Underground continuous pressure wave generating device

Abstract

The invention provides an underground continuous pressure wave generating device. The underground continuous pressure wave generating device comprises a rotary valve body, a driving motor and a speed reducer, the rotary valve body comprises a stator, a rotor and a rotary shaft. The driving motor drives the speed reducer, the rotating shaft and the rotor to rotate; the stator is mechanically connected with a shell of the continuous wave pulser and rotates along with the rotation of the drill rod; the front ends of valve ports of the stator and the rotor are designed according to a theoretical curve, and curves of the front ends of the valve ports of the stator and the rotor are designed by combining a fluid dynamics simulation analysis technology and a correlation algorithm; the distance between the stator and the rotor relative to the fluid inflow direction is an axial gap, and a radial gap is arranged in the radial direction. By adopting the scheme, the problems of high blocking risk and serious pressure wave signal loss in the prior art are solved, the stator and rotor valve port curve is optimally designed by utilizing the relevancy algorithm, the influence of the axial clearance and the radial clearance on the pressure wave is comprehensively considered to generate the high-quality continuous sine pressure wave, and support is provided for efficient and lossless transmission of underground data.

Description

Technical Field

[0001] The present invention relates to the technical field of downhole drilling information transmission optimization, and in particular to a downhole continuous pressure wave generating device for optimizing a drilling fluid continuous wave generator. Background Art

[0002] As the global demand for oil resources continues to rise, oil companies are required to increase production and reduce costs. In order to achieve these requirements, more advanced oil equipment is needed as support. With the development of emerging logging technology, while enhancing people's understanding of downhole conditions, it has also greatly increased the amount of downhole information collected, which has put forward higher requirements for downhole and uphole data transmission, and more and more higher data transmission rates are needed to transmit all downhole information to the ground in real time.

[0003] The methods available for transmitting downhole information to the surface mainly include drilling fluid pressure wave telemetry, acoustic wave telemetry, electromagnetic wave telemetry, wired drill pipe and other technologies. Among them, drilling fluid pressure wave telemetry is more stable in actual production practice, so it is widely used in drilling sites. The drilling fluid pressure wave method transmits downhole information through pressure changes in the drill string. The pressure wave generator periodically blocks the flow of drilling fluid and produces pressure changes in the well. Since the drilling fluid is incompressible, the pressure changes in the well can be transmitted to the ground, thereby achieving the purpose of signal transmission.

[0004] The three signals generated by the pressure wave generator are negative pulse, positive pulse and continuous wave. Among them, the drilling fluid positive pulse method and drilling fluid negative pulse method are widely used in industrial applications. These two methods have simple structure and low bit error rate, but the transmission signal rate is low, and there are certain limitations in transmission efficiency. At present, in practical applications, the field transmission rate is usually less than 2bit / s. The operating frequency of continuous wave telemetry can be very high, which makes high-speed data transmission possible. The continuous wave generator consists of a rotor and a stator. The rotor and the stator each have multiple blades. The rotor is driven by a motor. When it rotates, the continuous wave is generated by opening or partially closing the space between the stator and the rotor.

[0005] Although rotary pressure wave generators have been improved in the past few years, they still have shortcomings. So far, the stator and rotor orifices of pressure wave generators mainly include rectangular, triangular, fan-shaped leaf orifices, curved valve orifices, etc., but the pressure waves generated by these generators are not close to sinusoidal waves, but are composed of high-frequency harmonics. Based on this, according to the propagation characteristics of periodic mud pressure waves in long wellbores, the amplitude of these pressure waves decreases exponentially with increasing frequency, and the energy of the pressure signal reaching the ground is lost in the form of harmonics, which will bring about a series of problems such as large signal transmission attenuation, coding modulation and difficulty in signal processing.

[0006] Usually, drilling fluid contains solid particles and debris. These particles and debris need to pass through the outer orifice of the stator. If the orifice is too small, the risk of blockage will be greatly increased. Therefore, this requires a certain axial clearance and radial clearance between the stator and the rotor to reduce the risk of blockage. Although some studies on continuous wave generators have mentioned the view that there should be an axial clearance between the stator and the rotor, they only consider the effect of the shape of the valve port plane on the pressure wave, without comprehensively considering the effect of the axial clearance and the radial clearance on the pressure wave, resulting in a large deviation between the pressure wave actually generated by the rotary valve and the sinusoidal pressure wave.

[0007] To sum up, the existing technical solutions do not comprehensively consider the influence of the axial clearance and radial clearance of the stator and rotor on the pressure wave waveform, resulting in the stator and rotor orifice shape of the rotary valve being unable to produce a pressure wave close to a sinusoidal shape. It is necessary to establish a rotary valve structural design solution that comprehensively considers the axial clearance and radial clearance of the stator and rotor.

