GUIDANCE METHOD FOR MULTILATERAL DIRECTIONAL DRILLING

Abstract

Guidance methods for guiding the drilling, of wells while reducing trajectory drift. Each drilled well incorporates signalling devices which are used together or in a selected sequence to guide additional well drilling. With the progressive addition of the signalling devices spacing, positioning and connection of wells, particularly multilateral wells, is focused and precise.

Claims

1. A method for drilling in a predetermined configuration within a geologic formation, comprising: drilling in said formation a well having an inlet well and an outlet well; drilling with signalling for communication between said inlet well and said outlet well to form a continuous well having an interconnecting well segment between said inlet well and said outlet well, said interconnecting well segment having a predetermined geometric configuration relative to said inlet well and said outlet well within said formation; and signalling for communication from at least one of said inlet well, said outlet well and said interconnecting well segment to drill a second interconnecting well segment operatively connected to said continuous well in a predetermined geometric configuration within said formation.

2. The method as set forth in claim 1, wherein said inlet well and said outlet well are co-located.

3. The method as set forth in claim 1, wherein said geologic formation has an irregular and inconsistent thermal gradient.

4. The method as set forth in claim 1, further including the step of drilling a partial well proximate or distal from at least one of said inlet well and said outlet well for signalling for communication with at least one of said inlet well, said outlet well and said interconnecting well segment.

5. The method as set forth in claim 1, further including the step of establishing further signaling for communication from said continuous well and said second interconnecting well segment for guiding the drilling of further interconnecting well segments and continuous wells in operative connection in a predetermined configuration within said formation.

6. The method as set forth in claim 1, wherein signalling for communication comprises transceiving between said wells.

7. The method as set forth in claim 1, wherein signaling for communication is conducted simultaneously between wells.

8. The method as set forth in claim 1, wherein signaling for communication is conducted in a predetermined sequence between wells.

9. The method as set forth in claim 1, wherein said drilling is conducted independently from discrete locations for said inlet well and said outlet well for intersection to form said continuous well with said interconnecting well segment.

10. The method as set forth in claim 2, further including providing superterranean signalling devices, subterranean signalling devices and combinations thereof proximate said discrete locations for guiding drilling.

11. The method as set forth in claim 1, wherein said formation is a thermally productive formation.

12. The method as set forth in claim 1, wherein said formation is a geothermal formation.

13. The method as set forth in claim 1, further in conditioning at least said interconnecting well segment to facilitate thermal recovery by working fluid flow through said continuous well without casing or liner material in said interconnecting well segment.

14. The method as set forth in claim 13, wherein conditioning is effected by at least one of continuously, discontinuously, during, after and in sequenced combinations of drilling of at least one of said inlet wee, said outlet well and said and said interconnecting segment.

15. The method as set forth in claim 13, further including the step of dynamically modifying said conditioning responsive to signalling data from at least one of the operations of said inlet well, said outlet well and said interconnecting well segment.

16. A method for drilling in a predetermined configuration within a geologic formation, comprising: drilling in said formation a well having an inlet well and an outlet well; drilling a partial well proximate or distal from at least one of said inlet well and said outlet well for signalling for communication with at least one of said inlet well and said outlet well; and drilling an interconnecting well segment continuously connecting said inlet well and said outlet well with signaling for communication between at least one of said inlet well, said outlet well and said partial well.

17. The method as set forth in claim 16, further including the step of forming a second well having an inlet well and an outlet well from said partial well.

18. The method as set forth in claim 16, wherein said partial well comprises a plurality of individual spaced apart wells.

19. The method as set forth in claim 18, further including signalling between said plurality of individual spaced apart wells to form connected continuous wells.

20. The method as set forth in claim 16, wherein signalling comprises transceiving between wells.

Description

BRIEF DESCRIPTIONN OF THE DRAWINGS

[0033] FIG. 1 is a flow diagram indicating the general steps of the method;

[0034] FIGS. 2 and 2A are schematic illustrations of multilateral well arrangements;

[0035] FIG. 3 is a top plan view of FIG. 2;

[0036] FIG. 4 is a variation of the well arrangement according to a further embodiment;

[0037] FIG. 5 is another variation of the well arrangement according to a further embodiment;

[0038] FIG. 6 is a further variation of the well disposition of the multilateral arrangement;

[0039] FIG. 7 is another variation of the well disposition of the multilateral arrangement;

[0040] FIG. 8 is a still further variation of the well disposition of the multilateral arrangement;

[0041] FIG. 9 is another embodiment of the present invention with multilateral wells having a significantly reduced surface footprint; and

[0042] FIG. 10 is a schematic illustration of the closed loop system applicable to the geothermal embodiments; and

[0043] FIG. 11 is a schematic illustration of a further embodiment of the present invention.

