【作者】 钱进；

【导师】 崔若飞；

【作者基本信息】 中国矿业大学 ， 地球探测与信息技术， 2010， 博士

【摘要】 在煤田勘探中,裂隙的发育程度通常是影响煤层顶、底板稳定、煤矿瓦斯和矿井水的防治以及煤层气勘探和开发等方面的关键性因素。本文利用交错网格高阶有限差分地震数值模拟技术,对不同条件和状态下含裂隙煤储层中的地震波传播进行了详细的研究。首先,根据含裂隙煤储层双相介质弹性波基本方程结合Biot(1962)给出的应力和应变方程,推导出其相应的弹性波波动方程,并以此进一步推导出含裂隙煤储层双相介质的一阶应力-速度和速度-应力的交错网格高阶有限差分公式。通过修改其阻尼因子,推导出一种适合煤储层双相介质的改进型完全匹配层吸收边界条件差分公式,取得了较好的边界吸收效果,同时提高了计算效率。利用通量校正传输方法(Flux-corrected transport,FCT)对煤储层双相介质正演模拟时产生的数值频散进行了压制处理,并根据实例效果对比分析了其优缺点。其次,利用等效介质理论和一些理论经验公式推导出含裂隙煤储层各向异性和双相各向异性介质条件下的弹性参数,为煤储层数值模拟提供了理论参数基础;并以此设计出含裂隙煤储层正演数值模拟方法的流程,其中包括物性参数和正演数值模拟的计算流程。然后,利用交错网格高阶有限差分法,通过正演数值算例系统地讨论了不同条件下,地震波在含裂隙煤储层及相邻充水含水层不同状态(自然、充气和充水)中的波场分布及其传播特征,并利用地震属性技术定性地分析了其中的地震响应特征规律。研究表明,由不同状态下含裂隙煤储层所造成的弹性参数具有一定的差异,但这种差异在地震波场记录上反映并不明显,而利用地震属性技术却可以定性地分析出该差异,这为反演计算含裂隙煤储层提供了正演理论基础。最后,在正演分析成果的基础上,根据实际的三维地震资料,分别利用地震波阻抗和方位各向异性反演的原理,研究了含裂隙煤储层中的孔隙度和裂隙以及奥陶系灰岩顶部的孔隙度。研究表明,利用地震反演技术可以预测煤储层和奥陶系灰岩顶部的孔隙度,而利用方位各向异性反演技术也可以预测含裂隙煤储层中的裂隙发育密度和方向。更多还原

【Abstract】 In the coalfield exploration, the degree of development of fractures usually is a key factor, which affects many problems in coal mines such as the roof and floor stability of the coal seam, prevention and treatment of coal gas and water, and coalbed methane exploration and development as well. And in this paper, seismic wave propagation of fractured coal reservoirs under different conditions and status has been in a detailed study by high-order staggered grid finite-difference which is one of seismic numerical simulation methods.At first, according to elastic wave fundamental equation of two-phase medium and the stress and strain equation given by Biot at 1962, elastic wave equation of fractured coal reservoirs has been deduced. On this basis, high-order finite-difference formulas of first-order stress-velocity and velocity-stress for fractured coal reservoirs are obtained. And an improved absorbing boundary condition for perfectly matched layers is achieved by modifying its damping factor on the basis of the general absorbing boundary condition. Case study states that this method has not only achieved a very good absorbing effect of the boundary, but also impoved its computational efficiency. Besides, the numerical dispersion has been suppressed during the simulation of two-phase medium of coal reservoirs by using the Flux-corected transport (FCT) method. And its advantages and disadvantages also have been analyzed through examples contrast.Secondly, elastic constants of anisotropic and two-phase medium of fractured coal reservoirs are gained with effective media theory and some other experiential formulas, which provide a theoretical foundation for parameters. And thus forward flows of numerical simulation for fractured coal reservoirs are desighed including the calculation of petrophysical parameters and numerical simulation.Then, with high-order staggered grid finite-difference, wave field distribution and propagation characteristics of fractured coal reservoirs and its adjacent aquifers containing different states (natural, gas-saturated, water-saturated) have been made a systematic discussion, and the seismic response characteristics have been qualitatively analyzed with the seismic attributes. It states that elastic constants of fractured coal reservoirs containing different states have some differences. And these differences are not obvious at the seismic records, but can be qualitatively distinguished throughout the seismic attributes techonology. Therefore, forward theoretical foundation has been provided for the inverse calculation of fractured coal reservoirs.Finally, research has been done for the porosity and fractures in the fractured coal reservoirs and Ordovician limestone top by using seismic impedance and azimuth anisotropic inversion with the actual seismic data. Research findings state that porosity of fractured coal reservoirs and Ordovician limestone top can be calculated through the seismic inversion method, and density and orientation of fractures also can be predicted with the azimuth anisotropic method.更多还原