CN210289767U - Borehole three-component acoustic remote detection logging device - Google Patents
Borehole three-component acoustic remote detection logging device Download PDFInfo
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- CN210289767U CN210289767U CN201920856510.7U CN201920856510U CN210289767U CN 210289767 U CN210289767 U CN 210289767U CN 201920856510 U CN201920856510 U CN 201920856510U CN 210289767 U CN210289767 U CN 210289767U
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Abstract
The utility model provides an underground three-component sound wave far detection logging device, wherein an underground sound wave far detection instrument comprises a spiral pipe shape formed by winding spirally wound high-temperature resistant optical fibers on the outer side of a cylinder structure; the lower part of the cylindrical structure is vertically and sequentially provided with a fiber optic gyroscope and an underground array type sound source generator; the ground wellhead logging truck controls the underground sound wave remote detection instrument to go down and rise, provides power for the underground sound wave remote detection instrument, and drives the underground array type sound source generator to continuously and repeatedly transmit sound wave signals during operation; the ground DAS is connected with the spirally wound high-temperature-resistant optical fiber, laser pulses are emitted into the spirally wound high-temperature-resistant optical fiber, and backward scattering Rayleigh waves in the spirally wound high-temperature-resistant optical fiber are collected. The utility model provides a logging device is surveyed far to three-component sound wave in well can work for a long time under the high temperature, realizes the function of high-speed upwards transmission data.
Description
Technical Field
The utility model relates to a geophysical exploration technical field especially relates to a well three-component sound wave far detection logging device based on distributed optical fiber sensing technique.
Background
Sonic logging refers to a logging method for determining the quality of well cementing by studying the geological profile of a borehole using the differences in acoustic properties such as velocity, amplitude and frequency variations of a sound wave as it propagates through different rocks.
A controlled acoustic vibration source is placed in the well, and acoustic waves emitted by the acoustic source cause vibration of surrounding particles, bulk waves, i.e., longitudinal waves and transverse waves, are generated in the formation, and induced interfacial waves, i.e., pseudo-Rayleigh waves and Stoneley waves, are generated at the well wall-drilling fluid interface. These waves are used as carriers of formation information, received by downhole receivers, sent to the surface for recording, and are used for acoustic logging. The receivers and the sound sources are collectively called as a sound system, and the acoustic logging instruments can be divided into a compensated logging instrument (BHC), a long-source-distance acoustic logging instrument (LSS) and an array acoustic logging instrument according to the difference of arrangement and size of the sound system. The speed, amplitude and even frequency of the wave that propagates in the formation in the well changes due to changes in the rock composition, structure, and fluid composition in the pores of the formation. Sonic logging is divided into sonic logging and acoustic amplitude logging. Recording only changes in acoustic velocity is called sonic logging (AC), while recording changes in acoustic amplitude is called acoustic amplitude logging. In the acoustic velocity logging, a short-source acoustic system only records the propagation time difference of longitudinal waves (namely, head waves), a long-source distance acoustic system can record the propagation time difference of various wavetrains such as longitudinal waves, transverse waves, pseudo-Rayleigh waves, Stoneley waves and the like, so the acoustic velocity logging is also called full-wave acoustic logging, and an array acoustic instrument can record the sound velocity of the longitudinal waves, the sound velocity of the full wavetrain and the sound amplitude due to the complex acoustic system.
Sonic logging measures the formation acoustic velocity. The formation acoustic velocity is related to factors such as the lithology, porosity, and pore fluid properties of the formation. According to the propagation speed of the sound wave in the stratum, the porosity and lithology of the stratum, namely the property of pore fluid, can be determined. Sonic velocity logging can be used to classify lithology, determine porosity of oil and gas reservoirs, and to classify gas reservoirs, and can also provide velocity data necessary for seismic exploration.
The acoustic velocity logging is called acoustic velocity logging for short, and records the time required for the acoustic wave to pass through a 1 m rock stratum, and measures the time difference △ t (reciprocal of the longitudinal wave velocity of the stratum) of the formation gliding wave.
Based on the conventional acoustic logging and data processing method, stratum information within a range of several meters outside a well can be obtained, and with the demand of exploration and development, the acoustic logging can not meet the application demand only by providing information within a range of several meters around the well. One important advance in single well reflected acoustic far detection technology in recent years has been the use of dipole acoustic detection instruments to transmit and receive reflected signals deep in the formation. The characteristic that the emission frequency of an orthogonal dipole probe in the multi-pole array acoustic logging is low is utilized, the transmission is far in the stratum, the measured four-component data can reflect the information of the far stratum, the dipole component data processing and analyzing method of the far detection acoustic logging is utilized, the information of cracks and holes in the stratum far away from a borehole can be analyzed and obtained, the stratum structure information of a few meters to dozens of meters around the borehole can also be obtained, and then the direction, the inclination angle and the distribution of the cracks and holes in the stratum can be known.
