CN107060741B - Phase-control double-cross dipole logging method - Google Patents
Phase-control double-cross dipole logging method Download PDFInfo
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- CN107060741B CN107060741B CN201611104918.6A CN201611104918A CN107060741B CN 107060741 B CN107060741 B CN 107060741B CN 201611104918 A CN201611104918 A CN 201611104918A CN 107060741 B CN107060741 B CN 107060741B
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- 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
- E21B47/14—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 using acoustic waves
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- 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
- G01V1/52—Structural details
Abstract
The invention relates to a phase-control double-cross dipole well logging method, which comprises the following steps: at least one group of transmitting transducers is arranged in a first area of the logging instrument, wherein the first group of transmitting transducers comprises four transmitting transducers; at least one group of receiving transducer arrays are arranged in a second area of the logging instrument, and one group of receiving transducer arrays of the at least one group of receiving transducer arrays comprises a first group of receiving transducer arrays and a second group of receiving transducer arrays; sequentially exciting a first sub-group of transmitting transducers, a second sub-group of transmitting transducers, a third sub-group of transmitting transducers and a fourth sub-group of transmitting transducers to obtain a first transmitting signal, a second transmitting signal, a third transmitting signal and a fourth transmitting signal; the receiving transducer respectively receives the first transmitting signal, the second transmitting signal, the third transmitting signal and the fourth transmitting signal in sequence. The invention can better detect the anisotropy of the stratum azimuth under the conditions of lower signal-to-noise ratio and weak anisotropy by controlling the polarity and the amplitude of the orthogonal dipole transmitting transducer.
Description
Technical Field
The invention relates to the technical field of stratum surveying, in particular to a phase-control double-cross dipole well logging method.
Background
In the field of hydrocarbon exploration, quantitative assessment of formation fractures and earth stresses is becoming increasingly important for logging prior to hydrocarbon development as the development of unconventional hydrocarbon surveys is becoming more and more important. The cross dipole acoustic logging method can well detect anisotropy caused by cracks or ground stress, so that the cross dipole acoustic logging method becomes one of important methods for unconventional oil and gas exploration.
The cross dipole logging schematic diagram is shown in fig. 1, four transmitting transducers are arranged on a logging instrument, two transmitting transducers are arranged in specified X and X directions, the other two transmitting transducers are arranged in specified Y and Y directions, meanwhile, voltages with opposite polarities are added in the X and-X directions, signals received in corresponding X, Y directions are subtracted, and in-phase signals XX and YY and cross signals XY and YX are obtained, and the cross signals are generally the same.
The existing cross dipole well logging can provide 4 groups of well logging speeds in 3 independent directions, and when the signal-to-noise ratio is high, the anisotropy and the fast and slow transverse wave directions are obtained through processing, so that a means is provided for obtaining and evaluating the ground stress and the cracks.
These dipole logging techniques have at least the following disadvantages: when the included angle between the transmitting transducer of the crossed dipole and the fast and slow transverse waves is near 45 degrees, the medium with strong anisotropy is weak in quartering data display and is not beneficial to anisotropic detection and inversion, and if the data of four components are used for simultaneously or partially inverting two parameters of anisotropy, azimuth jump may occur.
The proposed double-cross dipole logging method needs four groups of transmitting transducers, so that the manufacturing cost of the instrument is increased, and the length of the instrument is increased possibly, so that the construction is inconvenient.
Disclosure of Invention
The invention aims to provide a phase-control double-cross dipole logging method under the conditions of lower signal-to-noise ratio and weak anisotropy, so as to better detect the anisotropy of the stratum azimuth.
In order to achieve the above object, the present invention provides a phase-controlled double-cross dipole well logging method, which comprises: arranging at least one group of transmitting transducers in a first area of the logging instrument, wherein the first group of transmitting transducers in the at least one group of transmitting transducers comprises four transmitting transducers which are distributed on the circumference of a first plane perpendicular to the axis of the logging instrument at equal intervals; at least one group of receiving transducer arrays are arranged in a second area of the logging instrument, wherein one group of receiving transducer arrays of the at least one group of receiving transducer arrays comprises a first group of receiving transducers and a second group of receiving transducers, the first group of receiving transducers and the second group of receiving transducers are respectively distributed on a second plane at equal intervals, and the second plane is parallel to the first plane; wherein the first set of receiving transducers comprises four receiving transducers; the second group of receiving transducers comprises four receiving transducers; sequentially exciting a first sub-group of transmitting transducers, a second sub-group of transmitting transducers, a third sub-group of transmitting transducers and a fourth sub-group of transmitting transducers to obtain a first transmitting signal, a second transmitting signal, a third transmitting signal and a fourth transmitting signal; the first sub-group of transmitting transducers comprise two transmitting transducers which form an included angle of 180 degrees with each other in the first group of transmitting transducers; the second sub-group of transmitting transducers comprises the remaining two transmitting transducers of one group of transmitting transducers in the at least one group of transmitting transducers except the first sub-group of transmitting transducers; the third subset of transmit transducers comprises the first set of transmit transducers; the fourth sub-group of transmit transducers comprises the first group of transmit transducers; the receiving transducer respectively receives the first transmitting signal, the second transmitting signal, the third transmitting signal and the fourth transmitting signal in sequence.