[0044] Similar numerals used in the Figures denote similar elements.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] Referring now to FIG. 1, shown is a general flow diagram for the overall steps in the method.

[0046] FIG. 2 is a schematic illustration of one embodiment of the present invention generally denoted by numeral 10. In the example, a U shaped well includes a pair of spaced apart generally vertical wells 12 (inlet) and 14 (outlet) and an interconnecting well segment 16, shown as a horizontal well, interconnecting the wells 12 and 14. This well may be pre-existing from an unused well, i.e. a SAGD arrangement or may be newly drilled. The technology discussed further herein is particularly useful to repurpose unused oil wells and it will become evident in the forthcoming disclosure that many aspects of the disclosed technology may be easily appended or substituted into existing oil and gas environments as easily as it is positioned in the geothermal industry.

[0047] In the example shown, a plurality of ancillary lateral horizontal wells 18, 20, 22 and 24 extend from a junctions 26 and 28, shown in the example as horizontal wells. In this manner all wells are commonly connected to a respective vertical well 12 or 14. In the scenario where the U shaped well is pre-existing, signal devices may be positioned along the vertical wells 12, 14 and the interconnecting well 16. These are schematically illustrated and represented by numeral 30. Suitable signal devices may be selected from the panacea of devices known in the art and may comprises receivers, transmitters, transceivers, inter alia. For purposes of suitable device examples, reference to Baker Hughes, Scientific Drilling, Halliburton etc. may be had for reference.

[0048] The devices can be modified or selected to be capable of monitoring at least one of drilling rate, spacing between wells, well to junction connection integrity, bit wear, temperature and fluid flow rate within a drilled well.

[0049] This area is mature in the art and thus detailed description is not necessary.

[0050] In situations where the U shaped well is not pre-existing, the well can be drilled in any configuration as an initial basis well with the signalling devices placed therein at a suitable time in the process with the view to either leaving them in situ permanently or positioned for time dependent retrieval.

[0051] Once positioned, in one embodiment, this provides a master for signal communication with the directional drilling of the second lateral well 20. The drilling arrangement (not shown) can include the capacity to receive guiding signals as a slave from the signal devices 30 and leave further signal devices 32 along the course of the horizontal well 20. Additional communication with the drilling arrangement and signal devices 30 and 32 is also possible.

[0052] Having established a second well 20 with signal devices 32, this can then act as a master for guidance signalling for a third lateral well 22. The drilling arrangement referenced previously functions in a similar manner for this drilling procedure. Further signal devices 34 are positioned along the course of well 22. By this arrangement, the second well benefits from the guidance of signal devices 30 and 32 either together or independently in any continuous or discontinuous sequence. As will be appreciated, this has the effect of significantly reducing trajectory drift during drilling owing to the plurality of sensor positions and locations.

[0053] In respect of the third lateral well 22, The drilling arrangement can include the capacity to receive guiding signals as a slave from the signal devices 30, 32 and 34 and leave further signal devices 36 along the course of the horizontal well 22. As with the previous examples, this well then benefits from the guidance of devices 30,32 and 34.

[0054] Finally, in the spirit of the above examples, signal devices 38 can be positioned in fourth lateral well 24 and communicate with devices 30,32,34 and 36.

[0055] It will be appreciated that the signal devices, as they are cumulative for the last multilateral well, progressively reduce the drift for each additional multilateral segment. This allows for the use of pre-existing/unused/abandoned wells since the initial well has less importance in the multilateral scenario. The initial master status diminishes in importance as more lateral wells are augmented to form the multilateral arrangement.

[0056] As delineated in the prior art, much of the existing technology in this area of technology has focused on the dual well or injection and production well systems inherent in SAGD environments. However, the precision associated with the technology allows for exceptional application in the geothermal area of technology and reference in that capacity will now be set forth.

[0057] The interconnecting segment 16 is shown as horizontal, however, the geometric disposition may be any angle that is suitable to maximize thermal recovery within the formation. To this end, FIG. 2A illustrates the other possibilities.

[0058] FIG. 3 is a top plan view of the disposition of the wells of FIG. 2.

