CN116411950A - Antenna system for detecting electromagnetic waves before drilling and measuring method - Google Patents
Antenna system for detecting electromagnetic waves before drilling and measuring method Download PDFInfo
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- E—FIXED CONSTRUCTIONS
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- E21B47/00—Survey of boreholes or wells
- E21B47/12—Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling
- E21B47/13—Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling by electromagnetic energy, e.g. radio frequency
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
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- E—FIXED CONSTRUCTIONS
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- E21B47/00—Survey of boreholes or wells
- E21B47/01—Devices for supporting measuring instruments on drill bits, pipes, rods or wirelines; Protecting measuring instruments in boreholes against heat, shock, pressure or the like
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- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B47/00—Survey of boreholes or wells
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Abstract
The invention discloses an antenna system for detecting electromagnetic waves before drilling and a measuring method, wherein the system comprises a front nipple, a screw rod and a far-ranging instrument, the front end of the front nipple is connected with a drill bit, and the rear end of the front nipple is connected with the far-ranging instrument through the screw rod. The front-end sub comprises an inclined transmitting antenna and a group of axial receiving antennas, and the far-edge detecting instrument comprises an inclined transmitting antenna, a group of axial receiving antennas and a plurality of groups of triaxial orthogonal receiving antennas. The invention can realize the function of front detection of a larger distance in front of the drill bit, and a plurality of groups of receiving antennas with different source distances can receive electromagnetic wave responses in different ranges of surrounding space, so that the information of un-drilled stratum with different depths in front of the drill bit can be obtained through inversion. The invention is beneficial to the problems of accurate landing of complex reservoir drilling, elimination of a pilot well, improvement of drilling meeting rate, drilling risk control, optimization of the reservoir, comprehensive fine evaluation of the reservoir and the like.
Description
Technical Field
The invention relates to the technical field of pre-detection logging, in particular to a pre-drilling detection electromagnetic wave antenna system and a measurement method.
Background
The logging technique of resistivity while drilling pre-detection can be divided into: logging while drilling lateral current resistivity and logging while drilling electromagnetic waves.
The existing logging instrument for logging while drilling lateral current resistivity and related technology mainly comprise: RAB, GVR, microScope instruments and AFR (azimuthal focusing resistivity) instruments are newly developed by Halliburton corporation in 1993, 1998 and 2008, respectively. The instrument adopts a current lateral measurement principle to realize the functions of lateral resistivity, drill resistivity measurement, resistivity imaging and the like. The resistivity of the drill bit has the capability of detecting the front of the drill bit, but the detection depth is too shallow, and the front view measurement range is generally within 1.2 m. In China, the national petroleum drilling institute in 2003 has introduced an NBRt near bit resistivity instrument, wherein bit resistivity also has a look-ahead measurement capability, the look-ahead measurement range being similar to that of a foreign while-drilling lateral current resistivity logging instrument.
Currently, only Schlumberger has advanced adeemla in 2016 and is named as IriSphere. IriSphere is composed of an inclined transmitting antenna and 2-3 receiving pup joints, each receiving pup joint is provided with 3 mutually orthogonal inclined receiving antennas, and the total length of the instrument is more than 23 m.
The prior logging instrument for detecting resistivity while drilling mainly has the following defects: the existing logging instrument for logging of the lateral current resistivity while drilling has the defects of limited detection range and short forward detection distance; the existing logging instrument for detecting electromagnetic waves before drilling is overlong in combination, a measuring signal is greatly influenced by bending and vibration of a drill collar, well drilling deflection is not facilitated, and safety risks of site construction operation are large.
Disclosure of Invention
The invention aims to overcome the defects of the existing instrument and provides a detection antenna system before drilling and a measurement method, wherein the antenna system is designed to combine a front short joint, a screw and a far-ranging instrument to obtain space responses in different surrounding ranges, and the information such as the stratum interface, the resistivity and the like in front of a drill bit is obtained through a geometric factor technology, so that a larger front detection distance is achieved. In order to achieve the above purpose, the present invention provides the following technical solutions:
an antenna system for detecting electromagnetic waves before drilling, which comprises a front nipple, a screw rod and a far-ranging instrument, wherein the front end of the front nipple is connected with a drill bit, the rear end of the front nipple is connected with the far-ranging instrument through the screw rod,
the front-end short section comprises an inclined transmitting antenna and a group of axial receiving antennas, wherein the front end of the inclined transmitting antenna is connected with the drill bit, and the axial receiving antennas are connected with the rear end of the inclined transmitting antenna.
