extracting thermal energy from a conventional geothermal reservoir is disclosed. The conventional geothermal reservoir has at least one naturally occurring fissure penetrating it. A production well can be drilled or accessed so as to intersect with at least one naturally occurring fissure. The at least one naturally occurring fissure provides a channel for pressurized hot or brine to the production well. By analyzing well log data, the location or depth of at least one naturally occurring fissure in the production well can be determined. One or more shaped blast lines can be detonated in the production well at a location or depth corresponding to the location or depth of at least one naturally occurring fissure. Detonation of the shaped blast line(s) can be configured to enlarge or widen the naturally occurring fissure at the intersection of the naturally occurring fissure and the production well, thereby reducing pressure loss and increasing the flow rate of pressurized hot or brine carried to the production well by the naturally occurring fissure. The method can be performed at multiple naturally occurring fissures connected to the production well. The method can also be applied to multiple production wells intersecting a conventional geothermal reservoir.

[0008] In the embodiment, the amount of heat obtained by the system can be increased by reducing pressure loss and increasing the flow rate of pressurized hot water or brine delivered to the production well by naturally occurring cracks.

[0009] In this embodiment, the detonation of a shaped blast wire (or more) can enlarge the opening size of at least one naturally occurring crack on the borehole surface.

[0010] In the embodiment, shaped explosive lines(s) may be positioned within the production well such that the penetration pattern of the shaped explosive lines(s) resulting from the detonation intersects with at least one naturally occurring crack.

[0011] In the embodiment, the shaped blast line(s) may be supported by a downhole tool. The position of the downhole tool can be aligned with the location of at least one naturally occurring crack obtained from well log data, so that the penetration pattern of the shaped blast line(s) produced by detonation intersects with at least one naturally occurring crack.

[0012] In the embodiment, the location of the downhole tool and the location of at least one naturally occurring crack can be defined in a reference coordinate system, such as a reference coordinate system that includes the well depth and azimuth angle.

[0013] In the embodiment, the downhole tool may have a central axis, and the shaped blast wire(s) may be supported by the downhole tool in an orientation substantially parallel to the central axis of the downhole tool.

[0014] In this embodiment, the production well can be configured to carry a flow of heated fluid through the well and deliver it to the surface.

[0015] In other embodiments, a method for extracting thermal energy from a geothermal reservoir involves drilling a production well that intersects the geothermal reservoir in two stages, including shallow and deep stages. In the shallow stage, a large-diameter well is drilled from the surface or near the surface to an intermediate depth. In the deep stage, a small-diameter well is drilled below an intermediate depth relative to the geothermal reservoir, so that the deep small-diameter well extends below the shallow large-diameter well relative to the geothermal reservoir.

[0016] In this embodiment, the production well can carry a flow of heated fluid through the well and deliver it to the surface.

[0017] In the embodiment, the geothermal reservoir may be a conventional geothermal reservoir containing at least one naturally occurring fissure that carries a pressurized flow of hot or saltwater deep into the production well.

[0018] In other embodiments, the geothermal reservoir may be an unconventional geothermal reservoir that provides a source of pressurized, high-temperature fluid that flows into the deep part of the production well.

[0019] In another aspect, a method for extracting thermal energy from a geothermal reservoir includes drilling a secondary production well so as to intersect a primary production well at a point above the geothermal reservoir.

[0020] In embodiments, both the primary and secondary production wells can carry the flow of heated fluid therethrough and deliver it to the surface.

[0021] In embodiments, the heated fluid can flow from the geothermal reservoir up through the primary production well to the intersection point and then flow up through both the primary and secondary production wells from that intersection point.

[0022] In embodiments, the geothermal reservoir can be a conventional geothermal reservoir that includes at least one naturally occurring fracture that carries a flow of pressurized hot water or brine to the primary production well below the intersection of the primary and secondary production wells.

[0023] In other embodiments, the geothermal reservoir may be an unconventional geothermal reservoir that provides a source of pressurized, high-temperature fluid that flows into the primary production well below the intersection of the primary and secondary production wells.

[0024] The present invention will be further described in the following detailed description by reference to a plurality of drawings described as non-limiting examples of the present invention. In the drawings, like reference numerals represent like parts throughout the several views of the drawings.

Brief Description of the Drawings

[0025] [Figure 1] FIG. is a schematic diagram of a geothermal system having a production well that intersects and connects with a naturally occurring fracture penetrating a conventional geothermal reservoir.