[0008] The information disclosed in the background technology section of the present invention is only intended to deepen the understanding of the general background technology of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art known to those skilled in the art. Summary of the invention

[0009] In order to solve the above problems, the present invention provides a downhole continuous pressure wave generating device, which is composed of a rotor-stator combination driven by a driving device and a motor. Its structure comprehensively considers the inlet and outlet pressure difference, the shape of the drilling fluid flow valve port, the axial clearance and radial clearance between the rotor and the stator, etc.; it can solve the problem that the continuous wave signal generated by the current continuous wave generator cannot be close to the sinusoidal pressure wave waveform, resulting in the loss of energy in the form of harmonics when the continuous wave signal reaches the ground, and can prevent the problem of solid particles in the drilling fluid clogging the rotary valve. Preferably, in one embodiment, the device includes: a rotary valve body, a driving motor and a reducer;

[0010] The rotary valve body comprises a stator, a rotor and a rotating shaft connected to the rotor;

[0011] The rotating shaft is connected to the driving motor and the reducer, and the driving motor drives the reducer, the rotating shaft and the rotor to rotate;

[0012] The stator is mechanically connected to the housing of the continuous wave pulser and rotates with the rotation of the drill pipe;

[0013] The stator and rotor adopt spatial special-shaped valve ports, and the front ends of the valve ports are designed according to the theoretical curve;

[0014] The rotor is located above the stator relative to the fluid inflow direction, the distance between the rotor and the stator relative to the fluid inflow direction is an axial gap, and a radial gap is provided between the rotor and the stator;

[0015] Among them, the curves at the front end of the stator and rotor valve ports are designed by combining fluid dynamics simulation analysis technology and correlation algorithm.

[0016] In one embodiment, the process of designing the curves of the front ends of the stator and rotor valve ports by combining the fluid dynamics simulation analysis technology and the correlation algorithm includes:

[0017] Set the initial parameters and correction coefficients of the valve port curve, and calculate the initial valve port curve based on the theoretical curve model;

[0018] Establish a three-dimensional structural model corresponding to the current valve port parameters, and use fluid dynamics simulation analysis to obtain the pressure wave curve;

[0019] Perform correlation calculation on the obtained pressure wave curve and the standard sine wave;

[0020] Then, the correction coefficient is adjusted according to the set strategy, the correction coefficient corresponding to the maximum correlation data is found as the target correction coefficient, and the target valve port curve is calculated according to the theoretical curve model using the target correction coefficient.

[0021] Optionally, in one embodiment, the valve ports of the stator and the rotor adopt the following theoretical curve model:

[0022]

[0023] Where R is the rotor radius, A0 is the total area of ​​the valve port, s is the axial clearance between the stator and rotor, ζ is the correction coefficient, k is the relative strength, n is the number of petals of the valve port, and λ is the influence coefficient of the orifice curve.

[0024] Furthermore, in one embodiment, the outer edge and the inner edge of the rotor are both circular, and are installed in concentric circles during installation. The rear end of the rotor valve port is designed as a straight line or a curve, and the theoretical curve at the rear end of the rotor valve port is independently designed relative to the theoretical curve at the front end of the valve port.

[0025] Preferably, in one embodiment, the stator and the rotor have the same shape, and the rotor can generate a target pressure wave when rotating forward or reverse at a constant speed, and the target pressure wave is a sinusoidal pressure wave.

[0026] As a further improvement of the present invention, in one embodiment, the connecting portion between the stator and the rotor valve port is smoothly connected in the form of a rounded corner or a curve, so that the sinusoidal pressure wave generated by the pulser is continuous.

[0027] Furthermore, in one embodiment, the rotating shaft adopts a streamlined shape to reduce the impact of the drilling fluid on the rotating shaft when passing through.

[0028] In an optional embodiment, the radial gap width between the stator and the rotor is set to the difference between the stator diameter and the rotor diameter.

[0029] In actual application, in one embodiment, the axial gap between the stator and the rotor adopts different gap values ​​according to the operating well depth. When the operating well depth is less than or equal to the set deep well operation requirement, a first-level axial gap is adopted. Otherwise, a second-level axial gap is adopted. The first-level axial gap is larger than the second axial gap. The second axial gap is designed to increase the continuous wave signal strength during deep well operations.

[0030] Optionally, in one embodiment, the stator and the rotor are made of high-hardness materials, including cemented carbide, diamond or ceramic.

[0031] Compared with the closest prior art, the present invention also has the following beneficial effects:

[0032] The present invention provides a downhole continuous pressure wave generating device, in which a drive motor drives a reducer, a rotating shaft and a rotor to rotate; a stator is mechanically connected to a housing of a continuous wave pulser and rotates with the rotation of a drill pipe; an axial gap is set between the rotor and the stator relative to the fluid inflow direction, and a radial gap is set between the rotor and the stator, thereby reducing the risk of blockage caused by solid particles or debris in the drilling fluid;

[0033] The front ends of the valve ports of the stator and rotor are designed according to theoretical curves, and the curves of the front ends of the stator and rotor valve ports are designed by combining fluid dynamics simulation analysis technology and correlation algorithm; the mathematical model is combined with computational fluid dynamics analysis to optimize the shape of the rotary valve, so that when the rotor rotates, the pressure wave signal generated becomes an ideal sine wave, which effectively reduces the degree of energy loss in the form of harmonics when the continuous wave signal reaches the ground, generates high-quality continuous sinusoidal pressure waves, and improves data transmission reliability and timeliness.