The remote edge detection instrument comprises an inclined transmitting antenna, a group of axial receiving antennas and a plurality of groups of triaxial orthogonal receiving antennas, wherein the front end of each axial receiving antenna is close to the inclined transmitting antenna, and the rear end of each axial receiving antenna is close to the orthogonal receiving antenna.
Preferably, the axial receiving antenna comprises a first receiving antenna and a second receiving antenna; the first receive antenna is proximate to the tilted transmit antenna.
Preferably, the source distance between the first receiving antenna and the second receiving antenna of the axial receiving antenna is different, and the normal direction of the first receiving antenna and the normal direction of the second receiving antenna are in the same direction with the axis of the drilling direction.
Preferably, the triaxial orthogonal receiving antenna comprises an axial antenna, a first orthogonal antenna and a second orthogonal antenna; the front end of the axial antenna is close to the first orthogonal antenna, and the rear end of the axial antenna is close to the second orthogonal antenna.
Preferably, the axial antenna is in the same direction as the axis of the drilling direction, the first orthogonal antenna and the second orthogonal antenna are perpendicular to the axis of the drilling direction, and the normal direction of the axial antenna is the normal direction; the normal direction of the first orthogonal antenna and the normal direction of the second orthogonal antenna are orthogonal to each other.
The invention relates to a measurement method of an antenna for detecting electromagnetic waves before drilling, which comprises the following steps of: the inclined transmitting antenna transmits electromagnetic wave signals with different frequencies;
the receiving antenna receives the electromagnetic wave signals with different frequencies; according to the inclined transmitting antenna, transmitting electromagnetic wave signals with different frequencies and receiving the electromagnetic wave signals with different frequencies by the receiving antenna, forming a transmitting antenna-receiving antenna groupAnd to obtain direct measurement signal G n (σ, F), wherein σ represents formation conductivity, F represents a function of instrument frequency, n represents an nth set of transmit antenna-receive antenna combinations, n=1, 2,3 … … n; from the direct measurement signal G n (sigma, F) calculating the measured signal coefficient delta of the transmitting antenna-receiving antenna combination by geometric factors n The method comprises the steps of carrying out a first treatment on the surface of the Each group of transmit-receive antennas measures the signal coefficient delta n And direct measurement signal G n (sigma, F) calculating the preamble signal Fw of different detection depths n The method comprises the steps of carrying out a first treatment on the surface of the According to the preamble signal Fw n Calculating the foreshortening distance LA n 。
Preferably, the inclined transmitting antenna in the electromagnetic wave signals with different frequencies is the inclined transmitting antenna of the front short joint or the far-ranging instrument.
Preferably, the receiving antenna in the electromagnetic wave signals with different frequencies received by the receiving antenna refers to an axial receiving antenna of the front nipple, or an axial receiving antenna of the far-reaching edge-penetrating instrument, or a triaxial orthogonal receiving antenna of the far-reaching edge-penetrating instrument.
Preferably, the axial receiving antenna of the front nipple, the axial receiving antenna of the far-edge detecting instrument and the triaxial orthogonal receiving antenna of the far-edge detecting instrument can simultaneously receive the electromagnetic wave signals.
Preferably, the direct measurement signal refers to the measurement voltage signal of the same transmitting-receiving antenna combination, which represents the sum of contributions from all spatial directions in front, back and side of the instrument within a certain range, and the measurement voltage G is used n (σ, F).
Preferably, the direct measurement signal G n (σ, F), n=1, 2,3 … … n, wherein the measurement signal G of the first transmit antenna-receive antenna combination 1 (sigma, F) means that the oblique transmitting antenna on the front nipple transmits electromagnetic wave signals and the n group three-axis orthogonal receiving antenna pair of the far-edge detecting instrument measures voltages.
Measurement signal G of second transmitting antenna-receiving antenna combination 2 (sigma, F) means that the oblique transmitting antenna on the front nipple transmits electromagnetic wave signals and theThe n-1 group of triaxial orthogonal receiving antenna pairs of the far-edge detecting instrument measure voltages.
Measurement signal G of third transmitting antenna-receiving antenna combination 3 (sigma, F) means that the oblique transmitting antenna on the front nipple transmits electromagnetic wave signals and the n-2 group triaxial orthogonal receiving antenna pair of the far-ranging instrument measures voltages.
And so on, the n-th transmitting antenna-receiving antenna combined measuring signal G n And (sigma, F) means that the inclined transmitting antenna on the front nipple transmits electromagnetic wave signals and the axial receiving antenna of the far-ranging instrument measures voltage to voltage.
