WO2016123803A1 - 一种用于测井的天线回路，天线系统及相应的测井方法 - Google Patents

一种用于测井的天线回路，天线系统及相应的测井方法 Download PDF

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Publication number
WO2016123803A1
WO2016123803A1 PCT/CN2015/072435 CN2015072435W WO2016123803A1 WO 2016123803 A1 WO2016123803 A1 WO 2016123803A1 CN 2015072435 W CN2015072435 W CN 2015072435W WO 2016123803 A1 WO2016123803 A1 WO 2016123803A1
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Prior art keywords
antenna
instrument
loop
antenna system
coil
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PCT/CN2015/072435
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English (en)
French (fr)
Inventor
韩尉善
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美国德州Lh科技有限责任公司
韩尉善
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Priority to PCT/CN2015/072435 priority Critical patent/WO2016123803A1/zh
Publication of WO2016123803A1 publication Critical patent/WO2016123803A1/zh

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
    • G01V3/18—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation specially adapted for well-logging

Definitions

  • the present invention relates to the field of antenna technology, and more particularly to an antenna loop, an antenna system and a corresponding logging method for logging.
  • Figure 1 shows a typical shape of a conventional antenna structure. It can be seen that it is characterized by relatively uniform transmission or reception of signals in various parts of the coil loop. Thus, the current flowing on the indiscriminate closed coil can be equivalent to a magnetic dipole, which greatly facilitates the design of the instrument and the processing of the received signal.
  • Geosteering is mainly for horizontal wells. Since horizontal wells can greatly increase the length of wells in oil and gas layers, thereby effectively increasing the output of single wells, they are increasingly used in oil production.
  • horizontal well drilling it is necessary to continuously detect the relative position of the drill bit to the formation interface in order to keep the drill bit in the target reservoir.
  • Early methods generally used gamma logging data or resistivity imaging data to determine this relative position.
  • the method is theoretically feasible, and the calculation results can clearly show the relationship between the measured signal and the distance from the instrument to the formation interface.
  • the operator cannot It is discriminated whether the measurement signal truly reflects the distance from the drill bit to the interface of the target layer, so the anti-interference is weak. Only when the instrument is close to the interface, can the distance from the drill bit to the interface be accurately determined, and the time left for the operator to adjust the drilling direction is not much.
  • XZ or ZX signal the intensity of the induced signal between the conventional longitudinal coil and the transverse coil
  • the method can be used to discriminate the distance between the drill bit and the formation interface earlier.
  • the company has developed two methods for measuring XZ or ZX signals: direct measurement and indirect measurement using a tilt coil (or equivalent tilt coil), which claims a detection range of about 5 meters, but due to the influence of the measurement environment, The actual effective range is still smaller, far from meeting the needs of oil production.
  • a tilt coil or equivalent tilt coil
  • the present invention provides an antenna loop for logging, the antenna loop comprising a primary contribution segment and a non-primary contribution segment, the primary contribution segment receiving or transmitting signal capability being significantly stronger than the non-primary contribution segment .
  • the antenna loop includes wires constituting the loop, and a substance or structure for significantly enhancing the ability to receive/transmit signals of the wires located in the main contribution section.
  • the antenna loop includes wires that form a loop, and a substance or structure that is used to significantly attenuate the ability of the wires of the non-primary contribution segments to receive/transmit signals.
  • the antenna loop includes a conductor constituting a loop, a substance or structure for significantly enhancing the ability of the conductor of the main contribution section to receive/transmit signals, and for significantly weakening the non-primary contribution The substance or structure of the ability of a segment of a wire to receive/transmit a signal.
  • a magnetic material is used to enhance the ability of the conductors of the main contribution section to receive/transmit signals.
  • the present invention also provides an antenna system for logging, comprising a metal skeleton and an antenna loop mounted on the metal skeleton, wherein the antenna loop includes a main contribution section, the main contribution section
  • the ability to receive or transmit signals is significantly stronger than in other segments.
  • the ability of the signals of other sections other than the main contribution section to receive/transmit signals is weakened by the metal skeleton.
  • the antenna system further comprises a signal shielding material, and the signal shielding facility is used for cutting The ability of a non-primary contribution segment to receive/transmit signals in a weak antenna loop.
  • the metal skeleton has a hole or a groove therein, and a wire of the non-main contribution segment in the antenna loop is placed in the hole or groove.
  • wires of the non-main contribution section of the antenna loop are tightly wound around the metal frame of the instrument.
  • the signal shielding material covers, or partially covers, or is wrapped, or partially wrapped in a non-primary contribution section of the antenna loop.
  • the signal shielding material is metal
  • the shape of the metal skeleton is a cylindrical shape matched with the drill pipe, and the shape of the antenna circuit is a circle shape covering only the circumference of the metal skeleton portion.
  • the antenna system further comprises a magnetic material placed in the metal skeleton groove, and the wires of the main contribution section in the antenna loop are placed on the magnetic material.
  • the wires of the non-main contribution section in the antenna loop are partially/all placed in a groove or a hole in the metal skeleton of the instrument.
  • wires of the non-main contribution zone in the antenna loop are shielded by the signal shielding facility.
  • the wire of the main contribution section is wound with the long axis of the cylindrical metal skeleton as an axis of symmetry.
  • wires of the main contribution section are obliquely wound around the metal skeleton.
  • the shape of the wire of the non-main contribution section may be any shape.
  • the shape of the wire of the non-main contribution segment may be any shape partially or completely placed on the side of the magnetic material.
  • wires of the non-primary contribution section are partially or completely placed under the magnetic material.
  • the present invention also provides an antenna system for logging, the antenna system being formed by connecting several of the aforementioned antenna loops in series.
  • the present invention also provides an antenna system for logging, characterized in that the antenna system is formed by connecting one or several conventional uniform antenna coils in series with at least the aforementioned antenna loop, the uniform antenna coil and the The antenna loops may be the same or different in the long axis position of the instrument.
  • the present invention also provides an antenna system for logging, the antenna system consisting of several separate aforementioned antenna loops, said antenna loops operating in a time division manner.
  • the plurality of independent antenna loops are the same in the long axis position of the instrument, but the azimuth angle is different.
  • the invention also provides a logging tool comprising an instrument coil system comprising a transmitting and receiving antenna, at least one of the transmitting and receiving antennas of the instrument coil system being the aforementioned antenna system.
  • the instrument coil is a single-issue single-receiving instrument coil system.
  • the instrument coil is a single-shot and double-receiving instrument coil system.
  • the instrument coil is a double-transmitting and double-receiving instrument coil system.
  • the invention also provides a logging method based on the foregoing logging tool, characterized in that it comprises the steps of:
  • step 2) is performed on the receiving coil measured by the step 1)
  • the electromotive force is induced to determine the orientation of the instrument and the formation interface.
  • step 2) using the induced electromotive force measurement signal obtained in step 1) calculateate and based on variables One or more of the amplitude, phase, real, and imaginary parts, calculate the distance from the instrument to the formation interface, and determine the orientation of the instrument and the formation interface; where ⁇ is the instrument rotation angle and V ( ⁇ ) is the instrument rotation angle
  • the induced electromotive force is ⁇ .
  • the V ( ⁇ ) -V ( ⁇ + ⁇ ) calculation is performed by using the induced electromotive force measurement signal obtained in the step 1), and according to the magnitude of the variable V ( ⁇ ) -V ( ⁇ + ⁇ ) , One or more of the phase, real part, and imaginary part, calculate the distance from the instrument to the formation interface and determine the orientation of the instrument and the formation interface; where ⁇ is the instrument rotation angle and V ( ⁇ ) is when the instrument rotates at ⁇ The induced electromotive force.
  • step 2) using the induced electromotive force measurement signal obtained in step 1) Calculate and based on variables One or more of the amplitude, phase, real, and imaginary parts, calculate the distance from the instrument to the formation interface, and determine the orientation of the instrument and the formation interface; where ⁇ is the instrument rotation angle and V ( ⁇ ) is the instrument The induced electromotive force when the rotation angle is ⁇ , Average (V ( ⁇ ) ) is the arithmetic mean of the measured signals of the induced electromotive force in the receiving coil.
  • step 1) measuring two sets of induced electromotive forces generated by two receiving coils under the action of the same transmitting coil;
  • the induced electromotive force measurement signal obtained in the step 1) is used. Calculate and based on variables One or more of the amplitude, phase, real, and imaginary parts, calculate the distance from the instrument to the formation interface, and determine the orientation of the instrument and the formation interface, and the azimuthal resistivity; where V1 ( ⁇ ) and V2 ( ⁇ ) They are the induced electromotive forces generated when the two receiving coils are operated by the same transmitting coil at an angle of ⁇ of the instrument.
  • step 1) measuring two receiving coils under the action of the same transmitting coil Two groups of induced electromotive forces;
  • the induced electromotive force measurement signal obtained in the step 1) is used. Calculate and based on variables One or more of the amplitude, phase, real part, and imaginary part, calculate the distance from the instrument to the formation interface and the formation resistivity; among them, Average(V1 ( ⁇ ) ) and Average(V2 ( ⁇ ) ) are two The arithmetic mean of the measured electromotive force measured signals in the receiving coils.
  • Electromotive force measurement signal Calculate and based on variables One or more of the amplitude, phase, real part, imaginary part, the distance from the instrument to the formation interface, the relative position of the instrument and the formation interface, and the formation resistivity; where V ij( ⁇ ) is the transmitting coil i
  • the induced electromotive force generated on the receiving coil j is equal to 1 or 2.
  • Electromotive force measurement signal Calculate and based on variables One or more of the amplitude, phase, real, and imaginary parts of the distance from the instrument to the formation interface and the formation resistivity; wherein Average(V ij( ⁇ ) ) is the transmission coil i produced on the receiving coil j
  • Average(V ij( ⁇ ) ) is the transmission coil i produced on the receiving coil j
  • the arithmetic mean of the measured values of the induced electromotive force, i, j is equal to 1 or 2.
  • the present invention has the following technical effects:
  • the antenna loop of the present invention is used as a transmitting antenna, which can effectively enhance the intensity of the reflected signal of the formation; if the antenna loop of the present invention is used as a receiving antenna, it can effectively detect A weak formation reflects the signal.
  • the invention is applied to a geosteering logging tool, which can greatly improve the distance and accuracy of the detection formation interface.
  • Figure 1 shows a partial typical shape of a conventional antenna structure
  • Figure 2a shows a schematic view of a metal cylinder with a grooved surface as a metal skeleton of the instrument
  • Figure 2b shows a schematic view of a metal cylinder with a hole on the surface of the instrument metal skeleton
  • Figure 3a shows a schematic cross-sectional view of a conventional antenna loop mounted in the groove of Figure 2a
  • Figure 3b shows a schematic cross-sectional view of a conventional antenna loop mounted into the hole of Figure 2b;
  • FIGS. 4a-c are diagrams showing various forms of a round-shaped side antenna loop in accordance with one embodiment of the present invention; wherein, Figure 4a shows a round-shaped side antenna loop in a cylindrical shape in accordance with one embodiment of the present invention.
  • 3D is a side view of the antenna of the embodiment of FIG. 4a
  • FIG. 4c is a plan view of the antenna circuit of the embodiment of FIG. 4a from a side view;
  • Figures 5a-d show examples of four wiring patterns of a round-shaped side antenna loop on the metal frame of the instrument
  • Figures 6a-c show schematic views of various forms of another circular-shaped antenna loop in accordance with another embodiment of the present invention; wherein Figure 6a shows another circular-shaped antenna loop on the side of the cylindrical instrument.
  • Figure 6b shows a three-dimensional view of the antenna loop of the embodiment of Figure 6a
  • Figure 6c shows a plan view of the antenna loop of the embodiment of Figure 6a from a side view;
  • Figures 7a-d show an example of four wiring patterns of the round-shaped antenna loop of Figure 6a on the metal frame of the instrument;
  • Figure 8a shows a side development view of another side-mounted round-shaped antenna circuit
  • Figure 8b shows a three-dimensional view of the side-mounted round-shaped antenna circuit of Figure 8a;
  • Figures 9a-d show schematic views of several tilt-placed antennas; wherein Figure 9a shows a schematic view of a rectangular circular antenna wound in the z-direction placed on an obliquely placed magnetic material, and Figure 9b shows along z A schematic diagram of a directional winding loop antenna placed on an obliquely placed magnetic material, and FIG. 9c shows a schematic view of a slant-wound rectangular round-shaped antenna placed on a magnetic material uniformly placed in the z direction, and FIG. 9d shows a slant winding Schematic diagram of an elliptical antenna placed on a magnetic material uniformly placed in the z direction;
  • Figure 10a shows a schematic cross-sectional view of a solution for reducing the ability to transmit and receive signals by placing a portion of the antenna underneath the magnetic material.