The characteristics of well logging and seismic exploration are comprehensively considered, non-uniform waves which are transmitted along the well wall and recorded by sound wave logging are changed into reflected waves of the outer layer interface of the well, the frequency of a sound source is reduced, and layer interface information of 10-15 m outside the well wall can be expected to be obtained. Therefore, a new well logging method, namely remote detection acoustic reflection wave well logging, is provided. Transmitting low frequency acoustic signals downhole, receiving reflected waves in seismic exploration has been confirmed from theoretical and actual well log data interpretation. The acoustic probe is excited by a narrow pulse with a large amplitude (4000V), so that a low-frequency acoustic signal with the frequency close to 10kHz and capable of being used for remote detection of reflected wave acoustic logging can be obtained. To receive the low frequency reflected wave signal, a receiving probe having a lower resonant frequency is selected.
An azimuth far detection acoustic imaging logging instrument (also called a far detection azimuth reflection acoustic logging instrument) is a new generation acoustic imaging logging instrument which can detect formations far away from the periphery of a borehole. The azimuth far detection reflection acoustic wave imaging logging instrument utilizes the measured reflection wave information to identify the reflector in the far distance range beside the well and quantitatively analyze the distance and the azimuth of the reflector from the shaft. The instrument adopts a phased array high-power transmitting technology, a direction array receiving technology and an original direct pressure-bearing type active transmitting and receiving sound system structure, so that the instrument can detect a reflector at a direction more than 40m away from a shaft, and the direction resolution is 22.5 degrees. The instrument has the advantages that the measurement principle, the structural design and characteristics, the performance parameters, the method simulation experiment and the field test verify the effect, the defects of too shallow logging detection depth and low seismic exploration resolution are effectively overcome, and a new technology is provided for the fine description of deep complex oil and gas reservoirs.
The existing underground sound wave far detection instrument uses a monopole or dipole or multipole piezoelectric sound wave transducer to receive a reflected wave signal which is reflected back to the borehole from a wave impedance interface far away from the borehole, and the monopole or dipole or multipole piezoelectric sound wave transducer and a matched amplifier, an analog-to-digital conversion and data storage device, an underground data transmission module and the like cannot work for a long time in a high-temperature environment (deep well). In addition, as the underground sound wave remote detection instruments are all electronic instruments at present, the underground data transmission module of the underground sound wave remote detection instrument can not solve the bottleneck problem that underground big data are transmitted to a control computer in a well logging truck at a high speed at a well head in real time at present.
SUMMERY OF THE UTILITY MODEL
The utility model aims at providing a well three-component sound wave far detection logging device based on distributed optical fiber sound wave sensing technique mainly is with installing the high temperature resistant optic fibre according to the spiral coiling in array sound source generator top in the pit, replaces present widely used monopole or dipole or multipolar piezoelectric type sound wave transducer, receives the sound wave signal of reflecting from the wave impedance interface of the more distant department of well distance to realize the purpose of sound wave far detection in the pit.
The technical scheme of the utility model:
the borehole three-component acoustic far detection logging device comprises a borehole acoustic far detection instrument, a ground wellhead logging truck and a ground DAS modulation and demodulation instrument;
the underground sound wave far detection instrument comprises a cylindrical structure and spirally wound high-temperature-resistant optical fibers, wherein the spirally wound high-temperature-resistant optical fibers are wound on the outer side of the cylindrical structure and are in a spiral pipe shape and serve as an underground sound wave signal receiving unit; the lower part of the cylindrical structure is vertically and sequentially provided with a fiber optic gyroscope and an underground array type sound source generator; the ground wellhead logging truck is connected with the underground array type sound source generator and the optical fiber gyroscope through the armored photoelectric composite cable;
the ground wellhead logging truck controls the underground sound wave remote detection instrument to go down and rise, provides power for the underground sound wave remote detection instrument, and drives the underground array type sound source generator to continuously and repeatedly transmit sound wave signals during operation;
a ground DAS modulation and demodulation instrument arranged at a wellhead is connected with a spirally wound high-temperature resistant optical fiber through an armored photoelectric composite cable, laser pulses are emitted into the spirally wound high-temperature resistant optical fiber, and backscattered Rayleigh waves in the spirally wound high-temperature resistant optical fiber under the well are collected.
