技术领域technical field
本发明总体上涉及海洋地震勘探，并且具体地涉及用于降低拖在勘探船后的传感器中、位于海底的传感器中或自治节点的传感器中的不期望的地震波反射和噪声的影响的设备和方法。The present invention relates generally to marine seismic surveying, and in particular to apparatus and methods for reducing the effects of undesired seismic wave reflections and noise in sensors towed behind a survey vessel, in sensors located on the ocean floor, or in sensors of autonomous nodes .
背景技术Background technique
如图1中所示，在拖曳式海洋地震勘探中，在近海面22的船舶20后拖曳着水听器阵列。这些水听器安装在多传感器电缆中，通常被称为拖缆24。该拖缆用作水听器的平台。同样拖在近海面的地震声源26周期性地放射声能。该声能通过海洋向下传播，从底层结构或水下地层28反射，然后通过海洋向上返回到水听器阵列。所反射的地震能量到达拖曳阵列接收点。该水听器阵列包括多个此类接收点，并且在每个接收点记录从海床30向上传播的地震声小波。随后，将水听器的记录处理成为底层结构的地震图像。As shown in FIG. 1 , in towed marine seismic surveying, a hydrophone array is towed behind a vessel 20 offshore surface 22 . These hydrophones are mounted in a multi-sensor cable, commonly referred to as streamer24. The streamer serves as a platform for the hydrophones. A seismic source 26, also towed offshore, periodically radiates acoustic energy. This acoustic energy travels down through the ocean, reflects off the underlying structure or subsurface formation 28, and returns up through the ocean to the hydrophone array. The reflected seismic energy reaches the towed array receiving point. The hydrophone array includes a plurality of such receiving points and at each receiving point records seismic acoustic wavelets propagating upwardly from the seabed 30 . Subsequently, the hydrophone recordings are processed into seismic images of the underlying structure.
噪声是拖曳式拖缆操作中的一个主要考虑因素。噪声源包括来自海面的膨胀噪声和波动噪声。而且，拖曳该拖缆穿过海水会引起噪声。这些噪声的一部分通过该拖缆传播，一部分通过水柱自身传播。处理噪声源的典型方法是使用时间滤波和空间滤波的组合。时间滤波是通过在时间上用应用到样本的权重对水听器信号进行离散数据采样来实现的。水听器信道还包括模拟滤波器以防止在频率大于采样速率一半时产生信号混迭。典型地，空间样本通过对多个独立的水听器输出进行分组求和来形成，从而使得衰减了沿拖缆的长度传播的噪声。这个空间采样对于在拖缆轴线垂直方向传播的噪声没有影响。典型的水听器组在12米的拖缆段中包括八个左右的水听器。Noise is a major consideration in towed streamer operations. Noise sources include swell noise and wave noise from the sea surface. Also, towing the streamer through sea water can cause noise. Some of this noise travels through the streamer, and some travels through the water column itself. A typical approach to dealing with noise sources is to use a combination of temporal and spatial filtering. Temporal filtering is achieved by discrete data sampling of the hydrophone signal over time with weights applied to the samples. The hydrophone channel also includes an analog filter to prevent signal aliasing at frequencies greater than half the sampling rate. Typically, spatial samples are formed by group summing of multiple independent hydrophone outputs such that noise propagating along the length of the streamer is attenuated. This spatial sampling has no effect on noise propagating perpendicular to the streamer axis. A typical hydrophone array includes eight or so hydrophones in a 12 meter streamer section.
声阻抗ρc是介质密度和介质中声速的乘积。只要声波碰到声阻抗发生变化，至少一部分声波能量会发生反射。未被反射的能量越过具有不同声阻抗的两个区域间的分界线传输（折射）。该压力波是气压波，这引起传播方向上的粒子运动。在两个不同同质介质间的平界面上，声波以与入射角θ1相等的角度反射，且以角度θ2折射。该折射角为：The acoustic impedance ρc is the product of the density of the medium and the speed of sound in the medium. Whenever a sound wave encounters a change in acoustic impedance, at least a portion of the sound wave energy is reflected. Energy that is not reflected is transmitted (refracted) across the boundary between two regions with different acoustic impedances. The pressure wave is an air pressure wave, which causes particle motion in the direction of propagation. On a plane between two different homogeneous media, sound waves are reflected at an angle equal to the incident angle θ1 and refracted at an angle θ2 . The angle of refraction is:
θ2=sin-1(c2sinθ1/c1)。θ2 =sin−1 (c2 sinθ1 /c1 ).
下标指的是声波从介质1移动到介质2，而c1和c2是每个介质中的声速。如果入射角θ1为零，则折射能量传输路径的角度θ2将会是零。The subscripts refer to the movement of sound waves from medium1 to medium2 , while c1 and c2 are the speeds of sound in each medium. If the angle of incidence θ1 is zero, the angle θ2 of the refracted energy transmission path will be zero.
对于入射角θ1为零且没有能量被转换为横波能量的情况，在海水-空气分界面的反射系数描述为：For the case where the incident angleθ1 is zero and no energy is converted into shear wave energy, the reflection coefficient at the seawater-air interface is described as:
在海水-空气分界面的反射能量为R2pp，或接近1，这使得海面是一个近似理想的声能反射器。从海底或感兴趣的目标返回之后，该能量再次由海面反射回拖缆。由于典型的水听器具有全向响应，因此水听器阵列还记录了重影响应，该重影响应是从海面反射并延时到达的且极性颠倒的地震声小波。该重影是向下传播的地震声波，当添加到希望的波形上时该地震声波会有损记录的地震图像。该重影引起的反射还可延续到海底或其他强反射物，并向上返回再次干扰期望的反射波并进一步降低图像质量。这些反射通常被称为多次波。The reflected energy at the seawater-air interface is R2pp , or close to 1, which makes the sea surface a nearly ideal reflector of acoustic energy. After returning from the sea floor or object of interest, this energy is again reflected by the sea surface back to the streamer. Since typical hydrophones have an omnidirectional response, the hydrophone array also records heavy effects, which are seismic wavelets that reflect from the sea surface and arrive with a time delay and reverse polarity. The ghosts are downwardly propagating seismic waves that, when added to the desired waveform, detract from the recorded seismic image. Reflections caused by this ghosting can also carry over to the bottom of the sea or other strong reflectors, and back up again to interfere with the desired reflected waves and further degrade image quality. These reflections are often called multiples.
