CN112925021B - Logging method for detecting stratum shear wave velocity radial distribution by surface wave - Google Patents
Logging method for detecting stratum shear wave velocity radial distribution by surface wave Download PDFInfo
- Publication number
- CN112925021B CN112925021B CN202110108769.5A CN202110108769A CN112925021B CN 112925021 B CN112925021 B CN 112925021B CN 202110108769 A CN202110108769 A CN 202110108769A CN 112925021 B CN112925021 B CN 112925021B
- Authority
- CN
- China
- Prior art keywords
- time difference
- wave
- curve
- stratum
- depth
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000000034 method Methods 0.000 title claims abstract description 33
- 239000000523 sample Substances 0.000 claims abstract description 81
- 239000006185 dispersion Substances 0.000 claims abstract description 55
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 50
- 238000006243 chemical reaction Methods 0.000 claims description 2
- 230000008859 change Effects 0.000 abstract description 13
- 230000005284 excitation Effects 0.000 abstract description 10
- 230000008569 process Effects 0.000 abstract description 6
- 238000012545 processing Methods 0.000 abstract description 4
- 238000005755 formation reaction Methods 0.000 description 47
- 239000007787 solid Substances 0.000 description 18
- 239000012530 fluid Substances 0.000 description 10
- 239000007788 liquid Substances 0.000 description 10
- 238000005259 measurement Methods 0.000 description 8
- 238000001514 detection method Methods 0.000 description 6
- 238000005553 drilling Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 230000001902 propagating effect Effects 0.000 description 4
- 230000003595 spectral effect Effects 0.000 description 4
- 238000013459 approach Methods 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 239000003208 petroleum Substances 0.000 description 3
- 230000004044 response Effects 0.000 description 3
- 240000007817 Olea europaea Species 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 238000012937 correction Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 239000011159 matrix material Substances 0.000 description 2
- 230000005404 monopole Effects 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 230000005405 multipole Effects 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
- G01V1/28—Processing seismic data, e.g. for interpretation or for event detection
- G01V1/30—Analysis
- G01V1/303—Analysis for determining velocity profiles or travel times
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
- G01V1/00—Seismology; Seismic or acoustic prospecting or detecting
- G01V1/40—Seismology; Seismic or acoustic prospecting or detecting specially adapted for well-logging
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
- Y02A90/30—Assessment of water resources
Landscapes
- Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Remote Sensing (AREA)
- Acoustics & Sound (AREA)
- Environmental & Geological Engineering (AREA)
- Geology (AREA)
- General Life Sciences & Earth Sciences (AREA)
- General Physics & Mathematics (AREA)
- Geophysics (AREA)
- Geophysics And Detection Of Objects (AREA)
Abstract
The invention discloses a logging method for detecting the radial distribution of stratum shear wave velocity by using surface waves, which comprises the following steps: the two transmitting probes are connected with the array receiving probe, the transmitting probes alternately transmit, and the receiving probe receives the waveform; extracting phase information of different frequencies in the array waveform during near-far source distance excitation by a phase method to generate a distribution curve and a time difference dispersion curve; respectively extracting time difference dispersion curves of transverse waves and surface waves in the distribution curve; converting the transverse wave time difference dispersion curve into a radial depth-time difference curve; subtracting the radial depth-time difference curves of the near source distance and the far source distance on the corresponding radial depth, and adding the time difference of the time difference dispersion curve at the surface wave cut-off frequency to obtain a transverse wave time difference along with the radial depth change curve at the depth; and obtaining a curve of the transverse wave time difference of all depth positions along with the change of radial depth, and taking the reciprocal as the transverse wave velocity to obtain a stratum transverse wave velocity profile around the well. The invention takes surface waves in the waveform received in the well as a measuring object and a processing target, and uses the surface waves to process the radial distribution of the formation transverse wave velocity.
Description
Technical Field
The invention belongs to the technical field of special instruments for measuring physical parameters of an open hole stratum and evaluating lithology in logging construction of petroleum engineering, and particularly relates to a logging method for detecting radial distribution of stratum transverse wave velocity by using surface waves.