[0059] Referring now to FIG. 4, shown is a variation of the well arrangement, generally referred to as a stacked arrangement, positioned within a geothermal gradient, G. In this embodiment, each multilateral arrangement 40 in the stack may have its own inlet well, 12, 12, 12, 12 and outlet well, 14, 14 and, 14 and 14. If feasible, each of the stacks 40 may be commonly connected to a single inlet well 12 and single outlet well 14. The appeal of the stacked arrangement is the possibility for higher thermal recovery in a smaller footprint.

[0060] FIG. 5 illustrates a further variation referenced as a fork arrangement. In this arrangement, the multilateral well arrangements 40 may be arranged in spaced apart coplanar relation or spaced apart parallel plane arrangement. Such arrangements are suitable where the overall footprint of the system is not an issue. The stacks of multilateral wells 40 may also be inclined, as illustrated, at any angle to be effective in capturing thermal energy from within the gradient, G, where the gradient is irregular and/or dispersed.

[0061] Turning now to FIG. 6, shown is an arrangement of multilateral wells 20, 22, 24, 26 and 28 dispersed in a radial spaced apart array relative to interconnecting well 16 referenced supra. The arrangement in the example is coaxial, however other variations will be appreciated by those skilled in the art.

[0062] Parts have been removed for clarity, but it will be understood that wells 20,22,24, 26 and 28 all have common connection with vertical wells 12 and 14 and junctions 26 and 28, the wells and junctions not being shown. This radial dispersion is of particular value in geothermal environments, since a greater amount of heat can be extracted within a given heat producing volume. In light of the directional drilling advancements set forth in the disclosure, such arrangements are possible and customizable depending upon the surrounding environment.

[0063] FIG. 7 illustrates a further variation. In this embodiment, a pair of the arrangements shown in FIG. 6 are interdigitated with similar wells 18, 20, 22, 24 and 26. The precision attributed to the drilling method, established herein facilitates the inter digitation. This arrangement enhances the thermal recovery within, for example a geothermal zone, without an impact on footprint. This clearly has capital expenditure benefits, but also allows for even greater energy servicing capability within a given area.

[0064] FIG. 8 schematically illustrates another variation where a pair of the arrangements from FIG. 7 are spaced, but in thermal contact.

[0065] For mitigation of temperature deviation from the heel of a well to its toe, the arrangements depicted in FIGS. 7 and 8 are useful. As an example, the direction of flow of a fluid within wells 18, 20, 22, 24 and 26, in reference to FIG. 7, may be opposite to the flow within wells 18, 20, 22, 24 and 26. In this manner, the heel of one well will be in thermal contact with the toe of another well, i.e. counter current.

[0066] Referring now to FIG. 9, shown is another embodiment of the present invention. In this embodiment, separate multilateral wells 40 may be geographically spread apart within a formation G. This embodiment connects multilateral wells, such as 42 and 44 to loop back together at terminus 46 for connection with outlet well 14, A second set of multilateral wells 42 and 44 may be coplanar or in a parallel plane with multilateral wells 42 and 44 and similarly loop back at terminus 46. The advantage in this arrangement is that the inlet/outlet footprint 48 is relatively small, however the thermal energy recovery capacity is very significant. This allows for one site at the footprint 48 to be multiply productive without the requirement for large plots of land.

[0067] In all examples, the inlet 12 and outlet 14 will include the known ancillary components, i.e. power generating devices, energy storage devices, linking, arrangements to the power grid, cogeneration systems inter alia. This has been omitted from FIGS. 1 through 9 for clarity. Further, it will be understood that the geothermal systems will be closed loop, meaning that the inlet, junctions, multilateral wells intervening power generating devices, etc., and outlet well will form a continuous circuit with the minimum of connecting conduit disposed in a superterranean position. General reference to this can be made with respect to FIG. 10.

[0068] The ancillary or intervening devices are referenced with numeral 50 which are positioned above ground level 52. The closed loop below ground level 52 is exaggerated in the example. Numeral 54 represents a superterranean transceiver device capable of communication with any one of or all the devices 30,32,34, 26 and 38.

[0069] As an alternative, as opposed to the master and slave communication arrangement described, signalling communication may be effected simultaneously with all devices selectively, continuously or in a predetermined sequence. This will depend on the specifics of the individual situation.

[0070] FIG. 11 illustrates a variation in the embodiments where a partially drilled well or borehole 56 may be positioned proximate other multilateral arrangements and include a signalling/transceiver device 56. The latter may communicate with other such devices 30, 38, 54 to guide the formation of the well arrangements as noted herein previously. Bore hole 56 may be further drilled to be integrated with the other wells as denoted by dashed line 60. Any number of bore holes 56 may be included to form further networked well arrangements within a formation.