RU2204008C2 - Method and device for superhigh frequency of electrothermomechanical drilling - Google Patents

Abstract

FIELD: well drilling, particularly, methods and technical facilities for drilling in hard rocks of prospecting and development wells, including horizontal and complicated directional wells in oil and gas industry. SUBSTANCE: rock cutting is effected by continuously rotating mechanical tool with pulses of superhigh frequency energy reducing rock strength. In this case, mechanical instrument is rotated at frequency depending on pulse duration. Device for method embodiment provides for superhigh frequency energy transmission to well bottom with the help of H₀₁ type wave through hollow flexible continuous drill pipe with low losses. Electromagnetic wave radiator is made in the form of cylindrical transmission adjustable resonator. EFFECT: higher efficiency of superhigh frequency electrothermomechanical drilling process. 3 cl, 5 dwg

Description

 The invention relates to drilling equipment, and in particular to methods and technical means of drilling in hard rocks of exploratory and production wells, including horizontal (GS) and complex directional (SNA) in the oil and gas industry.

 Known non-traditional effective methods of drilling wells in hard rocks, one of which is a microwave ETM drilling method [1]. This method does not require the creation of large axial forces, which is especially important when drilling with downhole motors ГС and СНС, since in this case, the transfer of large axial forces to the bottom is difficult due to the friction of the heavy drill string against the borehole wall.

 The physical essence of this method consists in the fact that during the rotation of the drilling body, powerful pulses of microwave energy are applied to the bottom of the well in resonance mode of electromagnetic waves, as a result of which their strength decreases on the surface layer of the rock and the layer breaks down through the thermal breakdown channels, after which the weakened rock is destroyed by the cutters of the drilling organ and is removed from the well by compressed air [2]. This method is accepted by us as a prototype. One of the important advantages of the opposed method is that the transfer of electromagnetic energy to the rocks is carried out in the mode of resonance of electromagnetic waves, which ensures almost complete transfer (up to 95%) of the energy supplied to the rocks and increases the efficiency of electromagnetic effects on the rocks due to the sharp resonant increase in the electric component of the electromagnetic field.

 Studies of the microwave ETM of the drilling method showed that the drilling speed of these methods for hard rocks is 2-3 times higher than the speed of drilling with a roller cone tool. The energy intensity of the fracture process decreases by about 1.5-2 times, and the axial force decreases by at least 5 times.

The disadvantages of the known microwave ETM drilling method include:
- inconsistent impact on the face of electromagnetic pulses and a mechanical tool, which reduces the real effectiveness of the destruction of rocks during drilling;
- not simultaneous, but sequential irradiation of the face zones with an electromagnetic field, as a result of which rock destruction at the face is carried out periodically with a period of 1 revolution, which also reduces drilling productivity.

 The aim of the proposed method is to increase the efficiency of the microwave ETM process of destruction of rocks during drilling.

Achieving this goal in the proposed method, including the combined impact on the bottom of the well with a strong electromagnetic field, reducing the strength of the rock and a mechanical cutting tool without the use of large axial loads, damaging the weakened rock, which is removed from the well by compressed air, and the transmission of microwave energy to the rock by pulses to The resonance mode of electromagnetic waves during continuous rotation of a mechanical tool is achieved by the fact that the mechanical tool is rotated with a frequency depending on the duration of the pulse, with the pulse duration t _u , the duration of the pause t _n between pulses, during which the weakened rock layer is additionally destroyed and removed from the bottom, as well as the rotation frequency n of the mechanical tool is determined based on the electrical, mechanical and thermal properties of the rock, as well as the density transmitted to the rock of power, in accordance with the dependencies established during research (the dimension of the values according to the international SI system):
t _u = ΔТ _cr • ρ • s / P _y (1)
t _n = (2-3) t _u (2)
n = 2ε • α ₃ / t _u (3)
where ΔТ _kr is the critical temperature difference (degrees) of the rock being destroyed by the condition of thermal breakdown during the pulse, is determined by the formula
ΔT _cr = 2δ _p (1-ν) / β • E _w (4)
δ _p is the tensile strength of the rock due to the temperature difference ΔT _cr during thermal breakdown (N / m ² ); ν is the Poisson's ratio (dimensionless); ρ - rock density (kg / m ³ ); s is the heat capacity of the rock (J / (kg • deg.)); β is the coefficient of linear expansion of the rock (dimensionless.); E _Yu - Young's modulus (N / m ² ); ε is the relative dielectric constant of the rock (dimensionless.); α ₃ - attenuation coefficient of the electromagnetic wave in the rock (dimensionless.) - the ratio of power lost in the destructible layer of the rock to the transmitted power; P _y - the density of the power transmitted to the rock (kW / m ³ ).