对于垂直传播的压力波来说，该重影在水听器在fnotch=c/2d处响应的频谱中产生一个陷波，其中c是声速，并且d是拖缆深度。按照惯例，地震拖缆被拖曳在10米或更浅的深度。在10米深度，陷波频率（fnotch）是75Hz。对于高地震图像分辨率，频率响应必须扩展到100Hz之外。因为陷波频率与拖曳深度成反比，因此，拖缆通常被拖曳在较浅的深度以提高地震图像的分辨率。由于来自海面的噪声对期望的地震信号形成了干扰， 因此在浅水中拖曳是有问题的。这些影响随天气变坏而恶化，有时会导致工作人员中断操作，直到天气变好。消除重影-陷波的影响使得能够在远离表面扰动更深的深度拖曳。For vertically propagating pressure waves, this ghost produces a notch in the frequency spectrum in which the hydrophone responds at fnotch = c/2d, where c is the sound velocity and d is the streamer depth. By convention, seismic streamers are towed at depths of 10 meters or less. At a depth of 10 meters, the notch frequency (fnotch ) is 75 Hz. For high seismic image resolution, the frequency response must extend beyond 100 Hz. Because notch frequency is inversely proportional to tow depth, streamers are typically towed at shallower depths to improve seismic image resolution. Towing in shallow water is problematic because noise from the sea surface interferes with the desired seismic signal. These effects worsen as the weather worsens, sometimes causing crews to interrupt operations until the weather improves. Elimination of ghost-notch effects enables towing at deeper depths away from surface disturbances.
在将地震传感器放置在海床的海底系统中，通过公知的技术（如p-z求和）来抑制重影和多次波。在声波中，压力p是个标量，而粒子速度u是个矢量。水听器用正全向响应来记录地震声波压力p。垂直定向的地震检波器或加速计采用对向上信号的正响应和对向下信号的负响应来记录地震声波粒子速度uz的垂直分量。在p-z求和中，速度信号在其添加到压力信号之前由海水的声阻抗ρc来衡量。还需要调整万向单轴传感器以对由任何接收信号的离轴到达所引起的粒子-运动传感器灵敏度的改变负责。如果使用加速计，可集成其输出信号以获得速度信号，或可以区分水听器信号，如此以来，可以更好的与加速计在光谱上匹配。这可产生一种具有对向上传播波的全响应和对向下传播波的至少部分地微弱响应以抑制重影和多次波的组合传感器。在由Monk等人发明的美国专利号为6539308的专利中描述了一种实现单一去重影痕迹的信号调节和信号整合方法。图2是粒子-速度传感器的响应的二维（2D）表示。图3是全向水听器的响应与垂直粒子-运动传感器的响应相加的2D表示。通过绕其垂直轴旋转这些2D响应能够想象到完整的三维响应。In subsea systems where seismic sensors are placed on the seabed, ghosts and multiples are suppressed by well known techniques such as pz summation. In sound waves, the pressure p is a scalar, and the particle velocity u is a vector. The hydrophone records the seismic acoustic pressure p with positive omnidirectional response. Vertically oriented geophones or accelerometers record the vertical component of the seismic acoustic particle velocity uz with a positive response to upward signals and a negative response to downward signals. In pz summation, the velocity signal is scaled by the acoustic impedance ρc of seawater before it is added to the pressure signal. The gimbaled uniaxial sensor also needs to be tuned to account for changes in particle-motion sensor sensitivity caused by any off-axis arrival of the received signal. If an accelerometer is used, its output signal can be integrated to obtain a velocity signal, or the hydrophone signal can be differentiated so that it can be better spectrally matched to the accelerometer. This can result in a combined sensor with a full response to upward propagating waves and an at least partially weak response to downward propagating waves to suppress ghosts and multiples. A method of signal conditioning and signal integration to achieve a single deghosting trace is described in US Patent No. 6,539,308 to Monk et al. Figure 2 is a two-dimensional (2D) representation of the response of a particle-velocity sensor. Figure 3 is a 2D representation of the response of an omnidirectional hydrophone summed with the response of a vertical particle-motion sensor. By rotating these 2D responses about their vertical axis a full three dimensional response can be imagined.
目前，在拖曳式拖缆采集中使用类似p-z求和的技术以允许在更深的深度拖曳而不受重影-陷波反射的干扰，已经引起了大家的兴趣。因为该拖缆受到由拖曳或海面效应引起的加速度比由期望地震反射引起的加速度大，因此操作地震拖缆中的粒子运动传感器存在问题。此外，这些多余的加速度与期望的反射响应位于相同的光谱带中。当拖曳舰船遇到了海浪，舰船速度受到小的扰动。典型地，该舰船还遇到偏航运动。图4描绘了通过速度变化32和偏航运动34施加给拖缆24的能量。图5是描绘导致拖缆24中的加速度和横波的能量的侧视图。（出于说明的目的，在图5中夸大了能量对拖缆的影响。）通过弹性拉伸部件36（典型地，在传感 阵列前面）衰减了大部分能量。虽然该能量大大地衰减了，但仍剩下一部分。由期望地震波反射产生的平面压力波引起的加速度a由下式给出：Currently, there has been interest in using techniques like p-z summing in towed streamer acquisitions to allow towing at greater depths without interference from ghost-notch reflections. Operating a particle motion sensor in a seismic streamer is problematic because the streamer is subjected to greater accelerations due to towing or sea surface effects than due to expected seismic reflections. Furthermore, these unwanted accelerations lie in the same spectral bands as the expected reflection response. When the towing ship encounters waves, the speed of the ship is slightly disturbed. Typically, the ship also experiences yaw motion. FIG. 4 depicts the energy imparted to the streamer 24 by velocity changes 32 and yaw motion 34 . FIG. 5 is a side view depicting the energy resulting in acceleration and shear waves in the streamer 24 . (The effect of energy on the streamer is exaggerated in Figure 5 for illustrative purposes.) Most of the energy is attenuated by the elastic stretch member 36 (typically in front of the sensing array). Although this energy is greatly attenuated, a portion remains. The acceleration a caused by the planar pressure wave produced by the reflection of the expected seismic wave is given by:
其中p=声波声压级，f是频率，并且Z是声阻抗。粒子速度测量系统的性能应当接近外界噪声限度。典型地，地震数据用户要求来自拖缆水听器系统的外界噪声低于3微巴。由于海水的声阻抗是1.5MPa.s/m，因此4Hz的3微巴压力波产生大约0.5μg的粒子加速度。图6展示了拖缆中间的典型电缆轴向加速度的频率响应的机械模型。在某些情况下，在4Hz存在只比主波峰低1.5数量级的次波峰表明电缆动态运动可以大于有待测量的地震信号。where p = acoustic sound pressure level, f is frequency, and Z is acoustic impedance. The performance of the particle velocity measurement system should be close to the ambient noise limit. Typically, seismic data users require ambient noise from the streamer hydrophone system to be less than 3 microbars. Since the acoustic impedance of seawater is 1.5 MPa.s/m, a 3 microbar pressure wave at 4 Hz produces a particle acceleration of approximately 0.5 μg. Figure 6 shows a mechanical model of the frequency response of a typical cable axial acceleration in the middle of the streamer. In some cases, the presence of a secondary peak at 4 Hz that is only 1.5 orders of magnitude lower than the main peak indicates that cable dynamic motion can be larger than the seismic signal to be measured.
