Seismic identification and development characteristics of water conducting fissure zone in goaf

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.