Background
In the process of petroleum exploration and development and during all ground drilling measurement, stratum transverse wave time difference has important significance on engineering construction design and lithology analysis and judgment. During the drilling process, the stratum or rock originally subjected to various stress states have important influence on the crushing mode and degree, and the detection of the crushing and loosening conditions of the stratum around the drilling hole has important significance on analyzing the stratum, knowing the stress state, constructing design and the like. The vibration is excited in the borehole, when sound waves propagate along the borehole, surface waves on the surface of the borehole also propagate on the borehole wall along with longitudinal waves and transverse waves of the stratum, and the amplitude of the waves coupled with the surface waves in the liquid in the borehole is large. The velocity of these waves is slightly less than the shear velocity of the formation, equal to it at its cut-off frequency; as the frequency increases, the velocity continuously decreases and gradually approaches the velocity of the fluid in the well. This is a characteristic surface wave dispersion curve in the well, which is caused by the borehole. This dispersion curve of the surface wave, which is connected to the shear wave velocity of the formation, has been used to calculate the shear wave velocity of the formation (the phase velocity at the position where the dispersion curve disappears when changing to a low frequency, i.e. the shear wave velocity of the formation) or to perform dispersion correction on the shear wave velocity of the formation (usually, because of dispersion, its velocity is lower than the shear wave velocity of the formation) extracted by the correlation method. The analysis of formation characteristics has never been done directly with surface waves.
The amplitude of the surface wave in the ground excited and received vibrations is also large. People process the dispersion curve by the received array waveform and use the dispersion curve to layer along with the jump of frequency, thus realizing the surface wave exploration method which takes the surface wave as the main measurement object and the processing target.
Disclosure of Invention
The invention provides a logging method for detecting the radial distribution of the formation transverse wave velocity by using surface waves according to the wave front shape and the propagation velocity characteristics of the surface waves in a borehole and the influence of a cylindrical borehole on the propagation characteristics of the surface waves, which can process the radial distribution of the formation transverse wave velocity from a measured waveform and expand the radial distribution to a low frequency to realize the detection target of a radial far distance (the reciprocal of a wave number corresponding to the cut-off frequency of the surface waves caused by the well radius).
The purpose of the invention is realized by the following technical scheme.
The invention relates to a logging method for detecting the radial distribution of the transverse wave velocity of a stratum by using surface waves, which comprises the following steps:
step one, two transmitting probes and an array receiving probe are connected together along the same axis in a hard mode, the two transmitting probes are located on the upper side or the lower side of the array receiving probe at the same time, an acoustic system formed by the two transmitting probes is integrally placed in an open hole along a well axis, the two transmitting probes alternately transmit, and all the probes in the array receiving probe receive logging waveforms at the same time; one of the two transmitting probes is close to the array receiving probe, and the other transmitting probe is far away from the array receiving probe and is respectively used as a near source distance transmitting probe and a far source distance transmitting probe;
respectively extracting phase information of different frequencies in the array logging waveform when the near-source distance transmitting probe and the far-source distance transmitting probe are excited by using a phase method, and generating a distribution curve of a two-dimensional plane and a time difference dispersion curve which are formed by wave number-frequency through the linear relation of the phase along with the source distance;
extracting time difference dispersion curves of stratum transverse waves and surface waves in the distribution curve of the two-dimensional plane respectively;
step four, converting the time difference dispersion curve of the formation transverse wave into a radial depth-time difference curve through a distribution curve of a two-dimensional plane, wherein the radial depth is the reciprocal of the wave number;
subtracting a radial depth-time difference curve obtained by the near source distance logging waveform and a radial depth-time difference curve obtained by the far source distance logging waveform on a radial depth corresponding to the depth of the measured stratum, and adding the time difference of the near source distance or far source distance time difference dispersion curve at the cut-off frequency of the surface wave to the obtained time difference curve to obtain a variation curve of the stratum transverse wave time difference at the depth along with the radial depth;
and step six, repeating the steps one to five to obtain variation curves of the stratum transverse wave time differences at all depth positions along with the radial depth, drawing the variation curves of the stratum transverse wave time differences at all depth positions along with the depth to form a profile of the stratum transverse wave time differences along with the depth, and obtaining the stratum transverse wave velocity profile of the stratum around the well, wherein the reciprocal of the stratum transverse wave time differences is the stratum transverse wave velocity.
In the first step, the distance between the near source distance transmitting probe and the array receiving probe is 0.2-1m, the distance between the far source distance transmitting probe and the array receiving probe is 2.5-3m, the near source distance transmitting probe and the far source distance transmitting probe independently excite vibration, the array receiving probe at least comprises four receiving probes which are distributed at equal intervals along the same axis, and all the joint probes simultaneously receive logging waveforms with different source distances.
The conversion mode of the radial depth-time difference curve in the fourth step is as follows: taking the reciprocal of the wave number corresponding to each distribution point on the distribution curve of the wave number-frequency two-dimensional plane to obtain the wavelength, taking the reciprocal as the abscissa as the radial depth of the distribution point, finding the frequency corresponding to the wave number on the formation transverse wave time difference dispersion curve in the wave number-frequency two-dimensional plane, and dividing the wave number by the frequency to obtain the time difference of the radial depth, so that the time difference dispersion curve is converted into a radial depth-time difference curve to obtain the time differences of different radial depths.
