Array acoustic wave instrument with adjustable spacing and sector number

Abstract

The invention discloses an array acoustic wave instrument with adjustable spacing and sector number, which is characterized in that according to the advantages and disadvantages of the current traditional VSP instrument and the traditional array acoustic logging instrument, a three-component probe is replaced by an N-component probe (1lt; = N < = 1025), so that the circumferential resolution is greatly improved. Moreover, the collection station is modularized, and the connection stage number, the spacing and the sector number can be adjusted according to needs. Besides, a flexible cable between the acquisition stations is replaced by a continuous pipe through which the cable penetrates, so that the final detection distance and the stratum resolution ratio can be adjusted, the pushing requirements of a horizontal well and a highly-deviated well can be met, and each stage of detector is provided with a pushing device to be attached to the well wall. Array sound waves and a traditional VSP instrument can be replaced, and high-resolution stratum measurement is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum well logging, and in particular relates to a variable spacing and azimuth array acoustic wave instrument. Background Art

[0002] Vertical seismic profiling (VSP) is a commonly used seismic exploration method. Its principle is to set up a source on the surface to excite seismic waves, and to place a detector vertically in the well to receive seismic waves. Then, the received waveform is corrected, superimposed, filtered, and processed to obtain a vertical seismic profile. Based on the obtained data, the age and lithology of the reflection layer can be determined, and the orientation of fractures outside the well can be detected. Compared with conventional ground seismic measurements, one advantage of VSP is that it can avoid some noise from the surface during ground observation. The main interference waves in ground seismic records mostly come from the upper part of the profile, while VSP directly observes inside the medium, so it can avoid and reduce the interference of the surface and easily identify the nature of the wave.

[0003] The borehole detector used in vertical seismic profiling is equipped with an extendable push arm so that the detector can be close to the borehole wall to ensure good acoustic coupling with the borehole wall. The seismic detector sensor in the currently commonly used VSP equipment is a three-component detector. The z-axis component in the well axis direction measures vertical seismic waves, and the x-axis and y-axis components in the horizontal direction measure seismic waves in two orthogonal directions on the horizontal plane. Since there are only two components in the horizontal direction, the azimuth resolution of the data collected in this way is very limited. At the same time, due to the large-scale application of directional drilling in recent years, the wellbore trajectory has become complex. Directional drilling often forms a curved, inclined, or even complex branched wellbore trajectory, which makes it difficult to lower and move the instrument. In the curved well section, the instrument may be subject to additional friction and resistance, affecting the lowering speed and stability. At present, conventional VSP detectors are connected by soft cables. When encountering horizontal wells and high-angle wells, the pushing requirements are usually not met.

[0004] Acoustic logging is an important geophysical exploration method developed in the 1950s. It uses the different propagation speeds and amplitude attenuation of sound waves in different rock formations to obtain information about underground rocks. It can identify gas layers, calculate rock formation porosity, and check cementing quality. Array acoustic logging technology is an acoustic logging method similar to VSP. It uses multiple receivers to collect sound waves to detect formation information outside the well. The formation detection distance of the array acoustic logging instrument is related to the source distance. The longer the source distance, the longer the formation detection distance. The vertical resolution of the array acoustic logging instrument is related to the spacing size. The shorter the spacing, the higher the vertical resolution. Usually, after the instrument is produced, the length of the source distance and spacing is fixed. For logging requirements with different formation detection distances and vertical resolutions, different specifications of acoustic logging instruments need to be lowered into the well, which greatly increases the project cost.

[0005] In order to develop complex oil and gas reservoirs, horizontal well technology has been widely used. However, traditional reservoir evaluation methods cannot accurately consider the influence of anisotropy, resulting in deviations in the estimation of reservoir parameters such as porosity, permeability and saturation. For example, anisotropy may affect the flow behavior of fluids in the reservoir, making the reservoir simulation results based on the isotropic assumption inaccurate. In order to improve the accuracy of reservoir evaluation, it is necessary to develop reservoir evaluation methods and models specifically for anisotropic formations, fully considering the differences in formation characteristics in different directions, but the azimuth resolution of conventional array acoustic instruments is difficult to meet the requirements. Summary of the invention

[0006] In order to overcome the above-mentioned shortcomings, the present invention provides an array acoustic wave instrument with adjustable spacing and number of sectors, a modular acquisition station, and the connection levels, spacing, and number of sectors can be adjusted as needed to adjust the detection distance, vertical resolution, and azimuth resolution of the instrument, thereby replacing the array acoustic wave logging instrument and the traditional VSP instrument to achieve high-resolution formation measurement.

[0007] The acquisition station refers to a detector that can collect N (1<=N<=1025, for example, N=5 means 1 in the Z axis plus 4 in the circumferential direction) components. Compared with the traditional three-component probe, the N-component probe can greatly improve the circumferential resolution.

