Part of a drill head for a plasma pulse geo drilling system

Abstract

In the case of a drill head initial part (2) as part of a drill head for a plasma pulse geo drilling system, the drill head initial part (2) comprising at least one electrode section (20) which has a plurality of metal bar electrodes (200) and to which a high-voltage feed (10) can be attached and it being possible for differently polarized voltage pulses to be applied to the bar electrodes (200) by a high-voltage pulse generator (1), continuous drilling operation with increased efficiency is intended to be achieved when using water as drilling fluid. This is achieved in that a drill head connection section (21) in the form of a frame with feed struts (210) and at least two connection flanges (211, 211') is electrically connectedly attached to or integrally formed on the electrode section (20), and the bar electrodes (200) of the electrode section (20) are configured oriented with the same length (L) with diameters (d) of less than 20 mm in a manner running parallel to each other and terminating on a planar electrode face, a cross-sectional area (Q) of the electrode section (20) over which the bar electrodes (200) are distributed being selected to be larger than or equal to a cross-sectional area (q) of the drill head connection section (21) over which feed struts (210) and the at least two connection flanges (211, 211') are distributed.

Description

[0001] Part of a drill head for a plasma pulse geo-drilling system

[0002] Technical area

[0003] The present invention describes a drill head initial part as part of a drill head for a plasma pulse geo-drilling system, wherein the drill head initial part comprises at least one electrode section with a plurality of metallic rod electrodes, to which a high-voltage supply can be fastened and the rod electrodes can be subjected to differently polarized voltage pulses by a high-voltage pulse generator.

[0004] State of the art

[0005] Access to deep energy resources (geothermal energy, hydrocarbons) from deep reservoirs will play a fundamental role in the coming decades. However, drilling to extract deep georesources is extremely expensive. Deep drilling into hard, crystalline rock poses a major challenge for conventional rotary drilling systems, resulting in high bit wear and frequent bit replacement, low penetration rates, and poor process efficiency.

[0006] With the goal of improving the overall economic efficiency of developing deep georesources in hard rock, we see Plasma Pulse GeoDrilling (PPGD) technology as a solution. The resulting Plasma Pulse GeoDrilling process and the necessary technical resources lead to a massive cost reduction and simplification of deep drilling compared to the use of conventional rotary drilling systems, if the Plasma Pulse GeoDrilling system is optimized.

[0007] Plasma Pulse Geo-Drilling (PPGD) technology, used in deep drilling processes—that is, deep drilling for the development of oil and natural gas deposits and geothermal wells—with final depths ranging from a few meters to several kilometers, originated in Russia. PPGD potentially demonstrates its advantages in crystalline rock, making it ideal for geothermal energy or other activities in hard rock.

[0008] PPGD technology uses high voltage of several hundred kilovolts in the form of nanosecond-fast electrical pulses through the rock, generating a plasma in the rock that shatters the rock from within, i.e., against its low tensile strength without mechanical abrasion from a drilling tool, thus creating a deep borehole. Rossi et al., "Advanced drilling technologies to improve the economics of deep georesource utilization," Applied Energy Symposium: MIT A+B, August 12-14, 2020, Cambridge, USA, suggest that using a drill bit initial section 2, a high-voltage pulse generator 1, and electrodes in a water-filled borehole 5, drilling and advance can be achieved using the high-voltage pulses. This avoids the use of a wearing drill bit, yet apparently still allows for a high rate of penetration (ROP), which creates a borehole shown.A high-voltage pulse initiates a plasma channel (streamer) 3. The streamer 3 propagates through the rock 4, fracturing the rock 4 from within. The electrodes are embedded in the drill head, and the process is surrounded by a drilling fluid 5 in the borehole (e.g., oil or water). The entire construction forms a plasma pulse geo-drilling system 0, as shown in Figure 1 according to the state of the art. However, for this method to effectively fracture rock, the plasma channel must run through the rock and not along the rock surface, i.e., through the fluid. This is primarily achieved by a rapid pulse rise. The rise time is an important factor due to the remarkable dependence of the dielectric strength of materials on the time of pulsed voltage application.