And fifthly, reflecting the fracture condition of the stratum around the well and the damage condition of the well hole by the change curve of the stratum transverse wave time difference along with the radial depth.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
(1) The invention realizes the measurement of the radial distribution of the formation shear wave velocity of the open hole well and directly provides the formation shear wave velocity distribution of the formation along the radial direction. The fracture of the drill bit on the stratum and the stratum shear wave velocity distribution of the stratum along the radial direction during the drilling process are described.
(2) The invention makes full use of the stratum transverse wave time difference information carried by the surface wave with the maximum amplitude in the logging waveform. The logging method, especially the measurement of formation transverse wave information, is enriched.
(3) The invention makes full use of the characteristics of surface waves, and uses the surface waves caused by the liquid-solid boundary of the well hole for measuring the transverse wave speed of the stratum and detecting the far distance in the radial direction.
Drawings
FIG. 1 is a schematic view of a surface wave at a liquid-solid planar interface;
FIG. 2 is a schematic of a surface wave at a liquid-solid circular interface;
FIG. 3 is a schematic diagram of a surface wave excited by an off-center acoustic source in a well fluid;
FIG. 4 is a schematic illustration of a surface wave excited by a central acoustic source in a borehole fluid;
FIG. 5 is a schematic representation of a two-dimensional spectral distribution and surface waves of an acoustic response in a borehole fluid;
FIG. 6 is a schematic of a surface wave in an actual monopole sonic logging instrument and an actual logging waveform;
FIG. 7 is a schematic diagram of the distribution positions of dispersion curves and surface waves processed from an array sonic logging waveform by a matrix method;
FIG. 8 (a) is a schematic diagram of two-dimensional spectral distribution (wavenumber-frequency) obtained from an array waveform by a matrix method;
fig. 8 (b) is a schematic diagram of a moveout dispersion curve (moveout-frequency) obtained from a two-dimensional spectral distribution obtained from an array waveform.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
The invention measures the transverse wave time difference of stratum with different radial depths according to the surface wave caused by the liquid-solid cylindrical interface of the well hole and the dispersion curve thereof. And obtaining a change curve of the stratum transverse wave time difference along with the radius, and obtaining a stratum transverse wave velocity profile of the stratum around the well.
As shown in fig. 1, the present invention is based on surface waves existing at the liquid-solid interface (pseudo sharp waves at the liquid-solid interface connected to the formation shear waves in the solid, not the Stoneley waves connected to the direct waves of the liquid). The equipotential surface of the wave is in the shape of an olive extending into the formation to a certain depth and is composed of a plurality of olive-shaped wave fronts with different phases. Propagating along the liquid-solid interface at a velocity slightly less than the shear wave velocity of the formation and therefore closely following the shear wave front in the wave front distribution at a particular time. Longitudinal and transverse waves in a solid are acoustic waves that propagate deep into the formation. The wavefront is circular (three-dimensionally spherical) see the two circular arcs of fig. 1. A surface wave is an olive-type wave front that exists at a certain depth on the surface solid side. Both propagation characteristics and the area of the formation reached are completely different. Surface waves exist only at the surface and can therefore be used to measure the area of the formation reached by the olive-type wave front. The lower the frequency, the larger the olive wavefront, and the deeper the depth of detection.
FIG. 2 shows the wave fronts of longitudinal and transverse waves and the wave fronts of surface waves of a solid at a circular liquid-solid interface, which have the same characteristics as those of a horizontal liquid-solid interface, and the wave fronts are also olive-shaped and penetrate into the stratum to a certain depth.
FIG. 3 shows longitudinal, transverse and surface waves of a solid outside a well and acoustic waves coupled thereto in a liquid inside the well when excited by an eccentric acoustic source inside the well. The surface wave is also behind the transverse wave, and the wave front is olive-shaped and penetrates into the stratum to a certain depth.
FIG. 4 shows longitudinal, transverse and surface waves of solid outside the well and acoustic waves coupled with the solid in the liquid inside the well when the sound source is excited in the middle of the well, wherein the surface waves are also behind the transverse waves, and the wave front is olive-shaped and penetrates into the stratum to a certain depth.
The above figure shows the wave fronts of longitudinal waves, transverse waves and surface waves in the well liquid and the solid outside the well at the frequency of 80kHz, and when the frequency is reduced, the wavelength is lengthened, the wave fronts of the surface waves extend to the deep part of the stratum, and the detection depth is deepened. However, due to the cylindrical boundary effect of the wellbore, the acoustic waves in the well fluid that couple with the formation shear and surface waves have a cut-off frequency below which none of the acoustic waves couple with the shear and surface waves. Therefore, the measurement of the radial distribution of the formation shear wave velocity by the surface wave in the borehole is only suitable for the case of using the surface wave above the cutoff frequency, and only the formation shear wave time difference distribution in a certain area around the well can be measured, and the formation too deep in the radial direction cannot be measured.