[0008] The cables between the acquisition stations are replaced from traditional soft cables to continuous tubes with adjustable length. This not only adjusts the final detection distance and formation resolution, but also adapts to the pushing requirements of horizontal wells and highly deviated wells.

[0009] Each level of the collection station is added with push-on and close to the well wall to ensure good sound coupling.

[0010] A gyroscope is added to each level of collection station to record the azimuth data of the collection station.

[0011] For VSP data acquisition, an array acoustic instrument with adjustable spacing and number of sectors can be implemented by the following steps:

[0012] First, before data collection, the number of acquisition stations, spacing, and number of probe components required for this acquisition are confirmed according to the needs. Then the instrument is lowered to the specified depth. The push arm of each acquisition station pushes the detector against the well wall to ensure good acoustic coupling between the detector and the formation. The control source excites the sound wave, and the acquisition stations at all levels record the sound wave. At the same time, the gyroscope of each acquisition station records the azimuth data of the current acquisition station.

[0013] For array acoustic logging data acquisition, an array acoustic instrument with adjustable spacing and number of sectors can be implemented by the following steps:

[0014] First, before logging, the number of detectors, source distance and spacing that need to be installed for this logging are confirmed according to the logging requirements, and then the instrument is assembled before logging; after assembly, the instrument is lowered to the specified depth, and then pulled up for logging, the transmitting transducer is controlled to excite the sound wave, and the detector transducer records the sound wave. At the same time, the gyroscope of the instrument records the azimuth data of the current instrument in real time.

[0015] The advantages of the embodiments of the present invention are:

[0016] 1. By improving the traditional array acoustic wave instrument and modularizing the detector on its basis, the level, spacing, and number of sectors of the receiver can be customized according to needs, so that the detection distance and resolution of the instrument can be adjusted at any time.

[0017] 2. The present invention replaces the traditional three-component probe with an N-component probe (1<=N<=1025) to greatly improve the circumferential resolution of the data.

[0018] 3. The cables between the acquisition stations are replaced from traditional soft cables to continuous pipes through which cables are passed, which can meet the pushing requirements of horizontal wells and highly deviated wells.

[0019] 4. The present invention has good application prospects in the fields of acoustic logging and seismic exploration. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0021] Figure 1a This is a schematic diagram of VSP data collection construction in a vertical well according to an embodiment of the present invention;

[0022] Figure 1b This is a schematic diagram of VSP data collection construction in a highly deviated well according to an embodiment of the present invention;

[0023] Figure 2 Schematic diagram of the structure of an annular distributed transducer according to an embodiment of the present invention;

[0024] Figure 3 A schematic diagram of a VSP data flow according to an embodiment of the present invention;

[0025] Figure 4 A schematic diagram of the structure of an array acoustic logging instrument according to an embodiment of the present invention;

[0026] Figure 5 It is a construction schematic diagram of an array acoustic logging instrument according to an embodiment of the present invention for measuring the position of an accident well in a rescue well; DETAILED DESCRIPTION

[0027] To make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be described below in conjunction with the drawings in the embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0028] [Example 1]

[0029] VSP data collection construction Figure 1a As shown, a seismic source 1 is placed on the ground, and a plurality of VSP geophones 3 are placed in a wellbore 2. Each geophone 3 includes a push arm 4 that allows the geophone 3 to be close to the wellbore wall or casing. The push arm 4 can be a spring, a retractable gate, or a pivot arm. The push arm 4 ensures that the geophone 3 is closely attached to the wellbore wall to ensure good acoustic coupling between the geophone and the wellbore wall. A continuous pipe 5 with adjustable length is connected between two geophones 3 to meet the pushing requirements of horizontal wells and highly deviated wells.

[0030] exist Figure 1b The schematic diagram of VSP data acquisition construction in the inclined shaft is shown in FIG. Figure 1a The structure is similar to that of the conventional VSP data acquisition system, but the borehole trajectory is a deviated well or a horizontal well. The measuring cable between the two detectors in conventional VSP data acquisition is a soft cable, which can usually only use gravity to make the detector reach the specified position. However, in horizontal wells or highly deviated wells, the soft cable cannot meet the pushing requirements. The two detectors 3 in the present invention are connected by a continuous pipe 5 with adjustable length. The continuous pipe 5 has high strength and high hardness, so sufficient thrust can be applied to it outside the well to ensure that the detector 3 reaches the specified depth position.

[0031] The detector 3 is an N (1<=N<=1025) component digital detector based on a micro-electromechanical system (MEMS), comprising a Z-axis component transducer and N-1 horizontal annular distributed transducers 7, such as Figure 2 As shown,.