[0026] [Figure 2]A graph of the pressure loss (loss of pressure head) along the flow path from a 3 mm crack that extends through a conventional geothermal reservoir, up the production well, and to the surface of the geothermal system is shown. The graph of pressure loss is labeled for various surface pressures applied at the surface wellhead in the range of 100 - 550 psi.

[0027] [Figure 3] A flowchart of an exemplary workflow showing the use of one or more shaped charge lines to expand the openings of one or more naturally occurring cracks that penetrate a conventional geothermal reservoir and intersect the production well of the geothermal system is shown.

[0028] [Figure 4] A reference coordinate system using well depth and azimuth is shown.

[0029] [Figure 5] A shaped charge line is shown.

[0030] [Figure 6] A downhole tool (e.g., labeled "capsule gun") that supports one or more shaped charge lines deployed in the wellbore for controlled visualization of the shaped charge line(s) in the wellbore is shown.

[0031] [Figure 7] A graph of the available power extracted from a conventional geothermal reservoir having different crack opening sizes in the range of 1 mm, 3 mm, and 5 mm is shown.

[0032] [Figure 8] A graph of the available power extracted from a conventional geothermal reservoir having different crack opening sizes in the range of 1 mm, 3 mm, and 5 mm and different wellbore diameters of 8.5 inches, 12.25 inches, and 18.5 inches is shown.

[0033] [Figure 9]This diagram illustrates an exemplary production well intersecting a conventional geothermal reservoir, where the production well is drilled in two stages: shallow and deep. In the shallow stage, a large-diameter well is drilled from the surface (or near the surface) to an intermediate depth. In the deep stage, a small-diameter well is drilled below the intermediate depth, so that the small-diameter well in the deep stage extends below the large-diameter well in the shallow stage relative to the geothermal reservoir.

[0034] [Figure 10] The graph shows the available power extracted from a conventional geothermal reservoir, which has a single production well with a diameter of 8.5 inches and production wells with two stages of 12.5 inches and 8.5 inches, and production wells at different depths with stages ranging from 2000, 4000, 6000, and 8000 feet.

[0035] [Figure 11] This describes an embodiment of a geothermal system in which secondary production wells are drilled so as to intersect with existing production wells located above a conventional geothermal reservoir.

[0036] [Figure 12] The graph shows the available power extracted from a system with a conventional geothermal reservoir featuring a single 8.5-inch diameter production well, and a system with 8.5-inch diameter primary production wells extending to the conventional geothermal reservoir, along with secondary production wells of 8.5 inches in diameter that intersect with the primary production wells above the conventional geothermal reservoir at different depths of 2,000 feet, 4,000 feet, 6,000 feet, and 8,000 feet. [Modes for carrying out the invention]

[0037] Details provided herein are illustrative and intended solely to illustrate embodiments of the disclosure of the subject matter of the invention, and are presented for the purpose of providing the most useful and readily understandable aspects of the principles and conceptual aspects of the disclosure. In this regard, no attempt is made to provide structural details beyond what is necessary for a basic understanding of the disclosure, and how the various forms of the disclosure are actually embodied will be apparent to those skilled in the art in conjunction with the drawings. Furthermore, similar reference numerals and symbols in the various drawings refer to similar elements.

[0038] Embodiments of this disclosure relate to improving or enhancing the performance of a geothermal system that includes a conventional geothermal reservoir, which is a storage space in subsurface rock containing a natural source of pressurized hot or brine. One or more production wells are drilled from the surface into and through the conventional geothermal reservoir, intersecting one or more naturally occurring fissures in the subsurface rock of the conventional geothermal reservoir. These naturally occurring fissures provide channels for pressurized hot or brine to and through the production well(s) to the surface. The thermal energy (heat) from the hot fluid flowing to the surface can be extracted and used by an energy conversion plant for power generation, large-scale heating or cooling, industrial / agricultural processes, or other geothermal applications.

