煤矿采空区四维地震特征分析及识别方法:以淮南煤田张集矿区为例

doi:10.19657/j.geoscience.1000-8527.2020.028

摘要/Abstract

摘要：

煤矿采空区塌陷是一个重要的地质问题,由于采空塌陷区地震、地质条件的复杂性,传统三维地震勘探探测方法难以准确查明采空区边界。本研究提出一种基于四维地震特征的煤矿采空区识别方法,并以淮南煤田张集煤矿为靶区开展采空区探测。该方法从模型驱动入手,通过建立煤层开采前、后地质模型及进行正演模拟,利用模型地震叠前时间偏移剖面回溯分析采空区引起的地震特征差异。根据模型数据采空区的地震反射特征,指导识别实际地震数据中的采空区,并通过地震解释圈定采空区范围。张集煤矿的实际四维地震数据分析结果显示,采空区域反射波连续性变差,采空区边界出现同相轴错断现象;因此,利用采空区四维地震特征差异能够有效识别煤矿采空区,并能准确圈定采空区的范围。

关键词: 采空区, 四维地震, 正演模拟, 淮南煤田

Abstract:

Gob subsidence is an important geological problem in coal mines, and can seriously impact coal production and represent a potentially-lethal safety risk. Therefore, detection of gob subsidence is important to ensure sustainable coal mining. Due to the complex seismic and geological conditions in the gob subsidence area, it is hard to identify accurately the gob boundary with conventional three-dimensional (3D) seismic exploration methods. Therefore, we propose a new, model-driven gob identification method based on four-dimensional (4D) seismic characteristics, and use the Zhangji coal mine in the Huainan coalfield as an example. In this method: (1) geological models before and after coal seam mining are established and forward modeling is performed; (2) the prestack time migration (PSTM) sections of the synthetic seismic data are used to back-analyze the seismic features of the gobs, which are identified according to the seismic feature variations caused by the gobs; (3) the seismic features of the gob areas (in synthetic seismic data) are used to guide the gob identification in real seismic data; (4) through seismic interpretations, the gob areal extent is constrained. Analysis of the real 4D seismic data from Zhangji coal mining area shows that the continuity of the gob reflection decreases, and the reflection is displaced at the gob boundary. Therefore, this detection method (based on the 4D seismic difference) can effectively detect the gobs and delineate their boundary.

Key words: gob area, 4D seismics, forward modeling, Huainan coalfield

中图分类号:

苑昊, 刘佳朋, 姜在兴. 煤矿采空区四维地震特征分析及识别方法:以淮南煤田张集矿区为例[J]. 现代地质, 2021, 35(04): 1018-1023.

YUAN Hao, LIU Jiapeng, JIANG Zaixing. 4D Seismic Characteristics in Coal Mine Gobs: A Case Study from the Zhangji Coal Mine in Huainan Coalfield[J]. Geoscience, 2021, 35(04): 1018-1023.

图/表 9

图1 淮南煤田张集煤矿区域地质概况[18]

Fig.1 Structural map of the Zhangji coal mine in Huainan coalfield[18]

图2 张集煤矿主要可采煤层柱状分布图[19]

Fig.2 Stratigraphic column of the main coal seams in the Zhangji coal mine[19]

表1 张集煤矿主要可采煤层情况统计

Table 1 Statistics of the main coal seams in the Zhangji coal mine

主要可采煤层编号	煤层厚度范围/m	煤层平均厚度/m	煤层顶底板主要岩性
13-1	0~8.280.0	4.78	砂岩、泥岩
11-2	0.78~3.95	2.61	砂质泥岩
8	0.60~6.03	3.11	砂质泥岩

图3 L13煤层采前地质模型(F1表示断层,L8、L11和L13分别表示L8、L11和L13号煤层)

Fig.3 Pre-mining geological model of coal seam L13 (F1 denoting fault, L8, L11 and L13 denoting coal seams)

图4 基于图3模型的叠前时间偏移剖面 (F1表示图3中的断层反射,R8、 R11和R13分别为图3中L8、 L11和L13煤层的反射波)

Fig.4 PSTM section of geological model in Fig.3 (Symbology as in Fig.3)

图5 L13煤层开采后地质模型 (F1表示断层,L8、L11和L13分别表示L8、L11和L13号煤层)

Fig.5 Post-mining geological model of coal seam L13 (Symbology as in Fig.3)

图6 基于图5模型的叠前时间偏移剖面 (Tf为开采后形成的类“环状断层”,F1为图5中的断层反射,R8、R11和R13分别为图5中L8、L11和L13煤层的反射波)

Fig.6 PSTM section corresponding to model in Fig.5 (Symbo-logy as in Fig.3, and Tf denoting the post-mining ring-like faults)

图7 13-1煤层开采前的横测线方向的叠前时间偏移剖面 (T3—T5分别为8、11-2和13-1煤层的反射波)

Fig.7 Pre-mining PSTM section of coal seam 13-1 in the cross-line direction (T3-T5 denoting the reflections of coal seams 8, 11-2 and 13-1, respectively)

图8 13-1煤层开采后横测线方向的叠前时间偏移剖面 (Tf为开采后形成的类“环状断层”,T3—T5分别为8、11-2和13-1煤层的反射波)

Fig.8 Post-mining PSTM section of coal seam 13-1 in the cross-line direction (Tf denoting the post-mining ring-like fault, other symbology as in Fig.7)

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