三维地震精细处理技术在识别煤田小断层中的应用

Application of 3D seismic fine processing technology in identifying small faults in coalfields

煤层中发育的断层构造不仅破坏煤层的连续性,而且往往与冒顶、突水、瓦斯突出等事故伴生,小断层等微幅构造的精确探测一直是煤田安全生产研究的重点。三维地震技术是目前获得煤区构造特征、识别小断层最有效技术手段之一,但常规地震数据处理技术难以满足现阶段煤田勘探精度的需求。笔者等针对煤田采区三维地震资料的特征,提出一种有效的煤田三维地震数据精细处理技术,通过对静校正、叠前去噪、振幅处理和反褶积等关键技术进行攻关试验,提高煤田三维地震资料的信噪比和分辨率,进而更好地识别小断层等微幅构造。通过对实际煤田三维地震资料进行精细处理测试表明,笔者等提出的精细处理技术对于煤田三维地震资料具有很好的实用性,在现有三维地震叠后偏移剖面基础上可以识别出煤层中5 m以内的小断层,验证了研究区煤田三维地震精细处理技术的有效性,体现了精细处理技术在煤田精细勘探中的重要作用。

Objectives:The fault structure developed in the coal seam not only destroys the continuity of the coal seam,but also is often associated with accidents such as roof collapse,water inrush,and gas outburst.Therefore,the accurate detection of small-scale structures such as small faults has always been the focus of coalfield safety production research.Three-dimensional( 3D) seismic technology is currently one of the most effective means to obtain structural characteristics of coal areas and identify small faults.However,conventional seismic data processing technology is difficult to meet the accuracy of current coal exploration,which leads to differences in the understanding of geological structures.Methods:According to the characteristics of 3D seismic data in coalfield mining area,an effective fine processing technology for 3D coalfield seismic data is proposed in this paper.Through the research on key technologies such as static correction,pre-stack denoising,amplitude processing and deconvolution,both the first arrival and reflected waves become smooth,the consistency is enhanced,and the static correction problem is effectively solved.The interference wave is effectively suppressed,and the signal-to-noise ratio of the profile is significantly improved.The low-frequency interference of the profile is well suppressed,the high-frequency signal is compensated,and the frequency band is broadened.Results:The final imaging profile is accurate,the continuity of the target layer is good,and the breakpoint is clear and reliable.In addition,based on the 3D seismic fine processing technology in this paper,in addition to accurately identifying small faults,the lateral distribution characteristics of the target layer are characterized by seismic imaging,and it is found that the target coal seam has small-scale structures such as small synclines and wide and gentle anticlines.Conclusions:The fine processing test of the actual 3D coalfield seismic data shows that our fine processing technology has good practicability.Small faults within 5 m in the coal seam can be identified on the basis of the existing 3D seismic post-stack migration profile,which verifies the effectiveness of the 3D seismic fine processing technology in the coalfields,and reflects the importance role of the fine processing technology in the fine exploration of coalfields.At the same time,it is noted that there are obvious thin interbeds of sand and mudstone in the deep part of the target coal seam,which are more discontinuous as they go deeper.It may mean that the seismic wave is insufficiently transmitted under the " shielding" effect of the coal seam,and the seismic imaging is poor;it may also indicate that there is tensile stress in the deep coal seam,and the continuity of the thin sand—mudstone interbed is damaged.In the actual coalfield development,the accurate determination of the stress state and deep structural characteristics of the coal seam plays a good guiding role in the safe production of coal mines.Therefore,the coalfield 3D seismic fine processing technology still faces more challenges.