Preferably, the step of sequentially exciting the first sub-group of transmitting transducers, the second sub-group of transmitting transducers, the third sub-group of transmitting transducers and the fourth sub-group of transmitting transducers to obtain the first transmitting signal, the second transmitting signal, the third transmitting signal and the fourth transmitting signal specifically includes: applying excitation with opposite polarities to two transmitting transducers which are included in the first group of transmitting transducers and have an included angle of 180 degrees with each other in the first sub-group of transmitting transducers to generate a first transmitting signal; applying excitation with opposite polarities to two transmitting transducers which are arranged in the second sub-group of transmitting transducers and have the included angles of 180 degrees with each other, and generating a second transmitting signal; applying the same polarity to two transmitting transducers in a pair of 90-degree included angles in the first group of transmitting transducers, and applying the opposite polarity to the same polarity to two transmitting transducers in the other pair of the first group of transmitting transducers; generating a third transmit signal; and keeping the polarity of two transmitting transducers forming an included angle of 180 degrees in the third sub-group of transmitting transducers unchanged, and changing the polarity of two transmitting transducers of the other pair in the third sub-group of transmitting transducers to form a fourth sub-group of transmitting transducers to generate a fourth transmitting transducer.
Preferably, the step of sequentially exciting the first sub-group of transmitting transducers, the second sub-group of transmitting transducers, the third sub-group of transmitting transducers and the fourth sub-group of transmitting transducers to obtain the first transmitting signal, the second transmitting signal, the third transmitting signal and the fourth transmitting signal further includes: respectively and sequentially receiving a first transmitting signal, a second transmitting signal, a third transmitting signal and a fourth transmitting signal by a receiving transducer to perform signal processing to obtain a first in-phase component signal, a second in-phase component signal, a third in-phase component signal and a fourth in-phase component signal; calculating to obtain a first transverse wave velocity, a second transverse wave velocity, a third transverse wave velocity and a fourth transverse wave velocity according to the first in-phase component signal, the second in-phase component signal, the third in-phase component signal and the fourth in-phase component signal; and determining the formation anisotropy parameters according to the first shear wave velocity, the second shear wave velocity, the third shear wave velocity and the fourth shear wave velocity.
Preferably, the included angle between two adjacent receiving transducers in the first group of receiving transducers is 90 degrees; the included angle between any receiving transducer in the second group of receiving transducers and any receiving transducer in the first group of receiving transducers is 45 degrees.
Preferably, when only the first group of receiving transducers receives, the receiving transducers respectively receive the first transmitting signal, the second transmitting signal, the third transmitting signal and the fourth transmitting signal in sequence, and perform signal processing to obtain a first in-phase component signal, a second in-phase component signal, a third in-phase component signal and a fourth in-phase component signal, specifically: superposing a first group of receiving transducer arrays and first transmitting signals respectively received by receiving transducers arranged in parallel with a first subgroup of crossed dipole transmitting transducers to obtain first in-phase component signals; superposing second transmitting signals respectively received by the first group of receiving transducer arrays and the receiving transducers arranged in parallel with the second subgroup of crossed dipole transmitting transducers to obtain second in-phase component signals; recording all data received by four receiving transducers in the first group of receiving transducer arrays, wherein the polarity of each receiver is the same as that of a transmitting transducer on the same axis, and then superposing signals of the four receivers to obtain a third in-phase component signal; recording all four receivers in the first group of receiving transducer arrays, wherein the polarity of each receiver is the same as that of a transmitting transducer on the same axis, and then superposing the signals of the four receivers to obtain a fourth in-phase component signal;
preferably, when there is a second group of receiving transducers to receive, the receiving transducers respectively receive the first transmitting signal, the second transmitting signal, the third transmitting signal and the fourth transmitting signal in sequence, and perform signal processing to obtain a first in-phase component signal, a second in-phase component signal, a third in-phase component signal and a fourth in-phase component signal, specifically: superposing a first group of receiving transducer arrays and first transmitting signals respectively received by receiving transducers arranged in parallel with a first subgroup of crossed dipole transmitting transducers to obtain first in-phase component signals; superposing second transmitting signals respectively received by the first group of receiving transducer arrays and the receiving transducers arranged in parallel with the second subgroup of crossed dipole transmitting transducers to obtain second in-phase component signals; respectively receiving third signals by two receiving transducers of a second group of receiving transducer arrays and the angular bisector of a transmitting transducer with the same polarity in a third subgroup of crossed dipole transmitting transducers, and superposing the third signals to obtain third in-phase component signals; and respectively receiving fourth signals by two receiving transducers of the second group of receiving transducer arrays and the angular bisector of the transmitting transducer with the same polarity in the fourth sub-group of crossed dipole transmitting transducers, and superposing to obtain a fourth in-phase component signal.
Preferably, the first shear wave velocity, the second shear wave velocity, the third shear wave velocity, and the fourth shear wave velocity are obtained by calculation according to the first in-phase component signal, the second in-phase component signal, the third in-phase component signal, and the fourth in-phase component signal, specifically: and respectively carrying out speed or time difference extraction on the first in-phase component signal, the second in-phase component signal, the third in-phase component signal and the fourth in-phase component signal by adopting a waveform inversion method and/or filtering and frequency dispersion correction to obtain a first transverse wave speed, a second transverse wave speed, a third transverse wave speed and a fourth transverse wave speed.