[0039] Where naturally occurring cracks intersect and fluid-couple with the system's production wells, flow losses can occur. Specifically, the opening of a naturally occurring crack at the intersection of production wells can act as a flow limiter, restricting the flow of fluid into the production well through the crack. This can limit the amount of heat acquired by the system and delivered to the surface, potentially reducing the system's productivity. These pressure losses are shown in Figure 2, which includes a graph of pressure losses (pressure head losses) along the flow path from a 3 mm naturally occurring crack up the production well to the surface of the geothermal system. The pressure losses along the flow path originate from a far-field through the 3 mm crack that enters the production well (x=0) and flows to the surface (x=8000). The pressure loss graph is labeled for various surface pressures applied to the wellhead on the surface, ranging from 100 to 550 psi. The graph in Figure 2 is derived from simulations and assumes that the naturally occurring crack is defined by a flat, parallel disk surrounding the production well with radial inflow. In this case, the opening of the naturally occurring crack forms an annular void of a clearly defined height (3 mm in this case), and the circumference of this annular void corresponds to the diameter of the well, surrounding the production well. The flow through the naturally occurring crack is assumed to be laminar, changing to turbulent at the point where the friction coefficients of laminar and turbulent flows are equal. The far field is assumed to be at a constant pressure source. The actual pressure drop for laminar flow is minimized. As the graph demonstrates, the pressure drop for turbulent flow is higher. The large pressure drop occurs at the entrance (intersection) of the naturally occurring crack into the production well.

[0040] According to one or more embodiments of the present disclosure, one or more downhole tools can be configured to place and detonate one or more shaped blast lines within a production well of a geothermal system to enlarge or widen a naturally occurring crack at the intersection of the naturally occurring crack and the production well, thereby reducing pressure loss and increasing the flow rate of pressurized hot or brine carried to the production well by the naturally occurring crack. This can increase the amount of heat acquired by the system and delivered to the surface, potentially increasing the productivity of the system. This can be performed with multiple naturally occurring cracks connected to the production well. This can also be applied to multiple production wells intersecting a conventional geothermal reservoir.

[0041] Figure 3 is a flowchart of an exemplary workflow using one or more shaped blast lines to enlarge openings or connections of one or more naturally occurring fissures that penetrate a conventional geothermal reservoir and intersect with production wells of a geothermal system.

[0042] In block 301, the production well (also commonly called a production well bore) is drilled to intersect with one or more naturally occurring cracks in the conventional geothermal reservoir. The one or more naturally occurring cracks penetrate the conventional geothermal reservoir and connect to the production well. The one or more naturally occurring cracks allow hot or brine fluid supplied from the conventional geothermal reservoir to flow into the production well, as shown in Figure 1. Conventional or unconventional drilling methods can be used. In the embodiment, the production well can optionally be completed as an open well bore with a drilling casing or drilling liner in at least one or more sections that intersect with one or more naturally occurring cracks in the conventional geothermal reservoir.

[0043] In Block 303, by analyzing well log data, the location or depth of one or more naturally occurring cracks intersected by the production wells in Block 301 can be determined. For example, the well depth of one or more naturally occurring cracks can be determined by analyzing borehole pressure measurements, caliper measurements, resistivity measurements, acoustic or ultrasonic borehole imaging measurements, and / or other downhole measurements. These measurements can be performed during drilling or after drilling using the wireline tool. For example, due to pressure loss during drilling, borehole pressure measurements can be analyzed. When drilling crosses a naturally occurring crack, the pressure in the borehole decreases. The depth of such pressure loss can be detected and used as the well depth of the naturally occurring crack. Figure 4 shows a reference coordinate system that uses well depths corresponding to the depth overlooking the production well. The reference coordinate system also uses azimuth angles measured relative to magnetic north.

[0044] In block 305, a downhole tool (e.g., a capsule gun) can be positioned within the production well of block 301, having one or more shaped explosive wires at locations corresponding to one or more naturally occurring cracks characterized in block 303 (e.g., well depth). The shaped explosive wire is a continuous core of explosive enclosed in an elongated, seamless metal sheath housing. As shown in Figure 5, this explosive can be shaped into an inverted "V" shape, with its length (indicated as "L") greater than its width (indicated as "W"), so that the continuous metal sheath liner and the enclosed explosive produce a uniform, linear cutting action upon detonation. Shaped explosive lines(s) can be positioned and oriented at well depth and azimuthal angle such that the penetration pattern of the shaped explosive lines(s) produced by detonation intersects with naturally occurring cracks in the well wall (rock wall), enlarging the size of the opening(s) of the naturally occurring cracks in the well wall and reducing the pressure loss of fluid flow through the naturally occurring cracks in the well wall (rock wall).

[0045] In block 307, the downhole tool may be operated to create a shaped blast line(s). The penetration pattern of the shaped blast line(s) produced by such detonation intersects with one or more naturally occurring cracks in the well wall, expanding or opening the naturally occurring crack(s) at the intersection of the crack(s) and the production well, reducing the pressure loss of the fluid flow through the naturally occurring crack(s) in the well wall (rock wall). This increases the fluid flow through the naturally occurring crack(s) connecting to the production well of the system, increasing the amount of heat acquired by the system and delivered to the surface, thereby improving the productivity of the system.

