RU2524101C2 - Electric pulse well drilling and electric pulse drill tip - Google Patents

Abstract

FIELD: oil-and-gas industry.

SUBSTANCE: invention relates to well and shaft drilling. Drilling of solid bodies by electric pulse discharges comprises destruction of said bodies by high-voltage electric discharges between HV and grounded electrodes by electric pulse drill tip. Descending flow of flushing electrically conducting fluid destructs solid bodies to form gas cavity nearby working area naked end of HV electrode. Drill tip comprises HV and grounded electrodes isolated by insulator furnished with openings for feed of flushing fluid. HV electrode is shaped to skirt while central grounded electrode is spring loaded. Said drill tip is equipped with second grounded electrode composed of ring arranged above HV electrode.

EFFECT: higher efficiency and ecological safety.

2 cl, 2 dwg, 4 tbl

Description

The invention relates to methods and devices for drilling wells and shafts during geological exploration, for sinking mining in the mining industry, in the oil and gas industry, the destruction of solids in construction, in the construction of power transmission towers, and can be used for drilling wells in permafrost areas with rocky soils, with soils of increased hardness, for the destruction of concrete and reinforced concrete products, cutting holes in concrete and reinforced concrete products.

A known method of electric pulse drilling of wells and the destruction of solids. So, for example, the electric-pulse method of drilling wells and a drilling rig is known (Bazhov V.F., Semkin B.V., Adam A.M. Optimization of electric-pulse destruction of rocks and artificial materials. // News of Higher Educational Establishments “Physics.” - 1996. - No. 4. - S.106-109).

The essence of this method lies in the fact that the electrodes of the drill bit mounted on the rock, which is covered with a flushing fluid, serves high voltage pulses of microsecond duration. An electric discharge channel is introduced into the rock with its subsequent destruction around the electric breakdown channel with the separation of the rock below it. In this case, the exposure time of the voltage pulse to the breakdown is chosen depending on the length of the interelectrode gap.

The main disadvantage of this method is the complexity of changing the time of exposure to voltage pulses.

A device for drilling solids with electric pulse discharges. So, for example, the SU electric impulse drill bit is known (AS 730027 dated 12/30/1971, publ. 04/16/1994). The essence of the drill bit is that it consists of high-voltage and grounded electrode systems separated by a dielectric, and dielectric pads are attached to the working surfaces of the high-voltage electrode system. The presence of dielectric pads causes a sharp distortion of the electric field at the end of the high-voltage electrodes and, as a result, leads to an increase in the rate of development of the discharge channel, which increases the likelihood and depth of the introduction of discharges into the rock.

The main disadvantage of this device for drilling solids with electric impulse discharges is the ability to drill only when using electrical insulating flushing drilling fluids and a high probability of a drill hanging in the well.

Another electropulse method of drilling wells is also known (Semkin B.V., Usov A.F., Kurets V.I. Fundamentals of electropulse fracture of materials. - S.-Pb .: Nauka, 1995 - P.7-11, 34-62 , 220-224 and C.11-16, 231-240). This method consists in the fact that the destructible rock is placed in a liquid that is electrical insulating for given parameters of high-voltage pulses. When applying high voltage pulses to the electrodes, the discharge is introduced into the rock and its destruction. At the same time, several parameters are optimized.

The main disadvantage of this analogue method is the optimization of only part of the parameters for electrical breakdown of the rock, and breakdown with opposing electrodes. However, when drilling wells, the conditions differ markedly, since the rock in the well has only one exposed surface, on which the electrodes are applied.

Closest to our proposed method and device for drilling solids is the electropulse method of drilling wells and a drill bit that we have chosen for the prototype (patent RU No. 2123596, C1, IPC E21C 37/18 from 10/14/1996, publ. 12/20/1998 Bull. No. 35).

According to the method selected for the prototype, the destruction of rocks located under a layer of electrical insulating washing liquid is carried out by high-voltage pulse discharges that occur inside the rock, and the main drilling parameters are selected from conditions that depend on the experimental values of the amplitude of the pulse voltage of the breakdown of rocks in the washing liquid, from the number of electrodes of the drill bit, the interelectrode gap of the drill bit and the diameter of the drill bit, the repetition frequency electric impulses expressed by empirical dependencies.