The utility model discloses array sound source generator in pit can be for array monopole, dipole or multipolar piezoceramics (crystal), electric spark source, electromechanical focus, sound source generators such as controllable focus in the pit, and the high temperature resistant optic fibre of the spiral coiling of array sound source generator top in pit replaces monopole or dipole or multipolar piezoelectric type sound wave transducer of present wide use. The underground array type sound source generator continuously and repeatedly transmits high-power sound wave signals to underground media around a borehole under the action of ground control signals and driving signals, low-frequency sound wave signals transmitted by a transmitting source are reflected back to the borehole at a reflection angle which is the same as an incident angle according to the Feliell's law after being transmitted to a wave impedance interface (a reflection surface) around the borehole, and the sound wave signals reflected back by the wave impedance interface at a position far away from the borehole can be received by the high-temperature-resistant optical fiber which is spirally wound above the underground array type sound source generator, so that the aim of underground sound wave remote detection is fulfilled. When the reflected sound wave reaches the borehole and acts on the high-temperature resistant optical fiber, the fluctuation signal of the reflected wave can cause the spirally wound high-temperature resistant optical fiber to generate strain (stretching or compressing), so that the phase of the backward Rayleigh scattering wave in the high-temperature resistant optical fiber is changed with the same frequency as the fluctuation signal. The collected phase data of the backward Rayleigh scattered waves are modulated and demodulated through hardware and software in a DAS modulation and demodulation instrument which is connected with spirally wound high-temperature resistant optical fibers near a ground wellhead, and then the phase change of the backward Rayleigh scattered waves can be converted into a fluctuation signal of reflected sound waves. By further processing and interpreting the reflected acoustic signals (data), the distance and the orientation of the far wave impedance interface from the borehole, the acoustic velocity of the media on both sides of the wave impedance interface, the elastic parameter characteristic or the viscoelastic parameter characteristic of the media on both sides, the lithology, the porosity, the permeability, the type and the saturation of the fluid in the pore of the underground medium outside the borehole, and the distribution rule of different fluids in the underground medium can be known.
The high-temperature resistant optical fiber wound spirally in the underground sound wave far detection instrument can completely collect reflected sound wave signals reflected remotely in a high-temperature deep well for a long time, and solves the problem that an underground monopole or dipole or multipole piezoelectric sound wave transducer, an amplifier, an analog-to-digital conversion and data storage device, an underground data transmission module and the like cannot work at high temperature for a long time. The spirally wound high-temperature-resistant optical fiber positioned in the armored photoelectric composite cable 5 can transmit backward Rayleigh scattering optical signals in the spirally wound high-temperature-resistant optical fiber to a ground DAS modulation and demodulation instrument at a high speed, and the bottleneck problem that a large amount of electrical signal data acquired by an underground logging instrument is difficult to realize high-speed upward transmission is solved.
The high-temperature resistant optical fiber is wound according to a spiral shape, the inside of the high-temperature resistant optical fiber is of a cylinder structure with the diameter of several centimeters, the cylinder structure is made of a solid or hollow composite material which can be curled or is made of a hollow metal pipe which can be curled, the high-temperature resistant single-mode or multi-mode optical fiber is wound on the cylinder structure according to a certain angle, the winding angle is 10-80 degrees, one or more layers of protective sleeves are sleeved outside the cylinder structure which is wound with the high-temperature resistant optical fiber according to the spiral shape, and the outermost layer is a metal or composite material armor which is resistant to compression and stretching and used for protecting the high-temperature resistant optical fiber wound on the cylinder structure according to the spiral shape from being damaged in.
The optical fiber gyroscope, namely an optical fiber inertial navigation directional positioning system is arranged between the high-temperature resistant optical fiber wound according to the spiral shape and the underground array type sound source generator. When the underground sound wave far detection instrument works, the optical fiber gyroscope synchronously records the real-time position, speed and attitude information of the underground array sound source generator and the high-temperature resistant optical fiber wound according to the spiral shape. When the underground sound wave far detection instrument is in communication connection with the multi-channel control and data acquisition subsystem in the ground logging truck, the underground sound wave far detection instrument uploads actually measured underground sound wave logging data to the ground control and data acquisition processing subsystem, and the optical fiber gyroscope uploads the actually measured real-time position, speed and attitude information of the underground array sound source generator and the high-temperature-resistant optical fiber wound according to the spiral shape to the ground control and data acquisition processing subsystem. The real-time position, speed and attitude information of the underground array sound source generator recorded by the optical fiber gyroscope in real time and the high-temperature resistant optical fiber wound according to the spiral shape are used for positioning and orienting underground remote detection sound wave data acquired by the system so as to identify the position and specific direction of a wave impedance interface far away from a borehole, and accurate and reliable detection of an underground target far away from the borehole is realized.
The ground DAS modulation and demodulation instrument is a high-performance phase demodulation-based time domain optical reflectometer phi-OTDR technology. And the method adopts the technology of injecting subcarriers, high energy, high extinction ratio, high optical signal-to-noise ratio and high coherent light pulse into the optical fiber to realize high-performance phi-OTDR technology so as to accurately extract phase change information from extremely weak Rayleigh scattering interference signals. In addition, a novel long-period fiber grating filter is introduced into the erbium-doped fiber amplifier to realize a low-noise optical amplification technology, so that the noise of optical signal amplification in a DAS modulation and demodulation instrument system is effectively reduced to improve the optical signal-to-noise ratio. Meanwhile, a multi-frequency, high-coherence and low-noise detection light pulse is adopted to realize a multi-frequency light pulse anti-attenuation technology so as to effectively inhibit the degradation influence of Rayleigh scattering signal random fading on the system performance. And finally, a feedback control circuit is introduced to carry out feedback control, so that the interferometer always works in a stable optical path difference state, and the influence of an external interference signal on the system stability and the signal fidelity is effectively inhibited by utilizing an interferometer active stabilization technology.