Acoustic waves propagating in the formation outside the well all have a corresponding coupled wave in the fluid in the well. Waves propagating in the solids outside the well may be reflected in the fluid in the well by measuring these coupled waves. For example, the longitudinal wave time difference of stratum is obtained by the coupled wave of longitudinal wave, and the radial distribution of the transverse wave time difference of stratum is obtained by the wave coupled with the transverse wave and surface wave in the liquid in well.
FIG. 5 is a two-dimensional spectral distribution (frequency, wavenumber are independent variables) of acoustic waves that can be measured in a borehole fluid when excited by an intermediate acoustic source. The contour lines describe the amplitude of the two-dimensional spectrum. The top is the acoustic wave that is coupled to the Stoneley wave propagating on the borehole wall surface and propagates at a fluid velocity, which is constant. Downward is the acoustic wave, also called the mode wave, which couples with the surface and shear waves. As the frequency increases, multiple mode waves exist. The mode wave in the lowest frequency interval is selected for measurement, and the change rule of the formation transverse wave time difference along with the radial direction is obtained.
FIG. 6 shows the acoustic tool sonde that has been implemented, with the far right side having a long source range transmitter sonde, the next short source range transmitter sonde, and the left side having an array receiver sonde (containing 8 sondes). Logging waveforms of 8 different source distances are measured in the open hole, wherein the logging waveform with the maximum amplitude is a transverse wave and a surface wave coupled sound wave.
The invention relates to a logging method for detecting the radial distribution of stratum shear wave velocity by using surface waves, which specifically comprises the following steps:
the method comprises the following steps that firstly, two transmitting probes and an array receiving probe are connected together along the same axis in a hard mode, the two transmitting probes are located on the upper side or the lower side of the array receiving probe at the same time, an acoustic system formed by the two transmitting probes is integrally placed in an open hole along a well axis, the two transmitting probes alternately transmit, and all the probes in the array receiving probe receive logging waveforms at the same time. The excitation mode of the invention can be upper emission or lower emission and symmetrical emission of the emission probes arranged at the upper and lower parts simultaneously.
One of the two transmitting probes is close to the array receiving probe, the other transmitting probe is far away from the array receiving probe and is respectively used as a near-source distance transmitting probe and a far-source distance transmitting probe, the distance between the near-source distance transmitting probe and the array receiving probe is about 0.2-1m, the distance between the far-source distance transmitting probe and the array receiving probe is about 2.5-3m, the near-source distance transmitting probe and the far-source distance transmitting probe independently excite vibration, the array receiving probe at least comprises four receiving probes which are distributed at equal intervals along the same axis, and all the connector probes simultaneously receive a plurality of logging waveforms with different source distances, as shown in fig. 6. Two vibration excitation sources with large source distance difference are excited separately, and two groups of array logging waveforms with large source distance difference are obtained at the same depth position respectively.
And secondly, respectively extracting phase information of different frequencies in the multiple array logging waveforms when the near-source-distance transmitting probe and the far-source-distance transmitting probe are excited by using a phase method, and generating a two-dimensional plane distribution curve (shown in figure 7) and a time difference dispersion curve (shown in figure 8), namely a time difference change curve along with the frequency, which are formed by wave number-frequency through a linear relation of the phase along with the source distance. And respectively obtaining distribution curves on a wave number-frequency plane of the acoustic logging by using the two groups of array logging waveforms to obtain wave numbers and frequency intervals.
And step three, extracting the time difference dispersion curves of the stratum transverse wave and the surface wave in the distribution curve of the two-dimensional plane respectively (the stratum transverse wave and the surface wave are connected together, and the curve near the low-frequency cut-off frequency is the stratum transverse wave time difference dispersion curve). Note that: the time difference dispersion curve of the formation longitudinal wave is close to a straight line and does not change along with the frequency, the time difference dispersion curve of the Stoneley wave slightly decreases along with the increase of the frequency, and the time difference is close to the time difference of liquid in the well; the time difference dispersion curves of the formation transverse wave and the surface wave are combined together, the time difference is between the formation transverse wave time difference and the Stoneley wave time difference, and the time difference is increased along with the increase of the frequency.
And step four, converting the stratum transverse wave time difference dispersion curve into a radial depth-time difference curve through a distribution curve of a two-dimensional plane. The radial depth of the acoustic logging surface wave is in inverse proportion to the wave number, and the radial depth is the reciprocal of the wave number. The farthest radial depth (reciprocal of the minimum wavenumber) is determined using the distribution curve of the two-dimensional plane.