[0009] The goal today is to use water or a water-based fluid as the drilling fluid to simplify the process. While the EPB (Electro-Pulse Boring) process, developed in Russia in the 1960s and using oil as the drilling fluid, required the use of an insulating and flushing medium, a new process now uses a water-based drilling fluid, which saves costs and protects the environment.

[0010] However, PPGD technology has not yet achieved the desired efficiency, time savings, and drilling quality. Consequently, this process and the plasma pulse geo-drilling system cannot successfully establish themselves on the market.

[0011] Description of the invention

[0012] The disadvantages known from the prior art described above are to be eliminated by the present optimized device and the method that can be carried out therewith.

[0013] The present invention aims to optimize a plasma pulse geo-drilling system for PPGD in such a way as to achieve continuous operation with maximum efficiency when using water or a water-based fluid as drilling fluid. Accordingly, a portion of the drill head for a plasma pulse geo-drilling system was designed.

[0014] Variations of feature combinations or minor adaptations of the invention can be found in the detailed description, illustrated in the figures and included in the dependent patent claims.

[0015] Short description of the drawings

[0016] A preferred embodiment of the subject matter of the invention is described below in conjunction with the accompanying drawings.

[0017] Further features, details and advantages of the invention will become apparent from the following description of preferred embodiments of the invention and the drawings. They are shown in

[0018] Figure 1 shows a schematic view of a plasma pulse geo-drilling system known from the prior art, wherein the reference numerals also apply in the remainder of the description of the invention.

[0019] Figure 2a shows a schematic perspective of an optimized drill head initial part, while

[0020] Figure 2b is a schematic side view of the drill head start section, without high voltage connections and generator and

[0021] Figure 2c shows a section of the sectional view along section line AA from Figure 2b through the electrode section of the drill head initial part.

[0022] Figure 3 shows a schematic perspective of another drill head initial section with slightly tilted outer rod electrodes. Description

[0023] The known plasma pulse geo-drilling system 0 with high-voltage pulse generator 1, to which a drill head initial part 2 comprising a drill head connection section 21 and a front-side electrode section 20 with a plurality of n rod electrodes 200 is connected by means of a high-voltage supply 10, has been optimized here. The entire drill head initial part 2, as part of a drill head comprising further features, is introduced into a borehole down to the borehole bottom. This allows for optimized excavation of rock 4 in a borehole filled with water as drilling fluid 5 or a water-based drilling fluid 5 containing less than or equal to 100% water, whereby the known plasma channel is generated in pulses.

[0024] In order to improve the excavation behavior during drilling using the plasma pulse geo-drilling system 0, the shape of the drill head initial part 2, or of the electrode section 20, in which a plurality of n rod electrodes are arranged here, is of particular importance.

[0025] It was known from the prior art that the number of electrodes should be increased or that electrodes with concentrically arranged "support shoes" were introduced. Rings and plates, as well as claws in various designs, were also arranged in the area of ​​the electrodes. However, these simple changes did not produce satisfactory results.

[0026] In order to optimize the excavation behavior and thus the excavation performance, an optimal arrangement and shape of the positive and negative electrodes had to be found that equally serves the entire drill cross-section and generates an over-excavation, especially in the edge zone of the drill head starting section 2, so that the drill head starting section 2 can reliably follow the tracking during the drilling process. A reliable supply of the high-voltage pulses must always be achieved and the entire drill head starting section 2 must have sufficient mechanical strength. This was achieved with the arrangement of rod electrodes 200 in the electrode section 20, which is described in more detail below. The lengths L of all rod electrodes 200 are selected such that all tips of the rod electrodes 200 are flush with a flat electrode surface, thus ensuring that all rod electrodes 200 rest evenly in the borehole, on the flat borehole floor.

[0027] The drill head initial part 2 is designed as a metallic frame, comprising at least the electrode section 20 and a drill head connection section 21, which are fastened or molded together.