  • Figures 10b-e illustrate an antenna loop in which a portion of the antenna is placed under the magnetic material in one embodiment of the present invention. Comparison of horizontal placement and oblique placement; wherein, Figure 10b shows a frontal three-dimensional view of the antenna loop of Figure 10a being horizontally placed on the metal frame of the instrument, and Figure 10c shows that the antenna loop of Figure 10a is horizontally placed on the metal skeleton of the instrument. a reverse three-dimensional view, FIG. 10d shows a front three-dimensional view of the antenna loop of FIG. 10a placed obliquely on the metal frame of the instrument, and FIG. 10e shows a reverse three-dimensional view of the antenna loop of FIG. 10a placed obliquely on the metal frame of the instrument;
  • FIGS 11a-d show several wiring patterns of the antenna loop shown in Figures 10a-e;
  • Figures 12a - 12f show schematic views of several vertical rounded antennas
  • Figure 13 is a schematic view showing the connection of the standing circular shaped antenna shown in Figure 12b to an external source;
  • Figure 14 is a schematic view showing an antenna loop in which two standing circular antennas are connected in series;
  • FIG. 15a-c are schematic views of a line loop in which an antenna of the present invention is connected in series with a conventional antenna; wherein, Fig. 15a shows an example of a conventional antenna loop, and Fig. 15b shows an example of an antenna loop of the present invention.
  • Figure 15c shows a composite antenna loop formed by the conventional antenna loop of Figure 15a in series with the antenna loop of the present invention of Figure 15b;
  • Figure 16 shows an equivalent circular antenna loop of the composite antenna loop of Figure 15c
  • Figure 17 shows an antenna system composed of a plurality of round-shaped antenna loops
  • Figure 18a shows an example in which the antenna of the present invention directly forms a closed loop with an external circuit
  • Figure 18b shows an example of a circular-shaped antenna accessing a peripheral circuit
  • Figures 19a-c show several antenna loops formed by connecting two rounded antennas in series
  • Figure 20 is a diagram showing an antenna loop for measuring an electric field in the z direction in one embodiment of the present invention.
  • Figure 21 shows a single-shot single-receiving coil system in one embodiment of the present invention
  • Figure 22 shows a simple formation model of the single-shot single-receiving coil system of Figure 21;
  • 23a-b are diagrams showing the variation of the electromotive force with the azimuth angle of the single-shot single-receiving coil of FIG. 21 in the formation model shown in FIG. 22;
  • Figures 24a-b show the variation of the mode and phase of the parameter Ratio1 as a function of the distance from the instrument to the formation interface
  • Figures 25a-b show the variation of the mode and phase of the parameter Ratio2 as a function of the distance from the instrument to the formation interface
  • Figure 26 shows the parameters The mode varies with the distance from the instrument to the formation interface
  • Figure 27 shows a conventional logging-while-drilling logging tool with a conventional coil as a transmitting antenna and two round-shaped antennas of the present invention as receiving antennas;
  • Figures 28a-b show the relationship between amplitude attenuation and phase offset between the receiving antennas R1 and R2 and the instrument azimuth, which can be calculated from Ratio3; where Figure 28a is the phase offset and Figure 28b is the amplitude attenuation. ;
  • Figures 29a-b show the relationship between the amplitude attenuation and phase offset between the receiving antennas R1 and R2 and the distance from the instrument to the formation interface when the azimuth angle is zero degrees; wherein Figure 29a is the phase offset, Figure 29b Is amplitude attenuation;
  • Figure 30 shows two conventional coils as transmitting antennas and distributed on both sides of the tow shaped logging antenna of the present invention
  • Figure 31 shows a dual-shot dual-receiving instrument consisting of a conventional coil as a transmitting antenna and a composite antenna as a receiving antenna;
  • Fig. 32 shows an apparatus comprising any one of a receiving antenna and an arbitrary number of transmitting antennas, wherein the relative positions of the receiving antenna and the transmitting antenna can be arbitrarily arranged.
  • the inventors have made in-depth research on the existing antenna system for logging, and found that the existing antenna system based on the indiscriminate closed loop has great limitations in signal accuracy and strength.
  • the main reasons are as follows:
  • the strength of the signal generated or received by the indiscriminate closed loop is directly related to the electric field curl.
  • the electromotive forces generated by the reflected signals of the ground layers received by the respective portions of the receiving coil often cancel each other out, thereby reducing the ability to detect weak signals.
  • the formation is generally considered to be parallel (1D) or even homogeneous (0D) in a relatively limited measurement range, so the traditional LWD coil design can meet a considerable part of the current logging industry.
  • traditional antennas are often not optimal designs. Especially when measuring weak ground interface reflection signals, traditional antennas measure signal accuracy and intensity. There are great limitations.
  • the main difference between the antenna system for logging of the present invention and the conventional antenna system is that the ability of each part of the loop of the novel antenna system to receive (receive antenna) or transmit (transmit antenna) signals is unbalanced.
  • the imbalance here may mean that the ability to accept or transmit signals on some (not all) loops is enhanced, or that the ability to receive or transmit signals on some (not all) loops is diminished. It is also possible that some portions of the signal receiving or transmitting capability are enhanced while the other portion of the signal receiving or transmitting capability is attenuated.
  • a method of increasing the signal strength in a partial loop is generally to add a magnetic material under the conductor, but the invention is not limited to this signal enhancement.
  • This ability to reduce or relatively reduce the transmit/receive signal of a part of the loop has a clear purpose, that is, the effective signal transmitted/received by the part of the loop in the target environment (such as the reflected signal of the formation interface) as a whole for the rest of the loop
  • the resulting effective signals must be reversed, at least interfering with each other.
  • the unbalanced transmission or reception capability also makes the antenna directional for the detection of complex formations.
  • the application of this new type of antenna is not only in the field of geosteering, for example, in cable logging for complex geological structures, and in the field of electromagnetic propagation to detect geodetic structures, but there is only a great application in the logging while drilling. Some examples of such antennas are given in the field of guidance.
  • FIG. 2a shows a schematic view of a metal cylinder with a grooved surface as the metal skeleton of the instrument.
  • the surface of the metal cylinder 202 is engraved with an annular groove 203 inwardly, and the antenna 204 is wound around Inside this annular groove.
  • Figure 2b shows a schematic view of a metal cylinder with holes on the surface of the metal skeleton of the instrument.
  • a surface of the metal cylinder 202 is engraved with a set of rectangular grooves 205, engraved between the grooves.
  • the apertures, the antennas 204 pass sequentially through the apertures to form an antenna loop.
  • the metal cylinder 202 is a cylinder having a cavity 201 therein for the passage of mud. Since the antenna is installed inside the metal groove, the external signal is largely shielded by the underside of the antenna and the side metal wall (the tangential component of the electric field on the metal surface is zero), and the received signal strength of the antenna is weakened. Therefore, in order to enhance the signal strength, a layer of magnetic material is often covered under the antenna. This part of the magnetic material tends to increase the signal by several to several tens of times.
  • FIG. 3a shows a schematic cross-sectional view of a conventional antenna loop mounted into a groove of the metal frame of the instrument of Figure 2a.
  • 301 represents the outer portion of the instrument
  • 302 represents the mounting coil portion
  • 303 represents the metal post portion after the notch
  • 304 represents the inner portion of the cylinder
  • arrow 307 on the coil indicates the winding direction of the coil 204 (all subsequent figures are only A winding direction of the coil is shown, but it should be noted that the coil of the present invention can also be wound in the reverse direction.
  • the magnetic material 305 is filled between the antenna and the metal cylinder, and the magnetic material 305 is formed into a column shape, and the cross section is circular (note Here, the magnetic material 305 may have different shapes here, and is not limited to the columnar body).
  • the coil 204 is wrapped with an insulating material.
  • Figure 3b shows a schematic cross-sectional view of a conventional antenna loop mounted into a hole in the metal skeleton of the instrument of Figure 2b.
  • the side walls 308 of the rectangular notch are perforated to allow the wires to pass.
  • Fig. 3a will be described below when describing the grooved structure on the surface of the metal cylinder, but the description is equally applicable to the structure shown in Fig. 3b.
  • Figure 3a antenna installation method The art is relatively simple, but the mechanical strength of the instrument is not as shown in Figure 3b. From Figures 3a-b, it can be seen that the various parts of the conventional antenna loop are relatively balanced and both serve as signals for transmission or reception. In Fig. 3b, a small portion of the antenna also passes through the side walls of the metal recess, and the signal is weakened here. However, this weakening is only subject to the need of the strength of the instrument, and does not achieve the purpose of weakening the effective signal strength of the reverse, and the final effect will only weaken the final overall signal strength.
  • the present invention proposes a novel antenna loop in which a part of the function of transmitting or receiving is deliberately relatively weakened or even completely shielded, thereby achieving the function of enhancing the overall signal strength.
  • a part of the function of transmitting or receiving is deliberately relatively weakened or even completely shielded, thereby achieving the function of enhancing the overall signal strength.
  • the following is a list of several new antenna implementations, but the overall scheme of the new antenna is by no means limited to these forms.
  • FIG. 4a-c are schematic views of a round-shaped side antenna loop according to an embodiment of the present invention; wherein, FIG. 4a shows a development view of the round-shaped side antenna loop of the embodiment on the side of the cylindrical instrument, Fig. 4b shows a three-dimensional perspective view of the antenna loop of this embodiment, and Fig. 4c shows a plan view of the antenna circuit side view angle of the embodiment.
  • the new antenna shown in Figures 4a-c does not wrap the entire instrument interface 360 degrees like a conventional antenna, but only a portion of the circumference of the instrument skeleton.
  • a round-shaped antenna such an antenna covering only a part of the circumference.
  • This winding angle ⁇ can be any one of values from 0 to 360 degrees. When ⁇ is 180 degrees, it can be called a semi-circular antenna.
  • the magnetic material 305 is indicated by a gray strip which is embedded in the groove of the instrument skeleton for enhancing the signal strength
  • the antenna loop 204 is wound around the surface of the instrument skeleton
  • the circuit access point (receiver antenna) can be any part of antenna loop 204. The same is true for all subsequent examples, and will not be pointed out in the following examples.
  • the winding direction of the antenna is ABCDA, as indicated by the arrow in Figure 4a.
  • the winding direction of the antenna can also be reversed. Legend later Unless otherwise emphasized, the reverse winding method is included, and the legend is no longer indicated.
  • the coil can be a coil or a multi-turn.
  • the CD segment in the loop is the part that weakens the intensity of the transmitted or received signal, so this section is placed on the side other than the magnetic material.
  • the CD segment can be grooved separately, or it can be carved, or with AB.
  • the segments are placed in the same groove without the location of the magnetic material 305. If it is a separate groove, the CD segment can also be covered with a highly conductive material such as metal to further weaken its transmitting or receiving function.
  • Fig. 4b in order to indicate the direction, the sides of the cylinder are shown as face I and face J, respectively, and the two perspective views of Fig. 4b show the antenna profile seen from two directions (IJ and JI).
  • FIG. 4b is schematic views, and the axial dimension of the cylinder does not represent the actual size of the metal skeleton of the instrument.
  • Fig. 4c is a plan view seen from a side view angle in two directions (IJ direction and JI direction).
  • the BC segment and the DA segment are opposite in direction, but due to their different positions, the circuit electromotive force is also affected to some extent. If the effect is large enough, the electromotive force generated thereon can be attenuated by placing the wire in a laterally engraved groove or engraving. Since the magnetic material is placed under the AB segment to enhance the signal strength generated by it, its contribution in the entire circuit is dominant, and it is referred to herein as the main contribution region circuit.
  • the main part of the CD segment of the non-main contribution area circuit is placed on the side of the main contribution area (BC and CA are mainly connected).