授予Rouquette的美国专利号7,167,413在地震拖缆中使用加速计来抑制重影-陷波效应。Rouquette使用质量-弹簧系统来降低电缆动力对加速计和负载传感器系统的影响以测量和抑制该加速计上的电缆运动感应噪声。Rouquette系统依赖众所周知的复杂机械关系，该关系不能与制造公差、老化和环境状况保持一致。Rouquette使用信号处理自适应算法来推导负载传感器和质量-弹簧系统与作用于原地加速计上的加速度的关系Rouquette描述了一种复杂的机械电子系统。US Patent No. 7,167,413 to Rouquette uses accelerometers in seismic streamers to suppress ghost-notch effects. Rouquette uses a mass-spring system to reduce the effect of cable dynamics on the accelerometer and load cell system to measure and suppress cable motion induced noise on the accelerometer. The Rouquette system relies on notoriously complex mechanical relationships that cannot be kept consistent with manufacturing tolerances, aging and environmental conditions. Rouquette uses signal processing adaptive algorithms to derive the relationship of the load cell and mass-spring system to the acceleration acting on the in situ accelerometer. Rouquette describes a complex mechatronic system.
由Tenghamn等人发明的美国专利号为7,239,577描述了一种使用声波粒子速度传感器抑制重影陷波的设备和方法。Tenghamn等人传授了流体阻尼、万向架固式地震检波器的使用。本领域众所周知的是选择封装该地震检波器的流体来提供悬挂在其平衡架上的传感器的阻尼。然而，本领域众所周知而在Tenghamn等人中没有描述的是质量-弹簧隔振系统可降低电缆机械运动对地震检波器响应的影响。由电缆机械运动引起的地震检波器的运动与地震检波器响应中的声波粒子运动是不可区分的。期望的地震波粒子运动被Tenghamn等人的电缆机械运动所掩盖。这个技术还产生图3中类似心形线的响应，其中，此处仍然有来自该平面且由沿着该拖缆轴线的拖缆激发引起的不期望的信号。US Patent No. 7,239,577 to Tenghamn et al. describes an apparatus and method for suppressing ghost notches using an acoustic particle velocity sensor. Tenghamn et al. teach the use of fluid damped, gimbaled geophones. It is well known in the art that the fluid enclosing the geophone is chosen to provide damping of the transducer suspended on its gimbal. However, what is well known in the art and not described in Tenghamn et al. is that a mass-spring vibration isolation system can reduce the effect of cable mechanical motion on geophone response. The motion of the geophone caused by the mechanical motion of the cable is indistinguishable from the motion of the acoustic particles in the geophone response. The expected seismic wave particle motion is masked by the mechanical motion of the cable by Tenghamn et al. This technique also produces a cardioid-like response in Figure 3, where there are still undesired signals from the plane and caused by streamer excitation along the streamer axis.
由Vaage等人发明的美国专利号7,359,283描述了一种组合负载传感器和粒子运动传感器来解决机械运动对粒子运动传感器的影响的方法。在该方法中，不使用某一频率f0以下的粒子运动传感器的响应，而只是从压力传感器响应和已知的压力传感器深度来估计。这些抑制的频率是拖缆的机械运动所期望的。在更低的感兴趣频率上，估计响应具有差的信噪比。某一频率以下的这种抑制不是最优的，因为它还抑制了重要低频段中的有用信号，在该低频段内可能存在深度目标数据。US Patent No. 7,359,283 by Vaage et al. describes a method of combining a load sensor and a particle motion sensor to address the effect of mechanical motion on the particle motion sensor. In this method, the response of the particle motion sensor below a certain frequencyf0 is not used, but only estimated from the pressure sensor response and the known depth of the pressure sensor. These suppressed frequencies are expected from the mechanical motion of the streamer. At lower frequencies of interest, the estimated response has a poor signal-to-noise ratio. This suppression below a certain frequency is not optimal because it also suppresses useful signals in the important low frequency band where depth target data may exist.
尽管这些专利都描述了抑制地震拖缆中的重影陷波的方法，但是没有充分论述拖缆绳和其他影响粒子-运动传感器或水听器测量的噪声的影响。所有这些专利还缺乏生成高保真、具有低至感兴趣的最低频率的良好信噪比的感应声波成分。Although these patents all describe methods of suppressing ghost notches in seismic streamers, the effects of streamer cables and other noise affecting particle-motion sensor or hydrophone measurements are not adequately addressed. All of these patents also lack the generation of high fidelity inductive acoustic components with good signal-to-noise ratio down to the lowest frequencies of interest.
发明内容Contents of the invention
这些缺点可由体现本发明特点的水下地震系统来克服。此类系统包括一个第一运动传感器和一个第二运动传感器，该第一运动传感器可以用于水下平台且具有一个第一响应，该第二运动传感器布置在该第一运动传感器附近且具有一个第二响应。该第一和第二响应的幅值对于平台运动而言近似，而对声波粒子运动则不同。These disadvantages are overcome by an underwater seismic system embodying features of the present invention. Such systems include a first motion sensor that may be used on an underwater platform and having a first response, and a second motion sensor disposed adjacent to the first motion sensor and having a Second response. The magnitudes of the first and second responses are similar for platform motion but different for acoustic particle motion.
一个版本包括一个第一运动传感器和一个第二运动传感器，该第一运动传感器具有一个第一声阻抗以生成表示平台运动和声波的第一传感器信号，该第二运动传感器布置在第一运动传感器附近且具有一个第二声阻抗以产生表示平台运动和表示由声波导致的衰减的粒子运动的第二传感器信号。用于组合该第一传感器信号和该第二传感器信号的装置衰减了由平台运动引起的噪声，并且生成对由声波引起的粒子运动的响应。One version includes a first motion sensor having a first acoustic impedance to generate a first sensor signal representative of platform motion and sound waves, and a second motion sensor disposed on the first motion sensor and having a second acoustic impedance to generate a second sensor signal indicative of platform motion and attenuated particle motion indicative of the acoustic wave. The means for combining the first sensor signal and the second sensor signal attenuates noise caused by platform motion and generates a response to particle motion caused by acoustic waves.
另一个版本包括一个第一运动传感器和一个布置在该第一运动传感 器附近的第二运动传感器。配置隔声罩来从声波粒子运动仅屏蔽的第二运动传感器。Another version includes a first motion sensor and a second motion sensor disposed adjacent the first motion sensor. Configure the acoustic enclosure to shield only the second motion sensor from acoustic particle motion.