[0032] Using an array acoustic wave instrument with adjustable spacing and sector number in an embodiment of the present invention to collect VSP data includes the following steps:

[0033] 1. The seismic source 1 generates seismic energy waves. The seismic waves pass through the strata and encounter the layer interface 6 with changed impedance in the strata. The seismic waves will be reflected or refracted.

[0034] 2. The geophone 4 will record the upgoing direct wave emitted from the seismic source 1 and the downgoing reflected wave reflected by the layer interface 7. At the same time, each geophone 4 has its own gyroscope to record the azimuth data of the current depth.

[0035] 3. The collected VSP data are pre-processed (including decoding, correlation, editing, and gain recovery) and then sent to the ground base station for storage and transmission.

[0036] 4. Process and interpret the preprocessed data, such as Figure 3 As shown in the figure, firstly, the first arrival direct wave is picked up to obtain the velocity and static correction processing, then the spectrum analysis and bandpass filtering are performed to filter out the interference signal and improve the signal-to-noise ratio. Then, static time shift is performed to align the events of the upgoing and downgoing waves respectively in time and display them in a form similar to the ground seismic profile, and then the upgoing and downgoing waves are separated by the difference in apparent velocity. Finally, the first wave events are added together through deconvolution and corridor stacking to form a single seismic trace. According to the spectrum analysis diagrams of various waves, the wave fields of upgoing and downgoing waves, and the corridor stacking channels, the geological layers can be calibrated, accurate velocity parameters can be extracted, and geological interpretation can be performed.

[0037] [Example 2]

[0038] like Figure 4 As shown, the acoustic logging instrument includes a transmitting transducer 8, a sound insulator 9, and a detector 3.

[0039] The detectors are arranged at equal intervals along the axial direction of the instrument housing to form an array. The number and spacing can be set according to requirements to perform formation measurements with different detection distances and different vertical resolutions.

[0040] The above-mentioned detector units all include N (1<=N<=1024) horizontal annular distributed transducers 7 .

[0041] Using an array acoustic wave instrument with adjustable spacing and sector number in an embodiment of the present invention to detect an interface outside a well comprises the following steps:

[0042] 1. Set the appropriate source distance and spacing according to the logging requirements.

[0043] 2. Lower the logging instrument to the specified depth, and then stimulate sound waves at multiple equally spaced detection points in the wellbore.

[0044] 3. Each detector unit receives and records the sound waves and, at the same time, records the instrument azimuth at the current depth.

[0045] 4. The waveforms collected by the short-source-spacing geophone array can be used to evaluate conventional reservoir parameters such as formation slowness, rock mechanics parameters and formation anisotropy.

[0046] 5. The waveform collected by the long-distance detector array can be used to obtain the imaging results of the reflector outside the well after separation of the reflected wave and reflection wave imaging inversion, so as to evaluate the geological structure beside the well, including fractures, faults, and inclined stratum interfaces.

[0047] [Example 3]

[0048] Figure 5 The schematic diagram of the construction of the sonic logging instrument of the present invention for measuring the position of the accident well in the rescue well is shown in FIG. The rescue well refers to a directional well drilled in a safe area near the accident well so that the two wells meet at a certain point in the formation. Subsequently, high-density drilling fluid or mud is input into the accident well through the rescue well to prevent leakage or blowout. Therefore, it is necessary to accurately detect the position and distance of the accident well.

[0049] like Figure 5 As shown, in this embodiment, there is an accident well 11 around the rescue well 10. Since the location of the two accident wells is unknown or the distance between them is far before logging, a combination of large spacing and source distance is selected during logging, so that the formation detection distance is far and the approximate location and orientation of the accident well can be more easily found. When the accident well is found and gradually approached, the spacing and source distance of the logging instrument are gradually reduced to achieve more precise measurements. The path of the sound wave in this embodiment is as follows:

[0050] The sound waves emitted by the transmitting transducer 8 are reflected by the accident well 11 and received by the detector 3. The multi-component detector can determine the direction of the accident well 11 according to the waveform strength received by different components and in conjunction with the gyroscope. The distance between the accident well 11 and the rescue well 10 can be determined by the arrival time of the received waveform.

Claims

1. An array acoustic wave instrument with adjustable spacing and number of sectors, comprising a transmitter, a detector and a push arm, wherein the push arm can be a spring, a retractable gate or a pivot arm, to ensure that the detector can be closely attached to the well wall, so as to ensure good acoustic coupling between the detector and the well wall; It is characterized in that The acquisition station is modular, and the connection levels, spacing, and number of sectors can be adjusted as needed.

2. The array acoustic wave instrument with adjustable spacing and sector number according to claim 1, characterized in that: The detector is an N-component detector (1<=N<=1025).

3. The array acoustic wave instrument with adjustable spacing and number of sectors according to claim 1, characterized in that: The collection stations are connected by continuous pipes with cables.

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