Measurement signal G of n+1th transmitting antenna-receiving antenna combination n+1 And (sigma, F) means that the inclined transmitting antenna on the front nipple transmits electromagnetic wave signals and the axial receiving antenna pair of the front nipple measures voltage.
Measurement signal G of n+2th transmitting antenna-receiving antenna combination n+2 (sigma, F) means that the oblique transmitting antenna of the far-ranging instrument transmits electromagnetic wave signals and the n group of oblique transmitting antennas of the far-ranging instrument transmits electromagnetic wave signals, and the axial receiving antenna pair of the far-ranging instrument measures voltage.
Measurement signal G of n+3th transmitting antenna-receiving antenna combination n+3 (sigma, F) means that the inclined transmitting antenna of the far-edge detecting instrument transmits electromagnetic wave signals and the n-1 group three-axis orthogonal receiving antenna pair of the far-edge detecting instrument measures voltages.
Analogize to the measurement signal G of 2n+2-th transmitting antenna-receiving antenna combination 2n+2 (sigma, F) means that the oblique transmitting antenna of the far-edge detecting instrument transmits electromagnetic wave signals and the axial receiving antenna pair of the far-edge detecting instrument measures voltages.
Preferably, the coefficient delta of the measurement signal n Determined by the equipotential surface of the three-dimensional geometry factor 90% contribution in the drilling direction.
Preferably, the preamble signal Fw of different detection depths is calculated n The calculation formula of (2) is as follows:
a preamble signal of a first probe depth:
a second probe depth preamble signal:
a preamble signal of a third probe depth:
similarly, the n-th probe depth preamble signal:
wherein n represents an n-th set of transmit antenna-receive antenna combinations, n=1, 2,3 … … n; i denotes the i-th set of transmit antenna-receive antenna combinations, i=n+1, n=1, 2,3 … … n; g n (sigma, F) is a measured voltage representing a duty cycle of the signal contribution to the total response from the space where the nth group of transmit antenna-receive antenna combinations receive; the delta is a measurement signal coefficient and represents G n (σ, F) differences in the contribution of the signal to the total response from the received space around; the Fw n For the preamble signal, denote G n (sigma, F) detecting a distance signal from the foremost end of the range to the instrument bit.
Preferably, the signal Fw is based on the preamble signal Fw n Calculating the foreshortening distance LA n The measured signal change of 10% is taken as a judgment standard for identifying the formation which is not drilled, namely Fw n The boundary distance corresponding to the curve change of 10% is LA n 。
The invention has the technical effects and advantages that:
1. the measuring point is arranged in front as much as possible. The instrument's forward detection distance needs to be subtracted by the measurement point-to-bit distance, which depends on the specific instrument and downhole tool combination implementation. In order to obtain a larger forward detection distance, the measuring point is as far forward as possible, and in the invention, a front nipple is designed and can be directly placed behind a drill bit;
2. the source distance is increased without increasing the instrument length. According to the electromagnetic wave logging principle, the detection range of the instrument and the source distance between a transmitting antenna and a receiving antenna are in an increasing function relation. In order to make the front detection range as large as possible, the source distance is increased while the length of the instrument is not increased, a screw rod which is necessary for drilling is arranged between the front nipple and the far-ranging instrument, the length of the screw rod is fully utilized, and the source distance is increased;
3. by adopting antennas with various angles of axial direction, inclination and orthogonality and antenna combination with different source distances, stratum information with different detection ranges can be measured, and stratum information with different depths in front of the drill bit can be accurately extracted through geometric factor calculation.