The trigger signal for triggering the ground DAS to start synchronous acquisition of three-component borehole acoustic data while the ground DAS is excited by the borehole acoustic source is a signal consistent with the trigger signal of the borehole acoustic emission source sent by the acoustic logging instrument on the logging truck, and can be directly sent to the trigger port of the ground DAS in a wired or wireless mode to serve as the trigger signal for starting the DAS to acquire the borehole acoustic data.
Three-component acoustic wave data distributed at each position of the spirally wound high-temperature resistant optical fiber can be obtained by carrying out modulation and demodulation processing on phase data of Rayleigh scattering light reflected from the spirally wound high-temperature resistant optical fiber acquired by a ground DAS modulation and demodulation instrument. According to the distance from any one wave detection point on the high-temperature resistant optical fiber wound according to the spiral shape to each sound source point, and the data of direct longitudinal wave travel time, direct transverse wave travel time, refracted wave travel time of the wave impedance interface outside the borehole and reflected wave travel time of the wave impedance interface reflected to the wave detection point are detected from the wave detection point, the longitudinal wave velocity, the transverse wave velocity, the velocity anisotropy of the longitudinal wave velocity and the transverse wave velocity in different directions of the underground medium, the attenuation coefficients (characteristics) of the longitudinal wave and the transverse wave propagating in the underground medium, the distance, the position and the direction of a wave impedance interface far away from a borehole can be obtained through inversion calculation, and then a two-dimensional or three-dimensional sound wave velocity model of the underground medium and a two-dimensional or three-dimensional elastic or viscoelastic parameter model of the underground medium are precisely and accurately established.
Therefore the utility model discloses still provide the measuring method of this well three-component sound wave far detection logging device, including following step:
s1: processing sound wave data acquired at the position of each underground spirally wound high-temperature-resistant optical fiber;
s2: calculating the average speed of sound waves from the known sound source point to each known detection point according to the travel time of direct sound waves from the position of the underground array type sound source generator to each optical fiber detection point and the distance from the position of the underground array type sound source generator to the known detection point;
s3: calculating the speed of the vertical longitudinal wave and the horizontal longitudinal wave of the sound wave at the position of the detection point according to the travel time of the direct wave which is excited at the position of the sound source and propagates upwards and the distance from the reflected wave which propagates into the borehole to the reflection point on the wave impedance interface which is wound according to the spiral shape and is far away from the borehole;
if the data processing personnel picks up the travel time of the sound wave directly reaching the longitudinal wave, the average speed of the longitudinal wave is calculated;
if the travel time of the sound wave directly reaching the transverse wave is picked up, the average speed of the transverse wave is calculated;
s4: if the acoustic velocity of the surrounding medium downhole is uniform, then the velocity of the longitudinal or transverse waves propagating vertically and horizontally across the well profile will be the same, with no velocity anisotropy; if the acoustic wave velocity of the underground medium is non-uniform, the vertical acoustic wave velocity measured at the downhole pickup point is different from the velocity of the acoustic wave incident in the horizontal direction or near horizontal direction or at a large angle; according to the phenomenon that the speeds of the sound waves propagating in the same medium along different directions are inconsistent, the anisotropy of the two-dimensional vertical speed and the horizontal speed of the sound wave speed along the cross section of the well is calculated;
if the sound wave speed of the underground medium is uniform, the sound wave speed of longitudinal waves or transverse waves which are vertically propagated and propagated along the peripheral horizontal direction is the same, and the velocity anisotropy does not exist, if the sound wave speed of the underground medium is non-uniform, the vertical sound wave speed measured at the position of a downhole receiving point is different from the velocity of sound waves which are incident to a borehole from the peripheral horizontal direction or a large angle, and the velocity anisotropy and the distribution characteristics of the sound wave velocity in a three-dimensional space around the borehole are calculated according to the phenomenon that the velocity of the sound waves propagated along different directions in the same medium is not uniform;
s5: for three-component sound wave data acquired along a wave detection point of a two-dimensional cross-well profile or three-component sound wave data acquired underground, a sound wave attenuation coefficient or a Q value of an underground medium can be calculated or extracted by a frequency spectrum ratio method, a centroid frequency shift method or a frequency spectrum fitting method according to the characteristics of the amplitude and the frequency spectrum change of the three-component sound wave recorded at different wave detection points.
The utility model has the advantages that:
the utility model provides a well three-component sound wave far detection logging device, the use is according to the high temperature resistant optic fibre of spiral coiling, can gather the long-distance reflection sound wave signal that returns in high temperature deep well the inside completely, need not any electron device and circuit in the pit, the difficult problem that monopole or dipole or multipolar piezoelectric type sound wave transducer and supporting high cost amplifier, analog-to-digital conversion and data storage device and data transmission module etc. can't work for a long time under the high temperature in the pit has been solved.