[0046] In this embodiment, the opening of a naturally occurring crack in the well wall may have a small height dimension compared to a large width or circumference dimension, such as a flat disc shape. In this configuration, the shaped blast wire can be configured such that the primary length dimension (L) of the shaped blast wire is greater than the secondary height dimension of the naturally occurring crack, and the secondary width dimension (W) of the shaped blast wire is smaller than the primary width or circumference dimension of the naturally occurring crack. The shaped blast wire can be positioned and oriented such that the primary length dimension (L) of the shaped blast wire extends in a direction that is approximately perpendicular to or intersecting the secondary height dimension of the naturally occurring crack, and the secondary width dimension (W) of the shaped blast wire extends in a direction that is parallel to or intersecting a portion of the primary width or circumference dimension of the naturally occurring crack. This configuration can alleviate constraints on aligning the position and orientation of the shaped blast wire with the opening of the naturally occurring crack. This reduces complexity and, in some cases, alignment errors, while enabling penetration patterns that intersect naturally occurring cracks by detonating shaped explosive lines (multiple possible), enlarging the size of openings in naturally occurring cracks in the well wall, and reducing pressure loss in fluid flow through naturally occurring cracks in the well wall (rock wall).

[0047] In the optional block 309, the operations of blocks 305-307 can be repeated using the same or additional downhole tools to place and detonate additional shaping blast lines(s), thereby reducing pressure loss in the fluid flow through other naturally occurring cracks(s) that intersect the production well.

[0048] In the optional block 311, the debris generated by the operation of 307 can be removed from the production well, for example, using a coil tube. This may also increase the flow rate of pressurized hot water or brine to the production well.

[0049] Figure 6 shows a downhole tool (e.g., labeled “Capsule Gun”) 600 that can be used as part of the workflow in Figure 3. Specifically, the Capsule Gun includes a tool body 601 that can be transported within the production well by a coil tube, wired cable, or other transport means. The tool body 601 supports a detonation control module 603 and one or more shaped blast wires (indicated as 605). The detonation control module 603 is operably coupled to the shaped blast wire(s) 605 and can be remotely controlled from the surface to activate the detonation of the shaped blast wire(s) 605. The position and orientation of the Capsule Gun 600 (e.g., well depth and azimuth) can be set so that the shaped blast wire(s) are positioned and oriented at a desired depth and azimuth within the production well, so that the penetration pattern of the shaped blast wire(s) resulting from the detonation intersects with naturally occurring cracks in the well wall (rock wall), as described herein. In some applications, the production well is substantially vertical, and naturally occurring cracks may be nearly horizontal. In this case, the shaped blast wire 605 can be positioned parallel to the central axis of the tool body so that the slot-like penetration pattern of the shaped blast wire resulting from the detonation intersects with and extends perpendicularly to the naturally occurring cracks in the well wall (rock face).

[0050] Figure 7 includes graphs of available power from conventional geothermal reservoirs with different crack opening sizes ranging from 1 mm, 3 mm, and 5 mm. Note that performance improves as the crack opening size increases from 1 mm to 3 mm. Similarly, performance improves further as the crack opening size increases from 3 mm to 5 mm, which is an improvement even greater than the improvement seen when the opening size increases from 1 mm to 3 mm. Figure 7 is derived from simulations, which assume an 8.5-inch borehole and the same pressure / temperature at the far field. The crack is modeled as a disk. The pressure loss at the actual crack is small compared to the pressure loss at the borehole entrance, as shown in Figure 2. The crack and the loss at the borehole entrance are characterized by flowing the well at various velocities and measuring the pressure at the bottom of the well.

[0051] Figure 8 shows graphs of available power extracted from conventional geothermal reservoirs with different crack opening sizes ranging from 1 mm, 3 mm, and 5 mm, and different well diameters of 8.5 inches, 12.25 inches, and 18.5 inches. The graphs in Figure 8 were derived from simulations similar to those described above for Figure 7. It should be noted that, in general, performance improves as the crack opening size increases from 1 mm to 3 mm, and further improves as the crack opening size increases from 3 mm to 5 mm.