[0034] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0036] Figure 1 It is a schematic structural diagram of a downhole continuous pressure wave generating device provided by one embodiment of the present invention;

[0037] Figure 2 It is a schematic diagram of the structure of a single stator of a downhole continuous pressure wave generating device provided by an embodiment of the present invention;

[0038] Figure 3 It is a schematic diagram of the structure of a single rotor of a downhole continuous pressure wave generating device provided by one embodiment of the present invention;

[0039] Figure 4 It is a front schematic diagram of the stator and rotor combination mode of the downhole continuous pressure wave generating device provided by an embodiment of the present invention;

[0040] Figure 5 It is a schematic diagram of the working flow field when the downhole continuous pressure wave generating device provided by another embodiment of the present invention is in operation;

[0041] Figure 6 It is a schematic diagram of the waveform pattern of the pressure wave generated by the downhole continuous pressure wave generating device provided in the embodiment of the present invention;

[0042] Figure 7 It is a schematic diagram of the valve port shape parameter design process of the downhole continuous pressure wave generating device provided by an embodiment of the present invention;

[0043] Figure 8 It is a schematic diagram comparing the waveform of the pressure wave generated by the downhole continuous pressure wave generating device provided by one embodiment of the present invention and the sine wave waveform;

[0044] Fig. 9 This is an example diagram of the waveform of the pressure wave actually output by the downhole continuous pressure wave generating device provided in the embodiment of the present invention;

[0045] Fig.10 is an example diagram of the frequency spectrum of the pressure wave actually output by the downhole continuous pressure wave generating device provided in the embodiment of the present invention;

[0046] In the figure, 1, stator, 2, front end of stator hole, 3, rear end of stator hole, 4, rotor, 5, front end of rotor hole, 6, rear end of rotor hole, 7, pulser housing, 8, driving device, 9, radial clearance, 10, axial clearance, 11, maximum signal value Pmax, 12, minimum signal value Pmin, 13, average signal value Pavg, 14, noisy pressure wave signal, 15, actual pressure wave signal. DETAILED DESCRIPTION

[0047] The following will describe the implementation methods of the present invention in detail in conjunction with the accompanying drawings and embodiments, so that the implementers of the present invention can fully understand how the present invention applies technical means to solve technical problems and achieve the implementation process of technical effects and implement the present invention specifically according to the above implementation process. It should be noted that as long as there is no conflict, the various embodiments and various features of the embodiments in the present invention can be combined with each other, and the technical solutions formed are all within the protection scope of the present invention.

[0048] Although the flowcharts describe the operations as sequential processes, many of the operations may be performed in parallel, concurrently, or simultaneously. The order of the operations may be rearranged. A process may be terminated when its operations are completed, but may also have additional steps not included in the accompanying drawings. A process may correspond to a method, function, procedure, subroutine, subprogram, etc.

[0049] Computer devices include user devices and network devices. Among them, user devices or clients include but are not limited to computers, smart phones, PDAs, etc.; network devices include but are not limited to a single network server, a server group consisting of multiple network servers, or a cloud composed of a large number of computers or network servers based on cloud computing. Computer devices can be operated alone to implement the present invention, or they can be connected to the network and implement the present invention through interactive operations with other computer devices in the network. The network where the computer device is located includes but is not limited to the Internet, wide area network, metropolitan area network, local area network, VPN network, etc.

[0050] The term "and / or" used herein includes any and all combinations of one or more of the associated listed items. When an element is referred to as being "connected" or "coupled" to another element, it may be directly connected or coupled to the other element, or intervening elements may be present.

[0051] The terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms "one", "one" and "item" used herein are also intended to include plural numbers. It should also be understood that the terms "include" and / or "comprise" used herein specify the existence of stated features, integers, steps, operations, units and / or components, without excluding the existence or addition of one or more other features, integers, steps, operations, units, components and / or combinations thereof.

[0052] With the development of emerging logging technologies, while people's understanding of downhole conditions has been enhanced, the amount of downhole information collected has also been greatly increased. This has put forward higher requirements for downhole and uphole data transmission, and a higher data transmission rate is increasingly needed to transmit all downhole information to the ground in real time. The methods available for transmitting downhole information to the surface mainly include: drilling fluid pressure wave telemetry, acoustic wave telemetry, electromagnetic wave telemetry, wired drill pipe and other technologies. Among them, drilling fluid pressure wave telemetry is more stable in actual production practice, so it is widely used in drilling sites. The drilling fluid pressure wave method transmits downhole information through pressure changes in the drill string. The pressure wave generator periodically blocks the circulation of drilling fluid and produces pressure changes in the well. Since the drilling fluid is incompressible, the pressure changes in the well can be transmitted to the ground, thereby achieving the purpose of signal transmission.