The high-temperature-resistant optical fiber wound according to the spiral shape and the high-temperature-resistant optical fiber in the underground armored photoelectric composite cable are the same optical fiber, backward Rayleigh scattering optical signals in the high-temperature-resistant optical fiber wound according to the spiral shape can be transmitted to a distributed optical fiber acoustic wave signal modulation and demodulation instrument (DAS) at the well head at a high speed, and the bottleneck problem that a large amount of electric signal data collected by an underground logging instrument are difficult to realize high-speed upward transmission is solved.
The utility model can greatly reduce the manufacturing cost of the equipment for collecting the three-component sound wave data underground, realize the high-efficiency collection of the three-component sound wave data underground with ultrahigh density or ultrahigh spatial resolution, the distance and the orientation of a wave impedance interface far away from a well hole, the medium acoustic wave speed on two sides of the wave impedance interface, the elastic parameter characteristic or the viscoelastic parameter characteristic of the media on the two sides can be known through processing and analysis, and the lithology, porosity, permeability, type and saturation of fluids in the pores of the subsurface media outside the wellbore, and the distribution rule of different fluids in the downhole medium, the information of cracks and holes in the stratum far away from the well bore and the information of the stratum structure of several meters to dozens of meters around the well can be obtained, and further knowing the orientation, inclination angle and distribution of cracks and holes in the stratum, and realizing the wide popularization and application of the acoustic logging remote detection technology.
Drawings
Fig. 1 is a schematic view of the working principle of the present invention.
Fig. 2 is a schematic diagram of the system structure of the present invention.
Fig. 3 shows the optical fiber wound spirally on the cylindrical structure AB and the sound wave propagated to the optical cable perpendicular to the direction of extension of the optical cable (AB direction) arranged in the vertical direction.
Fig. 4 shows the sound wave propagated to the optical cable according to the spiral winding high temperature resistant optical fiber and perpendicular to the optical cable extending direction (AB direction) on the cylindrical structure AB of the present invention.
Fig. 5 shows a high temperature resistant optical fiber wound in a spiral shape on a cylindrical structure AB and a sound wave propagated to the optical cable perpendicular to the direction of extension of the optical cable (AB direction) according to the present invention, which is developed on a plane.
Detailed Description
The invention will be further explained with reference to the drawings and the specific embodiments.
The following description of the embodiments of the present invention is provided to facilitate the understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and various changes may be made apparent to those skilled in the art within the spirit and scope of the present invention as defined and defined by the appended claims.
As shown in fig. 1 and fig. 2, the borehole three-component acoustic far detection logging apparatus includes a borehole acoustic far detection instrument, a surface wellhead logging truck 10, and a surface DAS modulation and demodulation instrument 11;
the underground acoustic far detection instrument comprises a cylindrical structure 1 and a high-temperature resistant optical fiber 2 wound according to a spiral shape, wherein the high-temperature resistant optical fiber 2 wound in the spiral shape is wound on the outer side of the cylindrical structure 1 to be in a spiral pipe shape and used as an underground acoustic signal receiving unit; the lower part of the cylindrical structure 1 is vertically provided with a fiber optic gyroscope 4 and an underground array type sound source generator 3; the device also comprises an armored photoelectric composite cable 5, wherein the armored photoelectric composite cable 5 is positioned in the cylindrical structure 1, and the ground wellhead logging truck 10 is connected with the underground array type sound source generator 3 and the optical fiber gyroscope 4 through the armored photoelectric composite cable 5; the ground DAS modulation and demodulation instrument 11 is connected with a high-temperature resistant optical fiber 2 which is wound on the outer side of the cylinder structure 1 and presents a spiral tube shape through an armored photoelectric composite cable 5.
The ground wellhead logging truck 10 controls the downhole and well-lifting of the downhole acoustic wave remote detection instrument, provides power for the downhole acoustic wave remote detection instrument, and drives the downhole array type acoustic source generator 3 to continuously and repeatedly emit acoustic signals during operation;
a ground DAS modulation and demodulation instrument 11 arranged at a wellhead is connected with a spirally wound high-temperature resistant optical fiber 2 through an armored photoelectric composite cable 5, emits laser pulses into the spirally wound high-temperature resistant optical fiber 2, and collects back scattering Rayleigh waves in the spirally wound high-temperature resistant optical fiber 2 underground.