[0052] In another embodiment, the performance of a geothermal system can also be improved by drilling production wells that intersect with conventional geothermal reservoirs in two stages, referred to herein as shallow and deep. In the shallow stage, a large-diameter borehole (e.g., 12.5 inches in diameter) is drilled from the surface (or near the surface) to an intermediate depth. In the deep stage, as shown in Figure 9, a small-diameter borehole (e.g., 8.5 inches in diameter) is drilled below the intermediate depth, so that the deep small-diameter borehole extends below the shallow large-diameter borehole to the conventional geothermal reservoir. The intermediate depth can be selected to balance the benefits of risk and cost. The deep borehole can be completed as an open wellbore with a drilling casing or drilling liner in a section that intersects with at least one naturally occurring fissure in the conventional geothermal reservoir. The naturally occurring fissure(s) carry pressurized hot water or brine flow into the depths of the production well. This architecture can also be used to access unconventional geothermal reservoirs that provide a source of pressurized, high-temperature fluid flowing deep into production wells.

[0053] Figure 10 includes graphs of available power extracted from a conventional geothermal reservoir, featuring a single production well with a diameter of 8.5 inches and production wells with two stages of 12.5 inches and 8.5 inches, varying in depth over a range of 2,000, 4,000, 6,000, and 8,000 feet. The graphs in Figure 10 were derived from a simulation similar to that described above for Figure 7. In this case, the production wells increase in diameter closer to the surface, allowing the fluid to flow into larger pipes. Note that the production wells with two stages of diameter perform better than single-diameter wells. Furthermore, performance can be progressively improved by moving the stage change downwards from 2,000 feet to 4,000 feet, 6,000 feet, and 8,000 feet.

[0054] In yet another embodiment, if an existing production well has been drilled, a secondary production well can be drilled above the conventional geothermal reservoir, intersecting the existing production well, as shown in Figure 11. In this case, the existing production well is called the primary well, and the fluid flows up from the conventional geothermal reservoir to the primary well at the intersection, and then flows up from that point through both the primary and secondary wells, as indicated by the arrows in Figure 11. The primary well can be completed as an open wellbore with a drilling casing or drilling liner in a section(s) that intersects with at least one or more naturally occurring fissures in the conventional geothermal reservoir. The naturally occurring fissure(s) carry a flow of pressurized hot or brine to the production well below the intersection of the primary and secondary production wells. This architecture can also be used to access a non-conventional geothermal reservoir, providing a source of pressurized hot fluid flowing into the primary production well below the intersection of the primary and secondary production wells.

[0055] Figure 12 includes graphs of available power extracted from a system with a conventional geothermal reservoir with a single 8.5-inch diameter producing well, and a system with a primary producing well extending down to the conventional geothermal reservoir, along with secondary producing wells of 8.5 inches in diameter that intersect the primary producing wells above the conventional geothermal reservoir at different depths of 2,000 feet, 4,000 feet, 6,000 feet, and 8,000 feet. The graph in Figure 10 is derived from a simulation similar to that described above for Figure 7. In this case, the secondary producing wells intersect the primary producing wells, allowing for an increased surface outflow area. Note that in a system with primary and secondary producing wells, the performance associated with a single producing well is improved. Furthermore, performance can be further improved by moving the depth of the intersection of the secondary and primary producing wells downwards from 2,000 feet to 4,000 feet, 6,000 feet, and 8,000 feet.

[0056] In further embodiments, a two-stage production well or a combination of a primary and secondary production well can be used in combination with the method for enlarging the size of the opening of a naturally occurring crack described herein.

[0057] This specification describes and illustrates several embodiments of geothermal systems and related methods used to obtain and extract thermal energy (heat) from geothermal reservoirs. While specific configurations of geothermal systems and related methods are disclosed, it will be understood that other configurations can be used as well. Accordingly, those skilled in the art will understand that further modifications can be made to the invention without departing from the spirit and scope of the invention as described in the claims.

[0058] While a few exemplary embodiments have been described in detail above, those skilled in the art will readily understand that many modifications are possible in the exemplary embodiments without substantially departing from the disclosure. Therefore, all such modifications are intended to fall within the scope of the disclosure as defined in the following claims. In the claims, the means-plus-function clause is intended to encompass not only the structures and structural equivalents described herein as performing the functions described, but also equivalent structures. Thus, while nails and screws cannot be structural equivalents in that nails use a cylindrical surface to join and fasten wooden parts, whereas screws use a helical surface, nails and screws can be equivalent structures in the context of fastening wooden parts. Except where a claim explicitly uses the term “means for” in conjunction with the function it relates to, it is the express intent of the applicant that no limitation of any claim herein is invoked under 35 U.S.C. § 112(6).

