【作者】 孙歧峰；

【导师】 杜启振；

【作者基本信息】 中国石油大学 ， 地质资源与地质工程， 2011， 博士

【摘要】 随着地震勘探的深入发展,油气勘探的目标逐渐转向复杂地表、复杂构造和复杂储层方向,对地震成像的精度提出了更高的要求。基于波动方程的叠前深度偏移是实现精细勘探,解决复杂油气藏勘探和开发的关键技术。因此,当前迫切需要发展能够适应复杂地质结构的波动方程叠前深度偏移成像技术。本文在任意广角波动方程(Arbitrarily Wide-Angle Wave Equation,简记为AWWE )理论研究的基础上,推导得到了频率-空间域声波AWWE ,进而得到二阶、三阶AWWE偏移算子,然后利用有限差分高阶分裂法进行求解,设计了一种新的偏移成像算法,并实现了声波AWWE方程的叠后和叠前深度偏移成像。声波OWWE是建立在对单程波波动方程(One Way Wave Equation,简记为OWWE )连续分裂近似的基础上,与传统的OWWE近似相比, AWWE更加准确地描述了地震波的传播。通过对AWWE偏移算子进行理论误差分析和不同参数的脉冲响应测试,结果表明优化AWWE偏移算子能够获得更大偏移倾角,对地震波传播的描述更加准确。AWWE偏移算子的阶数和参考速度的选取是影响偏移成像效果的重要因素,在脉冲响应和理论模型试验对比分析的基础上,提出了AWWE偏移算子的参数选取原则与优化策略,为AWWE偏移的实际应用和推广提供了重要参考。为了检验新算法的有效性和适应性,论文对Marmousi模型地震记录进行了叠后和叠前深度偏移成像试验,并与优化系数有限差分和傅立叶有限差分偏移方法从成像效果和计算效率等方面进行了对比。试验结果表明,新算法能够适应具有强横向变速和陡倾角等复杂地质结构的成像需要。与优化系数有限差分算法和Fourier有限差分算法偏移相比,基于AWWE偏移算法参数优化方法更加简单有效,对复杂地质体局部成像效果更好。与已有时间-空间域AWWE逆时偏移算法相比,新方法计算效率更高。基于AWWE方程的频率-空间域叠前深度偏移成像方法研究表明,新方法能够对复杂地质结构进行准确地偏移成像且具有较高的计算效率,因此,新方法的研究符合我国实现精细开发和解决复杂油气藏勘探难题的需要。更多还原

【Abstract】 With the development of seismic exploration, the targets of oil and gas exploration have been turning to complex surface, complex structures and complex reservoir, so seismic imaging technology is being challenged. Pre-stack depth migration based on wave equation is the key technology to achieve precise exploitation and overcome challenge of complex oil and gas exploration. Therefore, seismic migration technologies urgently need to be developed to adapt to the complex geological structure.In this paper, frequency-space domain acoustic arbitrarily wide-angle wave equation (abbreviated as AWWE ) was derived on the basis of the research of AWWE theory, then we get second and third order AWWE migration operator, and solve with finite difference high-split scheme in frequency-space domain, a new migration algorithm was designed and implemented acoustic AWWE equation post-stack and pre-stack migration. Compared with the traditional one-way wave equation (abbreviated as OWWE ) approximation, acoustic AWWE is based on successive division approximation of OWWE , so AWWE can be a more accurate description of the seismic wave propagation. By theoretical deviation analysis and the impulse response test with different parameters, the results show that the optimal AWWE migration operator can more accurately descript the phenomenon of seismic wave and get a greater imaging angle. The orders of AWWE migration operator and the selection of reference velocities are the important factors which can affect the result of migration. Based on the tests of impulse response and theoretical models, we presented the optimization strategies and principles of AWWE migration operator, and gived the significant guidance for the application of AWWE migration into practice. In order to test the effectiveness and adaptability, the new method is applied on the Marmousi model, and compared with the optimized finite difference and fourier finite-difference migration from imaging results and efficiency. Experimental results show that the new algorithm can adapt to the complex geological structure with strong lateral velocity variation and the steep dip. Compared with optimized finite difference and Fourier finite-difference migration method, the parameters optimization of new algorithm is more simple and effective, and can get better imaging on local of complex geological bodies. Compared with the AWWE scheme in the time-space domain, the proposed scheme has some advantages in computational efficiency.The research of pre-stack depth migration with frequency-space domain AWWE shows that the new method is an effective method to image the complex geological structure. So the new method can meet the need of precise exploitation and complex reservoir exploration in our country.更多还原