[0028] A plurality of n rod electrodes 200 protrude from the electrode section 20 in the direction away from the drill head connection section 21. The longitudinal direction is marked with the dashed arrow, with the arrowhead pointing in the feed direction of the drill head initial part 2.

[0029] For stability reasons, the n rod electrodes 200 are rod-shaped and solid, so that they are insulated from one another and distributed over the largest possible area along the cross-sectional area of ​​the electrode section 20. The n rod electrodes 200 are attached to the electrically conductive drill head connection section 21 in such a way that no arcing or short circuits occur at high electrical voltages. The drill head connection section 21 is therefore essentially designed as a metallic frame comprising several feed struts 210 with direct or indirect contact to the n rod electrodes 200 and at least two connecting flanges 211, 211' to which the feed struts 210 are attached or molded. The connecting flanges 211, 211' generally serve to attach the drill head initial section 2 to other components of the drill head and / or to the high-voltage supply line 10.

[0030] High-voltage cables 10 can be connected to the connection flanges 211, 211' as an embodiment of the high-voltage supply 10 of a high-voltage generator 1, which is indicated in Figure 2a with a high-voltage symbol. Sufficient stability must also be achieved in the drill head connection section 21 to prevent short circuits. Although no mechanical loads occur here as in conventional rotary drilling systems, since there is no rotational movement, the pressure with which the drill head initial section 2 is pressed onto the rock 4 in the feed direction is quite high. Ideally, the axial load on the drill head initial section 2 is practically zero. The rod electrodes 200 are each connected to the first connection flange 211 or to the second connection flange 211' without short circuits or arcing. This allows different rod electrodes 200 to have different polarizations.

[0031] Instead of high-voltage cables 10, mechanically more stable struts can also function as high-voltage supply 10, which create mechanical stabilization.

[0032] The feed struts 210 can be designed as metallic tubes or solid rods, while the at least two connecting flanges 211, 211' are preferably welded on. The distances between the feed struts 210, which have different polarities and are subjected to high voltage during operation, are selected to match the high voltage to prevent short circuits and flashovers. Since an aqueous fluid is used as drilling fluid 5 in the borehole, the specifications are defined accordingly so that the plasma channel 3 is preferably created by the rock 4 during operation. Figure 2b shows that the different feed struts 210 provide the voltage application and mechanical stability. Here, the distance between the at least two connecting flanges 211, 211' is approximately half the length of the entire drill head connection section 21. This is indicated by dashed vertical lines in Figure 2b.

[0033] In the electrode section 20, a uniform distribution of n rod electrodes 200 of equal thickness arranged parallel to one another, with rod electrode diameters d of greater than 5 mm, particularly preferably of 8 mm, but basically with a rod electrode diameter d of less than 20 mm, has proven to be advantageous, since only in this way could a homogeneous drilling result be achieved.

[0034] The length L of the n rod electrodes 200 between their tips and the drill head connection section 21 should be greater than 100 mm and preferably less than 200 mm, particularly preferably between 150 and 170 mm.

[0035] In relation to the length L of the rod electrodes 200 between the tip and the rear end of the rod electrode 200 to the distance a to the nearest neighbor between rod electrodes 200, L / a of 1:1 to 5:1 is advantageous. The length L of the rod electrodes 200 is measured independently of the attachment between the tip of the rod electrode 200 and the rear end of the rod electrode 200 opposite the tip.

[0036] Another feature of the drill head initial part 2 is a distance x between a first rod electrode mounting plane and a second rod electrode mounting plane of the various rod electrodes 200. This distance x should preferably correspond to one to three times the distance a. The total length of the drill head initial part 2 should be approximately greater than or equal to twice the length L of the rod electrodes 200, so that mechanical stability is sufficient.

[0037] In order to achieve a homogeneous plasma channel 3, a uniform distribution of the plasma channels 3 and, as a result, a homogeneous bore in water 5 as drilling fluid 5, the n rod electrodes 200 with different polarity were arranged such that the distance a between the next adjacent rod electrodes 200 is at least 10 mm, preferably greater than 40 mm, particularly preferably 48 mm.

