预应力地层井孔声场及其应用研究
文献类型：学位论文
| 作者 | 陈浩 |
| 学位类别 | 博士 |
| 答辩日期 | 2007-06-11 |
| 授予单位 | 中国科学院声学研究所 |
| 授予地点 | 声学研究所 |
| 关键词 | 声弹性理论 地应力 交叉偶极子 有限差分 摄动理论 |
| 其他题名 | Borehole acoustic wavefields in prestressed formation and its application |
| 学位专业 | 声学 |
| 中文摘要 | 本文针对应用交叉偶极子测井检测地应力的需要，深入而系统的研究地层在地应力作用下的井孔声场的传播规律和相应的地应力检测理论和方法。 本文在引入两类PK应力基础上，推导了预应力声场的波动方程，研究了其有限差分和摄动求解方法。研究了不含井孔地层在不同应力作用下的声波传播规律并用其验证了数值方法的可靠性。数值模拟表明，各向异性应力不仅诱发地层各向异性，而且还影响横波的初始相位。在差分模拟计算中，将完全匹配层吸收边界条件引入到旋转交错网格中，并发展了相关算法。 随后将上述方法应用于研究垂直和倾斜井孔的的预应力声场，取得了一些新颖的成果。研究表明，对高非线性岩石，用近似模型替代精确模型是可行的，从而简化了声场的计算。从数值和理论分析两个方面阐述了不同方向剪切应力对井中模式波相速度的影响。 提出了混合运用两种模拟退火方法对各向异性反演的目标函数进行全局优化的方法，该方法能明显提高方位反演的稳定性。同时研究了信噪比对多频率反演地应力大小的影响，并提出了一个综合反演地应力大小和地层非线性常数的方法。 针对岩石速度应力关系的非线性，尝试提出了一个基于声弹性理论的修正速度应力模型。 |
| 英文摘要 | This dissertation thoroughly treated borehole acoustic wave propagation excited by multipole sources in pre-stressed formations. Based on the wave propagation analysis, it also studied the prediction theory and principles for the formation stresses. Firstly, the wave equations for describing acoustic wave propagation in a pre-stressed medium are analyzed. A finite difference (FD) scheme is used to solve the equations for the formation under the stress with different magnitudes and directions. The results show that, the anisotropic stresses induce formation anisotropy, and the initial phase of the shear waves changes when the direction of stress changes. Furthermore, the wavefield in vertical and deviated well surrounded by a prestressed formation is computed using a 3-dimensional staggered FD algorithm. Some new results are obtained. The perfectly matched layer absorbing boundary condition is implemented with a rotated staggered FD. Both of the numerical results show that, only the shear stresses that are perpendicular to the borehole axis have an effect on the guided-wave velocities. Secondly，for anisotropy inversion, the hybrid method of two implementations of simulated annealing is proposed to obtain the best solutions of the nonlinear multimodal object function. The angle of fast principle wave obtained by the hybrid method is stable. The effect of signal to noise ratio to result of multi-frequency inversion method，which is used for the stresses and formation nonlinear constants simultaneously, is studied in detail, and a two-step inversion method is developed. Finally, a modified acoustoelastic mathematical model for nonlinear relations between the stress and velocity is proposed. The model can fit the measured velocities for dry rocks under certain hydrostatic stresses. |
| 语种 | 中文 |
| 公开日期 | 2011-05-07 |
| 页码 | 110 |
| 源URL | [http://159.226.59.140/handle/311008/146]  |
| 专题 | 声学研究所_声学所博硕士学位论文_1981-2009博硕士学位论文 |
| 推荐引用方式 GB/T 7714 | 陈浩. 预应力地层井孔声场及其应用研究[D]. 声学研究所. 中国科学院声学研究所. 2007. |
入库方式： OAI收割
来源：声学研究所
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