【作者】 王清振；

【导师】 李振春；

【作者基本信息】 中国石油大学 ， 地球探测与信息技术， 2008， 硕士

【摘要】 随着地震勘探领域向深层化发展,对深层地震资料的质量要求越来越高。为了提高深层地震资料的信噪比和分辨率,我们进行了深层地震波吸收机理,深层去噪和能量补偿方法的研究。本文首先研究了影响地震波衰减的主要因素,可归纳为以下几个方面:①与地下的地质情况有关的因素,如反射系数、反射界面形状引起的聚焦与发散、地层非弹性引起的地层吸收、薄互层引起的多次反射、地下不均匀体引起的散射等;②与近地表条件有关的因素,如震源强度和耦合情况、检波器灵敏度和耦合情况、近地表松散地层的强烈吸收等;③与炮检距有关的因素,如球面发散、传播路径不同引起的吸收变化等。要有效补偿深层能量,首先需要提高深层信号的信噪比。本文提出了分割法二维小波变换压制面波方法,较之常规的FK滤波能最大限度地保护了有效波。另外比较了KL变换,f-x预测预测去噪,小波阈值去噪等随机噪声压制方法的优缺点:KL变换去噪对于倾斜和弯曲同相轴压制噪声效果不好,去噪后损失部分信号能量,并降低了信号的分辨率;f-x预测去噪是假定同相轴是线性的,当同相轴不是线性延伸时,使同相轴发生部分畸变;二维小波变换阈值去噪在保持信号能量方面取得较好的效果,去掉的基本上全是噪声,且对信噪比比较低的资料效果也较显著。针对大地吸收衰减提出了时频分析法能量补偿技术。该方法的最大优点是不需要知道地层的品质因子,这就避开了求取地层吸收系数这一难题,从而使这一方法能够得到广泛应用。模型试算和实际资料试处理证明了这种方法的有效性。更多还原

【Abstract】 With deep layer becoming the major objective of seismic exploration, high quality seismic data was needed. In order to improve the signal-noise(S/N) ratio and resolution of deep seismic data, deep layer seismic absorption mechanism, deep de-noising technology and energy compensation technology was studied.This paper studied the main factors influencing seismic wave attenuation, which can be summarized as the following:①The factors related to underground geological conditions, such as the reflection coefficient, the focus and divergence caused by reflection interface shape, absorption arising from the formation of non-elastic formation, multiple reflections caused by thin alternating layers, the scattering caused by inhomogenous;②The relevant factors related to near-surface conditions , such as the strength and coupling of the source, detector sensitivity and coupling, the strong absorption caused by the near-surface stratigraphy loose;③The factors related to offset, such as spherical divergence, absorption changes caused by different transmission path.In order to enhance signal energy in deep layer, the S/N ratio must be improved. This paper presents a segmentation surface wave suppression using 2-D wavelet transform. Compared with conventional FK filtering, the advantages of this method is to maximize maintain effective wave. In addition, the advantages and disadvantages of the KL transform, f-x forecast de-noising, wavelet threshold de-noising was compared: When the events are horizontal, the conventional KL transform can enhance the events; but when the events are oblique or curving, using the conventional KL transform will destroy the continuity of effective events; F-x forecast de-noising adapt to linear events. When the events are not linear, using f-x forecast de-noising will cause event distortion. 2-D wavelet transform de-noising have good result in maintaining signal energy and suitable to low S/N data.For the earth attenuation, time-frequency analysis of energy compensation technology has been presented. The biggest advantage of this method is does not need to know the quality of formation, which seek to avoid the formation of this absorption coefficient, so that this method can be widely applied. Model spreadsheet and the actual data processing test proved the validity of the method.更多还原