Preferably, after the line velocity or the time difference is extracted from the first in-phase component signal, the second in-phase component signal, the third in-phase component signal, and the fourth in-phase component signal respectively to obtain a first shear velocity, a second shear velocity, a third shear velocity, and a fourth shear velocity, the logging method further includes: subtracting the first shear wave velocity from the second shear wave velocity, and taking an absolute value to obtain a first velocity difference; and subtracting the fourth shear wave speed from the third shear wave speed, and taking an absolute value to obtain a second speed difference.
Preferably, the formation anisotropy parameters comprise the magnitude of the fast transverse wave speed, the magnitude of the slow transverse wave speed and an included angle between the direction of the geomagnetic north and the direction of the fast transverse wave; determining a formation anisotropy parameter according to the first shear wave velocity, the second shear wave velocity, the third shear wave velocity and the fourth shear wave velocity, which specifically comprises the following steps: when the first speed difference is greater than the second speed difference, if the first shear wave speed is greater than the second shear wave speed, the fast shear wave speed is equal to the first shear wave speed, and the slow shear wave speed is equal to the second shear wave speed; or if the second shear wave speed is greater than the first shear wave speed, the fast shear wave speed is equal to the second shear wave speed, and the slow shear wave speed is equal to the first shear wave speed; when the second speed difference is greater than the first speed difference, if the third shear wave speed is greater than the fourth shear wave speed, the fast shear wave speed is equal to the third shear wave speed, and the slow shear wave speed is equal to the fourth shear wave speed; or if the fourth shear wave speed is greater than the third shear wave speed, the fast shear wave speed is equal to the fourth shear wave speed, and the slow shear wave speed is equal to the third shear wave speed; when the first speed difference and the second speed difference are both zero, the fast shear wave speed and the slow shear wave speed are equal to any one of the first shear wave speed, the second shear wave speed, the third shear wave speed or the fourth shear wave speed, and the stratum has no azimuthal anisotropy.
The invention provides a phase-control double-cross dipole well logging method, which can better detect the anisotropy of the stratum orientation under the conditions of lower signal-to-noise ratio and weak anisotropy by controlling the polarity and the amplitude of an orthogonal dipole transmitting transducer.
Drawings
FIG. 1 is a schematic diagram of a prior art cross-dipole logging configuration;
FIG. 2 is a flow chart of a phase-controlled double-cross dipole well logging method according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a phase-controlled double-cross dipole well logging provided in the second embodiment of the present invention;
FIG. 4 is a schematic diagram of another phased double cross dipole logging configuration provided in accordance with a second embodiment of the present invention;
fig. 5a and 5b are directivity diagrams of simulation and actual test of four-directional transmission in fig. 3 and 4 by means of polarity control.
FIG. 6 is a graph comparing results of a tetragonal emission with a set of dipole emissions in a horizontally transversely isotropic medium.
Detailed Description
The technical solution of the present invention is further described in detail by the accompanying drawings and the implementation examples.
Fig. 2 is a flowchart of a double cross dipole well logging method according to an embodiment of the present invention.
As shown in fig. 2, the double cross dipole logging specifically comprises the following steps:
step 101, a plurality of groups of transmitting transducers are arranged in a transmitting area of a logging instrument, wherein the plurality of groups of transmitting transducers comprise a first group of transmitting transducers, the first group of transmitting transducers comprise a first transmitting transducer, a second transmitting transducer, a third transmitting transducer and a fourth transmitting transducer, and the first transmitting transducers are distributed on the circumference of a first plane perpendicular to the axis of the instrument at equal intervals.
Specifically, a first transmitting transducer, a second transmitting transducer, a third transmitting transducer and a fourth transmitting transducer are arranged in the same plane, and the four transmitting transducers have the same performance; the four cross-dipole transmitters may be embodied as a first subset of cross-dipole transmit transducers and a second subset of cross-dipole transmit transducers; the first subset of cross-dipole transmit transducers may include a first transmit transducer and a third transmit transducer; the second subset of cross-dipole transmit transducers may comprise a second transmit transducer and a fourth transmit transducer; the first transmitting transducer, the second transmitting transducer, the third transmitting transducer and the fourth transmitting transducer are arranged at equal intervals and are sequentially distributed at intervals of 90 degrees.
102, setting at least one group of receiving transducer arrays in a second area of the logging instrument, wherein one group of receiving transducer arrays of the at least one group of receiving transducer arrays comprises a first group of receiving transducers and a second group of receiving transducers, the first group of receiving transducers are distributed on a second plane at equal intervals, the second group of receiving transducers are distributed on the second plane at equal intervals, and the second plane is parallel to the first plane; wherein the first set of receiving transducers comprises four receiving transducers; the second group of receiving transducers comprises four receiving transducers;
when 4-azimuth reception is employed, the angular separation between the receiving transducers in any array and the first, second, third and fourth transmitting transducers is n × 90 degrees, where n is 1,2, 3;
when 8-azimuth reception is employed, the angular separation between the receiving transducer and the first, second, third and fourth transmitting transducers in any array is m x 45 degrees, where m is 1,2,3 … … 7.