  • a novel antenna in which such a non-primary contribution region circuit is placed on the side of the main contribution region is called a side-mounted antenna.
  • the side view here is relative to the direction of the main axis of symmetry of the instrument (the cavity in the instrument).
  • Figures 5a-d show examples of four wiring patterns of a round-shaped side antenna loop on the instrument metal frame.
  • the principle of reducing the signal strength is the same, that is, the shielding effect of the metal on the signal is utilized.
  • Metal surface signal tangential direction is zero, metal interior The signal strength is zero).
  • 501 is a groove containing a magnetic material.
  • 502 is a section of the AB section of the antenna.
  • 305 is a magnetic material.
  • 503 is a cross-sectional view of the wire of the CD segment.
  • 202 is the cross section of the metal frame of the instrument, and 201 is the metal cavity in the middle of the instrument.
  • 505 is the central symmetry line of the instrument cylinder.
  • GH or DC is a separate notch 504 at the edge of the magnetic material groove, which may also cover the high conductance layer for enhanced effects.
  • GH or DC is placed in a separate engraved hole 506.
  • GH and DC are placed in the same groove 501 as the magnetic material, but placed at the edge, which can be on the magnetic material, Can be next to the magnetic material.
  • Figure 5d shows that the GH or DC is placed on the magnetic material but is wrapped or covered with a metal shield 507.
  • FIGs 6a-c show schematic views of a round-shaped antenna loop in accordance with another embodiment of the present invention.
  • 6a shows a development view of the circular antenna loop on the side of the cylindrical instrument
  • FIG. 6b shows a three-dimensional perspective view of the antenna loop of the embodiment
  • FIG. 6c shows the antenna loop from the side of the embodiment.
  • 305 is a magnetic material
  • 204 is an antenna loop.
  • the AB segment is the main contribution area, and the CD segment is deliberately weakened. Since the effect of the CD segment antenna is small, it does not matter that it is reversely wound with the AB segment as in the embodiment of Figs. 4a to c, or continues to be wound in the same direction as the example of Figs.
  • both ends of the cylinder The sides are shown as face I and face J, respectively, and the two perspective views of Figure 6b show the antenna profile seen from both directions (IJ and JI). It should be noted that the two perspective views of Fig. 6b are schematic views, and the axial dimension of the cylinder does not indicate the actual size of the metal skeleton of the instrument.
  • Figures 7a-d show an example of four wiring patterns of the round-shaped antenna loop of Figure 6a on the metal frame of the instrument. Since Figures 7a-d are very close to Figures 5a-d, they are not explained one by one. The difference between the wiring scheme shown in Figures 7a-d and Figures 5a-d is that the antenna is wound around the entire slot.
  • Figure 8a shows a side development view of a side-mounted round-shaped antenna loop in accordance with yet another embodiment of the present invention
  • Figure 8b shows a three-dimensional view of the side-mounted round-shaped antenna loop of Figure 8a.
  • the arrangement of Figures 8a-b is such that the round-shaped antenna shown in Figures 4a-c is obliquely wound around the metal frame of the instrument.
  • the round-shaped antenna shown in Figures 6a-c can also be obliquely wound on a metal pylon, and will not be illustrated by the legend.
  • Figures 9a-d show schematic views of several tilt-placed antennas; wherein Figure 9a shows a schematic view of a rectangular circular antenna wound in the z-direction placed on an obliquely placed magnetic material, and Figure 9b shows along z A schematic diagram of a directional winding loop antenna placed on an obliquely placed magnetic material, and FIG. 9c shows a schematic view of a slant-wound rectangular round-shaped antenna placed on a magnetic material uniformly placed in the z direction, and FIG. 9d shows a slant winding A schematic representation of an elliptical antenna placed on a magnetic material placed uniformly in the z direction. They also use magnetic materials to enhance part of the antenna signal to relatively attenuate the signals produced by other parts, resulting in a final enhanced signal strength.
  • Figure 10a shows a schematic cross-sectional view of a solution for reducing the ability to transmit and receive signals by placing a portion of the antenna underneath the magnetic material.
  • Figures 10b-e illustrate an antenna loop in which a portion of the antenna is placed under the magnetic material in one embodiment of the present invention.
  • Figure 10b shows a frontal three-dimensional view of the antenna loop of Figure 10a placed horizontally on the metal frame of the instrument
  • Figure 10c shows a three-dimensional view of the back of the antenna loop of Figure 10a placed horizontally on the metal frame of the instrument
  • Figure 10d A frontal three-dimensional view of the antenna loop of Figure 10a placed obliquely on the metal frame of the instrument is shown
  • Figure 10e shows a three-dimensional rear view of the antenna loop of Figure 10a placed obliquely on the metal frame of the instrument.
  • 305 is a magnetic material
  • 204 is an antenna loop
  • 202 is an instrument metal skeleton
  • 201 is an instrument lumen.
  • the winding method of the antenna is ABCDA, and the number of winding turns can be one turn or more.
  • the CD segment of the antenna loop is wound below the segment AB of the loop.
  • the lower portion referred to herein may be above the metal skeleton 202 under the magnetic material 305, and the CD segment may be placed in a small groove engraved at the bottom of the magnetic material groove, or may be placed in a carved hole in the instrument metal bracket.
  • the antenna loop of Figure 10a can be placed either horizontally or obliquely, such as at 45 degrees. It should be noted that other types of new antenna loops of the latter type can also be placed horizontally or obliquely on the instrument skeleton, and the tilt angle here is any angle, not just 45 degrees. It can be seen that the AB is the main contribution area, and the rest is the non-main contribution area of the loop. The new type of antenna in which the non-main contribution area is placed under the main contribution area is called a vertical antenna.
  • Figures 11a-d show several wiring arrangements for the antenna loop shown in Figures 10a-e.
  • 501 is a groove containing a magnetic material
  • 305 is a magnetic material.
  • 1101 is the AB conductor of the main contribution area
  • 1103 is a filling material such as metal, which plays a certain supporting role.
  • 1102 is a CD line.
  • 202 is the upper and lower sections of the instrument metal skeleton, and 201 is the inner cavity of the instrument.
  • 1104 is a groove engraved with a wire 1102 underneath the magnetic material, and 1105 is a hole in the metal skeleton below the magnetic material.
  • Figure 11a The medium CD is directly below the magnetic material, and the CD in Fig.
  • 11b is under the magnetic material, but on the side close to the groove wall. In fact, as long as the CD is in any position in the groove below the magnetic material, the signal strength can be reduced.
  • Fig. 11c shows that the CD has a small groove separately under the large groove, so that the shielding effect is better. The position of the small groove is not necessarily in the center of the bottom of the large groove. Other locations at the bottom of the large slot can also perform the same function.
  • 11d is a carved hole for the CD. The position of this carved hole can be in any position, not necessarily below the original groove. If it is on the side, it is 5b. It should be noted here that different grooves and wiring can be mixed on the same new antenna.
  • Figures 12a - 12f show several other vertical rounded antennas. The effects of these antennas are the same, that is, in the antenna loop, only the AB segment plays a major role.
  • the opening angle corresponding to AB may be any angle from 0 to 360.
  • 305 is a magnetic material
  • 204 is a closed antenna, which is wound in the ABCDA direction, and may be one turn or multiple turns.
  • 202 is the instrument metal skeleton
  • 201 is the cavity in the instrument.
  • 1201 is a material of a different nature than 305, and may be a magnetic material or a non-magnetic material such as a metal underlayer.
  • Example The magnetic material in Figure 12a is placed only below the main contribution area.
  • the CD segment in Figure 12b passes through a hole in the metal skeleton below the AB segment.
  • the CD passes through the metal skeleton on the other side of the AB section.
  • the CD is wound around the metal on the other side of the instrument outside the AB section.
  • the CD segment of Figure 12e is loaded with a signal shielding device, such as a metal skin, for use outside the antenna.
  • the non-magnetic material under the CD segment in Figure 12f does not act to enhance the signal, so the phase inversion relatively weakens the signal strength on the CD. If it is a metal mat, it can also directly weaken the signal on the CD. Their engraving and routing are the same as before, and will not be described here.
  • the novel antenna of the present invention is characterized in that the ability of a portion of the antenna loop to receive/transmit signals is different from that of other portions. It weakens or relatively weakens the antenna The ability of the loop portion to transmit or receive signals to achieve an enhanced overall signal strength.
  • the antenna can have an azimuthal directivity by relatively weakening the ability of the loop portion to transmit signals.
  • FIG. 13 shows that the novel antenna shown in FIG. 12b is connected as a transmitting antenna to the external source 1301 at position B.
  • Fig. 14 is a circuit in which two standing circular antennas are connected in series.
  • One antenna is ABCDA and the other is EFGHE.
  • the two antennas are in the same z-coordinate of the instrument (the metal lumen of the instrument), and the azimuths of the different XY planes are used in series with each other.
  • the composite antenna is used as a receiving antenna, it has an advantage that when the transmitting coil is the most common z-coil, if the ground layer is rotated symmetrically about the center line of the transmitting and receiving coil, and the two round-shaped antennas in the figure The opening angles ⁇ 1 and ⁇ 2 are the same, then the signal strength it receives is zero. This is also to say that the signal received by such an antenna is completely derived from the information of the non-axisymmetric formation.
  • the novel antenna of the present invention can be used in series with a conventional antenna.
  • Figure 15c shows a schematic diagram of a composite antenna obtained by connecting a novel antenna DEFGD (Fig. 15b) and a conventional antenna ABCA (Fig. 15a) in series (A with G, C connected to D).
  • the electronic component such as a digital oscillator or other methods can make the instrument have the three working modes of the conventional antenna, the novel antenna and the composite antenna in which the two antennas are connected in series.
  • the DE segment loop of the new antenna is similar to the shape of the loop position of the conventional antenna BC segment.
  • the composite antenna composed of the new antenna and the conventional antenna their contribution is zero and can be eliminated.
  • Such a composite antenna 15c can be equivalent to the circular-shaped antenna shown in FIG.
  • an instrument composed of a plurality of round-shaped antennas can perform multi-azimuth detection without rotating.
  • the five independent antenna subsystems 1701 to 1705 have the same long axis position and different azimuth angles.
  • the system can detect five different azimuth formation signals, thereby deriving the stratum boundary. information.
  • Fig. 18a shows an example in which the antenna of the present invention directly forms a closed loop with an external circuit, which is a variation of the novel antenna loop of the foregoing embodiment, wherein 204 is an antenna loop, 305 is a magnetic material, and 1301 is an antenna periphery.
  • a circuit including a signal source (transmitting antenna) or a signal receiver (receiving antenna).
  • Fig. 18b shows an example of a round-shaped antenna access peripheral circuit.
  • Figures 18a and 18b are virtually identical. When the main contribution area of the antenna is the same, the non-main contribution area antenna will not have a decisive influence on the antenna regardless of its shape. Similarly, similar variations can be made to the non-primary contribution area lines of other novel antennas of the present invention.
  • the invention includes any variation of the antenna of the non-primary contribution region.
  • Figures 19a-c show several antenna loops formed by connecting two rounded antennas in series.
  • the antenna loops of Figures 19a-c are similar to the antenna loops shown in Figures 4a-c, but the loops AB and CD are far apart and do not completely attenuate the signal strength of the CD segment, so this example can also be considered as two rounds.
  • the antenna opening is larger in Figure 19a and the antenna is almost closed in Figure 19b. This opening angle can be any one of 0 to 360 degrees. Since the BC segment and the DA segment are close together, the signals on them can cancel each other out.
  • the antenna When the opening is small, and there are pads under the AB section and the CD section, the antenna can be viewed as a quadrupole. If one of the AB or CD segments is attenuated (for example, without magnetic material), the antenna is a dipole.
  • Figure 19c shows the different magnetic materials laid under the antennas AB and CD. One is 1901, which is represented by solid gray, and the other is 1902, indicated by a dashed gray line.
  • the opening angles of the AB segment and the CD segment may also be different.
  • FIG. 20 shows an antenna loop in which the electric field in the z direction is mainly measured in an embodiment of the present invention, wherein the AB segment is the main contribution region, and the signals of the BC, CD, and DA segments are relatively weakened.
  • the geosteering is taken as an example to introduce the application of the novel antenna system proposed by the present invention in geosteering.