The radial depth-moveout curve is obtained by: taking the reciprocal of the wave number corresponding to each distribution point (wave number and frequency) on the distribution curve of the wave number-frequency two-dimensional plane to obtain the wavelength, taking the reciprocal as the abscissa as the radial depth of the distribution point, finding the frequency corresponding to the wave number on the formation transverse wave time difference dispersion curve (the formation transverse wave and the surface wave time difference dispersion curve are connected together, the curve disappears at a certain frequency when the frequency is reduced, the frequency is the cut-off frequency, dividing the frequency at the cut-off frequency of the curve by the wave number to obtain the transverse wave time difference of the formation), and dividing the wave number of the distribution point by the frequency of the distribution point to obtain the time difference of the radial depth, so that the time difference dispersion curve is converted into a radial depth-time difference curve to obtain the time differences of different radial depths. That is, a radial depth-time difference curve is constructed by using the radial depth as an independent variable and the time difference of the distribution curve corresponding to each wave number as a dependent variable.
Surface waves in the excitation response of an off-centered acoustic source in the borehole fluid may also be used to obtain radial depth-moveout curves using this approach, taking into account the path followed by a curved cylindrical surface. And converting the dispersion curve into a radial depth time difference curve. Surface waves excited by a dipole source and a multipole source in the well can also be used for converting a dispersion curve into a radial depth-moveout curve by using the processing method.
And fifthly, subtracting a radial depth-time difference curve obtained by the near source distance logging waveform and a radial depth-time difference curve obtained by the far source distance logging waveform on a radial depth corresponding to the depth of the measured stratum, adding the time difference of the far source distance or near source distance time difference dispersion curve at the cut-off frequency of the surface wave to the obtained time difference curve, namely the transverse wave time difference of the stratum, serving as the transverse wave time difference of the stratum at the radial depth, obtaining a variation curve of the transverse wave time difference of the stratum at the depth along with the radial depth, and reflecting the crushing condition and the borehole damage condition of the stratum around the well.
And (3) obtaining a radial depth-time difference curve by utilizing the excitation at different source distances, extracting the difference value of two time differences at the same wave number to be used as the transverse wave time difference value of the stratum with the radial depth (the reciprocal of the wave number), and adding the transverse wave time difference value of the stratum with the low frequency to obtain the stratum transverse wave time difference curve with the depth.
And step six, repeating the steps one to five to obtain variation curves of the stratum transverse wave time differences at all depth positions along with the radial depth, drawing the variation curves of the stratum transverse wave time differences at all depth positions along with the depth to form a profile of the stratum transverse wave time differences along with the depth, and taking the reciprocal of the stratum transverse wave time differences as the stratum transverse wave velocity to obtain the transverse wave velocity profile of the stratum around the well.
The time difference dispersion curves of the logging waveforms when two different source distances are excited are respectively obtained by utilizing the distribution curves of the wave number-frequency two-dimensional plane. And respectively obtaining time difference dispersion curves of the logging waveforms when the two different source distances are excited by utilizing the distribution curves of the wave number-frequency two-dimensional plane. The inverse of the wave number is taken as the radial depth, and a radial depth-moveout curve is obtained from the distribution curve on the wave number-frequency plane. Changes in the transverse wave moveout of the formation surrounding the well cause changes in the moveout in the measured transverse and surface wave dispersion curves.
The method is suitable for monopole sound wave well logging, petroleum well logging and well logging of various engineering on the ground, and the measurement is carried out on the ground and the side surface of a dam body after the transmitting and receiving probes are combined, the surface wave measurement is carried out along the surface when various roadways and tunnels are excavated, the reserved holes in dams, piers and various buildings are detected, coal well logging, nonferrous metal exploration well logging and various hydrogeology well logging methods are adopted, and the method is suitable for measuring the stratum transverse wave after all drilling, including various pavement exploration, goaf exploration, foundation exploration, karst exploration and the like.
The selection of the mode wave of each order and the dispersion shape of the mode wave coupled with the formation shear wave and the surface wave (pseudo sharp wave) in the liquid in the well bore:
under downhole conditions, the surface wave has a cutoff frequency, the frequency of the exciting surface wave cannot be less than the cutoff frequency, and the wave no longer exists after the frequency is less than the cutoff frequency. This conclusion is unique to cylindrical wellbores and teaches that using surface waves in a wellbore to detect the radial distribution of shear wave velocities in formations is conditional, only allowing detection of areas relatively shallow from the wellbore wall, and not allowing detection of shear wave velocities in very deep formations at very low frequencies as is the case with surface wave exploration.