In particular, arrays of receive transducers are arranged in a series of planes parallel to the transmit plane, each array may include four receive transducers or eight receive transducers. For four-direction receiving composed of four receiving transducers, each receiving transducer is respectively on the same axis with the first, second, third or fourth transmitting transducers, and for eight-direction receiving composed of eight receiving transducers, one receiving transducer is placed between two adjacent receiving transducers of the 4-direction receiving transducers, and the eight receiving transducers are on the same circumference. The eight directional receiving transducers may be divided into two groups, 4 receiving transducers of the first group are respectively on the same axis with the first, second, third or fourth transmitting transducers, four receiving transducers of the second group of receiving transducer arrays are respectively placed between two adjacent receiving transducers in the four receiving transducer arrays of the first group, and the second group is respectively spaced from the first group by multiples of 45 degrees in the eight directional receiving.
Step 103, exciting a first subset of cross dipole transmitting transducers to generate a first transmitting signal; receiving a first transmit signal with a 4 xN receive transducer in a first set of receive transducer arrays; simultaneously recording signals received by two receiving transducers arranged in parallel with the first subgroup of transmitting transducers and signals received by two receiving transducers arranged vertically;
specifically, two transmitting transducers with central angles of 180 degrees are arranged in a dipole transmitting transducer, namely, a first subgroup of dipole transmitting transducers are excited by applying excitation signals with opposite polarities, and a first subgroup of cross dipole transmitting transducers generate a first transmitting signal; and recording signals received by two receiving transducers in the receiving transducer array, which are arranged in parallel with the first sub-group of crossed dipole transmitting transducers, and two receiving transducers arranged vertically while exciting the first sub-group of dipole transmitting transducers.
104, exciting two other transmitting transducers with central angles of 180 degrees, namely a second sub-group of cross dipole transmitting transducers with opposite polarities to generate a second transmitting signal; receiving a second transmitting signal by adopting a 4 xN receiving transducer in the first group of receiving transducer arrays; simultaneously recording signals received by two receiving transducers arranged in parallel with the second subgroup of transmitting transducers and signals received by two receiving transducers arranged vertically;
specifically, two transmitting transducers in a second sub-group of dipole transmitting transducers are applied with excitation signals with opposite polarities for excitation, and a second sub-group of cross dipole transmitting transducers generate second transmitting signals; and recording signals of two receiving transducers arranged in parallel with the second subgroup cross dipole transmitting transducer and two receiving transducers arranged vertically in the receiving transducer array while exciting the second subgroup cross dipole transmitting transducer.
Step 105, exciting a third subset of dipole transmitting transducers to generate a third transmitting signal; receiving a third transmitting signal by adopting a 4 xN receiving transducer in a group of receiving transducer arrays;
specifically, two adjacent ones of the dipole transmitting transducers, i.e., transmitting transducers having a central angle of 90 degrees, are excited by applying excitation signals of one polarity in parallel, while the remaining two adjacent ones, i.e., transmitting transducers having a central angle of 90 degrees, are excited by applying excitation signals of the opposite polarity in parallel, forming a third subset of dipole transmitting transducers and a third transmitting signal. The third sub-group of transmitting transducers comprises all four transmitting transducers, and the third transmitting signal is to act on the four transmitting transducers simultaneously.
And (3) while exciting the third sub-group of dipole transmitting transducers, adopting the receiving signals of two receiving transducers in the angular bisectors of the two receiving transducers in the second group of receiving transducers and the two receiving transducers in the same polarity in the third sub-group of transmitting transducers for the eight-direction receiving transducers.
And for a four azimuth receiving transducer, four receiving transducers acquire simultaneously, each transducer having the same polarity as its transmitting transducer in one axis.
106, keeping the polarity of two transmitting and receiving transducers with 180-degree central angles in the third subgroup of transmitting transducers unchanged, and changing the polarity of the remaining two transmitting transducers with 180-degree central angles; forming a fourth sub-group of transmitting transducers; energizing a fourth subset of the transmitting transducers to produce a fourth transmit signal; the fourth transmit signal is received using a 4 xn receive transducer in the set of receive transducer arrays.
And (3) while exciting the fourth sub-group of dipole transmitting transducers, if the eight-direction receiving transducer is adopted, receiving signals by using two receiving transducers in the second group of receiving transducer arrays and at the angular bisector of two receiving transducers with the same polarity in the fourth sub-group of dipole transmitting transducers.
And for a four azimuth receiving transducer, four receiving transducers acquire simultaneously, each transducer having the same polarity as its transmitting transducer in one axis.
Step 107, processing the first transmitting signal and the second transmitting signal, and the signals measured by the third transmitting signal and the fourth transmitting signal to obtain a first in-phase component signal, a second in-phase component signal, a third in-phase component signal and a fourth in-phase component signal;
for the first transmitting signal and the second transmitting signal, two receiving transducers which pass through the instrument center in a group of receiving transducer arrays and are in 180 degrees receive the same transmitting signal data to be superposed to obtain an in-phase component and a cross component; wherein the same-phase component is parallel to the transmitting transducer, and the cross component is at an included angle of 90 degrees with the transmitting transducer;
specifically, in a first group of receiving transducer arrays, receiving transducers arranged in parallel with a first sub-group of transmitting transducers and receiving transducers arranged vertically receive first transmitting signals respectively; superposing first transmitting signal data received by a receiving transducer arranged in parallel with the first sub-group of cross dipole transmitting transducers to obtain a first in-phase component signal; subtracting first transmitting signal data received by a receiving transducer arranged in parallel with the first sub-group of cross dipole transmitting transducers to obtain a first in-phase component signal; superposing first transmitting signal data received by a receiving transducer vertically arranged with the first sub-group of cross dipole transmitting transducers to obtain a first cross component signal; specifically, the data of a first transmitting signal received by a receiving transducer vertically arranged with a first sub-group of cross dipole transmitting transducers is subtracted to obtain a first cross component signal.