附图说明Description of drawings
通过参照以下描述、所附权利要求和附图可更好的理解本发明的这些方面和特征，其中：These aspects and features of the present invention may be better understood with reference to the following description, appended claims and drawings, in which:
图1是典型的地震勘探操作的侧视图，展示了勘探船后缆绳下的一排水听器并描绘了到达拖曳阵列接收点的反射地震能量；Figure 1 is a side view of a typical seismic survey operation showing a row of hydrophones under a cable behind the survey vessel and depicting the reflected seismic energy reaching the receiving point of the towed array;
图2是粒子速度传感器响应的二维图；Figure 2 is a two-dimensional graph of the response of a particle velocity sensor;
图3是全向水听器响应与垂直粒子-速度传感器的响应相加的二维图；Figure 3 is a two-dimensional diagram of the addition of omnidirectional hydrophone responses to the responses of vertical particle-velocity sensors;
图4是如图1中的典型勘探的俯视图，描绘了拖曳速度波动和偏航；Figure 4 is a top view of a typical survey as in Figure 1, depicting tow velocity fluctuations and yaw;
图5是如图4中的勘探的侧视图，描绘了拖缆形式上的拖曳速度波动和偏航的夸大效果；Figure 5 is a side view of the survey as in Figure 4, depicting the exaggerated effect of drag velocity fluctuations and yaw on the streamer form;
图6是如图1中勘探中拖缆的典型加速度的图；Figure 6 is a graph of typical accelerations of the streamer in the survey of Figure 1;
图7是体现本发明特征的水下地震系统普通版的框图，包括两个具有不同声响应的运动传感器；Figure 7 is a block diagram of a generic version of an underwater seismic system embodying features of the present invention, including two motion sensors having different acoustic responses;
图8是如图7中的运动传感器对入射声能量的声波分量响应的频域框图；Fig. 8 is a frequency domain block diagram of the response of the motion sensor to the acoustic component of incident acoustic energy as in Fig. 7;
图9是如图7中的运动传感器对入射声能量的平台运动分量响应的频域框图；Fig. 9 is a frequency domain block diagram of the response of the motion sensor to the platform motion component of incident acoustic energy as in Fig. 7;
图10是如图7中的运动传感器的输出的时域图，该输出是对平台运动和声（压）波的响应；Figure 10 is a time-domain diagram of the output of a motion sensor as in Figure 7, the output being a response to platform motion and sound (pressure) waves;
图11是如图7中的运动传感器的输出的时域图，该输出是仅对平台运动的响应；Figure 11 is a time-domain diagram of the output of a motion sensor as in Figure 7, the output being a response to platform motion only;
图12是图10和图11输出间的差值，表示去除平台运动的声（压力）波信号；Fig. 12 is the difference between the outputs of Fig. 10 and Fig. 11, representing the acoustic (pressure) wave signal with platform motion removed;
图13是如图7中的地震系统的一个版本，其中该运动传感器封装在不同结构中，这提供了不同的声阻抗；Figure 13 is a version of the seismic system as in Figure 7, wherein the motion sensor is packaged in a different structure, which provides a different acoustic impedance;
图14A和14B是如图7中的另一个地震系统的剖视图，该系统具有多个轴对称排列在拖缆中的运动传感器；14A and 14B are cross-sectional views of another seismic system as in FIG. 7 having a plurality of motion sensors arranged axisymmetrically in the streamer;
图15是如图7中地震系统的另一个版本，其中每个运动传感器有一个不同的声截面以提供不同的声响应；Figure 15 is another version of the seismic system of Figure 7, wherein each motion sensor has a different acoustic cross-section to provide a different acoustic response;
图16是具有更高增益的图15的地震系统的另一个版本；Figure 16 is another version of the seismic system of Figure 15 with higher gain;
图17是如图7中的地震系统的侧视图，该系统安装在可旋转地从拖缆悬挂下来的电缆定位飞行器中；以及Figure 17 is a side view of a seismic system as in Figure 7 mounted in a cable positioning vehicle rotatably suspended from a streamer; and
图18是如图7中的地震系统的侧视图，该系统安装在与拖缆段间连接成直线的电缆定位飞行器中。Figure 18 is a side view of a seismic system as in Figure 7 installed in a cable location vehicle in line with the connection between the streamer sections.
具体实施方式detailed description
图7是体现本发明特征的水下地震系统19普通版的框图，该系统包括使用运动传感器或传感器组件的技术，对声波引起的信号具有不同的响应，而对平台（例如，拖缆、电缆或自治节点、运动）运动具有类似的响应，以提高为地震成像而获得的数据的信噪比。在图7中，两个运动传感器40、41和一个压力传感器42（通常为水听器）提供信号，对这些信号进行组合以生成噪声降低且去重影的信号。一组压力传感器可用于单个传感器的场合，例如，降低由沿该拖缆轴线传播的压力波引起的噪声。理想地，该运动传感器对直流电敏感且能够分解该重力向量，否则，需要一个额外的定向传感器。该第一运动传感器40具有对声波的响应，该响应理想地但不是必须地与海水的响应相等；如果要求更高的增益，其响应可以提高到超过海水的响应。第二运动传感器14具有对声波的响应，该响应与第一运动传感器40的响应明显不同。可用传感器在材料成分或几何形状方面的差别实现在声响应的这种差别。在本系统的所有版本中，选择两个传感器的材料和几何性质，从而使得它们对平台运动的机械响应匹配。例如，如果每个运动传感器被设计为以与二阶质量-弹簧系统相同的方式与电缆进行交互，则使得传感器的质量（包括附加质量，如果有的话）及它们相关联的弹簧系数相等。第一和第二运动传感器40、41的第一和第二输出44、45相减46，或在本地或在远程处理之后，以生成噪声降低的响应信号48，该信号表示由衰减了平台运动的声波引起的粒子运动。减法块46构成了一个用于组合第一传感器信号和第二传感器信号的装置。如果传感器之一的信号的相位相反，则用于组合第一传感器信号和第二传感器信号的装置将用加法块代替来实现。调节50噪声降低的响应以匹配压力传感器响应52，例如水听器信号，并用于p-z求和装置54来生成同样抑制了重影陷波和多次波的最终输出信号56。组合第一传感器信号和第二传感器信号的装置及p-z求和装置可通过模拟电路、数字逻辑电路或微处理器中的算法本地实现或由船上计算机或离线数据处理远程实现。FIG. 7 is a block diagram of a generic version of an underwater seismic system 19 embodying features of the present invention that includes technology using motion sensors or sensor assemblies that respond differently to signals induced by acoustic waves while responding to platforms (e.g., streamers, cables, etc.) or autonomous node, motion) motion with a similar response to improve the signal-to-noise ratio of data obtained for seismic imaging. In Figure 7, two motion sensors 40, 41 and one pressure sensor 42 (typically a hydrophone) provide signals which are combined to generate a noise-reduced and de-ghosting signal. A set of pressure sensors may be used where a single sensor would, for example, reduce noise caused by pressure waves propagating along the streamer axis. Ideally, the motion sensor is DC sensitive and able to resolve the gravity vector, otherwise, an additional orientation sensor is required. The first motion sensor 40 has a response to acoustic waves that is ideally but not necessarily equal to that of seawater; if higher gains are required, its response can be increased beyond that of seawater. The second motion sensor 14 has a response to sound waves that is significantly different from the response of the first motion sensor 40 . This difference in acoustic response can be achieved with differences in the material composition or geometry of the sensors. In all versions of the system, the materials and geometry of the two sensors are chosen such that their mechanical responses to platform motion match. For example, if each motion sensor is designed to interact with the cable in the same manner as a second-order mass-spring system, the masses of the sensors (including additional mass, if any) and their associated spring constants are made equal. The first and second outputs 44, 45 of the first and second motion sensors 40, 41 are subtracted 46, either locally or after remote processing, to generate a noise-reduced response signal 48 indicative of the attenuated platform motion Particle motion caused by sound waves. The subtraction block 46 constitutes a means for combining the first sensor signal and the second sensor signal. If the phases of the signals of one of the sensors are opposite, the means for combining the first sensor signal and the second sensor signal will be implemented with an addition block instead. The noise-reduced response is adjusted 50 to match a pressure sensor response 52, such as a hydrophone signal, and used in a p-z summation device 54 to generate a final output signal 56 that is also suppressed from ghost notches and multiples. The means for combining the first sensor signal and the second sensor signal and the p-z summing means can be implemented locally by an algorithm in an analog circuit, digital logic circuit or microprocessor or remotely by an onboard computer or offline data processing.