Claims

1. A method for extracting thermal energy from a conventional geothermal reservoir containing at least one naturally occurring fissure, The process of drilling or accessing production wells that intersect with the aforementioned conventional geothermal reservoir, A step of detonating at least one shaped blast line to enlarge or widen the naturally occurring crack in the conventional geothermal reservoir at the intersection of the naturally occurring crack and the production well, wherein the detonation step reduces the pressure loss of the fluid flow from the naturally occurring crack to the production well, A method characterized by comprising:

2. The reduction in pressure loss increases the fluid flow to the production well, and thus increases the amount of heat obtained. The method according to feature 1.

3. The detonation of the at least one shaped explosive line enlarges the opening size of the naturally occurring crack on the borehole surface. The method according to feature 1.

4. moreover, The process of positioning and oriented the at least one shaped explosive line(s) such that the penetration pattern of the at least one shaped explosive line resulting from the detonation intersects with the naturally occurring crack. The method according to claim 1, characterized by including the following:

5. The at least one shaped explosive wire is supported by a downhole tool. The method according to feature 1.

6. moreover, A step of determining the location of the naturally occurring crack from the well log data, A step of aligning the position of the downhole tool with the position of the naturally occurring crack as determined from the well log data, Includes, As a result, the penetration pattern of at least one shaped explosive line generated by the detonation intersects with the naturally occurring crack. The method according to specification 5.

7. The position of the downhole tool and the position of the naturally occurring crack are defined in a reference coordinate system. The method according to feature 6.

8. The aforementioned reference coordinate system includes well depth and azimuth angle. The method according to feature 7.

9. The downhole tool has a central axis, and the at least one shaping blast line is supported by the downhole tool in a direction substantially parallel to the central axis of the downhole tool. The method according to specification 5.

10. The aforementioned naturally occurring cracks carry pressurized hot water or saltwater flow to the production well. The production well is configured to transport the pressurized hot water or brine flow through the production well and deliver it to the surface. The method according to feature 1.

11. moreover, The process of detonating at least one additional shaping blast line to enlarge or widen the at least one additional naturally occurring crack in the conventional geothermal reservoir at the intersection of the production well and the at least one additional naturally occurring crack. Includes, To reduce the pressure loss of the fluid flowing into the production well from at least one additional spontaneously occurring crack. The method according to feature 1.

12. A method for extracting thermal energy from a geothermal reservoir, A process of drilling a production well intersecting the aforementioned geothermal reservoir in two stages, including shallow and deep drilling. Includes, A large-diameter well is drilled from the surface or near the surface to an intermediate depth in the shallow section, a small-diameter well is drilled below the intermediate depth so as to intersect with the geothermal reservoir, and the deep small-diameter well extends below the shallow large-diameter well to the geothermal reservoir. A method characterized by the following:

13. The production well carries the heated fluid flow through the production well and delivers it to the ground surface. The method according to 12, characterized by the features described above.

14. The geothermal reservoir includes a conventional geothermal reservoir containing at least one naturally occurring fissure that carries a pressurized flow of hot or saltwater to the depths of the production well. The method according to 12, characterized by the features described above.

15. The geothermal reservoir includes an unconventional geothermal reservoir that provides a source of pressurized, high-temperature fluid flowing into the deep part of the production well. The method according to 12, characterized by the features described above.

16. A method for extracting thermal energy from a geothermal reservoir, The process of drilling a secondary production well so as to intersect with the primary production well at a point above the aforementioned geothermal reservoir. The method characterized by comprising:

17. Both the primary and secondary production wells are configured to carry a flow of heated fluid through them and deliver it to the surface. The method according to 16, characterized by...

18. The heated fluid flows from the geothermal reservoir up through the primary production wells to the intersection, and then flows up through both the primary and secondary production wells from the intersection. The method according to feature 17.

19. The geothermal reservoir includes a conventional geothermal reservoir containing at least one naturally occurring fissure that carries a pressurized flow of hot or saltwater to the primary production well below the intersection of the primary production well and the secondary production well. The method according to 16, characterized by...

20. The geothermal reservoir includes an unconventional geothermal reservoir that provides a source of pressurized high-temperature fluid flowing into the primary production well below the intersection of the primary and secondary production wells. The method according to 16, characterized by...

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