【摘要】 本文基于天然气水合物发育区特有的构造沉积特征对各种地球物理响应的敏感性,研究了地震属性、AVO分析、陡倾角地层反转速度场建立、及伪井约束波阻抗反演等地震技术在天然气水合物预测中的应用及其效果。通过多信息联合分析与融合策略,优化集成有效地球物理技术,形成一套可靠的天然气水合物探测技术与流程。实际表明:综合分析反射强度、瞬时相位、层速度、相对波阻抗、绝对波阻抗、及AVO截距剖面等特征资料是识别天然气水合物底界似海底反射(BSR)的有效手段;综合应用地震、相对波阻抗、绝对波阻抗、层速度等剖面的特征可提高天然气水合物识别的有效性:而瞬时频率、能量半衰时、层速度、AVO截距、AVO乘积、AVO流体因子等剖面特征的有效组合能更准确有效地识别BSR以下的游离气。文中所总结的一套预测天然气水合物的优化组合地球物理技术在我国南海海域中已取得良好效果。更多还原

【Abstract】 Based on the sensitivity of geophysical response to gas hydrates contained in sediments, we studied the prediction of gas hydrates with seismic techniques, including seismic attributes analysis, AVO, inverted velocity field construction for dipping formations, and pseudo-well constrained impedance inversion. We used an optimal integration of geophysical techniques results in a set of reliable and effective workflows to predict gas hydrates. The results show that the integrated analysis of the combination of reflectivity amplitude, instantaneous phase, interval velocity, relative impedance, absolute impedance, and AVO intercept is a valid combination of techniques for identifying the BSR (Bottom Simulated Reflector) from the lower boundary of the gas hydrates. Integration of seismic sections, relative and absolute impedance sections, and interval velocity sections can improve the validity of gas hydrates determination. The combination of instantaneous frequency, energy half attenuation time, interval velocity, AVO intercept, AVO product, and AVO fluid factor accurately locates the escaped gas beneath the BSR. With these conclusions, the combined techniques have been used to successfully predict the gas hydrates in the Dongsha Sea area.更多还原