[0053] The three signals generated by the pressure wave generator are negative pulse, positive pulse and continuous wave. Among them, the drilling fluid positive pulse method and drilling fluid negative pulse method are widely used in industrial applications. These two methods have simple structure and low bit error rate, but the transmission signal rate is low, and there are certain limitations in transmission efficiency. At present, in practical applications, the field transmission rate is usually less than 2bit / s. The operating frequency of continuous wave telemetry can be very high, which makes high-speed data transmission possible. The continuous wave generator consists of a rotor and a stator. The rotor and the stator each have multiple blades. The rotor is driven by a motor. When it rotates, the continuous wave is generated by opening or partially closing the space between the stator and the rotor.

[0054] Although the rotary pressure wave generator has been improved in the past few years, it still has some shortcomings. At present, the stator and rotor orifices of the pressure wave generator mainly include rectangular, triangular, fan-shaped leaf orifices, curved valve orifices, etc., but the pressure waves generated by these generators cannot approach the sine wave type, but are composed of high-frequency harmonics. Based on this, according to the propagation characteristics of periodic mud pressure waves in long wellbores, the amplitude of these pressure waves decreases exponentially with the increase of frequency, and the energy of the pressure signal reaching the ground is lost in the form of harmonics, which will bring a series of problems such as large signal transmission attenuation, coding modulation and difficulty in signal processing. Usually, the drilling fluid contains solid particles and debris. These particles and debris need to pass through the outer orifices of the stator. If the orifice is too small, the risk of blockage will be greatly increased. Therefore, it is required that there is a certain axial gap and radial gap between the stator and the rotor to reduce the risk of blockage. Although some studies on continuous wave generators have mentioned the view that there should be a gap in the axial direction of the stator and rotor, they only consider the influence of the shape of the valve orifice plane on the pressure wave, and do not comprehensively consider the influence of the axial gap and radial gap on the pressure wave, resulting in a large deviation between the actual pressure wave generated by the rotary valve and the sine pressure wave.

[0055] In summary, the existing technical solutions do not comprehensively consider the influence of the axial clearance and radial clearance between the stator and rotor on the pressure wave waveform, resulting in the stator and rotor orifice shape of the rotary valve being unable to produce a near-sinusoidal pressure wave and unable to meet the requirements of drilling data transmission engineering.

[0056] In order to solve the above problems, the present invention provides a downhole continuous pressure wave generating device, which comprehensively considers the inlet and outlet pressure difference of the rotary valve, the shape of the drilling fluid flow valve port, the axial gap and radial gap between the rotor and the stator, etc.; the front end of the valve port of the stator and the rotor is designed according to the theoretical curve, and the curve of the front end of the stator and rotor valve port is designed in combination with the fluid dynamics simulation analysis technology and the correlation algorithm; the spacing between the stator and the rotor relative to the fluid inflow direction is set as the axial gap, and the radial gap is set between the radial directions. The adoption of this scheme overcomes the problems of high clogging risk and serious pressure wave signal loss in the prior art, and uses the correlation algorithm to optimize the design of the stator and rotor valve port curves, comprehensively considers the influence of the axial gap and the radial gap on the pressure wave to generate high-quality continuous sinusoidal pressure waves, and provides support for efficient and lossless transmission of downhole data.

[0057] Among them, a spatially anisotropic valve port rotary valve is adopted, and the structural parameters of the valve port are solved by combining fluid dynamics simulation analysis technology and correlation algorithm to optimize the design. The initial parameters and correction coefficients of the valve port curve are given, the initial valve port curve is calculated, and then a three-dimensional valve port structure model is established. Fluid dynamics simulation analysis is used to obtain the pressure wave curve, which is then compared with the sine wave for correlation, and then the correction coefficient is adjusted to find the correction coefficient at the maximum correlation to obtain the final stator and rotor valve port curve.

[0058] Next, the structural components, connection modes and functional principles of the system of the embodiment of the present invention are described in detail based on the drawings. Although the logical order of each operation is shown in the process of describing the operating principle of the system structure, in some cases, the operations shown or described can be performed in a different order than here.

[0059] Embodiment 1

[0060] Figure 1 The structure diagram of the downhole continuous pressure wave generating device provided by the first embodiment of the present invention is shown. Figure 1 It can be seen that the rotary valve includes: a rotary valve body, a driving motor and a reducer;

[0061] The rotary valve body comprises a stator 1, a rotor 4 and a rotating shaft connected to the rotor;

[0062] The rotating shaft is connected to the driving motor 8 and the reducer, and the driving motor drives the reducer, the rotating shaft and the rotor to rotate;

[0063] The stator is mechanically connected to the housing 7 of the continuous wave pulser and rotates with the rotation of the drill pipe;

[0064] The stator and rotor adopt spatial special-shaped valve ports, and the front ends of the valve ports are designed according to the theoretical curve;

[0065] The rotor is located above the stator relative to the fluid inflow direction, the distance between the rotor and the stator relative to the fluid inflow direction is an axial gap, and a radial gap is provided between the rotor and the stator;

[0066] Among them, the curves at the front end of the stator and rotor valve ports are designed by combining fluid dynamics simulation analysis technology and correlation algorithm.

[0067] like Figure 1 As shown, with the rotary valve of the embodiment of the present invention, the driving device 8 drives the rotor 4 to rotate, periodically blocking the flow of drilling fluid, thereby generating a drilling fluid continuous wave signal.

