【作者】 张慧；

【导师】 李振春；

【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】 社会工业的需求和油气勘探开发技术的不断发展,使得油气工业面临着越来越复杂的勘探开发任务。简单构造、大型构造和浅中层构造的油气田开发已远远不能满足社会工业对油气资源的需求,勘探开发的重点逐渐向复杂的非均质储层倾斜,这就对现代油气勘探技术提出了更高的要求。常规的基于均匀介质的地震波正演模拟和偏移成像技术在解决复杂的非均质储层的问题时会出现理论或应用等各方面的局限性,因此需要寻求其它的方法对复杂的非均匀介质进行深入研究。本文考虑包含碳酸盐岩裂缝型储层在内的,各种不同尺度(可同地震波场相比拟、小于地震波长或远小于地震波长的尺度)的非均质储层,对面向非均匀介质的地震波正演模拟方法和逆时偏移算法进行了深入研究。速度场离散是地震波正演和逆时偏移的第一步,速度模型网格划分的优劣与计算效率和计算精度密切相关。为了更方便的模拟非均匀介质,本文对速度模型网格剖分进行了改进,采用了空间网格步长可变的剖分方式。相对于传统的规则交错网格,步长可变的有限差分网格对非均质储层地质模型的离散化更为合理。基于交错变步长网格,本文推导了任意精度变网格空间离散公式,应用到波场正演计算和逆时偏移中。在交错变步长网格的基础上,本文发展了局部变时间采样来配合变步长网格技术。在全局时间层内,对精细划分的空间区域进行局部时间层加密计算。局部变时间采样使模型不同区域得以满足不同的稳定性条件,从而使时间计算变得宽松,从根本上提高了计算效率。面向非均匀介质提出时空双变网格有限差分算法(即:空间变步长交错网格和局部变时间采样),本文应用流体薄层理论对碳酸盐岩微裂缝型储层进行了正演模拟。总结了裂缝延伸、裂缝缝间距(裂缝密度)、裂缝缝宽等裂缝特征参数与地震波场响应之间的规律和认识。并根据碳酸盐岩裂缝型储层的特点,结合胜利探区实际地质情况,以胜利油区的富台潜山油藏为主要研究对象,应用流体薄层模型对含裂缝实际模型进行了正演模拟。地震偏移成像技术作为反射地震的关键性技术在地震勘探中占有重要地位,传统的基于射线理论的偏移算法和基于波动理论的单程波偏移算法,在处理非均匀介质的问题时,对陡倾角、纵横向速度的剧烈变化等现象存在算法的局限性。本文对基于弹性矢量波的多分量联合逆时偏移技术进行了研究。为了解决复杂的高角度微裂缝介质的偏移成像,本文将时空双变有限差分算子嵌入到弹性波逆时外推过程中,实现了对碳酸盐岩裂缝型储层的弹性矢量波逆时偏移。并从算法角度解决了逆时偏移计算量大、效率低下的问题。更多还原

【Abstract】 The demands of social industrial and development of oil exploration and development technology, makes the oil and gas industry facing more and more complex exploration and development tasks. Oil and gas development of simple structure, large-scale structure and shallow structure can not meet the demands. The exploration center is gradually inclineing to or inclined to complicated heterogeneous reservoirs, which raise higer request to moden oil and gas exploration technology. Conventional seismic forward modeling and migration technology are based on isotropic homogeneous media model, they more or less has some limitations on either theory or application when solving complex heterogeneous reservoir. So it is necessory to seek other methods for researching complex heterogeneous media.The paper considered a variety different scales heterogeneous reservoir (the scale of hetergeous body that larger than seismic wavelength, and smaller than seismic wavelength, and that can compared to seismic wavelength), fractured carbonate reservoir is also included, and carrying out thorough research on seismic forward modeling and migration methods orient to heterogeneous media problems.Discrete of seismic velocity model discrete is the first step of forward modeling, also is an essential step, and it is closely related to computational efficiency and accuracy. In order to facilitate the simulation of inhomogeneous medium, the paper improved velicity model FD mesh generation mode using variable spacing FD grid. Compared to the traditional staggered with fixed spacing, variable grid spacing is discrete heterogeneous geological model more reasonable. Based on variable spacing grid, the paper deduced variable grid discretization formula with arbitrary precision, applied to wave field forward modeling and reverse time migration. Based on variable grid method, the paper developed locally variable timestep scheme to match with variable grid method, which can be called as dual-variable grid method. In a global timestep the fine mesh regions are encrypt calculated by refined with fine time sampling, hence the differenct regions generateed with different grid size can satisfy different stability conditions. The time sampling in wavefield extrapolation can be relax, and improved calculation efficient basicly.Based on dual-variable grid scheme orient to heterogeneous media, the paper applied the thin fluid layer model theory simulated micro-fractured carbonate reservoir. The paper summed up the relationship and knowledge between fracture extension, fracutre density, fracture opening and so on facture characteristic parameters and seismic wave response. And according to the characteristics of fractured carbonate reservoirs, combined with the actual geological conditions of Shengli oilfield, use Fu Tai buried hill reservoir as the main research object, applied the thin fluid layer model to simulate seismic wave propogation of field fracture velocity model.Seismic migration technology as a key technology of reflection seismic plays an important role in seismic exploration. The traditional migration algorithms based on ray tracing theory and one-way wave migration algorithms based on wave equation theory get limitations on solving heterogeneous media, such as Steep glutenite、strong velocity contrast. The paper carried study on elastic reverse time migration based on full wave equation. In order to solve complex vertical micro-fractured media, the paper introduced the dual-variable FD grid into elastic vector reverse time migration extrapolation process, and realized elastic vector reverse time migration of micro-fractured media in carbonate reservoir. This soluted low efficiency and large computational capacity shortcuts of reverse time migration algorithm.更多还原