  • Figure 21 shows a single-shot single-receiving coil system (one transmitting coil, one receiving coil) in one embodiment of the present invention, wherein the transmitting coil is a conventional z-coil, and the receiving antenna is a circular-shaped antenna, and its structure is as Figure 4c, angle It is 90 degrees.
  • Figure 22 shows a simple formation model of the single-shot single-receiving coil system of Figure 21.
  • This model has two formations, a low resistance layer of 1 ohm meter, and a high resistance layer of 100 ohm meters.
  • the instrument moves in the horizontal direction (Z-axis direction) while rotating around the z-axis.
  • the rotation angle ⁇ is an angle between the opening direction of the receiving instrument and the x-axis direction.
  • the measured electromotive force is a function of the angle of rotation ⁇ , expressed as V ( ⁇ ) .
  • Figures 23a-b show the variation of the electromotive force with the azimuth angle of the single-shot single-receiving coil of Figure 21 in the formation model shown in Figure 22, wherein Figure 23a is a change in the imaginary part and a change in the real part of Figure 23b.
  • the curves indicate "distance 5 feet” and “distance 10 feet” are the results calculated when the horizontally placed instrument is 5 feet and 10 feet from the bottom interface.
  • the electromotive force measured by the electrode system shown in Fig. 21 can calculate the distance from the instrument to the formation interface by the following formula:
  • the Average (V) is the average value of the signal measured by one revolution of the instrument.
  • Figures 24a-b show the variation of the mode and phase of the parameter Ratio1 as a function of the distance from the instrument to the formation interface.
  • Figures 25a-b show the variation of the mode and phase of the parameter Ratio2 as a function of the distance from the instrument to the formation interface.
  • Figure 26 shows the parameters The mode varies with the distance from the instrument to the formation interface. Shown in the figure Can be used to calculate the distance between the instrument and the formation interface.
  • the measurement signal of the round-shaped antenna can be used to distinguish the relative position of the instrument to the formation interface, from Ratio1, Ratio2 and The mode, phase, real part, imaginary part, etc. can be used for the relative position of the instrument and the formation interface.
  • the interface In actual exploration, the interface is not strictly level, the starting point of the instrument rotation is unknown, and the measurement data is full of noise. Therefore, the induced electromotive force used in calculating the formation interface cannot be obtained by simple direct measurement, but calculated by simulating the normal rotation curve.
  • the sampled signal value in one cycle is ⁇ V i
  • i 1,n ⁇ , and the corresponding acquisition angle is ⁇ i
  • i 1,n ⁇ .
  • the sampling point is assumed to be uniformly sampled from 0 to 360 degrees.
  • V r and ⁇ r can be obtained by solving the following equations.
  • the sample values in this period may be combined processing of data of a plurality of sampling periods, such as a simple arithmetic average.
  • This calculation method has stable results and is simple to calculate and can be applied to various subsequent method examples.
  • Fig. 27 shows a logging while drilling tool in which a conventional coil is a transmitting antenna and two round shaped antennas of the present invention are receiving antennas.
  • the transmitting coil T can be combined with the round-shaped receiving antennas R1 and R2 to form the same combination as the coiling system shown in FIGS. 18a to b, and the relative position of the instrument and the formation interface can be calculated by using the respective measurement signals.
  • the distance from the instrument to the formation interface can also be used as the ratio.
  • V1 ( ⁇ ) and V2 ( ⁇ ) are the receiving antennas R1 of the instrument
  • Figures 28a-b show the relationship between amplitude attenuation and phase offset between the receiving antennas R1 and R2 and the instrument azimuth, which can be calculated from Ratio3.
  • Figure 28a is the amplitude attenuation and
  • Figure 28b is the phase offset.
  • Figures 29a-b show the relationship between the amplitude attenuation and phase offset between the receiving antennas R1 and R2 and the distance from the instrument to the formation interface when the azimuth angle is zero degrees.
  • Figure 29a is the phase offset and
  • Figure 29b is the amplitude attenuation.
  • the instrument configuration shown in Figure 27 can be used to measure the underlying resistivity and determine the relative position of the instrument and formation interfaces.
  • Figure 30 shows two conventional coils as transmitting antennas and distributed on both sides of the tow shaped logging antenna of the present invention.
  • the combined coil system T1-R, T1-R2, T2-R1, T2-R2 and the working principle of FIG. 21 are the same, the measuring method of the combined coil system T1-R1-R2 and the combination T2-R2-R1 and the measuring method of FIG. The same can be measured separately. Meanwhile, the coil system shown in Fig. 30 can perform the following compensation measurement.
  • V 11 ( ⁇ ) , V 12 ( ⁇ ) , V 21 ( ⁇ ), and V 22 ( ⁇ ) are the electromotive forces of the transmitting antenna T1 on the receiving antennas R1 and R2 and the transmitting antenna T2 on the receiving antennas R1 and R2, respectively.
  • Ratio4 The amplitude and complex angle of Ratio4 can be used for resistivity measurements, respectively.
  • Ratio5 calculates the amplitude, complex angle, imaginary part, real part, etc. as a function of the rotation angle of the instrument.
  • the regularity is the same as the regularity of the instrument structure of Fig. 27, and can be used to calculate the distance from the instrument to the formation interface.