[0068] Optionally, in one embodiment, the stator and the rotor are made of high-hardness materials, including cemented carbide, diamond or ceramic.

[0069] Figure 2 FIG. 2 shows a schematic diagram of a single stator structure of a downhole continuous pressure wave generating device provided by an embodiment of the present invention; Figure 2 As shown, the stator 3 and the pulser housing 7 are processed into one piece, and the stator 1 rotates with the rotation of the drill pipe. The drilling fluid enters the pulser along the direction shown in the figure, passes through the stator valve port, the rotor valve port, the rotating shaft in sequence, and then flows out. The stator 1 and the rotor 4 together constitute the rotary valve body. Whether the rotor 4 rotates forward or reverse, a sinusoidal pressure wave can be obtained.

[0070] Figure 3 A schematic diagram of the single rotor structure of the downhole continuous pressure wave generating device provided by an embodiment of the present invention is shown; preferably, in one embodiment, the outer edge of the rotor and the inner edge of the stator valve port are both circular, and the outer circular surface of the rotor is installed concentrically with the inner circular surface of the stator valve port to ensure that the valve port curve can coincide; the rear end 6 of the rotor valve port is designed as a straight line or a curve, and the theoretical curve of the rear end 6 of the rotor valve port is independently designed relative to the theoretical curve of the front end 5 of the valve port.

[0071] The rotor valve port curve shape is designed according to the following theoretical curve model:

[0072]

[0073] Where r(α) is the polar diameter corresponding to the curve point at the polar angle α, α represents the polar angle, R is the rotor radius, A0 is the total area of ​​the valve port, s is the axial clearance between the stator and rotor, ζ is the correction coefficient, k is the relative strength, n is the number of petals of the valve port, λ is the influence coefficient of the orifice curve, and τ is the relative opening degree of the valve.

[0074] Optionally, in one embodiment, the stator and the rotor have the same shape, and the rotor can generate a target pressure wave when rotating forward or backward at a constant speed, and the target pressure wave is a sinusoidal pressure wave. In actual application, the rotor 4 and the stator 1 together form a rotary valve, such as Figure 4As shown, the stator rotates slowly with the drill pipe. When the rotor 4 rotates, the drilling fluid channel formed by the rotor 4 and the stator 1 changes periodically, and a sinusoidal pressure wave is obtained. The sinusoidal pressure wave equation is as follows:

[0075]

[0076] Where k is the relative strength, ω is the rotor speed, n is the number of valve petals, and t is time.

[0077] Specifically, the stator 1 is mechanically connected to the pulser housing 7 and rotates with the rotation of the drill pipe. The rear end 3 of the stator valve port is designed in a straight line or a curve, and the front end 2 of the stator valve port is designed according to a theoretical curve.

[0078] The shape of the stator valve port curve is designed according to the following theoretical curve model:

[0079]

[0080] Where R0 is the stator radius, A0 is the total area of ​​the valve port, s is the stator-rotor axial clearance, ζ is the correction coefficient, k is the relative strength, n is the number of petals of the valve port, and λ is the orifice curve influence coefficient.

[0081] Preferably, in one embodiment, the connecting portion between the stator and the rotor valve port is smoothly connected in the form of a rounded corner or a curve, so that the sinusoidal pressure wave generated by the pulser is continuous.

[0082] Furthermore, in an optional embodiment, the rotating shaft adopts a streamlined shape to reduce the impact of the drilling fluid on the rotating shaft when passing through.

[0083] Figure 5 FIG. 2 is a schematic diagram showing the working flow field of the downhole continuous pressure wave generating device provided by another embodiment of the present invention when in operation; in actual application, the drilling fluid flows into the radial gap 9 through the pores of the stator, and then flows out of the rotary valve through the axial gap 10 and the gap of the rotor, as shown in FIG. Figure 5 In one embodiment, the radial gap width between the stator and the rotor is set to the difference between the stator diameter and the rotor diameter; the flow area calculation equation is:

[0084] A2(α)=0.5π(R0 2 -R 2 )

[0085] Where R0 is the stator radius and R is the rotor radius.

[0086] In actual application, the axial gap 10 does not affect the entire flow area of ​​the valve, and the gap is much smaller than the valve hole size. The axial gap 10 is located between the stator and the rotor, and the flow area calculation formula is:

[0087]

[0088] Where s is the stator-rotor axial clearance, λ(α) is the orifice curve influence coefficient, r(θ) is the valve port length that changes with θ, and θ is the angle integral variable.

[0089] When the axial gap increases, the blocking effect on the fluid will decrease, the intensity of the generated continuous wave signal will decrease, and the effective transmission distance of the continuous wave signal will become smaller, but the load torque of the motor will also decrease accordingly, which is beneficial to the precise control of the motor. When the axial gap decreases, the blocking effect on the fluid will increase, the intensity of the generated continuous wave signal will increase, and the effective transmission distance of the continuous wave signal will increase, which can be applied to deep well operations.

