Seismic identification and development characteristics of water conducting fissure zone in goaf
HOU Enke ,YUAN Feng,WANG Shuangming,XIE Xiaoshen,WU Baohai
导水裂隙带发育高度是保水采煤的关键参数,但导水裂隙带散射波、多次波发育,成像质量 差,地震识别难度大,很难精确获取导水裂隙带发育特征。 为进一步解决导水裂隙带地震识别问 题,并揭示导水裂隙带空间发育特征,通过测井、钻探资料分析和三维模型正演对导水裂隙带的地 震特征进行了研究。 研究结果表明:电阻率、自然伽马、自然电位和冲洗液漏失量均能表征导水裂 隙带发育高度,但单一因素解释误差较大,准确度低;谱分解、相干体、瞬时频率和蚂蚁追踪 4 种叠 后地震属性分析能够不同程度地反映出导水裂隙带发育位置、高度特征,但只能对导水裂隙带部分 部位实现较准确判断,无法准确反映导水裂隙带三维整体形态和发育特征。 在综合地质、地震资料 的基础上,根据电阻率、自然伽马、自然电位和冲洗液漏失量数据,利用主成分分析建立了导水裂隙 带定量解释指标,通过地震属性优选、叠后确定性反演、叠前弹性阻抗反演、各向异性检测,结合裂 隙指示曲线,利用神经网络反演形成裂隙指示数据体,对导水裂隙带发育高度和发育特征进行了定 量描述,提出了适宜回采工作面导水裂隙带发育特征的地震识别方法,并成功识别了陕北某矿首采 工作面导水裂隙带发育特征。 实践结果表明:综采工作面走向方向导水裂隙带发育形态呈“半马 鞍形” ,即发育高度由开切眼至面内逐渐降低并趋于平稳;工作面倾向方向导水裂隙带呈两边高中 间略低的形态特征,近似“ 马鞍形” ;采空区开切眼处导水裂隙带发育高度最大,两侧采空边界煤柱 处裂隙带发育高度略低,裂采比为 25.86 ~ 30.76;垮落带以高角度裂隙为主,水平方向呈网状,垮采 比为 3.44~5.72。 经验证,该导水裂隙带地震识别方法获取的导水裂隙带发育高度误差在 2.42~ 6.81 m,垮落带识别误差 1.60 ~ 12.89 m,误差相对较小,能够准确获取导水裂隙带三维空间发育特 征,可以为西部煤炭开采水资源和生态环境保护提供一定的方法支持。
The development height of water-conducting fracture zone is a key parameter of water-retaining coal mining and the decisive factor of underground aquifer leakage caused by coal mining. However, the scattered waves and multiple waves of water-conducting fracture zone are developed, the imaging quality is poor, and the seis- mic identification is difficult. Therefore, it is difficult to accurately obtain the development characteristics of the wa- ter-conducting fracture zone. In order to further solve the problem of seismic identification of water diversion fracture zone and reveal the spatial development characteristics of water diversion fracture zone, the seismic characteristics of water-conducting fracture zone are studied by analyzing well logging, drilling data and three-dimensional model for- ward modeling. The results show that resistivity, natural gamma ray, natural potential and flushing fluid leakage can all characterize the development height of water-conducting fracture zone, but single factor interpretation error is large and accuracy is low. The four post stack seismic attribute analyses of spectral decomposition, coherence cube, instan- taneous frequency and ant tracking can reflect the development position and height characteristics of the water conduc- ting fracture zone to varying degrees, but can only accurately judge some parts of the water conducting fracture zone, and cannot accurately reflect the three-dimensional overall shape and development characteristics of the water conduc- ting fracture zone. On the basis of comprehensive geological and seismic data, according to the data of resistivity, nat- ural gamma, natural potential and flushing fluid leakage, this paper uses principal component analysis to establish the quantitative interpretation index of water-conducting fracture zone, and the fracture indicator data volume is formed by seismic attribute optimization, pre-stack elastic impedance inversion and anisotropic fracture curve indication inversion. Also, the development height and characteristics of water-conducting fracture zone are described quantita- tively, and a seismic identification method suitable for the development characteristics of water-conducting fracture zone in medium-deep fully mechanized mining face is put forward, and the development characteristics of wa- ter-conducting fracture zone in the first mining face of a mine in northern Shaanxi are successfully identified. The prac- tical result shows that the development of the water-conducting fissure zone along the strike direction of the working face is “half-saddle shape”, that is, the development height gradually decreases from near the incision to the inside of the plane and tends to be stable. The water-conducting fissure zone in the direction of the working face is high on both sides. The slightly lower morphological feature in the middle is approximately “arched”. The height of the fissure zone at the cut hole in the goaf is the largest, about 178.42 m, and the height of the fissure zone at the coal pillars on both sides of the goaf boundary is slightly lower, with a crack-to-production ratio of 25.86-30.76. The caving zone fis- sures are developed violently, mainly high-angle fissures, and the horizontal direction is network-like, and the caving ratio is 3.44-5.72. It is verified that the error of the development height of the water-conducting fracture zone obtained by the seismic identification method is 2.42-6.81 m, and the error of the identification of the caving zone is 1.60-12. 89 m, which is relatively small. It can accurately obtain the three-dimensional spatial development characteristics of the water-conducting fracture zone, which can provide some method support for the coal mining water resources and ecological environment protection in the western China.
water-conducting fracture zone;Three-dimensional seismic;3D forward modeling and inversion;anisotro- py detection;water-retaining coal mining
1 研究区概况
2 导水裂隙带地震识别方法
2.1 地球物理特征
2.2 三维模型正演
2.3 导水裂隙带三维地震识别方法研究
3 应用实践
3.1 裂隙指示数据体合成
3.2 裂隙定量解释成果及精度分析
4 结论
主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会