鄂尔多斯盆地东缘MG区块煤层裂缝发育多尺度预测

Multi-scale prediction of coal seam fracture development in MG block, eastern margin of Ordos Basin

查明煤层裂缝的发育特征,对于煤层气开采及井下煤矿安全生产都具有重要意义。测井及地震是煤层裂缝的地球物理识别的有效手段,针对鄂尔多斯盆地东缘MG区块,利用电成像、电阻率、密度、声波时差、自然伽马、中子孔隙度和阵列声波等测井曲线对8+9号的煤层小尺度裂缝的地球物理响应进行了描述;利用OVT(Offset Vector Tile)域叠前方位AVO(Amplitude Variation with Offset)反演对8+9号煤层中等尺度的裂缝发育形态进行了预测;利用叠后本征相干属性、相干增强属性及裂缝模拟属性,对研究区8+9号煤层的大尺度裂缝展布形态进行了精细刻画。经测井、叠后地震数据及叠前反演分析可知,该区8+9号煤层主要发育北北东向和北西向裂缝。该工作的开展,建立了从微观测井到宏观地震的多尺度煤层裂缝地球物理预测手段,将为研究区煤层气勘探选区及煤层安全开采提供重要地质依据。

Finding out the development characteristics of coal seam fractures is of great significance for coalbed methane exploitation and safe production of underground coal mines. Logging and seismic are effective means of geophysical identification of coal seam fractures. Electrical imaging, resistivity, density, sonic differential time, natural gamma,neutron porosity and array acoustic logs are used to describe the small scale fracture morphology of No.8 and No.9 coal seams of MG block in the eastern margin of Ordos Basin. The middle-scale fracture of No.8 and No.9 coal seams was predicted by prestack Azimuth AVO inversion in OVT domain. And the large-scale fracture distribution of No.8 and No.9 coal seams in the study area was described in detail based on the poststack seismic intrinsic coherence, coherent enhancement attribute and fracture simulation attribute. According to the post-stack seismic data and pre-stack inversion analysis, the fractures of No.8 and No.9 coal seams in the study area developed two groups of NW and NNE trending fractures. This work has established a multi-scale geophysical prediction method of coal seam fractures from micro to macro, which will provide important geological basis for coalbed methane exploration selection and coal seam safety mining in the study area.