图8是图7中的两个运动传感器40、41的频域框图，表示了它们对入射能量的声波分量58的传递函数。该声波分量包括感兴趣的地震信号。第一传感器40和第二传感器41具有不同的声波传递函数H1(s)和H2(s)。传递函数H1(s)对声波粒子运动敏感，因此第一传感器40生成代表粒子运动的输出响应O1(s)。传递函数H2(s)对声波粒子运动不敏感，因此第二传感器41生成不包括周围声介质粒子的运动的输出响应O2(s)。图9是图7的两个运动传感器40、41的频域框图，表示它们对入射能量的平台运动分量59的传递函数。对平台运动而言，两个运动传感器40、41的传递函数H3(s)和H4(s)在幅值上成比例（或相等），但是在相位上可能相反。因此，两个传感器40、41对平台运动都具有类似的输出响应O3(s)和O4(s)。第一和第一运动传感器40、41对入射能量的复合传递函数对第一传感器来说是H1(s)和H3(s)的组合而对第二传感器来说是H2(s)和H4(s)的组合。两个传感器的复合响应对第一运动传感器来说是O1(s)和O3(s)的组合而对第二运动传感器来说是O2(s)和O4(s)的组合。图10是第一传感器40对入射能量的时域响应的实例表示，该入射能量包括平台运动和声波。第一传感器的响应44对平台噪声和声波二者都敏感。图11是第二传感器41对相同入射能量的相应响应。第二传感器的响应45只对入射能量的平台噪 声分量敏感。图12绘出了组合两个传感器的响应的结果，该组合通过从第一传感器的输出44减去第二传感器的输出45以生成图7中减去噪声的声波信号48。为了简化描述，尽管第二传感器对压力波的响应被视为零，但是对压力波可能有微小的响应或者甚至是负响应。此外，第一和第二传感器输出可能与拖缆震动并不完全匹配。但是，即使在这些情况下，信号相减仍然导致具有大大衰减的平台运动响应的声波响应，该平台运动响应能够按比例调节并通过p-z求和与水听器数据相组合。FIG. 8 is a frequency domain block diagram of the two motion sensors 40, 41 of FIG. 7 showing their transfer functions for the acoustic component 58 of the incident energy. The acoustic component includes the seismic signal of interest. The first sensor 40 and the second sensor 41 have different acoustic wave transfer functions H1 (s) and H2 (s). The transfer function H1 (s) is sensitive to acoustic particle motion, so the first sensor 40 generates an output response O1 (s) representative of the particle motion. The transfer functionH2 (s) is insensitive to acoustic particle motion, so the second sensor 41 generates an output responseO2 (s) that does not include the motion of the surrounding acoustic medium particles. FIG. 9 is a frequency domain block diagram of the two motion sensors 40, 41 of FIG. 7 showing their transfer functions for the platform motion component 59 of incident energy. For platform motion, the transfer functions H3 (s) and H4 (s) of the two motion sensors 40 , 41 are proportional (or equal) in magnitude, but may be opposite in phase. Therefore, both sensors 40, 41 have similar output responsesO3 (s) andO4 (s) to platform motion. The composite transfer function of the first and first motion sensors 40, 41 for incident energy is the combination of H1 (s) and H3 (s) for the first sensor and H2 (s) for the second sensor Combinations with H4 (s). The composite response of the two sensors is the combination of O1 (s) and O3 (s) for the first motion sensor and O2 (s) and O4 (s) for the second motion sensor. FIG. 10 is an example representation of the time domain response of the first sensor 40 to incident energy including platform motion and sound waves. The response 44 of the first sensor is sensitive to both platform noise and sound waves. Figure 11 is the corresponding response of the second sensor 41 to the same incident energy. The response 45 of the second sensor is only sensitive to the plateau noise component of the incident energy. FIG. 12 plots the result of combining the responses of the two sensors by subtracting the output 45 of the second sensor from the output 44 of the first sensor to generate the noise-subtracted acoustic signal 48 of FIG. 7 . To simplify the description, although the response of the second sensor to the pressure wave is considered to be zero, there may be a slight or even a negative response to the pressure wave. Also, the first and second sensor outputs may not exactly match the streamer vibrations. Even in these cases, however, signal subtraction still results in an acoustic response with a greatly attenuated platform motion response that can be scaled and combined with the hydrophone data by pz summation.
图7-9框图中表示的通用系统的不同特定版本使用不同级别的声阻抗以获得对声音小波响应的期望差别。如上所述，两个运动传感器40、41和压力传感器42安装在平台中、平台上或安装到平台。例如，可以将其封闭在水下拖缆中或安装在附装到拖缆上的电缆定位飞行器内。例如，这些运动传感器声学上相互隔离，但是位置相近且由分割器分成独立的区域。第一运动传感器封闭在具有表面的一个第一区域，该表面的声阻抗与周围海水的声阻抗近似，从而使得声波能够以最小的反射穿透该表面并作用于传感器。第二运动传感器位于在一个第二区域中的声绝缘的壳体内，且不受入射声波影响。拉力下的拖缆本身具有对声波的微弱且不稳定的响应。拖缆本身对声波的任何响应被记录为平台运动。因此，第一传感器具有对声波的成比例的响应；而第二传感器具有极小的响应。此外，校正该传感器组件以匹配对平台运动（例如，拖缆震动）的响应，例如，假如表现为二阶质量-弹簧系统可通过使它们的质量（包括附加质量，如果有的话）和相应的弹簧系数相等。从第一传感器信号减去（或本地或远程处理之后）第二传感器信号用大大衰减了的拖缆-运动响应生成期望的声波信号。Different specific versions of the general system represented in the block diagrams of Figures 7-9 use different levels of acoustic impedance to obtain the desired difference in the wavelet response to the sound. As mentioned above, the two motion sensors 40, 41 and the pressure sensor 42 are mounted in, on or to the platform. For example, it could be enclosed in an underwater streamer or installed in a cable positioning vehicle attached to the streamer. For example, the motion sensors are acoustically isolated from each other, but located in close proximity and divided into separate areas by a divider. The first motion sensor is enclosed in a first region having a surface with an acoustic impedance that approximates that of the surrounding sea water so that sound waves can penetrate the surface and act on the sensor with minimal reflection. The second motion sensor is located in the acoustically insulated housing in a second area and is not affected by incident sound waves. A streamer under tension itself has a weak and unstable response to sound waves. Any response of the streamer itself to the sound waves is recorded as platform motion. Thus, the first sensor has a proportional response to the sound waves; while the second sensor has a very small response. In addition, the sensor assembly is calibrated to match the response to platform motion (e.g., streamer vibrations), for example, if it behaves as a second-order mass-spring system by making their masses (including additional masses, if any) and the corresponding The spring constants are equal. Subtracting (either after local or remote processing) the second sensor signal from the first sensor signal generates the desired acoustic signal with a greatly attenuated streamer-motion response.