During the specific construction, as shown in fig. 1 and fig. 2, a special technical process is firstly performed on the tail end of the spirally wound high-temperature resistant optical fiber 2, such as installing an extinction device or tying a knot on the optical fiber to eliminate the strong reflection signal of the optical fiber at the tail end point, and then the head end of the spirally wound high-temperature resistant optical fiber 2 is connected to the DAS modem 11 installed on the ground. The underground sound wave far detection instrument is lowered to the bottom of the well from the wellhead through an armored photoelectric composite cable 5, and then the underground sound wave far detection instrument and a ground DAS modulation and demodulation instrument 11 are started simultaneously; the ground wellhead logging truck 10 controls the underground array type sound source generator 3 in the underground sound wave remote detection instrument to continuously emit sound waves, the ground DAS modulation and demodulation instrument 11 synchronously starts to record direct sound waves, refracted sound waves, reflected sound waves, surface waves and multiple-order wave signals which are transmitted into a borehole from the medium around the borehole and received by the spirally wound high-temperature resistant optical fiber 2 according to a trigger signal from the underground sound wave remote detection instrument, and the optical fiber gyroscope 4 records the real-time position, speed and attitude information of the underground array type sound source generator 3 and the spirally wound high-temperature resistant optical fiber 2 in real time; and simultaneously starting a winch on a wellhead ground logging truck 10, slowly lifting the underground sound wave remote detection instrument upwards through the armored photoelectric composite cable 5, continuously acquiring underground sound wave signals by the underground sound wave remote detection instrument, stopping the work of the underground array type sound source generator 3 and the ground DAS modulation and demodulation instrument 11 after the well section needing to be measured by the pre-designed underground sound wave remote detection instrument is finished, and lifting the underground sound wave remote detection instrument out of a wellhead.
The underground sound wave signal receiving unit of the embodiment is a high-temperature resistant optical fiber 2 which is spirally wound and is arranged above the underground array sound source generator.
More specifically, the main control device may be a computer-controlled ground DAS modem 11, which controls the acquisition and storage of all (DAS) downhole three-component acoustic data in real time, i.e., the data acquisition device is connected to the main control device, and the acquisition and storage of (DAS) downhole three-component acoustic data are completed by the control operation of the main control device on the data acquisition device. The sensing of the underground three-component sound wave signals is realized by a high-temperature resistant optical fiber 2 which is arranged above an underground array sound source generator and wound according to a spiral shape, and the system can directly measure the two-dimensional or three-dimensional sound wave speed of an underground medium and calculate the two-dimensional or three-dimensional elasticity or viscoelasticity parameters of the underground medium (stratum or rock stratum).
The underground array type sound source generator 3 can be an array type monopole, dipole or multipole piezoelectric ceramic (crystal), an electric spark seismic source, an electromechanical seismic source, an underground controllable seismic source and other sound source generators;
the high-temperature resistant optical fiber 2 is spirally wound and arranged above the underground array type sound source generator 3 and is used for sensing direct sound wave, refracted sound wave, reflected sound wave, surface wave and multiple wave signals excited by the underground array type sound source generator;
the underground array type sound source generator 3 and the spirally wound high-temperature resistant optical fiber 2 are arranged in the middle of the underground acoustic far detection instrument, and are used for recording real-time position, speed and posture information of the underground array type sound source generator 3 and the spirally wound high-temperature resistant optical fiber 2 when underground acoustic data are collected;
a ground DAS (data acquisition System) modulation and demodulation instrument 11 connected with the head end of a spirally wound high-temperature resistant optical fiber 2 on the ground of a work area receives phase change information of backward Rayleigh scattered waves of each point on the optical fiber caused by wave propagation of sound waves in the spirally wound high-temperature resistant optical fiber 2, converts the received phase change information of the backward Rayleigh scattered waves of the optical fiber into actual fluctuation signals of the sound waves through a modulation and demodulation circuit and data processing software in the instrument, converts the analog fluctuation signals into digital fluctuation signals through an analog-to-digital conversion circuit, and then stores the digital fluctuation signals into a computer for subsequent data processing work.
As shown in FIG. 2, when the surface wellhead logging truck 10 controls and drives the downhole acoustic wave remote detection instrument, acoustic waves emitted by the downhole array type acoustic source generator 3 into the medium around the borehole are sensed by the high temperature resistant optical fiber 2 wound spirally downhole. Due to the presence of the wave impedance interface 6 remote from the borehole, the direct acoustic waves 7 propagating from the borehole will reflect from the wave impedance interface 6 back into the borehole after encountering the wave impedance interface 6, with the angle of reflection being the same as the angle of incidence according to snell's law. The reflected acoustic waves 8 reflected back into the borehole are sensed by the refractory fiber 2. When the high-temperature resistant optical fiber 2 senses direct sound waves 7, reflected sound waves 8 and refracted sound waves 9 which are transmitted in a medium around a well, strain (stretching or compression) with the same frequency is generated at each point (each position) on the high-temperature resistant optical fiber 2 wound according to the spiral shape along with the transmission of the sound wave, the strain can cause the phase of the backward Rayleigh scattered waves at each point (each position) in the high-temperature resistant optical fiber 2 wound according to the spiral shape to generate corresponding change, the ground DAS modulation and demodulation instrument 11 can detect the change of the phase, the received phase change information of the backward Rayleigh scattered waves at each detection point (each position) in the high-temperature resistant optical fiber 2 wound according to the spiral shape is converted into actual fluctuation signals of the sound waves through a modulation and demodulation circuit and data processing software in the instrument, and the analog fluctuation signals are converted into digital fluctuation signals through an analog-to-digital conversion circuit in the DAS instrument, the digital wobble signal is then stored in a computer for subsequent acoustic data processing.
