测井方法在观测采空区上覆岩层导水裂隙带发育高度中的应用

Application of Well Logging in Gob Area Overburden Water Conducted Zone Height Observation

新安矿区主采煤层上部至小浪底库区水体之间地层主要以砂岩、泥岩和砂质泥岩互层为主,厚度90~210m。为研究该矿开采状态下上覆岩层破坏程度和导水裂隙发育高度,在井下3个不同采厚的工作面上布置了7个地面钻孔,采用声波扫描成像测井及其它测井参数对采前、采后上覆岩层进行动态观测。以K3钻孔为例,介绍了超声波扫描成像测井的原理及辨别井孔中裂缝发育程度的方法。K3孔在第一次测量时,井深217～218m处明显存在裂隙,但在第二次测量后该裂隙呈现出闭合反应,证实煤层开采放顶后上部岩石下沉使得原有裂隙闭合;同时发现自194m以上因煤层采空放顶后发育有高度为69.10m的裂隙带。根据新安煤矿K2、K3、K5、K6、K7号孔超声波扫描成像及其它常规测井的地质解释成果可见,该矿导水裂隙带的发育高度随着推进距离和采厚增大而增大,但新安矿区软硬互层上覆岩层的地质构造可有效抑制导水裂隙带的发育程度。

Strata between main mineable coal seams of the Xinan mine area and water body of the Xiaolangdi reservoir are mainly sandstone,mudstone and sandy mudstone interbeds with thickness of 90~210m.To study overburden destructing extent and water conducted zone height,7 surface boreholes have laid out aimed at 3 working faces with different shear heights,carried out dynamic overburden observation before and after mining by using ultrasonic scanning imaging logging and other logging parameters.To take the K3 borehole as an example,introduced principle of ultrasonic scanning imaging logging and methods to identify borehole fissure developing extent.During the first logging,fissures have found at depth 217~218m obviously,but after the second logging,the fissures present closed reaction,confirmed the closing of original fissures because of overburden subsided after coal seam caving;and also found a 69.10m fissure zone above depth 194m after caving.According to ultrasonic scanning imaging in boreholes K2,K3,K5,K6,K7 and other conventional well logging geological interpretation can see,height of water conducted zone increasing along with advancing distance and shear height increasing,but the nature of soft and hard interbeded overburden can suppress water conducted zone developing extent effectively.