In summary, the antenna system for detecting electromagnetic waves before drilling and the measuring method thereof provided by the invention provide an antenna system with a front short joint connected with a far-ranging instrument, which can realize the front detection function of a larger distance in front of a drill bit. The multiple groups of receiving antennas with different source distances can be used for receiving electromagnetic wave responses in different ranges of surrounding space, so that information of un-drilled stratum with different depths in front of the drill bit can be obtained through geometric factors. Conventional receive antenna pairs are capable of measuring resistivity near the borehole. The antenna system can be used for measuring the formation resistivity at different detection depths respectively, and the interface in the un-drilled formation, the conductivities at two sides of the interface and the distance between the instrument and the interface can be predicted through data processing and geometric factor calculation. In a resistivity contrast 1:100 formation, the reach-ahead distance is above 10m. By the method, the problems of accurate landing of the drilling of the complex reservoir, elimination of the pilot hole, improvement of drilling meeting rate, drilling risk control, optimization of the reservoir, comprehensive fine evaluation of the oil reservoir and the like are solved.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
FIG. 1 is a schematic diagram of the structure of the present invention;
FIG. 2 is a schematic diagram showing measurement of different range signals according to the present invention;
FIG. 3 is a graph of three-dimensional geometry factor 90% contribution equipotential surfaces;
FIG. 4 is a schematic diagram of the detection depth corresponding to different range signals according to the present invention;
FIG. 5 is a schematic diagram of the detection range in the present invention;
FIG. 6 is a graph of measurements of the instrument at different well angles;
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In order to solve the defects in the prior art, the invention discloses a system for detecting electromagnetic wave antenna before drilling and a measuring method, as shown in figure 1, wherein the system comprises a front nipple, a screw rod and a far-ranging instrument, the front end of the front nipple is connected with a drill bit, the rear end of the front nipple is connected with the far-ranging instrument through the screw rod, the front nipple comprises an inclined transmitting antenna and a group of axial receiving antennas, the front end of the inclined transmitting antenna is connected with the drill bit, and the axial receiving antennas are connected with the rear end of the inclined transmitting antenna; the remote edge detection instrument comprises an inclined transmitting antenna, a group of axial receiving antennas and a plurality of groups of triaxial orthogonal receiving antennas, and the triaxial orthogonal receiving antennas of the remote edge detection instrument are long-source-distance receiving antennas. The front end of the axial receiving antenna is close to the inclined transmitting antenna, and the rear end of the axial receiving antenna is close to the triaxial orthogonal receiving antenna.
Further, the axial receiving antenna comprises a first receiving antenna and a second receiving antenna; the first receiving antenna is close to the inclined transmitting antenna; the source distances of a first receiving antenna and a second receiving antenna of the axial receiving antennas are different, and the normal direction of the first receiving antenna and the normal direction of the second receiving antenna are in the same direction with the axis of the drilling direction; the triaxial orthogonal receiving antenna comprises an axial antenna, a first orthogonal antenna and a second orthogonal antenna; the front end of the axial antenna is close to the first orthogonal antenna, and the rear end of the axial antenna is close to the second orthogonal antenna. The axial antenna is in the same direction with the axis of the drilling direction, the first orthogonal antenna and the second orthogonal antenna are perpendicular to the axis of the drilling direction, and the normal direction of the axial antenna is the normal direction; the normal direction of the first orthogonal antenna and the normal direction of the second orthogonal antenna are orthogonal to each other.
The invention relates to a measurement method of an antenna for detecting electromagnetic waves before drilling, which adopts the system of the invention and comprises the following steps:
the inclined transmitting antenna transmits electromagnetic wave signals with different frequencies;
the receiving antenna receives the electromagnetic wave signals with different frequencies;
according to the inclined transmitting antenna, transmitting electromagnetic wave signals with different frequencies and receiving the electromagnetic wave signals with different frequencies by the receiving antenna, forming a transmitting antenna-receiving antenna combination, and obtaining a direct measurement signal G n (σ,F)；
From the direct measurement signal G n (sigma, F) calculating a measured signal coefficient delta of the transmit antenna-receive antenna combination by a geometric factor n ；
Measurement signal coefficient delta for each set of transmit-receive antenna combinations n And direct measurement signal G n (sigma, F) calculating the preamble signal Fw of different detection depths n ；
According to the preamble signal Fw n Calculating the foreshortening distance LA n 。
Further, the inclined transmitting antenna in the electromagnetic wave signals with different frequencies is the inclined transmitting antenna of the front short section or the far-ranging instrument.
Further, the receiving antenna in the electromagnetic wave signals with different frequencies received by the receiving antenna refers to an axial receiving antenna of a front nipple or an axial receiving antenna of a far-ranging instrument and a triaxial orthogonal receiving antenna of the far-ranging instrument. The axial receiving antenna of the front nipple, the axial receiving antenna of the far-edge detection instrument and the triaxial orthogonal receiving antenna of the far-edge detection instrument can simultaneously receive the electromagnetic wave signals.
Further, the direct measurement signal refers to the measurement voltage signal of the same transmitting and receiving antenna combination, and represents the sum of all the contributions from the front, rear and side space directions of the instrument within a certain range, and the measurement voltage G is used n (σ, F), where σ represents formation conductivity, F represents a function of instrument frequency, n represents the nth set of transmit antenna-receive antenna combinations, n=1, 2,3 … … n.