The main disadvantage of this method is the use as a washing liquid only electrical insulating washing liquid. Typically, these liquids are based on petroleum based liquids (e.g., solar oil). This is, first of all, a violation of the ecological situation not only of the well drilling site, but also the susceptibility of underground pollution by washing fluid products - washing fluid products entering aquifers and their pollution. This fact greatly limits the applicability of this method of drilling wells.

The device selected for the prototype represents the drill bit shown in FIG. 1 (patent No. 2123596) and consisting of high-voltage and grounded electrodes separated by a solid insulator.

The main disadvantage of the known method and device for drilling solids by electrical impulse discharges is the inability to use electrically conductive washing liquid, for example water or solutions based on it, for washing wells.

The technical result of the proposed method and device is the possibility of using electrically conductive flushing liquids. The proposed method and device can also eliminate the main disadvantages of the known technical solutions and increase the efficiency and environmental safety of well drilling by the electric pulse method.

The specified technical result, according to the proposed solution, is achieved by the fact that in the proposed method of drilling solids by electric pulse discharges, including the destruction of solids directly by high voltage pulsed electric discharges in solids between a high voltage and a grounded electrodes of an electric pulse drill bit, in the process of destruction of solids by a downward flow conductive wash fluid form a gas cavity around the bottom of the bare end is high volt electrode.

The specified technical result is also achieved by the fact that in the proposed electropulse drill bit containing high-voltage and grounded electrodes separated by an insulator made with windows for supplying flushing fluid, according to the proposed solution, the high-voltage electrode is made in the form of a skirt, and the central grounded electrode is spring-loaded, and the electric pulse the drill bit is equipped with a second grounded electrode made in the form of a ring located above the high-voltage electrode .

An example of a specific implementation of the proposed method. To compare the proposed and known methods of electric pulse drilling, an experimental drill bit was manufactured, the design of which is shown in Fig. 1. The high-voltage electrode 1 is installed along the axis of the drill with a diameter of 12 mm, which has a spring-loaded 2 stroke of 40 mm. The grounded electrode 3 is a continuation of the outer casing 4 of the drill string with an outer diameter of 89 mm, expanding cone-shaped towards the bottom face with an outer diameter of 100 mm. The electrodes 1 and 3 are separated by a solid insulator made of polyethylene 5. Inside the housing 4, a pipe 6 is coaxially arranged with an outer diameter of 68 mm. Inside the pipe 6, a high-voltage current lead 7 is coaxially located, which is isolated from the pipe 6 by the insulator 5. The gap between the pipes 4 and 6 is used to pump the flushing fluid 8. In the insulator 5 there are windows 9 for supplying the flushing fluid 8. On the rock sample 10 (rock was used rock - sandstone) a preventer 11 is installed, which provides sealing of the flushing fluid from spills on the surface and collecting solid products from drilling in the well. A flushing pump 12 is connected to the preventer 11 with a drilling product purification system that supplies flushing fluid to the drill bit.

For comparative tests, industrial water and diesel fuel were used as flushing liquids. During drilling, the following parameters were measured: breakdown voltage of the rock, energy of the electric discharge, the number of pulses and the average volume of the destroyed rock in one pulse. The flow rate of the washing liquid was measured by a liquid flow meter and was selected based on the optimal flow rate required to remove the drilling products and the formation of a gas-vapor cavity 13 (Fig. 1 and Fig. 2) around the bottom-hole exposed end of the high-voltage electrode 1.

Initial experiments were carried out to determine the breakdown stress and specific energy consumption per 1 cubic centimeter of drilled rock of an experimental drill bit in the absence of flushing, when the system was filled with water (Table 1) and when the system was filled with diesel fuel (Table 2). The breakdown of the rock was carried out at the front of the voltage pulse.

