一种基于Q层析技术的速度建模方法及应用

A velocity modeling method based on Q tomography and its application

由于气云等低速异常体的存在,陆上复杂勘探区地震资料受吸收、衰减影响严重。气云区数据的能量弱,反射信号难以识别,依赖剩余残差拾取的网格层析反演、沿层速度分析等传统深度偏移速度建模方法难以进行准确的速度更新。为此,提出一种应用Q层析反演技术对局部低速异常体高效、准确的速度建模方法。该方法的核心是利用基于峰值频率的Q层析反演建立Q模型,在Q模型的约束下开展有针对性的局部速度更新,有助于高效、准确地对局部低速异常体进行速度建模,有利于气云区以及一些特殊异常体的识别。在建模过程中,Q模型与速度模型相互促进、迭代更新、同步优化,最终达到提升叠前深度偏移成像品质的目的。理论模型分析论证了该方法的正确性。在中国西南部某复杂三维探区的应用效果显著,偏移剖面品质得到大幅度提升,表明了该方法在实际生产应用中的优势和可行性。

Due to the presence of low⁃velocity anomalies such as gas clouds,seismic data in complex offshore explo⁃ration areas are seriously affected by stratum absorption and attenuation.The amplitude energy of gas cloud data is weak,and the reflected signals are difficult to identify.The traditional velocity modeling methods of depth migration such as grid tomography inversion and horizon velocity analysis rely on residual picking up and are difficult to be car⁃ried out.Therefore,this paper proposes a new velocity modeling method based on Q tomography inversion techno⁃logy.The core of this method is to employ Q tomography inversion based on peak frequency to build a Q model.Meanwhile,under the constraint of the model,a targeted local velocity update is conducted for efficient and accurate velocity modeling of local low⁃velocity anomalies.During the modeling,the built Q model and velocity model ulti⁃mately improve the imaging quality of pre⁃stack depth migration through mutual promotion and iterative update and optimization.The experimental analysis of the theoretical model proves the correctness of this method,which yields significant application effects in complex 3D exploration areas of southwest China.Finally,this method is verified to have advantages and feasibility in practical production applications.