Respectively receiving second transmitting signals by receiving transducers arranged in parallel with a second sub-group of transmitting transducers and vertically arranged receiving transducers in the first group of receiving transducer arrays; superposing second transmitting signal data received by a receiving transducer arranged in parallel with the second sub-group of cross dipole transmitting transducers to obtain a second in-phase component signal; subtracting second transmitting signal data received by a receiving transducer arranged in parallel with the second sub-group of cross dipole transmitting transducers to obtain a second in-phase component signal; subtracting second transmitting signal data received by a receiving transducer vertically arranged with the second sub-group of cross dipole transmitting transducers to obtain a second cross component signal; specifically, the data of a second transmitting signal received by a receiving transducer vertically arranged with the second sub-group of cross dipole transmitting transducers is subtracted to obtain a second cross component signal.
When eight-direction reception is adopted for the third and fourth transmission signals:
respectively receiving third transmitting signals by two receiving transducers in the second group of receiving transducer arrays, wherein the two receiving transducers are positioned at the angular bisector of the transmitting transducers with the same polarity as the two transmitting transducers in the third sub-group of transmitting transducers; the polarity of the two receivers is respectively the same as that of the transmitting transducers at the two sides of the receivers, and the two signal data are superposed to obtain a third in-phase component signal; specifically, the two signal data are subtracted to obtain a third in-phase component signal.
Respectively receiving fourth transmitting signals by two receiving transducers in the second group of receiving transducer arrays, wherein the two receiving transducers are positioned at the angular bisector of two transmitting transducers with the same polarity in the fourth sub-group of transmitting transducers; the polarity of the two receivers is respectively the same as that of the transmitting transducers at the two sides of the receivers, the two signal data are superposed to obtain a fourth in-phase component signal, and specifically, the two signal data are subtracted to obtain the fourth in-phase component signal.
When four-direction reception is adopted for the third and fourth transmission signals:
in the first group of receiving transducer arrays, four receivers in each array record data simultaneously, the polarity of each receiver is the same as that of a transmitting transducer on the same axis, namely two positive polarities and two negative polarities, the four signals are superposed simultaneously to obtain a third or fourth in-phase component signal, and specifically, the difference value of the two positive polarities and the difference value of the two negative polarities are subtracted to obtain the third or fourth in-phase component signal.
And 108, respectively calculating the first in-phase component signal, the second in-phase component signal, the third in-phase component signal and the fourth in-phase component signal to obtain a first transverse wave velocity, a second transverse wave velocity, a third transverse wave velocity and a fourth transverse wave velocity.
Specifically, when the receiving transducer receives a signal transmitted by the same transmitting transducer, the path through which the transmitting signal passes is different, so that the receiving signal has a certain time delay; obtaining the time difference of receiving and transmitting signals according to the correlation among the receiving signals; and obtaining the transverse wave speed by the distance between the receiving transducers and the obtained time difference.
And respectively carrying out the calculation on the obtained first in-phase component signal, second in-phase component signal, third in-phase component signal and fourth in-phase component signal to obtain a first transverse wave velocity, a second transverse wave velocity, a third transverse wave velocity and a fourth transverse wave velocity.
In the process of processing the waveforms of the first in-phase component signal, the second in-phase component signal, the third in-phase component signal and the fourth in-phase component signal, a derivative of the transverse wave velocity is obtained by generally adopting a waveform inversion method; if necessary, the first in-phase component signal, the second in-phase component signal, the third in-phase component signal and the fourth in-phase component signal may also be filtered and subjected to dispersion correction, so as to filter some interference signals.
And step 109, obtaining a first speed difference and a second speed difference according to the first shear wave speed, the second shear wave speed, the third shear wave speed and the fourth shear wave speed.
Specifically, subtracting the first shear wave velocity from the second shear wave velocity, and then taking an absolute value to obtain a first velocity difference; and subtracting the fourth shear wave speed from the third shear wave speed, and then taking an absolute value to obtain a second speed difference.
And step 110, determining a formation anisotropy parameter according to the first shear wave velocity, the second shear wave velocity, the third shear wave velocity and the fourth shear wave velocity.
Specifically, the anisotropic parameters may include the magnitude of the fast shear wave velocity, the magnitude of the slow shear wave velocity, and the angle between the fast shear wave velocity and the direction of the predetermined subset of crossed dipole transmitting transducers, i.e. the azimuth angle.
When the first speed difference and the second speed difference are both zero, the magnitude and the direction of the fast and slow transverse wave speeds are both zero. Within the tolerance range, when the first speed difference and the second speed difference are both close to zero, the formation is not obviously anisotropic.
When the first speed difference and the second speed difference are relatively close in value and are not zero, the fast transverse wave speed can be any transverse wave speed of the first transverse wave speed and the second transverse wave speed, and the slow transverse wave speed is the corresponding other transverse wave speed; or the fast shear wave speed may be any one of the third shear wave speed and the fourth shear wave speed, and the slow shear wave speed may be the corresponding other shear wave speed.