The shape of the dispersion curve is due to the borehole and is characteristic of the surface waves in the wellbore. In the surface wave exploration, the velocity dispersion curve of the lowest-order surface wave is a straight line (the high-price surface wave is a curve), the frequency is reduced, the wavelength is increased, and the depth of a stratum related to an olive-shaped wave front is increased; the transverse wave velocity of the involved stratum has an influence on the velocity of the surface wave, which results in a change of the velocity of the surface wave, and sometimes even in a case that the velocity curve of the surface wave has a jump transition with the change of the frequency, and the position of the transition is related to the depth position of the stratum. In the wellbore liquid, the time difference of the surface wave changes along with the frequency, namely the dispersion curve, the frequency is increased, the time difference of the surface wave is increased, a straight section is not arranged, the straight section at the low frequency is the transverse wave time difference of the stratum, and the two are connected together. However, when the formation around the borehole wall is damaged and the transverse wave time difference increases, the olive-shaped wave front of the surface wave with high frequency is small, and the depth of the involved formation is shallow, at this time, the action and influence of the increase of the transverse wave time difference of the formation around the borehole wall on the surface wave time difference with high frequency are obvious, so that the time difference of the surface wave with these frequencies increases, which is specifically shown as follows: the time difference is added on the original surface wave frequency dispersion curve, and the shape of the frequency dispersion curve is changed and is not overlapped with the frequency dispersion curve at the far source distance low frequency.
A plurality of orders of mode waves exist in a shaft, the mode wave with the lowest order is selected for processing formation transverse wave time difference distribution, the influence of orders needs to be considered when a high-order mode wave is selected, order correction is carried out, and the mode wave is not generally adopted.
The reason for the difference in dispersion curves for different source distances is: the formation near the well wall is broken due to the borehole time difference, and the time difference is increased. The increased time difference is obvious in the waveform of the near source distance excitation, and because the waveform measured by the near source distance excitation mainly reflects the characteristics of wave number k which is relatively small and the wave incident to the well wall along the radial direction, the time difference dispersion curve of the waveform measured by the near source distance excitation becomes obvious. The method has the advantages that the method is not obvious in logging waveform excited by far source distance, and the measured waveform is response when the wave number k is larger and is less influenced by borehole wall stratum breakage when the far source distance is excited. The calculated dispersion curves of the waveforms resulting in the two source-to-source excitations differ at high frequency bands.
In the liquid in the well, two sound waves coupled with the surface wave and the transverse wave of the stratum are not separable in time and frequency domains. It is known from the dispersion curve of the time difference-frequency that the time difference gradually approaches the transverse wave time difference of the stratum as the frequency decreases. The time difference of the dispersion curves is always larger than the transverse wave time difference of the stratum. After the stratum near the well wall is broken, the time difference of longitudinal wave and transverse wave changes. However, the time difference, which is reflected on the surface wave time difference curve and increases with the increase in frequency, of the dispersion curve increases based on the transverse wave time difference at a deep portion in the radial direction of the formation. The primary difference describes the difference in the formation shear moveout. Therefore, we refer to the radial variation of the formation shear wave, which also includes the variation of the formation longitudinal wave time difference. This change is only a qualitative indication and needs to be further scaled to obtain the true distribution of the formation transverse wave time difference with the radius.
While the present invention has been described in terms of its functions and operations, which are illustrated in the accompanying drawings, it is to be understood that such embodiments are merely illustrative and not restrictive of the broad invention, and that this invention can be embodied in many forms without departing from the spirit and scope of the appended claims.
Claims (4)
1. A logging method for detecting the radial distribution of the transverse wave velocity of a stratum by using surface waves is characterized by comprising the following steps:
step one, two transmitting probes and an array receiving probe are connected together along the same axis in a hard mode, the two transmitting probes are located on the upper side or the lower side of the array receiving probe at the same time, an acoustic system formed by the two transmitting probes is integrally placed in an open hole along a well axis, the two transmitting probes alternately transmit, and all the probes in the array receiving probe receive logging waveforms at the same time; one of the two transmitting probes is close to the array receiving probe, and the other transmitting probe is far away from the array receiving probe and is respectively used as a near source distance transmitting probe and a far source distance transmitting probe;
respectively extracting phase information of different frequencies in the array logging waveform when the near-source distance transmitting probe and the far-source distance transmitting probe are excited by using a phase method, and generating a distribution curve of a two-dimensional plane and a time difference dispersion curve which are formed by wave number-frequency through the linear relation of the phase along with the source distance; respectively obtaining a distribution curve on a wave number-frequency plane of acoustic logging by using the two groups of array logging waveforms to obtain a wave number and a frequency interval;
extracting time difference dispersion curves of stratum transverse waves and surface waves in the distribution curve of the two-dimensional plane respectively;
step four, converting the time difference dispersion curve of the formation transverse wave into a radial depth-time difference curve through a distribution curve of a two-dimensional plane, wherein the radial depth is the reciprocal of the wave number;
subtracting a radial depth-time difference curve obtained by the near source distance logging waveform and a radial depth-time difference curve obtained by the far source distance logging waveform on a radial depth corresponding to the depth of the measured stratum, and adding the time difference of the near source distance or far source distance time difference dispersion curve at the cut-off frequency of the surface wave to the obtained time difference curve to obtain a variation curve of the stratum transverse wave time difference at the depth along with the radial depth;
and step six, repeating the steps one to five to obtain variation curves of the stratum transverse wave time differences at all depth positions along with the radial depth, drawing the variation curves of the stratum transverse wave time differences at all depth positions along with the depth to form a profile of the stratum transverse wave time differences along with the depth, and obtaining the stratum transverse wave velocity profile of the stratum around the well, wherein the reciprocal of the stratum transverse wave time differences is the stratum transverse wave velocity.
