煤矿瓦斯灾害源的高分辨率地震探测基础研究

Aims at the difficult problems for scientifically predicting the current gas disasters in coal mines of our country, the project will adopt these methods, include theoretical study, model measurement, forward modeling and investigating the seismic data of the gas outburst wells, to analyze the geophysical response characteristics about the high resolution logging in the gas-enriching coal strata, to analyze the transmitting law within the fracture coal strata about seismic wave, especially sheer wave, which will provide a theoretical foundation for detection the fracture in coal strata by conversion shear wave methods. It will study the seismic anisotropy response characteristics and mechanism about the gas-containing coal strata utilizing mathematical simulation and physical simulation. Researching and adopting the multi-method seismic data fusion will improve the interpreting precision about the crack density and azimuth in the gas-containing coal strata. Through investigating the elastic characteristics of the coal-bearing strata, especially the differences of the elastic characteristics and influence factors about the gas-containing coal strata, and investigating several reflection characteristics of the coal strata, the project will establish the methods for distinguishing the reflection amplitude differences between the high permeability and low permeability coal strata, and establish the AVO theoretical models about different lithological combinations of gas-enrichment areas and gas-burst positions. With comprehensive research on gas geology and geophysics, the project will construct the theoretical fundamental and methods for utilizing seismic prospecting technology to accurately predicting the gas-burst disaster sources which can provide an effective geological support for pre-warning gas disasters in coal mines.

本项目针对当前我国煤矿瓦斯灾害科学预测难题，希望通过理论研究、模型测量、正演模拟和瓦斯突出点地震资料的实际观测结果，分析和研究煤矿瓦斯富集地层的高分辨测井地球物理响应特征，分析煤系地层含裂隙介质中地震波-特别是横波的传播规律，为利用转换横波探测煤系地层裂隙提供理论基础；利用数学模拟和物理模拟，分析含瓦斯煤系地层各向异性对地震波的响应特征和机理。通过地震多方法数据融合，提高含瓦斯煤层裂隙密度和裂缝方位的解释精度。通过研究煤系地层的弹性特征，研究煤矿瓦斯富集区和非富集区的弹性特征差异及其影响因素，通过探讨煤层各种特征的反射特征，建立高渗透煤层与低渗透煤层的反射振幅差异识别方法、不同岩性组合下煤矿瓦斯富集带和煤层突出部位的AVO理论模型。通过瓦斯地质、地球物理的综合研究，建立起运用地震探测技术准确预测瓦斯突出灾害源的理论基础和方法，为实现煤矿瓦斯灾害预警提供有效的地质支撑。

针对当前我国煤矿瓦斯灾害科学预测问题，选择典型煤矿为研究靶区，分析研究了煤矿瓦斯富集地层的高分辨测井地球物理响应特征，建立煤体破碎度与测井间的定量关系，研究开发了以测井曲线为约束的煤层结构高分辨率三维地震反演方法，可实现煤层厚度、构造煤及其煤层顶底板岩性预测，开发了煤矿瓦斯富集区及突出部位地震数据分析与解释软件。通过正演模拟，研究了含裂隙煤层的多波地震响应，揭示了煤系地层含裂隙介质中地震波、特别是横波的传播规律，开发了三维地震测井综合解释软件，提出了煤层转换波裂隙反演方法，可实现对瓦斯煤层裂隙密度和裂隙方位的反演。开展了各向异性薄煤层AVO公式和TTI介质方位AVO公式的推导，阐明了各向异性薄煤层的AVO响应特征和方位AVO特征，研究了瓦斯富集部位AVO响应特征，建立瓦斯富集煤层与非瓦斯富集煤层的反射振幅差异识别模型，在此基础上，提出了基于AVO反演预测瓦斯含量的方法，并进行了实际应用。研制了矿井多波地震仪，并在矿井进行了适用性试验。依据煤田地质演化特征和构造背景，研究瓦斯突出部位地质特征、构造煤特征及其与地球物理的响应关系，结合地质和其它资料由裂隙发育参数确定地下煤系地层中的含瓦斯情况，确定瓦斯突出的地质主要控制因素和地球物理识别方法，建立煤-围岩与地质地球物理场的耦合关系，提出煤矿开采过程中瓦斯突出的地质预测理论与方法，从而实现煤矿重大瓦斯灾害的高精度预警。