Fig. 3 is a schematic view of a high temperature resistant optical fiber 2 wound in a spiral shape in a vertical direction, the high temperature resistant optical fiber 2 is wound in a cylindrical structural member at an angle α, a composite material or steel sheath for protecting the optical cable is added outside, and the outermost layer is a wear-resistant and pressure-resistant armor woven by a non-metal or metal material, fig. 4 is a perspective view of the high temperature resistant optical fiber 2 wound in a spiral shape in a vertical direction.
FIG. 5 is a schematic diagram of a high temperature resistant optical fiber 2 wound according to a spiral shape and extending along AB of a cylindrical structure 1 in a transverse direction, the high temperature resistant optical fiber 2 wound according to a spiral shape and extending along AB at a certain angle α on the cylindrical structure 1 becomes a straight optical fiber forming an angle of α with an end face extension line AA or BB of the cylindrical structure 1, if a vertical optical fiber is arranged in a well, when a reflected sound wave 8 propagating back to the well hole along a horizontal direction reaches the straight optical fiber arranged in the well hole, the fluctuation of the horizontal direction cannot cause strain of the straight optical fiber along the vertical extension direction of the straight optical fiber, and the phase of a backscattered Rayleigh wave at each point (each position) in the optical fiber can not be changed correspondingly, a horizontal sound wave signal vertically incident on the straight optical fiber cannot be detected by a ground DAS demodulation instrument 11, and theoretical analysis shows that the sensitivity of the wave signal which can be sensed by a straight optical fiber depends on (exists) the angle theta between the propagation direction of the wave signal and the extension direction of the optical fiber2The relationship (2) of (c). I.e. when the direction of wave propagation of the acoustic wave is parallel to the direction in which the optical fiber extends (theta 0 deg.), cos theta2When the optical fiber is equal to 1, the straight optical fiber is used for the wave signal (vertical direction)Up-propagating direct waves) reaches a maximum of 1; i.e. when the direction of wave propagation of the acoustic wave is perpendicular to the direction in which the optical fiber extends (theta 90 deg.), cos theta2At this time, the sensitivity of the straight optical fiber to the ripple signal (horizontal reflected wave) perpendicular to the extending direction of the optical fiber reaches a minimum value of 0, and thus the straight optical fiber cannot detect the ripple signal propagating perpendicular to the extending direction of the optical fiber.
After the fluctuation signal which is perpendicular to the high-temperature resistant optical fiber 2 wound in a spiral shape in fig. 3, 4 and 5 reaches the high-temperature resistant optical fiber, because the incident angle between the optical fiber on the high-temperature resistant optical fiber 2 wound in a spiral shape and the fluctuation signal is not 90 degrees but α degrees, the high-temperature resistant optical fiber 2 wound in a spiral shape can detect the direct sound wave which is vertically upwards propagated and the reflected sound wave 8 which is horizontally or greatly incident angle propagated, so that the high-temperature resistant optical fiber 2 wound in a spiral shape arranged underground can detect the full wave field signal of the sound wave propagated to the high-temperature resistant optical fiber 2 wound in a spiral shape, including the direct sound wave 7, the refracted sound wave 9, the reflected sound wave 8, the surface wave and the multiple waves, therefore, the utility model discloses can acquire underground three-component sound wave data.
After the collection of the underground three-component far detection sound wave data is finished, the three-component sound wave data collected at different underground depth positions are processed, and the average speed of the sound wave reaching each known detection point from the sound source point can be calculated very accurately and easily according to the travel time of the direct wave reaching each fluctuation signal detection point on the spirally wound high-temperature resistant optical fiber 2 from each sound source point, namely the underground array type sound source generator 3, and the distance from each sound source point to each known detection point. If the data processing personnel picks up the travel time of the direct longitudinal wave, the average velocity of the longitudinal wave is calculated. If the travel time of the direct shear wave is picked up, the average velocity of the shear wave is calculated.