2. A logging method for detecting the radial distribution of the transverse wave velocity of the stratum by using the surface wave as claimed in claim 1, wherein in the step one, the distance between the near source distance transmitting probe and the array receiving probe is 0.2-1m, the distance between the far source distance transmitting probe and the array receiving probe is 2.5-3m, the near source distance transmitting probe and the far source distance transmitting probe independently excite vibration, the array receiving probe comprises at least four receiving probes which are distributed at equal intervals along the same axis, and all the joint probes simultaneously receive logging waveforms with different source distances.
3. A logging method for detecting the radial distribution of the shear wave velocity of the stratum by using the surface wave as claimed in claim 1, wherein the conversion mode of the radial depth-time difference curve in the fourth step is as follows: taking the reciprocal of the wave number corresponding to each distribution point on the distribution curve of the wave number-frequency two-dimensional plane to obtain the wavelength, taking the reciprocal as the abscissa as the radial depth of the distribution point, finding the frequency corresponding to the wave number on the formation transverse wave time difference dispersion curve in the wave number-frequency two-dimensional plane, and dividing the wave number by the frequency to obtain the time difference of the radial depth, so that the time difference dispersion curve is converted into a radial depth-time difference curve to obtain the time differences of different radial depths.
4. A logging method for detecting the radial distribution of the transverse wave velocity of the stratum by using the surface wave as claimed in claim 1, wherein the variation curve of the transverse wave time difference of the stratum along with the radial depth in the fifth step reflects the crushing condition of the stratum around the well and the damage condition of the well hole.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110108769.5A CN112925021B (en) | 2021-01-27 | 2021-01-27 | Logging method for detecting stratum shear wave velocity radial distribution by surface wave |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110108769.5A CN112925021B (en) | 2021-01-27 | 2021-01-27 | Logging method for detecting stratum shear wave velocity radial distribution by surface wave |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112925021A CN112925021A (en) | 2021-06-08 |
| CN112925021B true CN112925021B (en) | 2023-03-21 |
Family
ID=76166733
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110108769.5A Active CN112925021B (en) | 2021-01-27 | 2021-01-27 | Logging method for detecting stratum shear wave velocity radial distribution by surface wave |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112925021B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114114401B (en) * | 2021-12-01 | 2024-04-23 | 北京华晖探测科技股份有限公司 | Method for shallow exploration by using SH wave excited by axisymmetric probe on ground |
| CN113982562B (en) * | 2021-12-01 | 2024-05-07 | 北京华晖探测科技股份有限公司 | Well cementation quality evaluation method based on array acoustic logging |
| CN114017014B (en) * | 2021-12-01 | 2023-10-24 | 北京华晖探测科技股份有限公司 | Acoustic logging wave acoustic method |
| CN118444382B (en) * | 2024-04-17 | 2024-10-08 | 中国矿业大学 | Imaging and collapse monitoring and early warning device and method for deep underground cavity of urban road |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108318918A (en) * | 2017-12-29 | 2018-07-24 | 福建省建筑设计研究院有限公司 | Underground unfavorable geologic body lossless detection method based on fine motion dispersion curve and H/V curves and application |
| WO2019071515A1 (en) * | 2017-10-12 | 2019-04-18 | 南方科技大学 | Surface wave detection method and terminal device |
| CN110273675A (en) * | 2019-07-08 | 2019-09-24 | 北京华晖盛世能源技术股份有限公司 | A kind of transient electromagnetic difference logging method and its system |
| CN110687602A (en) * | 2019-10-31 | 2020-01-14 | 山东电力工程咨询院有限公司 | Shallow seismic multi-wave combined exploration method |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6611761B2 (en) * | 2000-12-19 | 2003-08-26 | Schlumberger Technology Corporation | Sonic well logging for radial profiling |
| CN201187296Y (en) * | 2008-03-11 | 2009-01-28 | 西安威盛电子仪器有限公司 | Over casing tube digital array acoustic logging instrument |
| CN101907727B (en) * | 2010-08-17 | 2012-05-30 | 中国科学院地质与地球物理研究所 | Multi-component converted wave static correction method by using surface waves |