Table 1 U _pr , kV 180 200 220 250 280 330 350 400 450 500 W, J / cm ³ no rock breakdown no rock breakdown no rock breakdown no rock breakdown no rock breakdown 350 320 290 260 240

table 2 U _pr , kV 180 200 220 250 280 330 350 400 450 500 W, J / cm ³ no rock breakdown no rock breakdown no rock breakdown 310 280 230 180 190 220 250

From the data given in tables 1 and 2, it can be seen that at a voltage below the minimum working one (for water Up = 350 kV, and for diesel fuel Up = 310 kV) there is no introduction of the discharge channel into the rock and, as a result, there is no destruction . An increase in voltage leads to breakdown in the rock and its destruction, but the probability of introducing a discharge channel into the rock is less than 100%.

Further testing of the experimental drill was carried out using flushing. For a given diameter of the drill, the optimum flushing fluid flow rate of 15 m ³ / h was experimentally established, and in subsequent tests this flushing fluid flow rate remained unchanged.

Table 3 shows the experimental data during drilling, where industrial water was used as a flushing fluid.

Table 3 U _pr , kV 200 220 250 300 350 400 450 500 W _imp , J 320 387 500 720 980 1280 1620 2000 N _imp 150 150 150 150 150 150 150 150

$$Q_{\mathrm{from}R.\mathrm{and}mP\cdot \mathrm{from}{m}^3}$$

1.7 2,4 3.5 5.6 6.1 5.8 5.4 4.6 $$Q_{\mathrm{well}\mathrm{and}d\mathrm{to}.m^3/h\mathrm{but}\mathrm{from}}$$

fifteen fifteen fifteen fifteen fifteen fifteen fifteen fifteen

Table 4 shows the experimental data during drilling, where diesel was used as a flushing fluid.

Table 4 U _pr kV 200 220 250 300 350 400 450 500 W _imp j 320 387 500 720 980 1280 1620 2000 N _imp 150 150 150 150 150 150 150 150

$$Q_{\mathrm{from}R.\mathrm{and}mP\cdot \mathrm{from}{m}^3}$$

1.8 2.6 3.7 5.8 6.3 5.9 5.5 4.8 $$Q_{\mathrm{well}\mathrm{and}d\mathrm{to}.m^3/h\mathrm{but}\mathrm{from}}$$

fifteen fifteen fifteen fifteen fifteen fifteen fifteen fifteen

From the experimental data shown in tables 3 and 4, it can be seen that electropulse drilling when using water as a flushing fluid in its characteristics is practically not inferior to electropulse drilling when using diesel fuel as a flushing fluid. The proposed method even surpasses the previously known energy indicators, namely: there is a decrease in the level of stress on the breakdown of the rock and, as a result, a decrease in energy costs for the process of destruction of the rock. This fact can be explained on the basis of the following. It is known that the breakdown of solid dielectrics primarily depends on the electric field strength in a solid dielectric (see, for example, the book “High Voltage Technique” ./ Edited by Corresponding Member of the USSR Academy of Sciences MV Kostenko, pp. 126 ÷ 133 , -M.: “Higher school”, 1973), upon reaching which a conduction channel is formed in a solid dielectric and, as a result, its breakdown. In strongly inhomogeneous fields, an electric discharge occurs only in the region of high field strength near electrodes with a small radius of curvature. In the proposed device and method, after applying voltage to the high-voltage electrode 1 (see FIG. 1), when a certain critical voltage is reached, a breakdown of the gas cavity 13 occurs and a highly conductive discharge channel is formed. The electric field strength at the end of this channel is several orders of magnitude higher (the diameter of the incomplete discharge channel is less than a micron) than in a stationary electrode system, and the field strength changes in less than 10 ^-7 seconds (determined by the breakdown time of the gas cavity). It is also known that for short periods of exposure to voltage (less than 10 ^-5 ÷ 10 ^-6 sec), the dielectric strength of liquid dielectrics becomes higher than that of solid dielectrics (Semkin B.V., Usov A.F., Kurets V.I. Electropulse fracture of materials. - S.-Pb .: Nauka, 1995. - S.7-11). After the breakdown of the gas cavity, a breakdown of the liquid layer occurs between the gas cavity and the solid (if any), and then a breakdown of the solid (rock) occurs, and the rock is destroyed by the energy released in the discharge channel. The probability of rock breakdown increases to almost 100%, and the breakdown voltage decreases due to the higher electric field strength in the discharge gap.