  • Fig. 31 shows a dual-shot dual-receiving instrument consisting of a conventional coil as a transmitting antenna and a composite antenna as a receiving antenna.
  • the receiving antennas R11 and R12, and R21 and R22 may be used alone or in combination to form different instrument structures.
  • the instrument coil system consisting of T1-R11-R21-T2 is the same as that of Fig. 27, and can work separately.
  • the working principle is also the same as that of Fig. 27;
  • the instrument coil system consisting of T1-R12-R22-T2 is the same as the conventional coil system.
  • T1-R1-R2-T2 also constitute an instrument coil system, Where R1 is a combination of R11 and R12, and the measurement signal is
  • V T1R1( ⁇ ) V T1R11( ⁇ ) +V T1R12 ,
  • V T1R2( ⁇ ) V T1R21( ⁇ ) +V T1R22 ,
  • R2 is a combination of R21 and R22, and the measurement signal is
  • V T2R1( ⁇ ) V T2R11( ⁇ ) +V T2R12 ,
  • V T2R2 ( ⁇ ) V T2R21 ( ⁇ ) + V T2R22 .
  • V T1R11( ⁇ ) , V T1R21( ⁇ ) , V T2R11( ⁇ ) , V T2R21( ⁇ ) are the electromotive forces of the transmitting coil T1 to the receiving coils R11, R21 and the transmitting coil T2 to the receiving coils R11 and R21, respectively, which are The function of the rotation angle of the instrument;
  • V T1R12 , V T1R22 , V T2R12 , V T2R22 are the electromotive forces of the transmitting coil T1 to the receiving coils R12 and R22 and the transmitting coil T2 to the receiving coils R12 and R22, respectively, which are independent of the angle of rotation of the instrument.
  • the amplitude and complex angle of Ratio6 can be used to calculate the formation resistivity.
  • the amplitude, complex angle, imaginary part, and real part of Ratio7 can be used to calculate the distance from the instrument to the formation interface.
  • the instrument may have any receiving antenna and any one of the transmitting antennas, and the relative positions of the receiving antenna and the transmitting antenna may be arbitrarily arranged.
  • the receiving antenna and the transmitting antenna may be any of the foregoing novel antenna loops.
  • the X-axis of the missing antenna can be pointed or pointed to any orientation.

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Abstract

一种用于测井的天线回路，所述天线回路包括主贡献区段和非主贡献区段，所述主贡献区段的接收或发射信号能力明显强于非主贡献区段。同时还提供了相应的天线系统和测井方法。在复杂地质构造下，上述天线回路用作发射天线，能有效增强地层反射信号强度；上述天线回路用作接收天线，能有效探测微弱的地层反射信号。上述的天线回路，天线系统和测井方法应用在地质导向测井仪器上，能大幅提升探测地层界面的距离和精度。

Description

一种用于测井的天线回路，天线系统及相应的测井方法 技术领域
本发明涉及天线技术领域，具体地说，本发明涉及一种用于测井的天线回路，天线系统及相应的测井方法。
背景技术
传统天线形状常为圆形、椭圆形、多边形等，图1示出了传统天线结构的部分典型形状，可以看出，其特点为线圈回路各部分相对均匀的发射或接收信号。这样在无差别闭合线圈上流动的电流可以被等效成磁偶极子，极大的方便了仪器的设计和接受信号的处理。这些优势使得传统天线在电缆测井和随钻测井(Logging While Drilling，缩写为LWD)中都得到了广泛应用。尤其是对于地层电阻率测量等常规应用，传统天线很好的满足了生产需求。
然而，随着勘探技术的不断发展，地质导向，前探测等新技术涌现，常规天线在探测距离，信号强度和仪器尺寸都已经不能达到现代工业生产的需求了。这里以地质导向为例。地质导向主要是为水平井服务的。由于水平井能大幅增加井在油气层内的长度，从而有效地提升单井的产量，所以在现在石油生产中得到越来越广泛的应用。在水平井钻井过程中，需要不断探测钻头到地层界面的相对位置，以便让钻头始终保持在目标油气层中。早期的方法一般是采用伽玛测井资料或电阻率成像资料来判断这个相对位置。但由于这些方法对底层界面的探测距离非常短，当测井资料有显 示时，已经没有足够的时间调整钻头方向来避免钻头穿出目标油气层。操作人员只能通过这些资料来判断钻头是否出目的层，如果是，便调整钻头方向使之重新回到目的层。由于钻杆不能任意弯曲，钻头往往要几十米外才能重返目的层。为了克服这个缺点，相关公司采用传统的z(仪器长轴方向)线圈产生的电磁波传播随钻测井资料来判别仪器和底层界面的相对位置。该方法理论上是可行的，计算结果也能明显显示测量信号与仪器到地层界面的距离之间的关系，但在实际操作时，由于测量环境对仪器的影响和地层的复杂性，操作人员无法判别测量信号是不是真实反映钻头到目标层界面的距离，所以抗干扰性很弱。只有当仪器距离地层界面很近时，才能准确判断钻头到界面的距离，这时留给操作人员调整钻井方向的时间也不是很多了。从2005年起，几大石油仪器服务公司开始使用传统的纵向线圈和横向线圈之间的感应信号强度(即所谓的XZ或ZX信号)来判断仪器和地层界面之间的相对位置。由于在水平井条件下，该信号强度主要由仪器相对位置决定，所以该方法可以用来较早的判别钻头到地层界面之间的距离。相关公司开发了两种测量XZ或ZX信号的方法：直接测量和采用倾斜线圈(或等效的倾斜线圈)间接测量，这种仪器宣称的探测范围大约5米左右，但由于测量环境的影响，实际有效的范围还要小一些，远远不能满足石油生产的需求。市场急需要一种探测距离远，仪器长度小的地质导向仪器，而这些在传统的测井天线设计及方法下很难得到满足。
发明内容
本发明的任务是提供一种探测距离远的测井解决方案。
本发明提供了一种用于测井的天线回路，所述天线回路包括主贡献区段和非主贡献区段，所述主贡献区段的接收或发射信号能力明显强于非主贡献区段。
其中，所述主贡献区段的导线接收/发射信号的能力被显著增强。该方案中，所述天线回路包括构成回路的导线，以及用于显著增强位于所述主贡献区段的导线的接收/发射信号的能力的物质或结构。
其中，所述非主贡献区段的导线的接收/发射信号的能力被显著削弱。该方案中，所述天线回路包括构成回路的导线，以及用于显著削弱位于所述非主贡献区段的导线的接收/发射信号的能力的物质或结构。
其中，所述主贡献区段的导线的接收/发射信号的能力被显著增强，且所述非主贡献区段的导线的接收/发射信号的能力被显著削弱。该方案中，所述天线回路包括构成回路的导线，用于显著增强位于所述主贡献区段的导线的接收/发射信号的能力的物质或结构，以及用于显著削弱位于所述非主贡献区段的导线的接收/发射信号的能力的物质或结构。
其中，所述天线回路中，使用磁性材料来增强所述主贡献区段的导线的接收/发射信号的能力。
本发明还提供了一种用于测井的天线系统，包括金属骨架和安装在所述金属骨架上的天线回路，其特征在于，所述天线回路包括主贡献区段，所述主贡献区段的接收或发射信号能力明显强于其它区段。
其中，所述主贡献区段以外的其它区段的信号接收/发射信号的能力被所述金属骨架削弱。
其中，所述天线系统还包括信号屏蔽物质，所述信号屏蔽设施用于削 弱天线回路中非主贡献区段的接收/发射信号的能力。
其中，所述金属骨架内有刻洞或刻槽，所述天线回路中非主贡献区段的导线放入所述刻洞或刻槽内。
其中，所述天线回路中非主贡献区段的导线紧紧缠绕在仪器金属骨架上。
其中，所述信号屏蔽物质覆盖，或部分覆盖，或包裹，或部分包裹在天线回路中非主贡献区段上。
其中，所述信号屏蔽物质为金属。
其中，所述金属骨架的外形是与钻杆匹配的圆柱形，所述天线回路的形状是只覆盖所述金属骨架部分圆周的圆缺形。
其中，所述天线系统还包括放置在所述金属骨架刻槽内的磁性材料，所述天线回路中主贡献区段的导线被放置所述磁性材料上。
其中，所述天线回路中非主贡献区段的导线被部分/全部放置在仪器金属骨架上的刻槽或刻洞内。
其中，所述天线回路中非主贡献区段的导线被信号屏蔽设施屏蔽。
其中，所述主贡献区段的导线以圆柱形的金属骨架的长轴为对称轴缠绕。
其中，所述主贡献区段的导线倾斜缠绕在所述金属骨架上。
其中，所述非主贡献区段的导线的形状可以是任意形状。
其中，所述非主贡献区段的导线的形状可以是任意形状被部分或全部放置在磁性材料侧面。
其中，所述非主贡献区段的导线被部分或全部放置在磁性材料下面。
本发明还提供了一种用于测井的天线系统，所述天线系统由几个前述的天线回路串联而成。
其中，串联的几个所述天线回路在仪器长轴位置相同，但方位角不同。
本发明还提供了一种用于测井的天线系统，其特征在于，所述天线系统由一个或几个传统的均匀天线线圈与至少前述的天线回路串联而成，所述均匀天线线圈和所述天线回路在仪器长轴位置可以相同，也可以不同。
本发明还提供了一种用于测井的天线系统，所述天线系统由几个独立的前述天线回路组成，所述天线回路之间分时操作。
其中，所述的几个独立的所述天线回路在仪器长轴位置相同，但方位角不同。
本发明还提供了一种测井仪器，包括发射和接收天线组成的仪器线圈系，仪器线圈系的发射和接收天线中至少有一个为前述的天线系统。
其中，所述仪器线圈系为单发单收仪器线圈系。
其中，所述仪器线圈系为单发双收仪器线圈系。
其中，所述仪器线圈系为双发双收仪器线圈系。
本发明还提供了一种基于前述测井仪器的测井方法，其特征在于，包括步骤：
1)当仪器旋转时，测量所述的线圈系中至少一个接收线圈在至少一个发射线圈工作时在不同仪器旋转角度上的感应电动势，其中，参与测量的接收线圈和发射线圈中，至少有一个采用所述的天线回路；
2)根据所测的在不同仪器旋转角度上的感应电动势得出测井结果。
其中，所述步骤2)中，利用所述步骤1)所测量到的接收线圈上的 感应电动势来判别仪器和地层界面的方位。
其中，所述步骤2)中，利用步骤1)所得的感应电动势测量信号进行
Figure PCTCN2015072435-appb-000001
计算，并根据变量
Figure PCTCN2015072435-appb-000002
的幅度、相位、实部、虚部中的一项或多项，计算仪器到地层界面的距离和判别仪器和地层界面的方位；其中θ是仪器旋转角度，V(θ)是仪器在旋转角度为θ时的感生电动势。
其中，所述步骤2)中，利用步骤1)所得的感应电动势测量信号进行V(θ)-V(θ+π)计算，并根据变量V(θ)-V(θ+π)的幅度、相位、实部、虚部中的一项或多项，计算仪器到地层界面的距离和判别仪器和地层界面的方位；其中θ是仪器旋转角度，V(θ)是仪器在旋转角度为θ时的感生电动势。
其中，所述步骤2)中，利用步骤1)所得的感应电动势测量信号进行
Figure PCTCN2015072435-appb-000003
计算，并根据变量
Figure PCTCN2015072435-appb-000004
的幅度、相位、实部、虚部中的一项或多项，计算仪器到地层界面的距离和判别仪器和地层界面的方位；其中，其中θ是仪器旋转角度，V(θ)是仪器在旋转角度为θ时的感生电动势，Average(V(θ))是接收线圈中的感应电动势实测信号的算术平均。
其中，所述步骤1)中，测量两个接收线圈在相同发射线圈作用下产生的两组感应电动势；