[0090] Preferably, in one embodiment, the axial gap between the stator and the rotor adopts different gap values ​​according to the operating well depth. When the operating well depth is less than or equal to the set deep well operation requirement, a primary axial gap is adopted, otherwise, a secondary axial gap is adopted. The primary axial gap is larger than the second axial gap. The second axial gap is designed to increase the continuous wave signal strength during deep well operations.

[0091] By adopting the design scheme of the embodiment of the present invention, the axial gap can be reduced during deep well operation to increase the continuous wave signal strength, and can be increased during shallow well operation to reduce the motor load and improve the control accuracy.

[0092] The clearance values ​​of the axial clearance and the radial clearance are usually no more than 5 mm. In actual application, different types of wells can be divided into shallow wells and deep wells, and different combinations of radial clearances and axial clearances can be used for testing. The optimal clearance parameters that meet the set requirements are selected and stored in association with the well type and depth, forming a clearance setting list that can be directly called when used. On the basis of ensuring operating efficiency and pressure wave generation quality, the requirements for operators are lower, and practicality is better.

[0093] Figure 6 The schematic diagram of the waveform pattern of the pressure wave generated by the downhole continuous pressure wave generating device provided by the embodiment of the present invention is shown; the motor drives the rotor 4 to rotate to generate a periodic pressure wave signal. The pressure wave signal is is a continuous wave cycle, the upper limit of pressure is Pmax11, the lower limit is Pmin12, and the pressure fluctuation is modulated around the average pressure Pavg13, such as Figure 6 As shown, the waveform equation can be expressed as:

[0094]

[0095] Where P max is the highest signal value, P min is the minimum value of the signal, P avgis the signal average, ω is the rotor phase, is the vibration frequency.

[0096] The shape of the valve mouth curve of the stator and rotor is closely related to the quality of the periodic pressure wave. Taking into account the existence of an uncertain correction coefficient ζ in the curved valve mouth model, the researchers cannot obtain a unique solution during the curve solution process. Therefore, they use three-dimensional modeling, fluid dynamics analysis, and correlation coefficient method to calculate the correlation between the continuous wave pressure wave and the sinusoidal wave under different correction coefficients.

[0097] In an optional embodiment, the process of designing the curves of the front ends of the stator and rotor valve ports by combining the fluid dynamics simulation analysis technology and the correlation algorithm includes:

[0098] Set the initial parameters and correction coefficients of the valve port curve, and calculate the initial valve port curve based on the theoretical curve model;

[0099] Establish a three-dimensional structural model corresponding to the current valve port parameters, and use fluid dynamics simulation analysis to obtain the pressure wave curve;

[0100] Perform correlation calculation on the obtained pressure wave curve and the standard sine wave;

[0101] Then, the correction coefficient is adjusted according to the set strategy, the correction coefficient corresponding to the maximum correlation data is found as the target correction coefficient, and the target valve port curve is calculated according to the theoretical curve model using the target correction coefficient.

[0102] In practical application, the valve port structure design process of the rotary valve includes: firstly, the initial parameters and correction coefficients of the curve valve port are given, the initial valve port curve is calculated according to the theoretical curve model, and then a three-dimensional valve port structure model is established, and the fluid dynamics simulation is used to analyze the fluid dynamic pressure change ΔP(t) to obtain the pressure wave curve, and then the correlation coefficient with the sine wave is analyzed as the initial correlation coefficient ρ0, and then the correction coefficient ζ is adjusted, and the theoretical curve model is continuously substituted to calculate the valve port curve, and the correction coefficient when the maximum correlation coefficient is found to obtain the final stator and rotor valve port curve; as shown in the attached figure Figure 7 As shown;

[0103] In an optional embodiment, the initial parameters and correction coefficient ζ of the curve valve port are first given, and the correction coefficient is usually less than or equal to 1. In actual application, the initial correction coefficient can be set to 1, and the initial valve port curve r(α,ζ) is calculated according to the theoretical curve model, and then a three-dimensional valve port structure model is established, and the fluid dynamics simulation is used to analyze the fluid dynamic pressure change ΔP(t) to obtain the initial pressure wave curve, and then the initial correlation coefficient between the pressure wave curve and the sine wave is analyzed as a reference correlation coefficient ρ0, and then the correction coefficient is adjusted according to ζ=ζ-0.02, and the theoretical curve model is continued to be substituted to calculate the valve port curve, and the correction coefficient at the maximum correlation coefficient is found to obtain the final stator and rotor valve port curve;

[0104] In one embodiment, the valve port curve shape parameters of the stator and the rotor can be designed to be the same. In this case, when one of the two is determined, the calculation result can be directly used for the other.

[0105] In the process of adjusting the correction coefficient, the correlation coefficient calculated last time is used as the reference correlation coefficient ρ0, and the correlation coefficient corresponding to the valve port curve obtained by the updated correction coefficient is compared with the reference correlation coefficient. When judging the correlation coefficient ρ between the pressure wave curve and the sine wave corresponding to the current correction coefficient xy When it is greater than the reference correlation coefficient ρ0, continue to update the correction coefficient until the current correction coefficient corresponds to the correlation coefficient ρ between the pressure wave curve and the sine wave xy When it is initially smaller than the reference correlation coefficient ρ0 and the maximum correlation coefficient can be determined, the optimization calculation is completed, wherein the curve obtained by calculating the correction coefficient corresponding to the obtained maximum correlation coefficient is the valve port curve.