It is also known that in order to reduce pre-breakdown losses in electrode systems filled with water, the area of the high-voltage electrode in contact with water should be minimal (see, for example, G. A. Guly, P. P. Malyushevsky. High-voltage electric discharge in power pulsed systems. -Kiev, “Naukova Dumka”, 1977, S.30-34).

A specific implementation of the proposed method and device for drilling solids with electric pulse discharges.

Electric pulse drill bit (Figure 1 and Figure 2), consisting of a high-voltage 1 and a grounded 3 electrodes separated by an insulator 5 with windows 9 for supplying flushing fluid 8. The flow of flushing fluid 8 based on water entering through the windows 9 in the insulator 5, separating the high-voltage electrodes 1 and 3, forms a gas cavity 13 around the high-voltage electrode 1, which ensures that the exposed parts of the high-voltage electrode are not contacted with the washing liquid.

In addition (Figure 2), the high-voltage electrode 1 is made in the form of a skirt, the working surface of which is the end of the wide part of the electrode, and two grounded electrodes 3 are located: one in the center of the drill bit, and the second grounded electrode 3 in the form of a ring is located above the high-voltage which is connected to the outer casing 4.

The principle of operation of the proposed method and device for drilling solids with electric pulse discharges is as follows. Pridentor 11 is filled with water-based flushing fluid 8. The washing pump 12 is started. Under the action of a downward flow of washing liquid entering through the washing windows 9, a gas cavity 13 is formed around the exposed part of the high voltage electrode 1, which isolates the high voltage electrode from direct contact with the washing liquid. After the rinsing system has entered the operating mode (the rinsing system has been completely filled with rinsing liquid and air has been removed from the rinsing system), the high voltage pulse source is turned on. High voltage pulses are supplied to the electrode system 1 and 3 of the electric pulse drill bit. Under the action of high voltage on the high-voltage electrode, a breakdown of the gas cavity 13 surrounding the high-voltage electrode 1 occurs, then breakdown of the flushing fluid 8, and then breakdown of the rock 10. Under the action of high-voltage discharges, rock breaks off and breaks down. destruction occurs in the lower end of the drill. As the bottom deepens, the central part of the grounded electrode 3 extends (FIG. 2) under the action of the spring 2 and the interelectrode gap increases. The distance between the high-voltage electrode 1 and the side grounded ring electrode 3 becomes commensurate with the interelectrode gap located in the end part and high-voltage discharges are formed between the high-voltage electrode 1 and the ring grounded electrode 3. As a result of these discharges, rock breakdown and destruction occurs around the periphery of the drill, which contributes to the formation of a wider diameter of the well and the independence of the drill in the well itself, it also contributes to the formation of more a wide channel for the removal of drilling products to the surface. The drilling products together with the flushing fluid enter the preventer through the annulus, from which they are removed by any known method, and the cleaned flushing fluid again enters the face.

The absence of the need to rotate the drill bit about its axis, the constancy of electric fields in the bottomhole between the electrode system, the use of liquids based on water (or purely industrial water) as washing liquid, gives the undoubted advantages of the proposed method and device for drilling solids with electric pulse discharges over the known electric pulse drilling methods.

Claims (2)

1. The method of drilling solids by electrical impulse discharges, including the destruction of solids directly by high-voltage pulsed electrical discharges in solids between high-voltage and grounded electrodes of an electric impulse drill bit, characterized in that during the destruction of solids by a downward flow of electrically conductive washing fluid they form a gas cavity around the bottom hole the bare end of the high voltage electrode. 2. Electropulse drill bit containing high-voltage and grounded electrodes separated by an insulator made with windows for supplying flushing fluid, characterized in that the high-voltage electrode is made in the form of a skirt, and the central grounded electrode is spring-loaded, and the electropulse drill bit is equipped with a second grounded electrode, made in the form of a ring located above the high-voltage electrode.

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