If the first speed difference is obviously greater than the second speed difference, or the second speed difference is obviously greater than the first speed difference, the fast shear wave speed is the larger one of the first shear wave speed, the second shear wave speed or the third shear wave speed, and the fourth shear wave speed, and the slow shear wave speed is the smaller one of the first shear wave speed, the second shear wave speed or the third shear wave speed, and the fourth shear wave speed.
In one embodiment, the first velocity difference is greater than the second velocity difference, the first shear wave velocity is greater than the second shear wave velocity, and the fast shear wave velocity is equal to the first shear wave velocity, the slow shear wave velocity, and the like.
In another embodiment, the first velocity difference is greater than the second velocity difference, the second shear wave velocity is greater than said first shear wave velocity, the fast shear wave velocity is equal to said second shear wave velocity, and the slow shear wave velocity is equal to said first shear wave velocity.
In another embodiment, the second velocity difference is greater than the first velocity difference, the third shear wave velocity is greater than the fourth shear wave velocity, the fast shear wave velocity is equal to the third shear wave velocity, and the slow shear wave velocity is equal to the fourth shear wave velocity.
In other embodiments, the second velocity difference is greater than the first velocity difference, the fourth shear wave velocity is greater than the third shear wave velocity, the fast shear wave velocity is equal to the fourth shear wave velocity, and the slow shear wave velocity is equal to the third shear wave velocity.
In other embodiments, when the first velocity difference and the second velocity difference are both zero, the fast and slow shear wave velocities are equal to any one of the first shear wave velocity, the second shear wave velocity, the third shear wave velocity, or the fourth shear wave velocity, and the formation has no azimuthal anisotropy.
Therefore, the invention provides a phase-controlled double-cross dipole well logging method, which can better detect the anisotropy of the stratum azimuth under the conditions of lower signal-to-noise ratio and weak anisotropy by using one group of orthogonal dipole transmitting transducers and one group (two groups) of receiving transducers. Meanwhile, the size of the formation anisotropy can be directly given, the range of an included angle between the azimuth angle of the anisotropy and a group of dipole in-phase components with strong anisotropy can be controlled within a transformation range of 45 degrees, and the azimuth angle can be quickly and reliably determined through a processing method.
A cross-dipole transmission logging method according to one embodiment is further described below with reference to the accompanying drawings.
The embodiment of the invention provides two double-cross dipole well logging devices to realize the dipole well logging method provided by the first embodiment, as shown in fig. 3 and 4.
Fig. 3 is a schematic structural diagram of a double cross dipole logging provided in the second embodiment of the present invention.
As shown in fig. 3, the phased double cross dipole instrument includes 4 azimuth transmitting transducers and 4 azimuth receiving transducers. One group of cross dipole transmitting transducers work in the same mode as that in figure 1, the other group of cross dipoles work in the same mode as that in the figure, the two figures at the upper part are respectively a corresponding group of dipole transmitting and receiving mode combinations, and the two figures at the lower part are respectively a corresponding other group of dipole transmitting and receiving mode combinations. It can be seen that in the second set of cross dipole modes, each dipole transmit and receive would use all 4 transmit and receive transducers.
Fig. 4 is a schematic diagram of another dual-cross dipole logging structure according to the second embodiment of the present invention.
As shown in fig. 4, the phased double cross dipole instrument includes 4 orientations of transmit transducers and 8 orientations of receive transducers. One group of cross dipole transmitting transducers work in the same mode as that in figure 1, the other group of cross dipoles work in the same mode as that in the figure, the two figures at the upper part are respectively a corresponding group of dipole transmitting and receiving mode combinations, and the two figures at the lower part are respectively a corresponding other group of dipole transmitting and receiving mode combinations. It can be seen that in the second set of cross dipole modes, each dipole transmission will use all 4 transmissions, while reception requires only two receiving transducers.
Fig. 5a and 5b are directivity diagrams of simulation and actual test of four-directional transmission in fig. 3 and 4 by means of polarity control. This figure is a directivity pattern of a 4-azimuth dipole transmitting transducer excited in infinite water in the manner of the connection at the upper left of fig. 3 and 4, fig. 5a being a simulation of four perfectly identical ideal sound sources, and fig. 5b being a test result of an actual transducer in a water pool.
FIG. 6 is a graph comparing results of a tetragonal emission with a set of dipole emissions in a horizontally transversely isotropic medium. The black line (a 45 ° azimuth dispole) is the result of transmitting and receiving in the lower part of fig. 3, and the gray line (Two dipoles with 0 ° and 90 ° azimuths) is the result of transmitting and receiving in the manner of fig. 1 and switching the angle of transmission to reception to the orientation of the lower Two middle lines of the same polarity of fig. 3. The two are identical in time and phase, with a certain difference in amplitude. Through simulation, the amplitude of the signal can be improved under the same condition by a phase control mode.
The invention provides a phase-control double-cross dipole well logging method, which can better detect the anisotropy of the stratum orientation under the conditions of lower signal-to-noise ratio and weak anisotropy by controlling the polarity and the amplitude of an orthogonal dipole transmitting transducer.
Therefore, the invention provides a double-cross dipole logging method, which can directly give the size of the formation anisotropy by using two groups of angle intervals as an orthogonal dipole transmitting transducer and two groups of receiving transducer arrays, can also control the included angle range of an anisotropic azimuth angle and a group of dipole in-phase components with stronger anisotropy within a transformation range of 45 degrees, and can quickly and reliably determine the azimuth angle by using a processing method.