图13示出了图7-9的地震系统的一个特定版本，带有由中心分割器64声学上隔离的两个运动传感器60、61，以及一个压力传感器62。第一运动传感器60包含在带有刚性、透声的表面68的拖缆的第一区域66中。例如，表面68是被一个有弹性、透声的外皮70覆盖的穿孔的、刚性的壳 体。第一区域66的内部充满了液体。理想地，该外皮和液体都具有与周围海水相等的声阻抗。第一测试质量72悬挂在液体中，该质量具有一个理想地但不是必须地与液体的声响应相等的声响应；如果要求更高的增益，其响应可以提高到超过海水的响应。该第一测试质量72借助于用作运动传感器的位移、速度或加速度传感器连接到拖缆的表面。该第一传感器60使用拖缆的表面作为参照标准，且充当动态地耦合该测试质量和拖缆的弹簧。例如，该第一传感器可以是单晶体或PZT弯曲物。如果该传感器是一个单轴传感器，则多测试质量系统可以用于形成一个三轴传感器，其中对所有的测试质量进行校准从而匹配声音和动态响应二者。多轴测量的一个替代方案是：只要该质量传感器响应能够保持独立，为了多轴测量将多个传感器连接到同一个测试质量。在第一区域66隔离器对面的第二区域67的组件中将第二传感器61和第二测试质量73相连接。第二传感器的组件与第一传感器的组件不同，因为其壳体表面69具有一个远大于周期海水的声阻抗的声阻抗，且其内部67充满了空气以对壳体表面69中任何不可忽略的弹性进行说明。第二传感器壳体的硬度增加了其增强的声阻抗的影响，这允许该壳体充当一个隔音罩，类同于电磁学中的法拉第（Faraday）笼。用具有适当地高密度或声速的材料来设置第二壳体表面69的声阻抗。FIG. 13 shows a specific version of the seismic system of FIGS. 7-9 with two motion sensors 60 , 61 acoustically separated by a center divider 64 , and one pressure sensor 62 . The first motion sensor 60 is contained in a first region 66 of the streamer with a rigid, acoustically transparent surface 68 . Surface 68 is, for example, a perforated, rigid shell covered by a resilient, acoustically permeable skin 70. The interior of the first region 66 is filled with liquid. Ideally, both the skin and the liquid have an acoustic impedance equal to that of the surrounding sea water. The first test mass 72 is suspended in the liquid and has an acoustic response ideally but not necessarily equal to that of the liquid; if higher gains are required its response can be increased beyond that of sea water. This first test mass 72 is connected to the surface of the streamer by means of displacement, velocity or acceleration sensors acting as motion sensors. The first sensor 60 uses the surface of the streamer as a reference standard and acts as a spring that dynamically couples the test mass and streamer. For example, the first sensor may be a single crystal or a PZT bend. If the transducer is a uniaxial transducer, a multiple test mass system can be used to form a triaxial transducer where all test masses are calibrated to match both acoustic and dynamic response. An alternative to multi-axis measurements is to connect multiple sensors to the same test mass for multi-axis measurements, as long as the mass sensor responses can remain independent. The second sensor 61 and the second test mass 73 are connected in an assembly in the second area 67 opposite the first area 66 to the isolator. The assembly of the second sensor is different from that of the first sensor in that its housing surface 69 has an acoustic impedance much greater than that of periodic seawater, and its interior 67 is filled with air to resist any non-negligible Elasticity is explained. The stiffness of the second sensor housing increases the effect of its enhanced acoustic impedance, which allows the housing to act as an acoustic enclosure, similar to a Faraday cage in electromagnetism. The acoustic impedance of the second housing surface 69 is set with a material having a suitably high density or sound velocity.
体现本发明的地震系统的另一个版本如图14A和14B所示，带有两组运动传感器80、81和一个压力传感器82。在这个版本中，第一组传感器80和第二组传感器81连接到承载拖缆震动的单个刚性本体84。该刚性本体具有一个大直径的第一部分86、一个较小直径的第二部分87和连接第一和第二部分的过渡段88。较小直径部分87是带有一个内侧83和一个外侧85的管状形体。第一组传感器80围绕着刚性本体84的第二部分87的一部分，并且连接到其外侧85。可用三个或更多个单独的传感器构成该第一组80。如果不采用轴对称，则该第一组传感器80而是位于该刚性本体的旁边。由覆盖在穿孔的刚性壳体上的柔性膜构成的透声表面90把该传感器系统和周围海水分开。该刚性本体84的第二部分87与表 面90之间的第一空腔92充满了液体。理想地，表面90和液体具有与周围海水的声阻抗相等的声阻抗。具有与图13中的第一测试质量相同的声学特性的第一测试质量94悬浮在第一空腔92中，并且围绕着刚性本体84的第二部分87。该第一测试质量94通过第一组运动传感器80机械地连接到该刚性本体84的外侧85，该第一组运动传感器具有与图13版本中的第一传感器60相同的特性，但是刚性本体84作为其参照标准。第二空腔93完全包含在刚性本体84的管状第二部分87中。该第二空腔93包含一个悬浮在液体中的第二测试质量95，且通过连接到该刚性本体的内侧83的第二组运动传感器81连接到刚性本体84。校正第二组传感器81的动态响应，以对拖缆震动具有匹配第一组80的响应的响应。然而，不同于第一测试质量94，对第二测试质量95的声响应没有要求。刚性本体84自身用作对第二组传感器81的隔声罩，且由具有相对高的声阻抗的材料组成。同轴排列的有益之处是多个独立的传感器对每个测试质量的加速度作出响应。组合该运动传感器的输出信号获得实际加速度值的更稳健估计。与描述的一样，第一组和第二组传感器80、81对径向运动敏感；如果需要三轴的敏感性，则每个与该拖缆轴线成一直线的空腔可包括一个附加的测试-质量-传感器系统。Another version of the seismic system embodying the present invention is shown in Figures 14A and 14B, with two sets of motion sensors 80,81 and one pressure sensor 82. In this version, the first set of sensors 80 and the second set of sensors 81 are connected to a single rigid body 84 that carries the vibrations of the streamer. The rigid body has a first portion 86 of large diameter, a second portion 87 of smaller diameter and a transition section 88 connecting the first and second portions. The smaller diameter portion 87 is a tubular shape with an inner side 83 and an outer side 85 . The first set of sensors 80 surrounds a portion of the second portion 87 of the rigid body 84 and is connected to the outer side 85 thereof. The first group 80 can be made up of three or more individual sensors. If axial symmetry is not employed, the first set of sensors 80 is instead located alongside the rigid body. An acoustically transparent surface 90 consisting of a flexible membrane covering a perforated rigid shell separates the sensor system from the surrounding seawater. A first cavity 92 between the second portion 87 of the rigid body 84 and the surface 90 is filled with liquid. Ideally, the surface 90 and the liquid have an acoustic impedance equal to that of the surrounding sea water. A first test mass 94 having the same acoustic properties as the first test mass in FIG. 13 is suspended in the first cavity 92 and surrounds the second portion 87 of the rigid body 84 . The first test mass 94 is mechanically connected to the outer side 85 of the rigid body 84 by a first set of motion sensors 80 having the same characteristics as the first sensor 60 in the version of FIG. as its reference standard. The second cavity 93 is completely contained within the tubular second portion 87 of the rigid body 84 . The second cavity 93 contains a second test mass 95 suspended in a liquid and is connected to the rigid body 84 through a second set of motion sensors 81 connected to the inner side 83 of the rigid body. The dynamic response of the second set of sensors 81 is corrected to have a response to streamer vibrations that matches the response of the first set 80 . However, unlike the first test mass 94 , there are no requirements on the acoustic response of the second test mass 95 . The rigid body 84 itself acts as an acoustic enclosure for the second set of sensors 81 and is composed of a material with a relatively high acoustic impedance. The benefit of the coaxial arrangement is that multiple independent sensors respond to the acceleration of each test mass. Combining the output signals of the motion sensors obtains a more robust estimate of the actual acceleration value. As described, the first and second sets of sensors 80, 81 are sensitive to radial motion; if triaxial sensitivity is required, each cavity in line with the streamer axis may include an additional test - Quality - sensor system.
图15示出了地震系统的另一个版本。带有刚性的、透声表面98的拖缆有两个运动传感器100、101（比如，对直流电敏感的、三轴的加速计）和一个压力传感器102（比如，水听器）。例如，该表面98可包括一个穿孔的、刚性的壳体，该壳体被一个有弹性、透声的外皮所覆盖。可通过微型机电系统（MEMS）、PZT、单晶体、或具有类似效用的任何其他技术来实现该加速计。运动传感器100、101牢固地安装到第一和第二刚性壳体104、105以能够直接测量任何动态拖缆运动。两个传感器都声学上连接到该电缆表面98，但是例如通过中心分割器106声学上相互隔离。第一和第二壳体104、105的每一个将构建为使得第一壳体的质量加上其包围的质量等于第二壳体加上其包围的质量。设计壳体和拖缆表面98之间的动态连接器103用作具有相同弹簧系数的二阶质量-弹簧系统，因此， 维持了相等的质量-弹簧关系。另一方面，这些壳体具有不同的声截面，因此，它们对声压力波生成不同的响应。具体地，第一传感器100生成一个很好地表示声粒子运动的第一传感器信号108；第二传感器101生成一个对声波基本上不敏感的第二传感器信号109。用不同的几何体也可能是不同的材料构造传感器壳体以产生不同的截面且从而为每个传感器产生不同的传递函数。在本地或在在远程处理之后，从第一传感器信号108减去第二传感器信号109以提供期望的压力波信号，该信号对拖缆运动具有大大衰减了的响应。例如，可用开孔泡沫塑料作为每个壳体104、105和表面98之间的动态连接器103。充满被校正从而匹配周围海水的声阻抗的液体，该泡沫塑料还可以作为透声连接器。在这个例子中，考虑到液体和充满了空气，对该第一壳体104进行密封从而说明壳体中任何不可忽视的弹性；以及，对第二壳体105穿孔或开槽，且允许其用周围的液体充满。壳体之间整体密度中的综合差异说明它们对入射压力波的不同响应。Figure 15 shows another version of the seismic system. A streamer with a rigid, acoustically transparent surface 98 has two motion sensors 100, 101 (eg, DC-sensitive, three-axis accelerometers) and a pressure sensor 102 (eg, hydrophones). For example, the surface 98 may comprise a perforated, rigid shell covered by a resilient, acoustically permeable skin. The accelerometer may be implemented by microelectromechanical systems (MEMS), PZT, single crystal, or any other technology of similar utility. Motion sensors 100, 101 are rigidly mounted to first and second rigid housings 104, 105 to enable direct measurement of any dynamic streamer motion. Both sensors are acoustically connected to the cable surface 98 but are acoustically isolated from each other, for example by a center divider 106 . Each of the first and second shells 104, 105 will be constructed such that the mass of the first shell plus its enclosed mass is equal to the second shell plus its enclosed mass. The dynamic connector 103 between the housing and the streamer surface 98 is designed to function as a second order mass-spring system with the same spring constant, thus maintaining an equal mass-spring relationship. On the other hand, these shells have different acoustic cross-sections, therefore, they generate different responses to acoustic pressure waves. Specifically, the first sensor 100 generates a first sensor signal 108 that is well representative of the motion of acoustic particles; the second sensor 101 generates a second sensor signal 109 that is substantially insensitive to acoustic waves. Constructing the sensor housing with different geometries and possibly different materials results in different cross-sections and thus different transfer functions for each sensor. Either locally or after remote processing, the second sensor signal 109 is subtracted from the first sensor signal 108 to provide the desired pressure wave signal with a greatly attenuated response to streamer motion. For example, open cell foam may be used as the dynamic connector 103 between each shell 104 , 105 and the surface 98 . Filled with a liquid calibrated to match the acoustic impedance of the surrounding seawater, the foam also acts as an acoustically transparent connector. In this example, the first housing 104 is sealed to account for any non-negligible elasticity in the housing, taking into account liquids and being filled with air; and, the second housing 105 is perforated or slotted and allows its use The surrounding fluid is filled. The combined difference in bulk density between the shells accounts for their different responses to incident pressure waves.
