煤田勘探中四维地震正演模型研究

Research on 4D seismic forward modeling in coalfield exploration

煤田采空区的识别和圈定是煤田安全性生产的关键,目前常规的勘探手段难以精确的识别煤田采空区和定位采空区边界。本研究在对鄂尔多斯盆地黄陵煤炭矿区采空区多年研究的基础上,从煤田四维地震理论出发,通过地质模型模拟黄陵矿区煤田开采前后煤层和临近地层的厚度和延展范围在三维空间的变化,在此基础上构建煤田开采前后四维地震正演模型,我们采用Zoeppritz方程和褶积模型来获取零偏移距下煤田开采前后的地震响应,通过对开采前后地震信号的分析和研究,识别煤田开采过程中的采空区范围,标定采空区边界。研究表明,在采空区煤层和上下地层的反射波同相轴连续性明显变差,采空区边缘处同相轴开始出现错段,证明了四维地震识别煤层采空区域和圈定采空区的边界的有效性。

The identification and delineation of goaf in coalfield is the key to the safety of coalfield production. At present,conventional exploration means are difficult to accurately identify the goaf and locate the boundary of goaf. This study Huangling coal mining area in ordos basin based on the study of the mined-out area for many years, from coalfields Four-dimensional theory, through simulation of Huangling mining area geological model before and after coal mining coal seam and the thickness of the adjacent formation and the change of the extended range in three-dimensional space, on the basis of the construction of4 D seismic forward model before and after coal mining, we adopt Zoeppritz equation. And convolution model to obtain the seismic response before and after coal mining at zero offset. Through the analysis and study of seismic signals before and after mining, the scope of goaf in the process of coal mining is identified, and the boundary of goaf is calibrated. The results show that the continuity of the in-phase axis of the reflected wave in the coal seam and the upper and lower strata in the goaf is obviously worse, and the in-phase axis starts to appear the wrong segment at the edge of the goaf, which proves the effectiveness of the four-dimensional seismic identification of the coal seam goaf domain and the delineation of the boundary of the goaf.