Those of skill would further appreciate that the various illustrative components and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied in hardware, a software module executed by a processor, or a combination of the two. A software module may reside in Random Access Memory (RAM), memory, Read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (9)
1. A phase-controlled double-cross dipole logging method, comprising:
arranging at least one group of transmitting transducers in a first area of a logging instrument, wherein a first group of transmitting transducers in the at least one group of transmitting transducers comprises four transmitting transducers which are distributed on the circumference of a first plane perpendicular to the axis of the instrument at equal intervals;
at least one group of receiving transducer arrays are arranged in a second area of the logging instrument, wherein one group of receiving transducer arrays of the at least one group of receiving transducer arrays comprises a first group of receiving transducers and a second group of receiving transducers, the first group of receiving transducers and the second group of receiving transducers are respectively distributed on a second plane at equal intervals, and the second plane is parallel to the first plane; wherein the first set of receiving transducers comprises four receiving transducers; the second set of receiving transducers comprises four receiving transducers;
sequentially exciting a first sub-group of transmitting transducers, a second sub-group of transmitting transducers, a third sub-group of transmitting transducers and a fourth sub-group of transmitting transducers to obtain a first transmitting signal, a second transmitting signal, a third transmitting signal and a fourth transmitting signal; wherein the first sub-group of transmitting transducers comprises two transmitting transducers with an included angle of 180 degrees in the first group of transmitting transducers; the second subset of transmitting transducers comprises the remaining two transmitting transducers of one of the at least one set of transmitting transducers except for the first subset of transducers; the third subset of transmit transducers comprises the first set of transmit transducers; the fourth subset of transmit transducers comprises the first set of transmit transducers;
the receiving transducer respectively receives the first transmitting signal, the second transmitting signal, the third transmitting signal and the fourth transmitting signal in sequence.
2. A method as claimed in claim 1, wherein the step of sequentially exciting the first, second, third and fourth subsets of transmitting transducers to obtain the first, second, third and fourth transmitting signals comprises:
applying excitation with opposite polarities to two transmitting transducers which are included in the first group of transmitting transducers and have an included angle of 180 degrees with each other in the first sub-group of transmitting transducers to generate a first transmitting signal;
applying excitation with opposite polarities to two transmitting transducers which are included in the second sub-group of transmitting transducers and have the included angles of 180 degrees with each other, and generating a second transmitting signal;
applying the same polarity to two transmitting transducers in a pair of 90 degrees included angles in the first group of transmitting transducers, and applying the opposite polarity to the same polarity to two transmitting transducers in the other pair in the first group of transmitting transducers; generating a third transmit signal;
and keeping the polarity of two transmitting transducers forming an included angle of 180 degrees in the third sub-group of transmitting transducers unchanged, and changing the polarity of two transmitting transducers of the other pair in the third sub-group of transmitting transducers to form a fourth sub-group of transmitting transducers to generate a fourth transmitting transducer.
3. A method as claimed in claim 2, wherein the step of sequentially exciting the first, second, third and fourth subsets of transmitting transducers to obtain the first, second, third and fourth transmit signals further comprises:
respectively and sequentially receiving the first transmitting signal, the second transmitting signal, the third transmitting signal and the fourth transmitting signal by the receiving transducer to perform signal processing to obtain a first in-phase component signal, a second in-phase component signal, a third in-phase component signal and a fourth in-phase component signal;
calculating to obtain a first shear wave velocity, a second shear wave velocity, a third shear wave velocity and a fourth shear wave velocity according to the first in-phase component signal, the second in-phase component signal, the third in-phase component signal and the fourth in-phase component signal;
and determining a formation anisotropy parameter according to the first shear wave velocity, the second shear wave velocity, the third shear wave velocity and the fourth shear wave velocity.
4. A method as claimed in claim 1, wherein adjacent two receiving transducers of the first set of receiving transducers are angled at 90 degrees; and an included angle between any receiving transducer in the second group of receiving transducers and any receiving transducer in the first group of receiving transducers is 45 degrees.
5. A logging method according to claim 3, wherein when only the first group of receiving transducers receives, the receiving transducers respectively receive the first transmitting signal, the second transmitting signal, the third transmitting signal and the fourth transmitting signal in sequence, and perform signal processing to obtain a first in-phase component signal, a second in-phase component signal, a third in-phase component signal and a fourth in-phase component signal, specifically:
superposing the first group of receiving transducer arrays and first transmitting signals respectively received by receiving transducers arranged in parallel with the first sub-group of transmitting transducers to obtain first in-phase component signals;
superposing second transmitting signals respectively received by the first group of receiving transducer arrays and the receiving transducers arranged in parallel with the second subgroup of transmitting transducers to obtain second in-phase component signals;
recording all data received by four receiving transducers in the first group of receiving transducer arrays, wherein the polarity of each receiver is the same as that of a transmitting transducer on the same axis, and then superposing signals of the four receivers to obtain a third in-phase component signal;
and recording all four receivers in the first group of receiving transducer arrays, wherein the polarity of each receiver is the same as that of a transmitting transducer on the same axis, and then superposing the four receiver signals to obtain a fourth in-phase component signal.