所述步骤2)中，利用步骤1)所得的感应电动势测量信号进行
Figure PCTCN2015072435-appb-000005
计算，并根据变量
Figure PCTCN2015072435-appb-000006
的幅度、相位、实部、虚部中的一项或多项，计算仪器到地层界面的距离和判别仪器和地层界面的方位，及方位电阻率；其中这里V1(θ)和V2(θ)分别是两个接收线圈在相同发射线圈工作时，在仪器旋转角度为θ就角度时产生的感应电动势。
其中，所述步骤1)中，测量两个接收线圈在相同发射线圈作用下产 生的两组感应电动势；
所述步骤2)中，利用步骤1)所得的感应电动势测量信号进行
Figure PCTCN2015072435-appb-000007
计算，并根据变量
Figure PCTCN2015072435-appb-000008
的幅度、相位、实部、虚部中的一项或多项，计算仪器到地层界面的距离和地层电阻率；其中，Average(V1(θ))和Average(V2(θ))分别是两个接收线圈中的感应电动势实测信号的算术平均。
其中，所述步骤1)中，测量两个接收线圈分别在两个不同发射线圈作用下产生的四组感应电动势；所述步骤2)中，利用步骤1)所得的双发双收四组感应电动势测量信号进行
Figure PCTCN2015072435-appb-000009
计算，并根据变量
Figure PCTCN2015072435-appb-000010
的幅度、相位、实部、虚部中的一项或多项，计算仪器到地层界面的距离、仪器和地层界面的相对位置和地层电阻率；这里Vij(θ)是指发射线圈i在接收线圈j上产生的感应电动势，i，j等于1或2。
其中，所述步骤1)中，测量两个接收线圈分别在两个不同发射线圈作用下产生的四组感应电动势；所述步骤2)中，利用步骤1)所得的双发双收四组感应电动势测量信号进行
Figure PCTCN2015072435-appb-000011
计算，并根据变量
Figure PCTCN2015072435-appb-000012
的幅度、相位、实部、虚部中的一项或多项计算仪器到地层界面的距离和地层电阻率；其中Average(Vij(θ))是指发射线圈i在接收线圈j上产生的感应电动势的实测值的算术平均，i，j等于1或2。
与现有技术相比，本发明具有下列技术效果：
1、在复杂地质构造下，如本发明的天线回路用作发射天线，能有效增强地层反射信号强度；如本发明的天线回路用作接受天线，能有效探测 微弱的地层反射信号。
2、本发明应用在地质导向测井仪器上，能大幅提升探测地层界面的距离和精度。
附图说明
以下，结合附图来详细说明本发明的实施例，其中：
图1示出了传统天线结构的部分典型形状；
图2a示出了一种作为仪器金属骨架的表面带有刻槽的金属柱体的示意图，图2b示出了一种作为仪器金属骨架的表面带有孔洞的金属柱体的示意图；
图3a示出了传统天线回路安装到图2a刻槽里的截面示意图，图3b示出了传统天线回路安装到图2b刻洞里的截面示意图；
图4a～c示出了本发明一个实施例的圆缺形侧置天线回路的各种形式的示意图；其中，图4a示出了本发明一个实施例的圆缺形侧置天线回路在柱形仪器侧面的展开图，图4b示出了图4a实施例的天线回路的三维立体图，图4c示出了图4a实施例的天线回路从侧视角度的平面图；
图5a～d示出了圆缺形侧置天线回路在仪器金属骨架上的四种布线方式的示例；
图6a～c示出了本发明另一个实施例的另一种圆缺形天线回路的各种形式的示意图；其中，图6a示出了另一种圆缺形天线回路在柱形仪器侧面的展开图，图6b示出了图6a实施例的天线回路的三维立体图，图6c示出了图6a实施例的天线回路从侧视角度的平面图；
图7a～d示出了图6a的圆缺形天线回路在仪器金属骨架上的四种布线方式的示例；
图8a示出了另一种侧置圆缺形天线回路的侧面展开图，图8b示出了图8a的侧置圆缺形天线回路的三维立体图；
图9a～d示出了几种倾斜放置的天线的示意图；其中，图9a示出了沿z方向缠绕的矩形圆缺天线放置在倾斜放置的磁性材料上的示意图，图9b示出了沿z方向缠绕的环形天线被放置在倾斜放置的磁性材料上的示意图，图9c示出了倾斜缠绕的矩形圆缺形天线放置在z方向均匀放置的磁性材料上的示意图，图9d示出了倾斜缠绕的椭圆形天线放置在z方向均匀放置的磁性材料上的示意图；
图10a示出了通过把部分天线放置在磁性材料下方来达到减弱收发信号能力的方案的截面示意图，图10b～e示出了本发明一个实施例中部分天线放置在磁性材料下方的天线回路被水平安置和倾斜放置的对比；其中，图10b示出了图10a天线回路被水平安置在仪器金属骨架上的正面三维图，图10c示出了图10a天线回路被水平安置在仪器金属骨架上的反面三维图，图10d示出了图10a天线回路被倾斜放置在仪器金属骨架上的正面三维图，图10e示出了图10a天线回路被倾斜放置在仪器金属骨架上的反面三维图；
图11a～d示出了图10a～e所示的天线回路的几种布线方式；
图12a～12f示出了几种立置圆缺形天线的示意图；
图13示出了图12b所示的立置圆缺形天线与外界发射源连接的示意图；
图14示出了两个立置圆缺天线相串联而成的天线回路的示意图；
图15a～c示出了本发明的天线与传统天线串联而成的线回路的示意图；其中，图15a示出了传统天线回路的一个示例，图15b示出了本发明的天线回路的一个示例，图15c示出了图15a的传统天线回路与图15b的本发明的天线回路串联形成的复合天线回路；
图16示出了图15c的复合天线回路的等效圆缺形天线回路；
图17示出了多个圆缺形天线回路组成的天线系统；
图18a示出了本发明的天线与外接电路直接形成闭合回路的一个示例，图18b示出了圆缺形天线接入外围电路的一个示例；
图19a～c示出了几种由两个圆缺天线串联而成的天线回路；
图20示出了本发明一个实施例中以测量z方向电场为主的天线回路；
图21示出了本发明一个实施例中的单发单收线圈系；
图22示出了图21的单发单收线圈系所工作的一个简单地层模型；
图23a～b示出了图21的单发单收线圈系在图22所示地层模型中电动势随方位角的变化；
图24a～b示出了参量Ratio1的模和相位随仪器到地层界面的距离的变化；
图25a～b示出了参量Ratio2的模和相位随仪器到地层界面的距离的变化；
图26示出了参量
Figure PCTCN2015072435-appb-000013
的模随仪器到地层界面之间距离的变化；
图27示出了一个传统线圈为发射天线和两个本发明所提出的圆缺形天线为接收天线的随钻测井仪器；
图28a～b示出了接受天线R1和R2之间的幅度衰减和相位偏移与仪器方位角之间的关系，该关系可由Ratio3计算；其中，图28a是相位偏移，图28b是幅度衰减；
图29a～b示出了当方位角为零度时接受天线R1和R2之间的幅度衰减和相位偏移与仪器到地层界面的距离之间的关系；其中，图29a是相位偏移，图29b是幅度衰减；
图30示出了两个传统线圈作为发射天线且分布在两个本发明所提出的圆缺形接收天线的两边的随钻测井仪器；
图31示出了一个由传统线圈作为发射天线和由复合天线作为接收天线组成的双发双收仪器；
图32示出了任意个接收天线和任意个发射天线组成的仪器，其中接收天线和发射天线的相对位置可以任意排列。
具体实施方式
下面结合附图和实施例对本发明做进一步地描述。
发明人对现有的用于测井的天线系统做了深入研究，发现现有的基于无差别闭合回路的天线系统在信号精度和强度都有很大的局限性。主要原因如下：无差别闭合回路所产生或接收的信号的强度是和电场旋度直接相关的。这里以接收线圈为例，接收线圈各部分(主要是延线圈中心对称的部分)所接收的由地层反射信号产生的电动势经常是相互抵消的，从而降低了对弱小信号的探测能力。在传统的电阻率测量领域，相对有限的测量范围内，地层通常被认为平行的(1D)，甚至是均匀介质(0D)，所以传统LWD的线圈设计能够满足现在测井业中相当一部分需求。但对于相对复杂的地层结构和地质导向等应用领域，传统天线往往不是最优设计。尤其在测量较弱的地层界面反射信号时，传统天线测量信号精度和强度都 有很大的局限性。
本发明的用于测井的天线系统与传统的天线系统的主要区别是：新型天线系统的回路各个部分接收(接收天线)或发射(发射天线)信号的能力是不均衡的。这里的不均衡可能是指有些部分(不能是全部)回路上的信号接受或发射的能力得到加强，也可能是指有些部分(不能是全部)回路上的信号接收或发射的能力被减弱了，也可能有些部分的信号接收或发射的能力被加强的同时另一部分的信号接收或发射的能力被减弱。通常增强部分回路中的增加信号强度的方法是在导线下面添加磁性材料，但本发明并不限于这种信号增强方式。减弱(甚至消除)信号强度的手段相对更多，例如借助随钻测井仪器中的金属骨架来屏蔽部分电路，或在部分导线外包信号屏蔽层(常用金属皮)等。如果只有部分回路的发射/接受能力得到增强，那么其它部分回路也可以看作发射/接收能力被相对削减了。这种削减或相对削减部分回路的发射/接收信号能力是有明确目的的，就是这部分回路在目标环境中所发射/接收的有效信号(如地层界面的反射信号)整体而言对回路其它部分所产生的有效信号一定是反向的，至少是相互干扰的。通过这部分的削减，能够达到整体有效信号强度增加的效果。发射或接收能力的不均衡性也使得所述天线对复杂地层的探测有了方向性。这种新型天线的应用领域不仅仅在地质导向领域，例如在针对复杂地质构造的电缆测井，用电磁传播探测大地构造等领域都有巨大应用前景，但这里仅在随钻测井中的地质导向领域对这种天线进行一些举例说明。
在随钻测井中，由于工作环境恶劣，天线一般被安装在一个金属柱体外侧的刻槽里，柱体内为空心，用于通过泥浆。本文中把这个金属柱体叫 做仪器骨架或仪器金属骨架，体内的空心叫做仪器内腔。图2a示出了一种作为仪器金属骨架的表面带有刻槽的金属柱体的示意图，在该方案中，金属柱体202表面向内刻有一个环状凹槽203，天线204就缠绕在这个环状凹槽内。图2b示出了一种作为仪器金属骨架的表面带有孔洞的金属柱体的示意图，该方案中，金属柱体202表面向内刻有一组矩形的凹槽205，在各凹槽间刻有小孔，天线204在小孔中依次通过，构成天线回路。这里金属柱体202为圆柱体，其中具有内腔201，用于泥浆通过。由于天线是安装在金属槽内部，外界信号很大程度被天线下面和侧面金属壁所屏蔽掉(金属表面电场切向分量为零)，天线接收信号强度减弱。因此，为了增强信号强度，往往会在天线下覆盖一层磁性材料。这部分磁性材料往往会使信号得到几倍到几十倍的增强。
图3a示出了传统天线回路安装到图2a的仪器金属骨架的刻槽里的截面示意图。在图3a中，301表示仪器外部分，302表示安装线圈部分，303表示刻槽后金属柱体部分，304表示柱体内部分，线圈上的箭头307表示线圈204缠绕方向(以后所有图示都只显示一种线圈缠绕方向，但需说明，本发明的线圈也可以反向缠绕)，在天线和金属柱体之间填充磁性材料305，磁性材料305制作成柱状，其截面为圆形(需说明的是，这里磁性材料305也可以有不同形状，并不局限于柱状体)。线圈204之外用利用绝缘材料包裹。图3b示出了传统天线回路安装到图2b的仪器金属骨架的刻洞里的截面示意图。图3b中，矩形刻槽的侧壁308上打孔，以便让导线通过。为了方便，下文在描述在金属柱体表面刻槽结构时，只描述图3a的形状，但所描述的内容同样适用于图3b所显示的结构。图3a的天线安装方式工 艺比较简单，但仪器机械强度不如图3b。从图3a～b中，可以看到传统天线回路各部分是相对均衡的，都担当信号的发射或接收任务。图3b中也有小部分天线在金属凹槽侧壁通过，信号在这里被削弱。但这种削弱只是服从仪器强度的需要，而不会达到削弱反向有效信号强度的目的，最终效果只会减弱最终整体信号强度。
与传统天线相对应，本发明提出了一种新型天线回路，该天线回路中部分发射或接收的功能被故意相对减弱甚至完全屏蔽掉，从而达到整体增强信号强度的功能。它的实现方式有很多种，下面列举几种新型天线的实现方式，但新型天线的整体方案决不仅仅局限于这几种形式。
图4a～c示出了本发明一个实施例的圆缺形侧置天线回路的示意图；其中，图4a示出了该实施例的圆缺形侧置天线回路在柱形仪器侧面的展开图，图4b示出了该实施例的天线回路的三维立体图，图4c示出了该实施例的天线回路侧视角度的平面图。
图4a～c所示的新型天线不像一般传统天线那样360度缠绕了整个仪器界面，而只是缠绕了仪器骨架的部分圆周。本文中把这种只覆盖部分圆周的天线叫圆缺形天线。这个缠绕角度Ф可以是从0到360度中的任意一个值。当Ф是180度时，可称作半圆形天线。在图4a中，磁性材料305用灰色长条表示，它镶嵌在仪器骨架的刻槽内，用来增强信号强度，天线回路204缠绕在仪器骨架表面，信号发生器(发射天线)或信号接收器(接收天线)的电路接入点可以是天线回路204中的任何一部分。以后的所有实例中也是如此，在以后的实例说明中就不再一一指出了。天线的缠绕方向是ABCDA，如图4a中箭头所示。天线的缠绕方向反向亦可。以后图例 中除非特别强调，否则都包含反向缠绕方式，而图例说明中就不再指出了。这里线圈可以是一匝线圈，也可以是多匝。在以后的图例中也是一样的，不再单独说明。回路中CD段是要削弱其发射或接收信号强度的部分，所以这段被放在磁性材料以外的一侧，为安装CD段，可以单独的刻槽，也可以是刻洞，亦或与AB段放在同一个刻槽内无磁性材料305的位置。如果是单独的刻槽，CD段之上还可以覆盖金属等高导电材料，以进一步削弱其发射或接收功能。图4b中，为了表示方向，圆柱体两端的侧面分别表示为面I和面J，图4b的两幅立体图表示从两个方向(IJ和JI)看到的天线分布图。需指出的是，图4b的两幅立体图均为示意图，圆柱体轴向的尺寸并不表示仪器金属骨架的实际尺寸。图4c是从两个方向(IJ方向和JI方向)侧视角度看到的平面图。BC段和DA段方向相反，但由于它们位置不同，也会对电路电动势进行某种程度的影响。如果这种影响足够大时，可以通过把导线放入在横向加刻的刻槽或刻洞等办法减弱其上产生的电动势。由于AB段下方放有磁性材料来加强其产生的信号强度，所以整个回路中它的贡献是主要的，本文中把它称作主贡献区域电路。图中非主贡献区域电路的主要部分CD段被放置在主贡献区域的侧面，(BC和CA主要起连接作用)。本文中把这种非主要贡献区域电路被放置在主贡献区域侧面的新型天线叫侧置型天线。这里的侧置是相对仪器主对称轴(仪器中腔)方向而言。