[0106] Combined with Figure 7 , set the initial reference correlation coefficient ρ0 to 0, give the valve port parameter α and the initial correction coefficient, calculate the initial curve based on this, analyze the dynamic pressure change data, and compare it with the dynamic pressure change data of the standard sine wave curve to calculate the initial correlation coefficient ρ xy ;

[0107] Then, the correlation coefficient obtained in the previous calculation is used as the reference correlation coefficient ρ0, and the correction coefficient ζ is updated to calculate the updated valve port curve in combination with the given valve port parameters. Then, the corresponding three-dimensional model is constructed and the dynamic pressure change data ΔP(t) is analyzed. The correlation coefficient ρ is calculated by comparing it with the dynamic pressure change data of the standard sine wave curve. xy , repeat until the current correlation coefficient value ρ xy After reaching the peak, a clear downward trend is formed. In practical application, the following logic is used for judgment: if the current correlation coefficient value ρ xy If it is greater than the previous reference correlation coefficient ρ0, the correction coefficient ζ will continue to be updated and calculated until the correlation coefficient ρ of the corresponding curve of the current correction coefficient is xy If it is smaller than the previous reference correlation coefficient ρ0, the larger reference correlation coefficient ρ0 is used as the maximum (optimal) correlation coefficient, and the correction coefficient corresponding to the correlation coefficient is used as the target correction coefficient for calculating the valve port curve. In practical applications, given the initial valve port parameter polar arc angle α, the range can be [0,2π], r(α) can be scanned and calculated from 0 to form a curve; in addition, the initial reference correlation coefficient can be set to 0;

[0108] Furthermore, in order to avoid the influence of calculation error on the accuracy of calculation results, when selecting the optimal correlation coefficient, you can set:

[0109] When the current correlation coefficient ρ xy If the current correlation coefficient is smaller than the previous reference correlation coefficient ρ0, the correction coefficient ζ is continued to be calculated to further calculate the correlation coefficient corresponding to the curve calculated by the updated correction coefficient. If the continuous calculation results show that the current correlation coefficient is smaller than the previous reference correlation coefficient, when the set number of times is reached, it is determined that the trend has fallen after reaching the peak value, and the maximum correlation coefficient is selected as the optimal correlation coefficient. The correction coefficient corresponding to the correlation coefficient is used as the target correction coefficient for calculating the valve port curve, which can ensure the reliability of the optimal correlation coefficient.

[0110] The valve ports of the stator and rotor adopt the following theoretical curve model:

[0111]

[0112] Where R is the rotor radius, A0 is the total area of ​​the valve port, s is the axial clearance between the stator and rotor, ζ is the correction coefficient, k is the relative strength, n is the number of petals of the valve port, and λ is the influence coefficient of the orifice curve.

[0113] Implementation Cases

[0114] Taking the design parameters shown in Table 1 below as an example, the signal frequency is set to 2 Hz, and the pressure wave curves under different correlation coefficients are obtained; Figure 7 The calculation process shown calculates the pressure wave and obtains the correlation coefficient under different correction coefficients, such as Figure 8 As shown in Table 2, the correlation coefficient results are shown. It can be seen that when the correction coefficient ζ=0.9, the correlation coefficient is the largest, and the obtained pressure wave waveform is closest to the sine wave.

[0115] Based on the valve port curve when the correction coefficient ζ = 0.9, a rotary valve is designed and tested experimentally, and the following results are obtained: Fig. 9 The actual waveform shown is the actual output waveform 14, while the actual output waveform 14 is generated by the designed rotary valve periodically blocking the drilling fluid. The theoretical output waveform 15 is a standard sine wave. By comparing the actual output waveform 14 with the standard sine wave theoretical output waveform 15, it can be found that the actual output waveform 14 has a slight noise due to the actual impact of the project, but it is not much different from the theoretical output waveform 15. After removing the noise, it can be regarded as a more standard sine wave.

[0116] Table 1 Design parameters

[0117]

[0118] Table 2 Correlation coefficients under different correction factors

[0119]

[0120] The waveform spectrum of the continuous pressure wave generated by this implementation case is as follows: Fig.10As shown, the generated waveform spectrum is basically maintained at 2 Hz, that is, a 2 Hz sinusoidal pressure wave is generated. The spatial special-shaped valve port rotary valve proposed by the present invention can generate a relatively standard sinusoidal pressure wave.