| CN102830433B (en) * | 2012-08-16 | 2014-10-01 | 中国石油化工股份有限公司 | Method for calculating anisotropy azimuth angle by using dipole transverse wave logging information based on frequency domain |
| CN103233727B (en) * | 2013-05-13 | 2015-04-08 | 中国石油大学(华东) | Inversion method of stratum shear wave velocity radial sections |
| CN103244104B (en) * | 2013-05-13 | 2015-06-24 | 中国石油大学(华东) | Method for extracting sleeve wave attenuation rate through dispersion correction |
| CN110242292A (en) * | 2019-07-15 | 2019-09-17 | 北京华晖盛世能源技术股份有限公司 | A kind of open hole well stratum vertical direction resistivity test device, method and system |
| CN111856551A (en) * | 2020-06-22 | 2020-10-30 | 山东电力工程咨询院有限公司 | Shallow layer transverse high-resolution Rayleigh wave exploration method and system |
-
2021
- 2021-01-27 CN CN202110108769.5A patent/CN112925021B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2019071515A1 (en) * | 2017-10-12 | 2019-04-18 | 南方科技大学 | Surface wave detection method and terminal device |
| CN109923440A (en) * | 2017-10-12 | 2019-06-21 | 南方科技大学 | Surface wave prospecting method and terminal device |
| CN108318918A (en) * | 2017-12-29 | 2018-07-24 | 福建省建筑设计研究院有限公司 | Underground unfavorable geologic body lossless detection method based on fine motion dispersion curve and H/V curves and application |
| CN110273675A (en) * | 2019-07-08 | 2019-09-24 | 北京华晖盛世能源技术股份有限公司 | A kind of transient electromagnetic difference logging method and its system |
| CN110687602A (en) * | 2019-10-31 | 2020-01-14 | 山东电力工程咨询院有限公司 | Shallow seismic multi-wave combined exploration method |
Non-Patent Citations (1)
| Title |
|---|
| Formation resistivity measurement based on a transient electromagnetic field excited by an acoustic probe in an open-hole;Xiaofei Sheng等;《Journal of Geophysics and Engineering》;20200430;第222-230页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN112925021A (en) | 2021-06-08 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN112925021B (en) | Logging method for detecting stratum shear wave velocity radial distribution by surface wave | |
| CN109613616B (en) | Geological comprehensive three-dimensional detection method for shallow karst tunnel | |
| CN103233727B (en) | Inversion method of stratum shear wave velocity radial sections | |
| US7639563B2 (en) | Method for sonic indication of voids in casing cement | |
| CN108026769B (en) | Measurement and processing for detecting weak boundary layers in hydrocarbon bearing laminated formations using acoustic logging devices | |
| CA2844051C (en) | System and method for determining shear wave anisotropy in a vertically transversely isotropic formation | |
| EP2587227A1 (en) | Downhole tool for determining flow velocity | |
| WO2009055196A2 (en) | In-situ determination of yield stress state of earth formations | |
| CN101285381B (en) | Process for inversing soft ground horizontal wave velocity by leaky mode waves | |
| US11086040B2 (en) | Time-reversed nonlinear acoustics for wellbore integrity characterization | |
| US8681582B2 (en) | Method for sonic indication of formation porosity and lithology | |
| US11525936B2 (en) | Through casing formation slowness evaluation with a sonic logging tool | |
| EA003846B1 (en) | Method and system for acoustic frequency selection in acoustic logging tools | |
| CN114233276B (en) | Array acoustic logging well cementation quality evaluation interpretation plate based on cased well response | |
| CN101793973A (en) | While-drilling electric method | |
| Roshan et al. | Borehole deformation based in situ stress estimation using televiewer data | |
| CN114017014B (en) | Acoustic logging wave acoustic method | |
| CN109444980B (en) | Efficient deep geothermal resource exploration method | |
| AU2002249800B2 (en) | Method for customizing seismic explosives | |
| RU2305298C1 (en) | Method for controlling position of drilling bit during drilling | |
| CN114114401B (en) | Method for shallow exploration by using SH wave excited by axisymmetric probe on ground | |
| Giozza et al. | Refining Hydraulic Fracture Design in Tight Gas Reservoirs Using a New Generation of Slim Dipole Tools | |
| CN110805433B (en) | While-drilling sound wave remote detection system and method | |
| AU745543B2 (en) | Method of borehole compensation of earth formation characteristic measurements using depth measurements | |
| Xu et al. | Imaging small geological structure in coal mines based on reflected acoustic logging of underground cross-seam boreholes |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |