绕射波分离关键技术研究

发布时间：2018-05-17 01:05

本文选题：绕射波分离 + 绕射目标成像　；参考：《中国石油大学(华东)》2015年硕士论文

【摘要】：随着对构造、岩性油气藏的精细勘探和进一步开发,地下复杂构造尤其是小尺度地质体的高分辨率成像作为高精度地震解释的重要前提,在油气勘探中的作用日益显著。作为当前地震解释的主要目标,断层、尖灭、河道、裂缝、盐丘边界以及碳酸盐岩缝洞储集体等地质构造在地震剖面上通常表现为丰富的绕射地震响应。然而,常规地震处理技术将镜面反射波作为主要研究对象,绕射波往往被忽略或者视为干扰噪音滤除;即使将其偏移归位,能量较弱的绕射波成像结果也会被强反射能量淹没。由于在处理过程中丢失了绕射波所携带的高分辨率信息,常规地震处理得到的成像分辨率较低。因此,充分利用地震资料中的绕射波信息,实现绕射波单独成像,提高小尺度地质目标体的成像分辨率及识别精度对于复杂地质条件下的高精度地震解释具有非常重要的研究意义和社会价值。本文通过分析绕射波在不同地震道集中的响应特征,对绕射波分离关键技术进行研究,提出了针对绕射波的高分辨率地震成像技术,进而服务于复杂地质条件下的高精度地震解释。本文首先介绍了倾角域绕射波分离与成像方法,主要包括以下几个方面:(1)依据高斯束角度域叠前偏移思路,推导并实现了倾角域共成像点道集(CIG)的提取;(2)实现了基于相似谱扫描的倾角域绕射波分离方法,该方法可在倾角域较好的压制反射同相轴稳相顶点附近用于相干叠加的反射能量,得到的绕射波单独成像结果可有效突出绕射能量,进而提高绕射目标的成像分辨率;(3)针对基于相似谱扫描的绕射波提取算法在压制反射顶点附近的反射能量时,反射切除半径只能是固定值,影响波场分离效果,提出了基于反射能量预测的倾角域绕射波提取方法,该方法可在很好保留绕射波的前提下最大限度的压制反射波,最终绕射波单独成像结果的分辨率和精度都进一步提高。鉴于倾角域绕射波分离方法对低信噪比资料的适应性不足等缺点,提出了基于反稳相滤波的绕射波分离与成像方法,该方法通过在传统的克希霍夫偏移算子中引入反稳相滤波器,使满足Snell定律的镜面反射波得到有效压制,实现绕射波的提取。数值试算证明该绕射波提取方法对断阶等小尺度绕射目标具有更好的分辨能力,成像精度更高。另外,针对边界绕射波特有的极性反转现象,在绕射波成像过程中引入极性校正因子,可以使边界绕射波完全收敛,进而提高断阶边界的识别精度。
[Abstract]:With the fine exploration and further development of structures and lithologic reservoirs, the high-resolution imaging of complex underground structures, especially small scale geological bodies, as an important prerequisite for high-precision seismic interpretation, plays an increasingly important role in oil and gas exploration. As the main target of seismic interpretation at present, geological structures such as faults, pinches, river channels, fractures, salt dome boundaries and carbonate fractures and caverns are usually characterized by abundant diffraction seismic responses on seismic profiles. However, conventional seismic processing technology takes specular reflection as the main object of study. Diffraction waves are often ignored or regarded as interference noise filtering, and even if they are shifted back, the imaging results of weak diffraction waves will be submerged by strong reflection energy. Due to the loss of high resolution information carried by diffraction waves in the process of processing, the imaging resolution of conventional seismic processing is relatively low. Therefore, we can make full use of the diffraction wave information in seismic data to realize the imaging of diffraction wave separately. It is of great significance and social value to improve the imaging resolution and recognition accuracy of small scale geological objects for high-precision seismic interpretation under complex geological conditions. By analyzing the response characteristics of diffraction wave in different seismic trace concentration, the key technology of diffraction wave separation is studied in this paper, and a high resolution seismic imaging technique for diffraction wave is proposed. Then it can be used for high precision seismic interpretation under complex geological conditions. In this paper, we first introduce the method of obliquity domain diffraction wave separation and imaging, including the following aspects: 1) according to the prestack migration of Gao Si beam angle domain, The extraction of common imaging point gathers in dip domain is derived and realized. (2) the method of diffraction wave separation in dip domain based on similar spectrum scanning is realized. This method can be used to suppress the reflection energy of coherent superposition near the vertex of coaxial stable phase in the obliquity domain, and the diffraction wave imaging results can effectively highlight the diffraction energy. Then the imaging resolution of diffraction target is improved. (3) for the diffraction wave extraction algorithm based on similar spectral scanning, when the reflection energy near the reflection point is suppressed, the reflection cutting radius can only be a fixed value, which affects the separation effect of the wave field. Based on the prediction of reflection energy, an obliquity domain diffraction wave extraction method is proposed. The method can suppress the reflected wave in maximum extent on the premise of keeping the diffraction wave well, and the resolution and accuracy of the individual imaging result of the diffraction wave are further improved. In view of the inadaptability of the obliquity domain diffraction wave separation method to the low signal-to-noise ratio (SNR) data, a method of diffraction wave separation and imaging based on inverse stable phase filtering is proposed. By introducing an inverted phase filter into the traditional Kirchhoff migration operator, the mirror reflection wave satisfying Snell's law can be effectively suppressed and the diffraction wave can be extracted. Numerical results show that the proposed method has better resolution ability and higher imaging accuracy for small scale diffraction targets. In addition, the polarity correction factor is introduced in the imaging process of diffraction wave, which can make the boundary diffraction wave converge completely and improve the recognition accuracy of broken order boundary.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P631.4;P618.13

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