[0121] The embodiment of the present invention provides a downhole continuous pressure wave generating device, which is composed of a rotor-stator combination driven by a driving device and a motor. The structure comprehensively considers the influence of the inlet and outlet pressure difference, the shape of the valve port of the continuous wave pulser rotary valve, and the axial clearance and radial clearance design parameters between the rotor and the stator on the properties of the generated continuous pressure wave; the function of emitting a drilling fluid pressure wave signal in the form of a sine wave is realized, and the axial clearance and radial clearance between the stator and the rotor are optimized and designed, thereby reducing the risk of blockage caused by the presence of solid particles or debris in the drilling fluid;

[0122] Furthermore, the embodiment of the present invention combines mathematical models with computational fluid dynamics analysis to optimize the shape parameters of the rotary valve, so that when the rotor rotates, the pressure wave signal generated becomes an ideal sine wave, solving the problem of energy loss in the form of harmonics when the continuous wave signal reaches the ground;

[0123] In addition, the present invention arranges to smoothly connect the connecting parts of the stator and the rotor valve port in a rounded manner, so that the sinusoidal pressure wave generated by the pulser is continuous, thereby reducing energy loss.

[0124] In the downhole continuous pressure wave generating device provided by the embodiment of the present invention, each module or unit structure can be operated independently or in combination according to the actual structural combination requirements or operation control requirements to achieve corresponding technical effects.

[0125] It should be understood that the embodiments disclosed in the present invention are not limited to the specific structures, processing steps or materials disclosed herein, but should be extended to equivalent substitutions of these features understood by ordinary technicians in the relevant field. It should also be understood that the terms used herein are only used for the purpose of describing specific embodiments and are not meant to be limiting.

[0126] The "one embodiment" mentioned in the specification means that a particular feature, structure or characteristic described in conjunction with the embodiment is included in at least one embodiment of the present invention. Therefore, the phrase "one embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0127] Although the embodiments disclosed in the present invention are as above, the above contents are only embodiments adopted for facilitating the understanding of the present invention and are not intended to limit the present invention. Any technician in the technical field to which the present invention belongs can make any modifications and changes in the form and details of the implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be subject to the scope defined in the attached claims.

Claims

1. A downhole continuous pressure wave generating device, characterized in that: The device comprises: a rotary valve body, a driving motor and a reducer; The rotary valve body comprises a stator, a rotor and a rotating shaft connected to the rotor; The rotating shaft is connected to the driving motor and the reducer, and the driving motor drives the reducer, the rotating shaft and the rotor to rotate; The stator is mechanically connected to the housing of the continuous wave pulser and rotates with the rotation of the drill pipe; The stator and rotor adopt spatial special-shaped valve ports, and the front ends of the valve ports are designed according to the theoretical curve; The rotor is located above the stator relative to the fluid inflow direction, the distance between the rotor and the stator relative to the fluid inflow direction is an axial gap, and a radial gap is provided between the rotor and the stator; Among them, the curves at the front end of the stator and rotor valve ports are designed by combining fluid dynamics simulation analysis technology and correlation algorithm.

2. The device according to claim 1, characterized in that The process of designing the curves of the stator and rotor valve front ends by combining fluid dynamics simulation analysis technology and correlation algorithm includes: Set the initial parameters and correction coefficients of the valve port curve, and calculate the initial valve port curve based on the theoretical curve model; Establish a three-dimensional structural model corresponding to the current valve port parameters, and use fluid dynamics simulation analysis to obtain the pressure wave curve; Perform correlation calculation on the obtained pressure wave curve and the standard sine wave; Then, the correction coefficient is adjusted according to the set strategy, the correction coefficient corresponding to the maximum correlation data is found as the target correction coefficient, and the target valve port curve is calculated according to the theoretical curve model using the target correction coefficient.

3. The device according to claim 1, characterized in that The valve ports of the stator and rotor adopt the following theoretical curve model: Where R is the rotor radius, A0 is the total area of ​​the valve port, s is the axial clearance between the stator and rotor, ζ is the correction coefficient, k is the relative strength, n is the number of petals of the valve port, and λ is the influence coefficient of the orifice curve.

4. The device according to claim 1, characterized in that The outer edge and the inner edge of the rotor are both circular, and are installed in concentric circles. The rear end of the rotor valve port is designed as a straight line or a curve, and the theoretical curve at the rear end of the rotor valve port is independently designed relative to the theoretical curve at the front end of the valve port.

5. The device according to claim 1, characterized in that The stator and the rotor have the same shape. When the rotor rotates forward or backward at a constant speed, a target pressure wave can be generated, and the target pressure wave is a sinusoidal pressure wave.

6. The device according to claim 1, characterized in that The connecting part of the stator and the rotor valve port is smoothly connected in the form of a rounded corner or a curve, so that the sinusoidal pressure wave generated by the pulser is continuous.

7. The device according to claim 1, characterized in that The rotating shaft adopts a streamlined shape to reduce the impact of drilling fluid on the rotating shaft when it passes through.

8. The device according to claim 1, characterized in that The radial gap width between the stator and the rotor is set to be the difference between the stator diameter and the rotor diameter.

9. The device according to claim 1, characterized in that The axial gap between the stator and the rotor adopts different gap values ​​according to the operating well depth. When the operating well depth is less than or equal to the set deep well operation requirement, the first-level axial gap is adopted. Otherwise, the second-level axial gap is adopted. The first-level axial gap is larger than the second axial gap. The second axial gap is designed to increase the continuous wave signal strength during deep well operation.

10. The device according to claim 1, characterized in that The stator and the rotor are made of high-hardness materials, including hard alloy, diamond or ceramic.

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