Further, as shown in fig. 2, the measurement signal G of the first transmit antenna-receive antenna combination 1 (sigma, F) means that the oblique transmitting antenna on the front nipple transmits electromagnetic wave signals and the n group triaxial orthogonal receiving antenna pair of the far-ranging instrument measures voltages; measurement signal G of second transmitting antenna-receiving antenna combination 2 (sigma, F) means that the oblique transmitting antenna on the front short section transmits electromagnetic wave signals and the n-1 group triaxial orthogonal receiving antenna pair of the far-ranging instrument measures voltages; measurement signal G of third transmitting antenna-receiving antenna combination 3 (sigma, F) means that the inclined transmitting antenna on the front short section transmits electromagnetic wave signals and the n-2 group triaxial orthogonal receiving antenna pair of the far-ranging instrument measures voltages; analogize to the above, the measurement signal G of the nth transmit antenna-receive antenna combination n And (sigma, F) means that the inclined transmitting antenna on the front nipple transmits electromagnetic wave signals and the axial receiving antenna of the far-ranging instrument measures voltage to voltage.
Further, the (n+1) th transmitting antenna-receiving antenna combined measurement signal G n+1 (sigma, F) means that the inclined transmitting antenna on the front nipple transmits electromagnetic wave signals and the axial receiving antenna of the front nipple is used for measuringA voltage; measurement signal G of n+2th transmitting antenna-receiving antenna combination n+2 (sigma, F) means that the inclined transmitting antenna of the far-edge detecting instrument transmits electromagnetic wave signals and the n group of inclined transmitting antennas of the far-edge detecting instrument transmits electromagnetic wave signals, and the axial receiving antenna pair of the far-edge detecting instrument measures voltage; measurement signal G of n+3th transmitting antenna-receiving antenna combination n+3 (sigma, F) means that the inclined transmitting antenna of the far-edge detecting instrument transmits electromagnetic wave signals and the n-1 group triaxial orthogonal receiving antenna pair of the far-edge detecting instrument measures voltages; analogize to the measurement signal G of 2n+2-th transmitting antenna-receiving antenna combination 2n+2 (sigma, F) means that the remote edge-detecting instrument transmits electromagnetic wave signals obliquely to the pair of axial receiving antennas of the remote edge-detecting instrument to measure voltages.
Direct measurement signal G n (σ, F) represents the sum of all the spatial contributions from the instrument front, back and side over a range. G for different transmit and receive antenna combinations n The difference in the contribution of the regions of the received space to the total response is (sigma, F), the measured signal coefficient of which can be represented by delta.
With the system of the invention, the measurement signal G of the first transmitting antenna-receiving antenna combination 1 (sigma, F) the detection range is large, the 2 nd, 3 … … n transmitting antenna-receiving antenna combined measuring signal G 2 (σ,F)、G 3 (σ,F)……G n The (sigma, F) detection range decreases in turn, and the signal coefficient delta is measured according to each group of transmitting-receiving antennas n And direct measurement signal G n (sigma, F) calculating the preamble signal Fw of different detection depths n The method comprises the steps of carrying out a first treatment on the surface of the According to the preamble signal Fw n Calculating the foreshortening distance LA n 。
Further, according to the measurement signal G of the first transmit antenna-receive antenna combination shown in fig. 5 1 The (sigma, F) detection range is large, the measured signal is the sum of the responses from the formations 1,2, except that the contributions of the formations 1,2 are different. Likewise, the measurement signals G of the 2 nd and 3 th … … n transmitting antenna-receiving antenna combinations 2 (σ,F)、G 3 (σ,F)……G n The (sigma, F) detection range decreases in turn, the measurement signal is again the sum of the responses from the formations 1,2,except that the contribution of formation 2 is greater. The formation 1 is a drilled formation, the resistivity of which can be measured.
Further, as shown in fig. 3, by making the source distance between the transmitting antenna and the receiving antenna be L by the geometric factor 90% contributing to the equipotential surface in the drilling direction, the equipotential surface in the drilling direction in fig. 3 is at 2L. Calculating the measured signal coefficients of each group of transmitting-receiving antennas, i.e. G 1 (σ,F)、G 2 (σ,F)、 G 3 (σ,F)……G n Coefficient delta of (sigma, F) 1 、δ 2 、δ 3 ……δ n 。
Further, the signal coefficient delta is measured n Determined by the equipotential surface of the three-dimensional geometry factor 90% contribution in the drilling direction. And solving the equipotential surface position contributed by 90% of the three-dimensional geometric factors of the transmitting-receiving antennas of each group of source distances, and calculating the weight of the geometric factors of the transmitting-receiving antennas of each group of source distances, namely the measurement signal coefficient.