图16示出了旨在提高系统的总增益的图15的地震系统的修改版。该第一传感器110声学上和动态地表现为与图15中的第一传感器100相同。该第二传感器111生成一个对压力波的响应和一个拖缆运动响应，该对压力波的响应与第一传感器110的响应匹配，该拖缆运动响应与该第一传感器在幅值上相等，而在相位上相反。和图15中一样构建第一壳体114和第二壳体115，特别是在声截面和密度方面，因此，它们对电缆运动具有类似的质量-弹簧响应，但是对入射声压力波具有一个明显不同的响应。此外，该第二壳体115包括一个测试质量116，该测试质量被设计为在液体中摆动并具有匹配第一壳体114的响应的声波响应。另一方面，测试质量对拖缆运动的响应远小于壳体的响应，这是因为测试质量悬浮在液体中而壳体机械连接到电缆表面。测试质量116依靠使用第二壳体作为参照标准的位移、运动或加速度传感器111不牢固地连接到第二壳体115。在这个例子中，使用由压电材料组成的悬臂式加速计作为运动传感器。多个加速计可用于构成一个三轴传感器，其中对每个测试质量进行校正从而匹配第一壳体114在其各个轴线的声响应。因此，可以正向地（即同相）检 测到施加到该测试质量116上而不是第二壳体115上的运动的压力波。因此，来自第一传感器110和第二传感器111的压力信号在幅值和符号上匹配。相反地，负向地（即，反相）检测影响第二壳体115而不是测试质量116的拖缆震动。因此，来自传感器的震动信号在幅值上匹配，但具有相反的符号。在这种情况下，通过加法118，而不是减法，组合来自两个传感器110、111的信号以生成大大衰减了的拖缆运动响应且同时提高声波响应的增益。替代地，可使用第一壳体114中的另一个悬挂式测试质量。但是，由于第一传感器信号的极性将同样颠倒，因此必须通过减法而不是加法与该第二传感器信号相组合。Figure 16 shows a modification of the seismic system of Figure 15 aimed at increasing the overall gain of the system. This first sensor 110 behaves acoustically and dynamically identically to the first sensor 100 in FIG. 15 . The second sensor 111 generates a response to pressure waves that matches the response of the first sensor 110 and a streamer motion response that is equal in magnitude to the first sensor, And opposite in phase. The first housing 114 and the second housing 115 are constructed as in Fig. 15, especially in terms of acoustic cross-section and density, so that they have a similar mass-spring response to cable motion, but have a distinct response to incident acoustic pressure waves. different responses. In addition, the second housing 115 includes a test mass 116 that is designed to oscillate in the liquid and has an acoustic response that matches the response of the first housing 114 . On the other hand, the response of the test mass to the movement of the streamer is much smaller than that of the shell, because the test mass is suspended in the liquid and the shell is mechanically attached to the surface of the cable. The test mass 116 is loosely connected to the second housing 115 by virtue of the displacement, motion or acceleration sensor 111 using the second housing as a reference standard. In this example, a cantilever accelerometer composed of piezoelectric material is used as the motion sensor. Multiple accelerometers may be used to form a three-axis sensor, where each test mass is calibrated to match the acoustic response of the first housing 114 in its respective axis. Accordingly, moving pressure waves applied to the test mass 116 but not to the second housing 115 can be detected in the forward direction (i.e., in phase). Thus, the pressure signals from the first sensor 110 and the second sensor 111 are matched in magnitude and sign. Conversely, streamer shocks affecting the second housing 115 rather than the test mass 116 are detected negatively (ie, out of phase). Thus, the shock signals from the sensors match in magnitude, but have opposite signs. In this case, the signals from the two transducers 110, 111 are combined by addition 118, rather than subtraction, to generate a greatly attenuated streamer motion response while increasing the gain of the acoustic response. Alternatively, another suspended test mass in the first housing 114 may be used. However, since the polarity of the first sensor signal would also be reversed, it must be combined with this second sensor signal by subtraction rather than addition.
如图17中所示，地震系统19的传感器部分可安装在拖缆电缆120中或通过卡圈124可旋转地连接到拖缆的电缆定位设备（比如，电缆矫正或电缆管理飞行器122）中。如图18中所示，在首尾拖缆段128、129之间直线连接的电缆定位设备126可放置在地震系统19的传感器部分中。明显地，这些传感器可安装在另一些设备中，这些设备可附装在拖缆、海底电缆或自治节点内部、上面或附装到这些设备。As shown in FIG. 17 , the sensor portion of the seismic system 19 may be mounted in the streamer cable 120 or rotatably connected to the streamer by a collar 124 in a cable positioning device such as a cable straightening or cable management vehicle 122 . As shown in FIG. 18 , a cable positioning device 126 connecting linearly between the fore and aft streamer sections 128 , 129 may be placed in the sensor portion of the seismic system 19 . Obviously, these sensors may be installed in other devices which may be attached in, on or to streamers, submarine cables or autonomous nodes.
具有对直流电和对由美国德克萨斯州休斯顿ION Geophysical公司制造的VectorSeis传感器类似的响应的三轴加速计适于本发明的多个实施方案。由于地震小波中没有直流分量，因此，该运动传感器的直流响应用于检测传感器相对重力的方位。设计拖缆轴线的已知方向为传感器的一个轴线。由于该拖缆轴线方向已知且重力向量是经过测量的，因此传感器的方向以及因而到达的感测地震小波的方向可以相对重力电子地旋转，从而使得，可以接受向上的地震小波以及拒绝向下的地震小波。A three-axis accelerometer with a similar response to direct current and to a VectorSeis sensor manufactured by ION Geophysical Corporation of Houston, Texas, USA is suitable for various embodiments of the present invention. Since there is no DC component in the seismic wavelet, the DC response of the motion sensor is used to detect the orientation of the sensor relative to gravity. The known direction of the design streamer axis is one axis of the sensor. Since the direction of the streamer axis is known and the gravity vector is measured, the orientation of the sensor, and thus the direction of the arriving sensed seismic wavelet, can be electronically rotated relative to gravity, such that upward seismic wavelets are accepted and downwards are rejected. seismic wavelet.
可以使用检测运动的任意传感器。该传感器可以是对位置、速度或加速度响应的任何运动传感器。例如，如在由Tenghamn等人发明的美国专利号为7,239,577的专利中所述的万向第一地震检波器可以与第二地震检 波器组合并封装，从而使得它对任何声波具有很小的响应或没有响应，以及对拖缆运动具有相同的响应，以实现期望的结果。只要具有适当的传感器性能，可以使用压电加速计。Any sensor that detects motion can be used. The sensor can be any motion sensor that responds to position, velocity or acceleration. For example, a gimbaled first geophone as described in U.S. Patent No. 7,239,577 to Tenghamn et al. can be combined and packaged with a second geophone such that it has little response to any acoustic waves or no response, and the same response to streamer motion, to achieve the desired result. Piezoelectric accelerometers can be used as long as they have appropriate sensor performance.
如果传感器不能确定其自身方向，传感器系统可包括单独的定位传感器。可替代地，机械装置（比如平衡系统）可用于将传感器固定在已知的方位。附装到拖缆上的飞行设备（有时被称为飞行器）还可以用于强制将传感器移动到期望的方位。If the sensor cannot determine its own orientation, the sensor system may include a separate positioning sensor. Alternatively, a mechanical device, such as a balancing system, can be used to hold the sensor in a known orientation. A flying device (sometimes called a vehicle) attached to the streamer can also be used to force the sensor to a desired orientation.
本发明并不意味着限制用于拖曳式海洋拖缆。所述技术还可用于其他平台，比如海底电缆和自治节点系统。此外，所述传感器系统可用于单独地收集地震数据；或者，它们能够捆绑在一起且共同使用，组合它们的数据来降低局部流动模式的影响。The present invention is not meant to be limited to use with towed marine streamers. The technology can also be used on other platforms, such as submarine cables and autonomous node systems. Furthermore, the sensor systems can be used to collect seismic data individually; alternatively, they can be bundled together and used together, combining their data to reduce the effects of local flow patterns.
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US29765610P | 2010-01-22 | 2010-01-22 | |
| US61/297,656 | 2010-01-22 | ||
| PCT/US2011/022059WO2011091252A2 (en) | 2010-01-22 | 2011-01-21 | Seismic system with ghost and motion rejection |
| Publication Number | Publication Date |
|---|---|
| CN102812382A CN102812382A (en) | 2012-12-05 |
| CN102812382Btrue CN102812382B (en) | 2016-12-14 |
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| TR01 | Transfer of patent right | Effective date of registration:20231208 Address after:louisiana Patentee after:Dijix LLC Address before:Texas, USA Patentee before:ION GEOPHYSICAL Corp. |