[0038] In addition to an arrangement of parallel rows and columns of rod electrodes 200 with the same polarity, wherein each rod electrode 200 has two nearest neighbors on both sides in the same row and one left and one right nearest neighbor in each neighboring column, a further embodiment has proven to be more efficient.

[0039] The electrode arrangement pattern shown in Figure 2c is based on a hexagonal arrangement of rod electrodes 200, wherein a rod electrode 200 of a first polarity is arranged in the center of a hexagon and six further rod electrodes 200' are arranged along the circumference of the hexagon at its corners. Even in such an arrangement, the distances a between nearest neighboring electrodes are equal to distance a. Except for rod electrodes 200 in the edge region, each rod electrode 200 has six nearest neighbors at a distance a. These nearest neighbors can have the same or opposite polarity, i.e., be subjected to a correspondingly polarized electrical voltage. For this purpose, rod electrodes 200 must be connected to the suitable connection flange 211.Arrangements are preferred in which rod electrodes 200, each with alternating polarity, are arranged along the circumference of the hexagon, running around the centrally positioned rod electrode 200.

[0040] The cross-sectional area Q of the electrode section 20 must be selected to be greater than or equal to the cross-sectional area q of the drill head connection section 21 so that the drill head initial section 2 creates a sufficiently large borehole and can be guided into the borehole. The cross-sectional area q or the maximum diameter here corresponds to the diameter of the second connection flange 211'.

[0041] By designing the drill head initial part 2 as a frame, waste can be transported away using drilling fluid 5.

[0042] The connecting flanges 211, 211' result in an extremely stable, short-circuit and arc-over-free installation of the high-voltage supply 10 to the drill head start section 2.

[0043] In a further design of the electrode section 20, the outer rod electrodes 200', which are furthest from the central longitudinal axis, are not arranged parallel to the longitudinal axis, but rather at an angle away from the longitudinal axis. This embodiment is schematically illustrated in Figure 3, with only an upper half of the drill head initial section 2' shown. The angle of the outer rod electrodes 200' to the longitudinal axis should be 1.5° or more.

[0044] With the drill head initial section 2 described above, even so-called loops several kilometers deep can be drilled efficiently, cost-effectively, using water as drilling fluid 5, and without significant mechanical wear. The decisive factor is the most homogeneous and even contact of the n rod electrodes 200 on the rock. The drill head initial section 2 is guided and placed on the rock 4, then one or more voltage pulses are applied until the drill head initial section 2 is guided again. Ideally, the drill head initial section 2 is balanced, relieved, or loaded in such a way that it automatically and continuously follows the borehole bottom, which moves with the drilling progress.

[0045] The rod electrodes 200 described here enable point support of the rod electrodes 200 distributed across the entire drill cross-section, as the rod electrodes 200 are distributed over the cross-sectional area of ​​the electrode section 20. There are no electrical cross-connections between the individual rod electrodes 200, and the distances between the feed struts 210 and connecting flanges 211, 211' are selected accordingly. The ends of the individual rod electrodes 200 are preferably designed as spherical heads with a defined radius, i.e., they do not taper. Rock fragments excavated during operation, so-called cuttings, are reduced in size by the uniform, homogeneous arrangement of the rod electrodes 200 in such a way that the transport diameter for removal is reliably achieved and wedging of the cuttings in the drill head initial section 2 is prevented.Good drilling results were achieved in the tests carried out, which are also advantageous in continuous drilling operations.