Further, the measurement signal with the larger detection depth is subtracted from the measurement signal with the smaller detection depth, and the coefficient of the measurement signal is obtained through three-dimensional geometric factor calculation. The forepoling signal reflects the distance of the instrument from the interface and the formation resistivity at different depths of investigation on either side of the interface. According to the G n (sigma, F) and delta n Calculating the front detection signals Fw with different detection depths n The calculation formula of (2) is as follows:
a preamble signal of a first probe depth:
a second probe depth preamble signal:
a preamble signal of a third probe depth:
similarly, the n-th probe depth preamble signal:
wherein n represents an n-th set of transmit antenna-receive antenna combinations, n=1, 2,3 … … n; g n (sigma, F) is a measured voltage representing a duty cycle of the signal contribution to the total response from the space where the nth group of transmit antenna-receive antenna combinations receive; the delta is different detection depths and represents G n (σ, F) differences in the contribution of the signal to the total response from the received space around; the Fw n For the preamble signal, denote G n (sigma, F) detecting a distance signal from the foremost end of the range to the instrument bit.
Further, the method is based on the preamble Fw n Calculating the pre-detection distance LA n The measured signal change of 10% is taken as a judgment standard for identifying the formation which is not drilled, namely Fw n The boundary distance corresponding to the curve change of 10% is LA n 。
The invention will be further illustrated with reference to specific examples.
Taking the invention as an example of drilling a two-layer stratum vertical well, as shown in FIG. 5, the antenna system of the invention is adopted to measure the signal G of the first transmitting antenna-receiving antenna combination 1 The (sigma, F) detection range is large, the measured signal is the sum of the responses from the formations 1,2, except that the contributions of the formations 1,2 are different. Likewise, the second, third and fourth transmitting antenna-receiving antenna combinations measure the signal G 2 (σ,F)、G 3 (σ,F)、G 4 The (σ, F) detection range is smaller and the measurement signal is the sum of the responses from formation 1, formation 2 as well, except that the contribution of formation 2 is greater. The formation 1 is a drilled formation, the resistivity of which can be measured and then calculated from the inverse of the resistivity to give the conductivity. By making the source distance between the transmitting antenna and the receiving antenna be L by the geometric factor 90% contributing to the equipotential surface in the drilling direction, the equipotential surface in the drilling direction in FIG. 3 is at 2L. Calculating the geometric factor weight of each group of transmitting-receiving antennas, namely G 1 (σ,F)、G 2 (σ,F)、G 3 (σ,F)、G 4 Coefficient delta of (sigma, F) 1 、δ 2 、δ 3 、δ 4 Then the preamble signal of different probe depth can be obtained:
pre-probe signal of instrument first probe depth:
pre-probe signal of instrument second probe depth:
pre-probe signal of instrument third probe depth:
the instrument fourth probe depth pre-probe signal:
with reference to fig. 4, the geometrical factor 90% contributes to the equipotential surface in the drilling direction, and the source distance between the transmitting antenna and the receiving antenna is L, further, the geometric factor 90% contributes to the equipotential surface in the drilling direction, and the geometric factor is further equal to the geometrical factor n As a criterion for identifying an unerring formation, i.e. Fw n The boundary distance corresponding to the curve change of 10% is LA n ，n＝1，2，3，4。
FIG. 6 shows that in a 1:100 single-boundary formation, the resistivity at both sides of the boundary is 1Ω·m and 100deg.Ω·m, respectively, and the conductivity σ can be obtained from the resistivity, and further the front curve Fw of 4 depths of investigation can be obtained 1 、 Fw 2 、Fw 3 、Fw 4 . Wherein Fw 1 The detection depth is the largest, firstly, theDetermining that an interface exists, taking the change of the measured signal by 10% as a determination standard for identifying the formation which is not drilled, and Fw 1 The front detection distance is greater than 10m. Due to Fw 1 The detection range is the largest, and the resistivity Rt1 of the first layer in the drilling underground is greatly influenced by the resistivity Rt2 of the second layer in the underground, namely the conductivity sigma 1 of the first layer in the drilling underground is greatly influenced by the conductivity sigma 2 of the second layer in the underground. To measure the signal Fw n The change by 10% is used as a judging standard for identifying the formation which is not drilled, namely Fw n The boundary distance corresponding to the curve change of 10% is LA n 。
Finally, it should be noted that: the foregoing description is only illustrative of the preferred embodiments of the present invention, and although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described, or equivalents may be substituted for elements thereof, and any modifications, equivalents, improvements or changes may be made without departing from the spirit and principles of the present invention.