 As a result of the application of the proposed method, the drilling speed of the microwave ETM method in comparison with the mechanical roller cone method will increase up to 4-5 times, and the axial force will decrease by at least an order of magnitude. We do not know how to drill wells that have a combination of the above characteristics, which means that the proposed method meets the requirements for inventions.

 A device for drilling a microwave ETM method is known, including a drilling rig with a feed system, a microwave energy generator, a drill string with a waveguide transmission line, a rock cutting tool with a cutting tool and a built-in electromagnetic energy emitter in the form of a tunable resonator [3]. The specified device is accepted by us as a prototype.

The disadvantages of this device are:
- large losses of microwave energy in the waveguide transmission line, made in the form of a rectangular waveguide operating on a wave of type H ₁₀ , as a result of which this device can only be used for drilling shallow wells with a length of up to about 50 m;
- asymmetric arrangement of the microwave energy emitter relative to the axis of the device, in connection with which the destruction of the rock is carried out periodically with a period of 1 revolution, which reduces the efficiency of drilling;
- inconsistent impact on the bottom of the microwave electromagnetic field and a mechanical tool, which also reduces the efficiency of drilling microwave ETM drilling device.

The aim to which the invention is directed is to increase the efficiency of drilling a microwave ETM drilling device and expand its scope. To achieve this goal in the proposed device for microwave ETM drilling, including a drilling rig with a feed system, a microwave energy generator, a drill string with a waveguide transmission line, a rock cutting tool with a cutting tool and an integrated emitter of electromagnetic energy in the form of a tunable resonator, the difference is drill string for transmission of electromagnetic energy of microwave to the bottom ₀₁ on the H-type wave, low loss, it is formed as a hollow flexible continuous drill pipe, and an emitter lektromagnitnoy energy provided exciter electromagnetic waves thus pass tunable resonator is cylindrical, the upper part is limited by end attached to the diaphragm with connection openings of agent, and the bottom adjacent to the bottom, the wedge is divided by partitions into two or more waveguide channels. In order to ensure microwave energy transfer through the downhole motor, the rotor shaft of the motor is hollow.

 These signs can eliminate these drawbacks inherent in the well-known microwave ETM drilling device, and will make it possible to drill deep wells, including horizontal (horizontal wells) and complex (SSS) with low losses of microwave energy and small axial loads.

 We are not aware of devices for microwave ETM well drilling that have a combination of the above features, which means that the proposed device meets the requirements for inventions. Figure 1 shows a General view of the microwave ETM drilling rig for drilling a horizontal well and SSS; in FIG. 2 - rock-breaking organ; in FIG. 3 - view In figure 2 (view of the end face of the rock cutting body); figure 4 is a section along aa in figure 2; figure 5 is a view of B in figure 2.

Installation, FIG. 1, includes rock-cutting microwave ETM body 1; downhole motor 2 with a hollow shaft; a flexible continuous pipe 3 wound on a winch drum, through the inner cavity of which a microwave electromagnetic energy is fed to the face at the wave of type H ₀₁ and a compressed gaseous agent is used to clean the face of the destroyed rock; drill pipe feeder 4, downhole; drill rig 5 with a winch for winding a flexible continuous pipe 3 on a drum; 6 - microwave power unit, consisting of a power supply and a microwave generator, which is connected by a rotating waveguide connection (not shown) to the end of the drill pipe extending through the axis of the drum; compressor 7 - for supplying a gaseous treatment agent to the drill pipe 3.

 The rock-breaking organ 1, FIGS. 2, 3, 4 and 5, contains a cutting tool 9; microwave energy emitter, made in the form of a tunable tuned resonator 8 through passage, the lower part of which adjacent to the bottom is formed by a housing 10 and wedge walls 11 fixed therein, which divide the cylindrical cavity of the resonator into two or more number of waveguide channels 12 leading to the bottom, cutters 13, outlining the ends of the housing 10 and the wedge walls 11. To the upper part of the razonator 8 by means of a thread 14 is attached an exciter of electromagnetic waves 15, consisting of a housing 16 and a transition 17 with a cylindrical of the waveguide 18 to rectangular waveguides 19, ending with communication holes 20 in the diaphragm 21 attached to the end face of the pathogen 15 of the electromagnetic waves 21. Between the housing 10 of the resonator 8 and the housing 16 of the pathogen 15 are placed adjusting rings 22.

 The operation of the proposed device and the method of microwave ETM well drilling with its help is as follows. Before the rock-cutting organ is lowered into the well, a tunable cylindrical tuned resonator 8 embedded in it is tuned to the maximum microwave energy transfer to the rock, which is controlled by measuring the standing wave coefficient (VSWR) in the waveguide line. In this case, the resonator 8 is tuned modulo the coefficient of the reflected wave by either replacing the diagram 21 with another with different sizes of the communication hole 20 or by adjusting the microwave generator in frequency. The resonator 8 is adjusted according to the phase of the reflection coefficient by changing the length of the resonator 8 by changing the number of adjusting rings 22.