图5a～d示出了圆缺形侧置天线回路在仪器金属骨架上的四种布线方式的示例。这几种示例的天线回路中，削减信号强度的原理是相同的，就是利用金属对信号的屏蔽作用。(金属表面信号切向方向为零，金属内部 信号强度为零)。在图5a～d中，501是装有磁性材料的刻槽。502是天线AB段的截面。305是磁性材料。503是CD段的导线截面图。202是仪器的金属框架的截面，201是仪器中间的金属内腔。505是仪器柱体的中心对称线。仪器下截面由于没有天线回路通过，所以可以没有磁性材料或刻槽。如果仪器覆盖角度大于180度时，仪器下面也可能有天线电路通过，由于道理是相同的，就不单独叙述了。在图5a中，GH或DC是在磁性材料刻槽边的单独刻槽504，为了增强效果，上面还可以覆盖高电导层。在图5b中GH或DC是放在单独的刻洞506内，图5c中GH和DC放在了与磁性材料相同的刻槽内501，但被放置在边缘处，可以在磁性材料上，也可以在磁性材料旁边。图5d是GH或DC就放在磁性材料上，但外面被包裹或覆盖了金属屏蔽层507。图中没有显示BC，DA的布线和刻槽方式。事实上它们刻槽和布线与CD相近，只是方向是横向的。这里要指出的是刻槽和布线的方式远远不止上述几种，但它们都遵循一个规则，就是要想办法相对削弱CD段的信号强度。
图6a～c示出了本发明另一个实施例的一种圆缺形天线回路的示意图。其中，图6a示出了该圆缺形天线回路在柱形仪器侧面的展开图，图6b示出了该实施例的天线回路的三维立体图，图6c示出了该实施例的天线回路从侧视角度的平面图。同样，305是磁性材料，204是天线回路。AB段是主贡献区域，CD段是被故意削弱了的。因为CD段天线的作用很小，所以它无所谓是像图4a～c的实施例一样与AB段反向缠绕，还是像图5a～d的例子一样同向继续缠绕。事实上只要其产生的信号足够小，就可以是任意缠绕方式。另外，与图4b类似，图6b中，为了表示方向，圆柱体两端 的侧面分别表示为面I和面J，图6b的两幅立体图表示从两个方向(IJ和JI)看到的天线分布图。需指出的是，图6b的两幅立体图均为示意图，圆柱体轴向的尺寸并不表示仪器金属骨架的其实际尺寸。
图7a～d示出了图6a的圆缺形天线回路在仪器金属骨架上的四种布线方式的示例。由于图7a～d与图5a～d非常接近，就不一一说明了。图7a～d所示的布线方案与图5a～d的区别是天线缠绕了整个刻槽。
图8a示出了根据本发明再一个实施例的一种侧置圆缺形天线回路的侧面展开图，图8b示出了图8a的侧置圆缺形天线回路的三维立体图。图8a～b的方案是把图4a～c所示的圆缺形天线倾斜缠绕在仪器金属骨架上。同理，图6a～c所示圆缺形天线也可以倾斜缠绕在金属挂架上，就不再用图例说明了。
图9a～d示出了几种倾斜放置的天线的示意图；其中，图9a示出了沿z方向缠绕的矩形圆缺天线放置在倾斜放置的磁性材料上的示意图，图9b示出了沿z方向缠绕的环形天线被放置在倾斜放置的磁性材料上的示意图，图9c示出了倾斜缠绕的矩形圆缺形天线放置在z方向均匀放置的磁性材料上的示意图，图9d示出了倾斜缠绕的椭圆形天线放置在z方向均匀放置的磁性材料上的示意图。它们也都通过磁性材料增强部分天线信号来相对削弱其它部分所产生的信号，从而达到最终增强信号强度的结果。
本发明中，也可以通过把部分天线放置在磁性材料下方来达到减弱收发信号能力。图10a示出了通过把部分天线放置在磁性材料下方来达到减弱收发信号能力的方案的截面示意图，图10b～e示出了本发明一个实施例中部分天线放置在磁性材料下方的天线回路被水平安置和倾斜放置的对 比；其中，图10b示出了图10a天线回路被水平安置在仪器金属骨架上的正面三维图，图10c示出了图10a天线回路被水平安置在仪器金属骨架上的背面三维图，图10d示出了图10a天线回路被倾斜放置在仪器金属骨架上的正面三维图，图10e示出了图10a天线回路被倾斜放置在仪器金属骨架上的背面三维图。图10a～e中，305是磁性材料，204是天线回路，202是仪器金属骨架，201是仪器内腔。天线的缠绕方式是ABCDA，缠绕圈数可以为一匝，也可以多匝。天线回路的CD段缠绕在回路AB段下方。这里所指的下方可以是在磁性材料305之下金属骨架202之上，CD段可以安置在磁性材料刻槽底部刻的小槽，也可以安置在仪器金属支架内的刻洞。图10a～e中有部分区段用虚线表示，其含义是指明这部分回路区段上的信号被削弱了。在以后相关的图例中，虚线都表示被削弱信号强度的那部分天线。如图10b～e所示，图10a的天线回路既可以被水平安置，也可以被倾斜放置，例如45度倾斜放置。需要说明的是，后面的其它类型的新型天线回路也都可以水平或倾斜放置在仪器骨架上，并且这里的倾斜角度是任意角度，而不仅仅是45度。可以看出，在AB是主贡献区域，其余部分是回路的非主贡献区域，把这种非主贡献区域被放置在主贡献区域下方的新型天线叫立置型天线。
图11a～d示出了图10a～e所示的天线回路的几种布线方式。其中，501是装有磁性材料的刻槽，305是磁性材料。1101是主贡献区域AB导线，1103是金属等填充材料，它起到一定的支撑作用。1102是CD线。202是仪器金属骨架上下截面，201是仪器中腔。图中1104是在磁性材料下方为导线1102而刻的槽，1105是磁性材料下方金属骨架内的刻洞。图11a 中CD在磁性材料正下方，图11b中CD在磁性材料下，但在靠近刻槽壁的一侧。其实，只要CD在磁性材料下方刻槽内的任何位置都可以达到削减信号强度的作用。图11c为CD在大刻槽下单独又刻了一个小槽，这样屏蔽效果更好。小槽的位置不一定在大槽底部中央。大槽底部其它位置也可以起到同样的作用。11d是为CD单独刻了一个刻洞。这个刻洞的位置其实可以在任何位置，不一定非要在原有刻槽下方。如果在侧面，就是5b了。这里需要指出，不同的刻槽和布线可以在同一个新型天线上混用。
图12a～12f显示了另外几种立置圆缺形天线。这几种天线效果是一样的，就是天线回路中，只有AB段起主要贡献。AB对应的张角，如图12c～12f所示的角度φ，可以是0到360中任何角度。图例中305是磁性材料，204是闭合天线,沿ABCDA方向缠绕，可以是一圈，也可以是多圈。202是仪器金属骨架，201是仪器中空腔。1201是与305不同性质的材料，可以是磁性材料，也可以是非磁性材料，例如金属垫层。例子图12a中磁性材料只布置在主贡献区域下方。图12b中CD段在AB段下方金属骨架内的刻洞中穿过。图12c中CD在AB段外的另一侧的金属骨架中穿过。图12d中CD在AB段外另外一侧仪器金属骨架外紧贴近金属处绕过。图12e中CD段在天线外用加载了信号屏蔽装置，例如金属皮。图12f中CD段下方的非磁性材料不能起到加强信号的作用，所以变相相对削弱了CD上的信号强度。如果是金属垫层，还可以直接削弱CD上的信号。它们的刻槽和布线方式与以前的相同，这里就不再叙述了。
由上面的例子所示，本发明的新型天线的特点就是天线回路中的部分区段接收/发射信号的能力与其它部分不同。它通过削弱或相对削弱天线 回路部分区段的发射或接收信号的能力来达到增强整体信号强度的作用。对于回路是对称形状的天线，通过这种相对削弱回路部分区段接发信号能力的办法还可以使天线具有方位角上的方向性。削弱或相对削弱部分区段收发信号能力的方法有很多种，上面的例子只是其中的一部分，其它的方法还有很多。本专利不只是限于这些例子。
上述例子中，都没有给出天线与仪器电路相连的节点。事实上新型天线可以在回路任意位置与仪器的电路相连。作为例子，图13显示图12b所示的新型天线作为发射天线在位置B与外界发射源1301相连。
本发明的新型天线之间可以在相同或不同位置串联使用，来达到特定的效果。图14是两个立置圆缺天线相串联而成形成的回路。一个天线是ABCDA，另一个是EFGHE。两个天线在仪器相同z坐标(仪器金属内腔走向)，不同XY平面方位角相互串联使用。这种复合天线如果作为接收天线，它有一个优点，就是当发射线圈是最常见的z线圈，那么如果地层是以发射接收线圈中心连线为轴旋转对称,且图中两个圆缺形天线张角φ1和φ2相同，那么它接收的信号强度为零。这也是说这种天线所接收的信号，完全来源于非轴对称地层的信息。
本发明的新型天线可以和传统天线串联在一起使用。图15c所示为新型天线DEFGD(图15b)和传统天线ABCA(图15a)相串联(A连G，C连D)得到的复合天线示意图。当新型天线和传统天线在同一位置或相近位置时，借助数字振荡器等电子元件或其它方法，可以使仪器同时拥有传统天线、新型天线和两种天线串联在一起的复合天线三种工作形式。
在图15c中，新型天线的DE段回路与传统天线BC段回路位置形状相 同，但方向相反，这样在新型天线和传统天线组成的复合天线中，它们的贡献和为零，可以消去。这样的复合天线15c可以等效为图16所示的圆缺形天线。
同一套仪器内可以拥有多套新型天线，它们可以组合使用达到特定的效果。例如如图17所示，多个圆缺形天线组成的仪器可以在不转动的情况下也可以进行多方位角的探测。在图17中，5个独立的天线子系统1701～1705在仪器长轴位置相同，方位角不同，当仪器滑行时，该系统还是可以探测5个不同方位角的地层信号，从而推算出地层边界信息。
图18a示出了本发明的天线与外接电路直接形成闭合回路的一个示例，它是前述实施例的新型天线回路的一种变形，其中，204是天线回路，305是磁性材料，1301是天线外围电路，包括信号源(发射天线)或信号接收器(接收天线)。图18b示出了圆缺形天线接入外围电路的一个示例。图18a和18b实际上是相同的。当天线主贡献区域是一样的，非主贡献区域天线无论变成什么形状，不会对天线有决定性影响。同理，本发明的其它新型天线的非主贡献区域线路都可以做出类似的变形。本发明包括非主贡献区域的天线的任何变形。
图19a～c示出了几种由两个圆缺天线串联而成的天线回路。图19a～c的天线回路与图4a～c所示的天线回路相似，但回路AB和CD相隔较远，并且不完全消减CD段的信号强度，因此也可以把这个例子看成两个圆缺天线串联而成的天线回路。图19a中天线开口较大，图19b中天线几乎是闭合的。这个张角可以是0到360度中任意一个。由于BC段和DA段很近，它们上面的信号可以相互抵消。当开口很小时，且AB段和CD段下面都垫有 相同的磁性材料，则此天线可以看成四级子。如果AB或CD段有一方信号得到消减(例如不铺设磁性材料)，则此天线是偶极子。图19c显示的是此天线AB和CD下铺设不同的磁性材料，一个是1901，用实体灰色表示，一个是1902，用灰色虚线表示。这里AB段与CD段的张角也可以不同。
图20示出了本发明一个实施例中以测量z方向电场为主的天线回路，其中AB段是主贡献区域，BC，CD，DA段信号得到相对减弱。
下面以地质导向为例介绍一下本发明所提出的新型天线系统在地质导向上的应用。
图21示出了本发明一个实施例中的单发单收线圈系(一个发射线圈，一个接收线圈)，其中发射线圈为传统的z线圈，接收天线为一个圆缺形天线，它的结构如图4c所示，角度
Figure PCTCN2015072435-appb-000014
为90度。
图22示出了图21的单发单收线圈系所工作的一个简单地层模型。这个模型有两个地层，1欧姆米的低阻层，和100欧姆米的高阻层。仪器沿着水平方向(Z轴方向)移动，同时绕z轴旋转。旋转角度θ是接收仪器开口方向与x轴方向夹角。当仪器旋转时，测量的电动势为旋转角度θ的函数，表示为V(θ)。
图23a～b示出了图21的单发单收线圈系在图22所示地层模型中电动势随方位角的变化，其中图23a为虚部的变化，图23b实部的变化。曲线标示“距离5英尺”和“距离10英尺”为当水平放置的仪器距离底层界面5英尺和10英尺情况下计算的结果。
图21所示的电极系测量的电动势可以通过下面的公式计算仪器到地层界面的距离：
Figure PCTCN2015072435-appb-000015
其中
Figure PCTCN2015072435-appb-000017
为圆缺天线面对底层界面，
Figure PCTCN2015072435-appb-000018
为圆缺天线背对底层界面图，Average(V)为仪器旋转一周所测信号的平均值。
图24a～b示出了参量Ratio1的模和相位随仪器到地层界面的距离的变化。
图25a～b示出了参量Ratio2的模和相位随仪器到地层界面的距离的变化。
图26示出了参量
Figure PCTCN2015072435-appb-000019
的模随仪器到地层界面之间距离的变化。图中显示
Figure PCTCN2015072435-appb-000020
可以被用来计算仪器到地层界面之间距离。
从图23a～b、图24a～b、图25a～b和图26可知：圆缺形天线的测量信号能够用来辨别仪器对地层界面的相对位置，其中从Ratio1、Ratio2和
Figure PCTCN2015072435-appb-000021
的模、相位、实部、虚部等可以用于仪器和地层界面相对位。
实际勘探中，界面并不严格水平，仪器旋转起始点未知，测量数据充满噪音，所以计算地层界面时所用到感应电动势不能由简单的直接测量得到，而是通过模拟正旋曲线计算出来的。例如接收线圈的信号的振幅A(θ)可以表示为V(θ)＝V0+Vrsin(θ+θr)，这里起始角度θr和正旋幅度质Vr都是未知的，V0是一个固定量，它的值主要由发射线圈在均匀介质(电阻100欧姆米)假设下产生的电场决定的，并可以通过实测信号简单算术平均得到。假设一个周期内的采样信号值是{Vi|i＝1,n},对应的采集角度为{θi|i＝1,n}。不失一般性，采样点假设是在0到360度内均匀采样。这里只需要对一个周期内的 采样值进行正旋和余旋函数作为权值的算术叠加，之后通过解下面方程组就可以得到Vr和θr。
Figure PCTCN2015072435-appb-000022
为了增强抗噪性，这个周期内的采样值可以是多个采样周期的数据联合处理而来，例如简单的算术平均。这种计算方法结果稳定，计算简单，可以应用于以后各个方法实例中。