Claims (14)
1. An antenna system for detecting electromagnetic waves before drilling, which comprises a front nipple, a screw rod and a far-ranging instrument, and is characterized in that the front end of the front nipple is connected with a drill bit, the rear end of the front nipple is connected with the far-ranging instrument through the screw rod, wherein,
the front-end short section comprises an inclined transmitting antenna and a group of axial receiving antennas, wherein the front end of the inclined transmitting antenna is connected with a drill bit, and the axial receiving antennas are connected with the rear end of the inclined transmitting antenna;
the remote edge-detecting instrument comprises an inclined transmitting antenna, a group of axial receiving antennas and a plurality of groups of triaxial orthogonal receiving antennas, wherein the front end of each axial receiving antenna is close to the inclined transmitting antenna, and the rear end of each axial receiving antenna is close to the orthogonal receiving antenna.
2. An antenna system for detecting electromagnetic waves before drilling according to claim 1,
the axial receiving antenna comprises a first receiving antenna and a second receiving antenna; the first receive antenna is proximate to the tilted transmit antenna.
3. An antenna system for pre-drilling detection of electromagnetic waves as claimed in claim 2,
the source distances of a first receiving antenna and a second receiving antenna of the axial receiving antennas are different, and the normal direction of the first receiving antenna and the normal direction of the second receiving antenna are in the same direction with the axis of the drilling direction.
4. An antenna system for detecting electromagnetic waves before drilling according to claim 1,
the triaxial orthogonal receiving antenna comprises an axial antenna, a first orthogonal antenna and a second orthogonal antenna;
the front end of the axial antenna is close to the first orthogonal antenna, and the rear end of the axial antenna is close to the second orthogonal antenna.
5. An antenna system for pre-drilling detection of electromagnetic waves as claimed in claim 4,
the axial antenna is in the same direction with the axis of the drilling direction, the first orthogonal antenna and the second orthogonal antenna are perpendicular to the axis of the drilling direction, and the normal direction of the axial antenna is the normal direction; the normal direction of the first orthogonal antenna and the normal direction of the second orthogonal antenna are orthogonal to each other.
6. A method for measuring an antenna for detecting electromagnetic waves before drilling, said method employing the antenna system according to any one of claims 1-5, characterized in that said method comprises the steps of:
the inclined transmitting antenna transmits electromagnetic wave signals with different frequencies;
the receiving antenna receives the electromagnetic wave signals with different frequencies;
transmitting electricity of different frequencies according to the inclined transmitting antennaThe magnetic wave signal and the receiving antenna receive the electromagnetic wave signals with different frequencies to form a transmitting antenna-receiving antenna combination, and obtain a direct measurement signal G n (σ, F), wherein σ represents formation conductivity, F represents a function of instrument frequency, n represents the nth set of transmit antenna-receive antenna combinations, n=1, 2,3 … … n;
from the direct measurement signal G n (sigma, F) calculating the measured signal coefficient delta of the transmitting antenna-receiving antenna combination by geometric factors n ；
Each group of transmit-receive antennas measures the signal coefficient delta n And direct measurement signal G n (sigma, F) calculating the preamble signal Fw of different detection depths n ；
According to the preamble signal Fw n Calculating the foreshortening distance LA n 。
7. The method for detecting an electromagnetic wave antenna before drilling according to claim 6, wherein,
the inclined transmitting antenna in the electromagnetic wave signals with different frequencies is the inclined transmitting antenna of the front short joint or the far-ranging instrument.
8. The method for detecting an electromagnetic wave antenna before drilling according to claim 6, wherein,
the receiving antenna in the electromagnetic wave signals with different frequencies is the axial receiving antenna of the front nipple, the axial receiving antenna of the far-ranging instrument and the triaxial orthogonal receiving antenna of the far-ranging instrument.
9. The method for detecting electromagnetic wave antenna before drilling according to claim 8, wherein,
the axial receiving antenna of the front nipple, the axial receiving antenna of the far-edge detection instrument and the triaxial orthogonal receiving antenna of the far-edge detection instrument can simultaneously receive the electromagnetic wave signals.
10. The method for detecting an electromagnetic wave antenna before drilling according to claim 6, wherein,
the direct measurement signal refers to the measurement voltage signal of the same transmitting-receiving antenna combination, which represents the sum of all the contributions from the front, back and side of the instrument in a certain range, and the measurement voltage G is used n (σ, F).