6. A logging method according to claim 3, wherein when there is reception by the second group of receiving transducers, the receiving transducers respectively receive the first transmitting signal, the second transmitting signal, the third transmitting signal and the fourth transmitting signal in sequence and perform signal processing to obtain a first in-phase component signal, a second in-phase component signal, a third in-phase component signal and a fourth in-phase component signal, specifically:
superposing the first group of receiving transducer arrays and first transmitting signals respectively received by receiving transducers arranged in parallel with the first sub-group of transmitting transducers to obtain first in-phase component signals;
superposing second transmitting signals respectively received by the first group of receiving transducer arrays and the receiving transducers arranged in parallel with the second subgroup of transmitting transducers to obtain second in-phase component signals;
respectively receiving the third transmitting signals by the two receiving transducers of the second group of receiving transducer arrays and the two receiving transducers at the angular bisector of the transmitting transducers with the same polarity in the third sub-group of transmitting transducers, and superposing to obtain third in-phase component signals;
and respectively receiving the fourth transmitting signals by the two receiving transducers of the second group of receiving transducer arrays and the angular bisector of the transmitting transducer with the same polarity in the fourth sub-group of transmitting transducers, and superposing to obtain a fourth in-phase component signal.
7. A logging method according to any of claims 5 or 6, wherein a first shear velocity, a second shear velocity, a third shear velocity and a fourth shear velocity are calculated from the first in-phase component signal, the second in-phase component signal, the third in-phase component signal and the fourth in-phase component signal, in particular:
and respectively carrying out speed or time difference extraction on the first in-phase component signal, the second in-phase component signal, the third in-phase component signal and the fourth in-phase component signal by adopting a waveform inversion method and/or filtering and frequency dispersion correction to obtain a first transverse wave speed, a second transverse wave speed, a third transverse wave speed and a fourth transverse wave speed.
8. A method as defined in claim 7, wherein after performing velocity or time difference extraction on the first in-phase component signal, the second in-phase component signal, the third in-phase component signal, and the fourth in-phase component signal to obtain the first shear velocity, the second shear velocity, the third shear velocity, and the fourth shear velocity, respectively, the method further comprises:
subtracting the first shear wave velocity from the second shear wave velocity, and taking an absolute value to obtain a first velocity difference;
and subtracting the fourth shear wave speed from the third shear wave speed, and taking an absolute value to obtain a second speed difference.
9. A method as claimed in claim 3, wherein the formation anisotropy parameters include magnitude of fast transverse wave velocity, magnitude of slow transverse wave velocity, and angle between direction of geomagnetic north and direction of fast transverse wave; the determining of the formation anisotropy parameters according to the first shear wave velocity, the second shear wave velocity, the third shear wave velocity and the fourth shear wave velocity specifically comprises the following steps:
when the first speed difference is larger than the second speed difference, if the first shear wave speed is larger than the second shear wave speed, the fast shear wave speed is equal to the first shear wave speed, and the slow shear wave speed is equal to the second shear wave speed; or
If the second shear wave velocity is greater than the first shear wave velocity, the fast shear wave velocity is equal to the second shear wave velocity, and the slow shear wave velocity is equal to the first shear wave velocity;
when the second speed difference is greater than the first speed difference, if the third shear wave speed is greater than the fourth shear wave speed, the fast shear wave speed is equal to the third shear wave speed, and the slow shear wave speed is equal to the fourth shear wave speed; or
If the fourth shear wave velocity is greater than the third shear wave velocity, the fast shear wave velocity is equal to the fourth shear wave velocity, and the slow shear wave velocity is equal to the third shear wave velocity;
when the first speed difference and the second speed difference are both zero, the fast shear wave speed and the slow shear wave speed are equal to any one of the first shear wave speed, the second shear wave speed, the third shear wave speed or the fourth shear wave speed, and the stratum has no azimuthal anisotropy.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1621860A (en) * | 2003-11-24 | 2005-06-01 | 中国石油天然气集团公司 | Multipolar acoustic velocity log transmitting transducer |
| CN103147747A (en) * | 2013-03-29 | 2013-06-12 | 中国石油大学(华东) | Acoustic logging-while-drilling device and acoustic logging-while-drilling method |
| EP2506039A3 (en) * | 2011-03-28 | 2013-08-14 | Conocophillips Company | Methods for Seismic Fracture Parameter Estimation and Gas Filled Fracture Identification From Vertical Well Log Data |
| CN104481526A (en) * | 2014-12-08 | 2015-04-01 | 中国科学院声学研究所 | Double-cross dipole well-logging method |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US7529150B2 (en) * | 2006-02-06 | 2009-05-05 | Precision Energy Services, Ltd. | Borehole apparatus and methods for simultaneous multimode excitation and reception to determine elastic wave velocities, elastic modulii, degree of anisotropy and elastic symmetry configurations |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1621860A (en) * | 2003-11-24 | 2005-06-01 | 中国石油天然气集团公司 | Multipolar acoustic velocity log transmitting transducer |
| EP2506039A3 (en) * | 2011-03-28 | 2013-08-14 | Conocophillips Company | Methods for Seismic Fracture Parameter Estimation and Gas Filled Fracture Identification From Vertical Well Log Data |
| CN103147747A (en) * | 2013-03-29 | 2013-06-12 | 中国石油大学(华东) | Acoustic logging-while-drilling device and acoustic logging-while-drilling method |
| CN104481526A (en) * | 2014-12-08 | 2015-04-01 | 中国科学院声学研究所 | Double-cross dipole well-logging method |
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