If the acoustic velocity of the surrounding medium downhole is uniform, then the velocity of the longitudinal or transverse wave propagating vertically upward and horizontally across the well profile will be the same, with no velocity anisotropy; if the acoustic velocity of the subsurface medium is non-uniform, then the vertical acoustic velocity measured at the downhole pickup will be different from the velocity of the acoustic waves incident horizontally or near horizontally or at large angles; according to the phenomenon that the speeds of the sound waves propagating in the same medium along different directions are inconsistent, the anisotropy of the vertical speed and the horizontal speed of the sound wave speed along the two-dimensional medium passing through the well section is calculated;
if the sound wave velocity of the underground medium is uniform, the sound wave velocity of longitudinal waves or transverse waves which are vertically propagated and propagated along the peripheral horizontal direction is the same, and the velocity anisotropy does not exist, if the sound wave velocity of the underground medium is non-uniform, the vertical sound wave velocity measured at the position of a downhole receiving point is different from the velocity of sound waves which are incident along the horizontal direction or a large angle, and the velocity anisotropy and the distribution characteristics of the sound wave velocity in the three-dimensional space around the borehole are calculated according to the phenomenon that the velocities of the sound waves which are propagated along different directions in the same medium are not uniform;
for two-dimensional three-component sound wave data acquired at different detection points along a two-dimensional cross-well profile or three-dimensional three-component sound wave data acquired underground, the sound wave attenuation coefficient or the Q value of the underground medium can be calculated or extracted by a frequency spectrum ratio method, a centroid frequency shift method or a frequency spectrum fitting method according to the characteristics of the amplitude and the frequency spectrum change of the three-component sound wave recorded at different detection points.
In the implementation of the embodiment, the high-temperature resistant optical fiber 2 which is arranged on the upper part of the underground sound wave far detection instrument and is wound according to the spiral shape is utilized to directly measure the two-dimensional or three-dimensional sound wave speed of the medium around the well and calculate the elasticity or viscoelasticity parameters of the underground medium (stratum or rock stratum), so that a two-dimensional or three-dimensional sound wave speed model of the underground medium and a two-dimensional or three-dimensional elasticity or viscoelasticity parameter model of the underground medium can be accurately established, and the two-dimensional or three-dimensional sound wave speed model and the two-dimensional or three-dimensional elasticity or viscoelasticity parameter model are used for carrying out data processing and imaging on underground sound wave data, such as an isotropic wave equation. The real-time position, speed and attitude information of the underground array type sound source generator 3 which records by the optical fiber gyroscope 4 in real time and the high-temperature resistant optical fiber 2 wound according to the spiral shape can accurately determine the specific position of the wave impedance interface far away from the well and the distance from the well during offset imaging, thereby really realizing the accurate detection of the geological target far away from the well underground, analyzing the crack and hole information in the stratum far away from the well, and obtaining the stratum structure information from several meters to dozens of meters around the well, and further knowing the crack, hole position, inclination angle and distribution in the stratum.
Claims (2)
1. The borehole three-component acoustic far detection logging device is characterized by comprising a borehole acoustic far detection instrument, a ground wellhead logging truck (10) and a ground DAS modulation and demodulation instrument (11);
the underground sound wave far detection instrument comprises a cylindrical structure (1) and spirally wound high-temperature resistant optical fibers (2), wherein the spirally wound high-temperature resistant optical fibers (2) are wound on the outer side of the cylindrical structure (1) to form a spiral pipe shape and serve as an underground sound wave signal receiving unit; the lower part of the cylindrical structure (1) is vertically and sequentially provided with an optical fiber gyroscope (4) and an underground array type sound source generator (3); the well logging device is characterized by further comprising an armored photoelectric composite cable (5), wherein the armored photoelectric composite cable (5) is located in the cylindrical structure (1), and the ground wellhead well logging truck (10) is connected with the underground array type sound source generator (3) and the optical fiber gyroscope (4) through the armored photoelectric composite cable (5);
the ground wellhead logging truck (10) controls the underground sound wave remote detection instrument to go down and rise, provides power for the underground sound wave remote detection instrument, and drives the underground array type sound source generator (3) to continuously and repeatedly emit sound wave signals during operation;
a ground DAS modulation and demodulation instrument (11) arranged at a wellhead is connected with a spirally wound high-temperature resistant optical fiber (2) through an armored photoelectric composite cable (5), laser pulses are emitted into the spirally wound high-temperature resistant optical fiber (2), and backscattered Rayleigh waves in the spirally wound high-temperature resistant optical fiber (2) under the well are collected.
2. The borehole three-component acoustic remote sensing logging device according to claim 1, wherein the spirally wound high temperature resistant fiber (2) is a single mode or multi-mode fiber wound on the cylindrical structure (1) at a certain angle, the winding angle is between 10 degrees and 80 degrees, a protective sleeve is sleeved outside the cylindrical structure (1) wound with the spirally wound high temperature resistant fiber (2), and the outermost layer of the protective sleeve is a metal or composite armor which is resistant to compression and stretching.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110067554A (en) * | 2019-06-06 | 2019-07-30 | 中油奥博(成都)科技有限公司 | Three-component sound wave far detects well logging apparatus and its measurement method in well |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110067554A (en) * | 2019-06-06 | 2019-07-30 | 中油奥博(成都)科技有限公司 | Three-component sound wave far detects well logging apparatus and its measurement method in well |
| CN110067554B (en) * | 2019-06-06 | 2024-03-29 | 中油奥博(成都)科技有限公司 | Well three-component acoustic wave remote detection logging device and measurement method thereof |
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