11. A method for detecting electromagnetic wave antenna before drilling according to claim 10, characterized in that the direct measurement signal G n (σ, F), n=1, 2,3 … … n, wherein,
measurement signal G of a first transmit antenna-receive antenna combination 1 (sigma, F) means that the oblique transmitting antenna on the front nipple transmits electromagnetic wave signals and the n group three-axis orthogonal receiving antenna pair of the far-edge detecting instrument measures voltages;
measurement signal G of second transmitting antenna-receiving antenna combination 2 (sigma, F) means that the oblique transmitting antenna on the front nipple transmits electromagnetic wave signals and the n-1 group triaxial orthogonal receiving antenna pair of the far-ranging instrument measures voltages;
measurement signal G of third transmitting antenna-receiving antenna combination 3 (sigma, F) means that the oblique transmitting antenna on the front nipple transmits electromagnetic wave signals and the n-2 group triaxial orthogonal receiving antenna pair of the far-ranging instrument measures voltages;
and so on, the n-th transmitting antenna-receiving antenna combined measuring signal G n (sigma, F) means that the inclined transmitting antenna on the front nipple transmits electromagnetic wave signals and the axial receiving antenna of the far-ranging instrument measures voltage to voltage;
measurement signal G of n+1th transmitting antenna-receiving antenna combination n+1 (sigma, F) means that the inclined transmitting antenna on the front nipple transmits electromagnetic wave signals and the axial receiving antenna pair of the front nipple measures voltage;
measurement signal G of n+2th transmitting antenna-receiving antenna combination n+2 (sigma, F) means that the oblique transmitting antenna of the far-edge probe transmits electromagnetic wave signals and the nth group of the far-edge probeThe inclined transmitting antenna transmits electromagnetic wave signals, and the axial receiving antenna pair of the far-ranging instrument measures voltage;
measurement signal G of n+3th transmitting antenna-receiving antenna combination n+3 (sigma, F) means that the inclined transmitting antenna of the far-edge detecting instrument transmits electromagnetic wave signals and the n-1 group three-axis orthogonal receiving antenna pair of the far-edge detecting instrument measures voltages;
analogize to the measurement signal G of 2n+2-th transmitting antenna-receiving antenna combination 2n+2 (sigma, F) means that the oblique transmitting antenna of the far-edge detecting instrument transmits electromagnetic wave signals and the axial receiving antenna pair of the far-edge detecting instrument measures voltages.
12. The method for detecting an electromagnetic wave antenna before drilling according to claim 6, wherein,
coefficient delta of the measurement signal n Determined by the equipotential surface of the three-dimensional geometry factor 90% contribution in the drilling direction.
13. The method for detecting electromagnetic wave antenna while drilling according to claim 6, wherein the pre-detection signals Fw with different detection depths are calculated n The calculation formula of (2) is as follows:
a preamble signal of a first probe depth:
a second probe depth preamble signal:
a preamble signal of a third probe depth:
similarly, the n-th probe depth preamble signal:
where n represents the n-th set of transmit antenna-receive antenna combinations, n=1, 2,3 … … n; i denotes the i-th set of transmit antenna-receive antenna combinations, i=n+1, n=1, 2,3 … … n; g n (sigma, F) is a measured voltage representing a duty cycle of the signal contribution to the total response from the space where the nth group of transmit antenna-receive antenna combinations receive; delta is the measurement signal coefficient and represents G n (σ, F) differences in the contribution of the signal to the total response from the received space around; the Fw n For the preamble signal, denote G n (sigma, F) detecting a distance signal from the foremost end of the range to the instrument bit.
14. The method for detecting an electromagnetic wave antenna before drilling according to claim 6, wherein,
said signal Fw is based on the preamble signal Fw n Calculating the foreshortening distance LA n The measured signal change of 10% is taken as a judgment standard for identifying the formation which is not drilled, namely Fw n The boundary distance corresponding to the curve change of 10% is LA n 。
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| CN113236227A (en) * | 2021-06-24 | 2021-08-10 | 徐梓辰 | Flexible well logging device and method |
| CN117967298A (en) * | 2024-03-27 | 2024-05-03 | 中国科学院地质与地球物理研究所 | Electromagnetic wave-front vision detector while drilling and detection method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113236227A (en) * | 2021-06-24 | 2021-08-10 | 徐梓辰 | Flexible well logging device and method |
| CN117967298A (en) * | 2024-03-27 | 2024-05-03 | 中国科学院地质与地球物理研究所 | Electromagnetic wave-front vision detector while drilling and detection method |
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