[0046] List of reference symbols

[0047] 0 Plasma Pulse Geo Drilling System

[0048] 1 high-voltage pulse generator

[0049] 10 High-voltage supply (e.g. high-voltage cable)

[0050] 2 Drill head initial part

[0051] 20 Electrode section

[0052] 200 n Stick electrodes d Stick electrode diameter (preferably 8mm) a Distance to nearest neighbor (preferably > 40mm, 48mm)

[0053] L Length of the rod electrodes between tip and

[0054] Drill head connection section

[0055] Q Cross-sectional area of ​​the electrode section 20

[0056] 21 Drill head connection section

[0057] 210 Feed strut

[0058] 211, 211' Connection flange q Cross-sectional area of ​​the drill head connection section 21

[0059] 3 plasma channels / streamers

[0060] 4 rock

[0061] 5 Drilling fluid (preferably water or water-based

[0062] Liquid)

Claims

Patent claims 1. Drill head start section (2) as part of a drill head for a plasma pulse geo-drilling system (0), wherein the drill head start section (2) comprises at least one electrode section (20) with several metallic rod electrodes (200) to which a high-voltage supply (10) can be attached and the rod electrodes (200) can be subjected to differently polarized voltage pulses by a high-voltage pulse generator (1), characterized in that a drill head connection section (21) in the form of a frame with supply struts (210) and at least two connection flanges (211, 211') is electrically connected or integrally attached to the electrode section (20), facing away from the side of the rod electrode tips, and the rod electrodes (200) of the electrode section (20) are aligned parallel to each other and terminate on a flat electrode surface with the same length (L) made of metallic tubes or solid rods with diameters (d) less than 20 mm. are designed,wherein a cross-sectional area (Q) of the electrode section (20), on which the rod electrodes (200) are distributed, is chosen to be greater than or equal to a cross-sectional area (q) of the drill head connection section (21) on which feed struts (210) and the at least two connection flanges (211, 211') are distributed.

2. Drill head starting part (2) according to claim 1, wherein the plurality of rod electrodes (200) form parallel rows and columns of rod electrodes (200), each rod electrode (200) having two nearest neighbors in the same row and each having a left and a right nearest neighbor in each neighboring column. Drill head start part (2) according to claim 1, wherein an electrode arrangement pattern of the plurality of rod electrodes (200) is based on a hexagonal arrangement of rod electrodes (200), wherein a rod electrode (200) of a first polarity is arranged in the center of a hexagon and six further rod electrodes (200') are arranged along the circumference of the hexagon at its vertices. Drill head start part (2) according to claim 3, wherein, except for rod electrodes (200) in the edge region, each rod electrode (200) has six nearest neighbors at the same distance (a), which have the same or opposite polarity.Drill head start part (2) according to claim 3 or 4, wherein the rod electrodes (200) along the hexagonal circumferential line around the central rod electrode (200) can be subjected to alternately polarized electrical voltage and are accordingly electrically connected to the connecting flanges (211, 211'). Drill head start part (2) according to any one of the preceding claims, wherein the distance (a) between directly adjacent rod electrodes (200) is the same and at least 10 mm. Drill head start part (2) according to any one of the preceding claims, wherein the ratio of the length (L) of the rod electrodes (200) between the tip and the rear end of the rod electrode (200) to the distance (a) to the nearest neighbor between rod electrodes (200) L / a is between 1:1 and 5:

1.

8. Drill head start part (2) according to one of the preceding claims, wherein a distance (x) between a first rod electrode mounting plane and a second rod electrode mounting plane of the different rod electrodes (200) corresponds to a value between one and three times the distance (a).

9. Drill head start part (2) according to one of the preceding claims, wherein the projecting ends of the rod electrodes (200) are each designed as a ball head with a defined radius.

10. Drill head start part (2) according to one of the preceding claims, wherein the length (L) of the rod electrodes (200) between their tips and the drill head connection section (21) is greater than 100mm and preferably less than 200mm, particularly preferably between 150 and 170 mm.

11. Drill head start part (2) according to one of the preceding claims, wherein the total length of the drill head start part (2), electrode section (20) and drill head connection section (21) together is greater than or equal to twice the length (L) of the rod electrodes (200).

12. Drill head start part (2) according to one of the preceding claims, wherein the distance between the at least two connection flanges (211, 211') corresponds to a maximum of half the length of the entire drill head connection section (21).

13. Drill head start part (2) according to one of the preceding claims, wherein outer parts furthest from a central longitudinal axis of the drill head start part (2) Rod electrodes (200') are arranged at an angle of more than 1.5° away from the longitudinal axis.

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