图27示出了一个传统线圈为发射天线和两个本发明所提出的圆缺形天线为接收天线的随钻测井仪器。其中发射线圈T可以和圆缺形接收天线R1、R2分别组合形成和如图18a～b所示线圈系一样的组合，可以分别利用各自测量信号计算仪器和地层界面相对位。同时仪器到地层界面的距离也可以利用比值
Figure PCTCN2015072435-appb-000023
的复角、模、实部、虚部等计算。其中V1(θ)和V2(θ)为仪器的接收天线R1
和R2接收的电动势。
图28a～b示出了接受天线R1和R2之间的幅度衰减和相位偏移与仪器方位角之间的关系，该关系可由Ratio3计算。图28a是幅度衰减，图28b是相位偏移。图29a～b示出了当方位角为零度时接受天线R1和R2之间的幅度衰减和相位偏移与仪器到地层界面的距离之间的关系。图29a是相位偏移，图29b是幅度衰减。
从图28、29可知：图27所示的仪器结构可以用来测量底层电阻率和确定仪器和地层界面的相对位置。
图30示出了两个传统线圈作为发射天线且分布在两个本发明所提出的圆缺形接收天线的两边的随钻测井仪器。组合线圈系T1-R、T1-R2、T2-R1、T2-R2和图21的工作原理相同，组合线圈系T1-R1-R2和组合T2-R2-R1的测量方式与图27的测量方式相同，可以分别测量。同时，图30所示的线圈系可以进行如下补偿测量。
Figure PCTCN2015072435-appb-000024
Figure PCTCN2015072435-appb-000025
其中V11(θ)、V12(θ)、V21(θ)和V22(θ)分别为发射天线T1在接收天线R1和R2和发射天线T2在接收天线R1和R2上的电动势。
Ratio4的幅度和复角可以分别用于电阻率测量。Ratio5计算得幅度、复角、虚部、实部等为仪器旋转角度的函数，其规律和图27的仪器结构的规律性相同，可用于可以计算仪器到地层界面的距离。
本发明讨论的新型天线回路可以和其它天线组合使用。作为例子，图31示出了一个由传统线圈作为发射天线和由复合天线作为接收天线组成的双发双收仪器。接收天线R11和R12，及R21和R22可以分别单独使用，也可以组合使用，从而形成不同的仪器结构。其中T1-R11-R21-T2组成的仪器线圈系和图27的相同，可以单独工作，工作原理也和图27的相同；T1-R12-R22-T2组成的仪器线圈系和传统的线圈系相同，可以单独使用，以便当仪器滑动时，测量地层电阻率；T1-R1-R2-T2也组成一个仪器线圈系， 其中R1为R11和R12的组合，其测量信号为
VT1R1(θ)＝VT1R11(θ)+VT1R12，
VT1R2(θ)＝VT1R21(θ)+VT1R22，
R2为R21和R22的组合，其测量信号为
VT2R1(θ)＝VT2R11(θ)+VT2R12，
VT2R2(θ)＝VT2R21(θ)+VT2R22。
其中VT1R11(θ)、VT1R21(θ)、VT2R11(θ)、VT2R21(θ)分别为发射线圈T1对接受线圈R11、R21和发射线圈T2对接受线圈R11、R21的电动势，它们是仪器旋转角度的函数；VT1R12、VT1R22、VT2R12、VT2R22分别为发射线圈T1对接受线圈R12、R22和发射线圈T2对接受线圈R12、R22的电动势，它们和仪器旋转角度无关。
Figure PCTCN2015072435-appb-000026
Figure PCTCN2015072435-appb-000027
Ratio6的幅度和复角可可以用来计算地层电阻率，Ratio7随仪器旋转角度变化的幅度、复角、虚部、实部等可以用来计算仪器到地层界面的距离。
图21、图27、图30和图31是四个为了说明问题而列举的例子，并不是说仪器限于这四种结构。实际上，仪器可以有任意个接收天线和任意个发射天线组成，接收天线和发射天线的相对位置可以任意排列，如图32所示，接收天线和发射天线可以是前述任意一种新型天线回路，并且圆缺天线的X轴可以指向或分别指向任意方位。
最后应说明的是，以上实施例仅用以描述本发明的技术方案而不是对本技术方法进行限制，本发明在应用上可以延伸为其它的修改、变化、应用和实施例，并且因此认为所有这样的修改、变化、应用、实施例都在本发明的精神和教导范围内。

Claims (39)

  1. 一种用于测井的天线回路，其特征在于，所述天线回路包括主贡献区段和非主贡献区段，所述主贡献区段的接收或发射信号能力明显强于非主贡献区段。
  2. 根据权利要求1所述的天线回路，其特征在于，所述天线回路包括构成回路的导线，以及用于显著增强位于所述主贡献区段的导线的接收/发射信号的能力的部件。
  3. 根据权利要求1所述的天线系统，其特征在于，所述天线回路包括构成回路的导线，以及用于显著削弱位于所述非主贡献区段的导线的接收/发射信号的能力的部件。
  4. 根据权利要求1所述的天线系统，其特征在于，所述天线回路包括构成回路的导线，用于显著增强位于所述主贡献区段的导线的接收/发射信号的能力的部件，以及用于显著削弱位于所述非主贡献区段的导线的接收/发射信号的能力的部件。
  5. 根据权利要求2所述的天线系统，其特征在于，所述用于显著增强位于所述主贡献区段的导线的接收/发射信号的能力的部件为磁性材料部件。
  6. 一种用于测井的天线系统，包括金属骨架和安装在所述金属骨架上的天线回路，其特征在于，所述天线回路包括主贡献区段，所述主贡献区段的接收或发射信号能力明显强于其它区段。
  7. 根据权利要求6所述的天线系统，其特征在于，所述主贡献区段以外的其它区段的信号接收/发射信号的能力被所述金属骨架削弱。
  8. 根据权利要求6所述的天线系统，其特征在于，所述天线系统还包括信号屏蔽物质，所述信号屏蔽设施用于削弱天线回路中非主贡献区段的接收/发射信号的能力。
  9. 根据权利要求6所述的天线系统，其特征在于，所述金属骨架内有刻洞或刻槽，所述天线回路中非主贡献区段的导线放入所述刻洞或刻槽内。
  10. 根据权利要求6所述的天线系统，其特征在于，所述天线回路中非主贡献区段的导线紧紧缠绕在仪器金属骨架上。
  11. 根据权利要求8所述的天线系统，其特征在于，所述信号屏蔽物质覆盖，或部分覆盖，或包裹，或部分包裹在天线回路中非主贡献区段上。
  12. 根据权利要求11所述的天线系统，所述信号屏蔽物质为金属。
  13. 根据权利要求6所述的天线系统，所述金属骨架的外形是与钻杆匹配的圆柱形，所述天线回路的形状是只覆盖所述金属骨架部分圆周的圆缺形。
  14. 根据权利要求13所述的天线系统，其特征在于，所述天线系统还包括放置在所述金属骨架刻槽内的磁性材料，所述天线回路中主贡献区段的导线被放置所述磁性材料上。
  15. 根据权利要求13所述的天线系统，其特征在于，所述天线回路中非主贡献区段的导线被部分/全部放置在仪器金属骨架上的刻槽或刻洞内。
  16. 根据权利要求13所述的天线系统，其特征在于，所述天线回路中非主贡献区段的导线被信号屏蔽设施屏蔽。
  17. 根据权利要求13所述的天线系统，其特征在于，所述主贡献区段的导线以圆柱形的金属骨架的长轴为对称轴缠绕。
  18. 根据权利要求13所述的天线系统，其特征在于，所述主贡献区段的导线倾斜缠绕在所述金属骨架上。
  19. 根据权利要求13所述的天线系统，其特征在于，所述非主贡献区段的导线的形状可以是任意形状。
  20. 根据权利要求19所述的天线系统，其特征在于，所述非主贡献区段的导线的形状可以是任意形状被部分或全部放置在磁性材料侧面。
  21. 根据权利要求19所述的天线系统，其特征在于，所述非主贡献区段的导线被部分或全部放置在磁性材料下面。
  22. 一种用于测井的天线系统，其特征在于，所述天线系统包括由权利要求1所述的数个天线回路串联而成的一个完整的回路。
  23. 根据权利要求22所述的天线系统，其特征在于，串联的几个所述天线回路在仪器长轴位置相同，但方位角不同。
  24. 一种用于测井的天线系统，其特征在于，所述天线系统由一个或数个传统的均匀天线线圈与至少一个权利要求1所述的天线回路串联而成，所述串联是将传统的均匀天线线圈和所述天线回路串联而形成一个完 整的回路，所述均匀天线线圈和所述天线回路在仪器长轴位置可以相同，也可以不同。
  25. 一种用于测井的天线系统，其特征在于，所述天线系统由权利要求1所述的数个天线回路组成，所述天线回路相互独立且分时操作。
  26. 根据权利要求25所述的天线系统，其特征在于，所述的数个所述天线回路在仪器长轴位置相同，但方位角不同。
  27. 一种测井仪器，包括发射和接收天线组成的仪器线圈系，其特征在于，仪器线圈系的发射和接收天线中至少有一个为权利要求6～26中任意一项所述的天线系统。
  28. 根据权利要求27所述的测井仪器，其特征在于，所述仪器线圈系为单发单收仪器线圈系。
  29. 根据权利要求27所述的测井仪器，其特征在于，所述仪器线圈系为单发双收仪器线圈系。
  30. 根据权利要求27所述的测井仪器，其特征在于，所述仪器线圈系为双发双收仪器线圈系。
  31. 一种基于权利要求27～30中任意一项所述的测井仪器的测井方法，其特征在于，包括步骤：
    1)当仪器旋转时，测量所述的线圈系中至少一个接收线圈在至少一个发射线圈工作时在不同仪器旋转角度上的感应电动势；
    2)根据所测的在不同仪器旋转角度上的感应电动势得出测井结果。
  32. 根据权利要求31所述的测井方法，其特征在于，所述步骤2)中，利用所述步骤1)所测量到的接收线圈上的感应电动势来判别仪器和地层界面的方位。
  33. 根据权利要求32所述的测井方法，其特征在于，所述步骤2)中，利用步骤1)所得的感应电动势测量信号进行
    Figure PCTCN2015072435-appb-100001
    计算，并根据变量
    Figure PCTCN2015072435-appb-100002
    的幅度、相位、实部、虚部中的一项或多项，计算仪器到地层界面的距离和判别仪器和地层界面的方位；其中θ是仪器旋转角度，V(θ)是仪器在旋转角度为θ时的感生电动势。
  34. 根据权利要求32所述的测井方法，其特征在于，所述步骤2)中，利用步骤1)所得的感应电动势测量信号进行V(θ)-V(θ+π)计算，并根据变量V(θ)-V(θ+π)的幅度、相位、实部、虚部中的一项或多项，计算仪器到地层界面的距离和判别仪器和地层界面的方位；其中θ是仪器旋转角度，V(θ)是仪器在旋转角度为θ时的感生电动势。
  35. 根据权利要求32所述的测井方法，其特征在于，所述步骤2)中，利用步骤1)所得的感应电动势测量信号进行
    Figure PCTCN2015072435-appb-100003
    计算，并根据变量
    Figure PCTCN2015072435-appb-100004
    的幅度、相位、实部、虚部中的一项或多项，计算仪器到地层界面的距离和判别仪器和地层界面的方位；其中，其中θ是仪器旋转角度，V(θ)是仪器在旋转角度为θ时的感生电动势，Average(V(θ))是接收线圈中的感应电动势实测信号的算术平均。
  36. 根据权利要求32所述的测井方法，其特征在于，所述步骤1)中，测量两个接收线圈在相同发射线圈作用下产生的两组感应电动势；
    所述步骤2)中，利用步骤1)所得的感应电动势测量信号进行
    Figure PCTCN2015072435-appb-100005
    计算，并根据变量
    Figure PCTCN2015072435-appb-100006
    的幅度、相位、实部、虚部中的一项或多项，计算仪器到地层界面的距离和判别仪器和地层界面的方位，及方位电阻率；其中这里V1(θ)和V2(θ)分别是两个接收线圈在相同发射线圈工作时，在仪器旋转角度为θ就角度时产生的感应电动势。
  37. 根据权利要求32所述的测井方法，其特征在于，所述步骤1)中，测量两个接收线圈在相同发射线圈作用下产生的两组感应电动势；所述步骤2)中，利用步骤1)所得的感应电动势测量信号进行
    Figure PCTCN2015072435-appb-100007
    计算，并根据变量
    Figure PCTCN2015072435-appb-100008
    的幅度、相位、实部、虚部中的一项或多项，计算仪器到地层界面的距离和地层电阻率；其中，Average(V1(θ))和Average(V2(θ))分别是两个接收线圈中的感应电动势实测信号的算术平均。
  38. 根据权利要求32所述的测井方法，其特征在于，所述步骤1)中，测量两个接收线圈分别在两个不同发射线圈作用下产生的四组感应电动势；所述步骤2)中，利用步骤1)所得的双发双收四组感应电动势测量信号进行
    Figure PCTCN2015072435-appb-100009
    计算，并根据变量
    Figure PCTCN2015072435-appb-100010
    的幅度、相位、实部、虚部中的一项或多项，计算仪器到地层界面的距离、仪器和地层界面的相对位置和地层电阻率；这里Vij(θ)是指发射线圈i在接收线圈j上产生的感应电动势，i，j等于1或2。
  39. 根据权利要求32所述的测井方法，其特征在于，所述步骤1)中，测量两个接收线圈分别在两个不同发射线圈作用下产生的四组感应电动势；所述步骤2)中，利用步骤1)所得的双发双收四组感应电动势测量信号进行
    Figure PCTCN2015072435-appb-100011
    计算，并根据变量
    Figure PCTCN2015072435-appb-100012
    的幅度、相位、实部、虚部中的一项或多项计算仪器到地层界面的距离和地层电阻率；其中Average(Vij(θ))是指发射线圈i在接收线圈j上产生的感应电动势的实测值的算术平均，i，j等于1或2。
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