 According to formulas (1), (2) and (3), the rotational speed of the rock-breaking organ, as well as the pulse and pause duration, is established depending on the density of power transmitted to the rock.

During drilling, during rotation of the rock cutting body, pressed against the bottom by the feeder 4, to the pathogen 15 from the microwave generator (not shown) through the internal cavity of the drill pipe 3, powerful microwave energy pulses are supplied, which the pathogen 15 transfers to the communication holes 20 and through them excites in the resonator 8, electromagnetic waves are then radiated into the rock through the waveguide channels 12. Moreover, in order to drastically reduce energy losses, it is transmitted on a wave with small losses of type H ₀₁ . As a result of exposure to the rock with a microwave energy pulse, it softens and is destroyed along the thermal breakdown channels.

 Due to the fact that the quality factor of a tunable cylindrical tuned resonator is low, and the limits of changes in the electrical properties of rocks in the microwave range are narrowed, the resonator practically does not require tuning during drilling.

 After each impulse, during a pause, with the help of a mechanical tool, additional destruction of the weakened rock layer and its removal from the well by a compressed gaseous agent is performed. After removing the weakened rock layer using an automatic control system, another impulse is given and the drilling process is repeated.

Sources of information:
1. USSR author's certificate 231465, IPC E 21 c, published on November 28, 68 Bulletin 36.

 2. Tsyganenko S.M. Combined microwave mechanical drilling method. Abstracts at the seminar IGD them. A.A. Skochinsky November 21-23, 1990 "New in the theory, technology and drilling technique", M., 1991, p. 10-13.

 3. USSR author's certificate 394547, Е 21 с 37/18, published on 08/22/73, Bulletin 34, Е 21 с 21/00.

Claims (3)

1. The method of microwave ETM drilling, according to which the destruction of the rock is carried out by combined exposure to the bottom of the well with a strong electromagnetic field, reducing the strength of the rock, and a mechanical cutting tool that does not require large axial loads, damaging the weakened rock during rotation, which is removed from the well by a gaseous agent , while the transfer of microwave energy to the rock is produced by pulses in the resonance mode of electromagnetic waves with continuous rotation of a mechanical tool, distinguishing Take into account that the mechanical tool is rotated with a frequency depending on the duration of the pulse, while the pulse duration t _u , the duration of the pause t _n between pulses, during which the weakened rock layer is further destructed and removed from the bottom, and the rotation frequency n of the mechanical tool is determined based on from the electrical, mechanical and thermal properties of the rock, as well as the density of the microwave power transmitted to the rock in accordance with the dependencies:
t _u = ΔТ _cr • ρ • s / P _y ,
t _n = (2 ÷ 3) t _u ,
n = 2ε • α ₃ / t _u ,
ΔT _cr = 2δ _p (1-ν) / β • E _w ,
where ΔТ _kr is the critical temperature difference of the rock layer being destroyed by the condition of thermal breakdown during the pulse, deg. ;
δ _p is the tensile strength of the rock due to the temperature difference ΔТ _cr during thermal breakdown, N / m ² ;
ν is the Poisson's ratio (dimensionless);
ρ is the density of the rock, kg / m ³ ;
s - heat capacity of the rock, J / kg • deg. ;
β is the coefficient of linear expansion of the rock (dimensionless.);
E _Yu - Young's modulus, N / m ² ;
ε is the relative dielectric constant of the rock (dimensionless.);
α ₃ - attenuation coefficient of the electromagnetic wave in the rock (dimensionless.) - the ratio of power lost in the destructible layer of the rock to the transmitted power;
P _y - the density of the power transmitted to the rock, kW / m ³ . 2. A device for microwave ETM drilling, including a drilling rig with a feed system, a microwave energy generator, a drill string with a waveguide transmission line, a rock cutting tool with a cutting tool and an integrated electromagnetic energy emitter in the form of a tunable tuned resonator, characterized in that for drilling horizontal and difficult directional boreholes using a downhole motor, the drill string for transmission of electromagnetic energy of microwave to the bottom on the wave types H ₀₁ with small losses, is designed as a hollow a continuous drill pipe, and the electromagnetic energy emitter is equipped with an electromagnetic wave exciter, while the tunable through-flow resonator is cylindrical, the upper part of which is limited by a diaphragm with communication holes attached to the exciter end, and the lower one adjacent to the bottom is divided by two or more wedge walls waveguide channels.  3. The device according to p. 2, characterized in that, in order to transfer microwave energy through the downhole motor, the rotor shaft of the motor is made hollow.

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