基于Wood阻抗法的悬浮模式天然气水合物饱和度预测方法

A method for predicting the natural gas hydrate saturation in suspended mode based on Wood impedance method

岩石物理研究表明,Wood法目前被认为是预测悬浮模式天然气水合物饱和度较好的一种方法,但该方法因纵波阻抗与水合物饱和度之间关系复杂而很难在叠后反演中得到推广。本文提出了一种用于悬浮模式水合物饱和度预测的新方法——Wood阻抗法,该方法是在通过对现有Wood法进行推导分析简化的基础上形成的一种预测方法,可以较清晰地表现水合物层纵波阻抗与水合物饱和度的关系。在假设海域含水合物基质是由粉砂和黏土2种物质组成的基础上,开展了Wood阻抗法实验误差分析,Wood阻抗法理论预测的水合物饱和度与实际水合物饱和度比较接近。基于神狐海域数据开展了二维应用,结果表明Wood阻抗法预测的水合物饱和度与实际饱和度测量范围比较接近,具有一定的推广和应用价值。

The petrophysical study shows that currently the Wood method is considered to be a good method for predicting the saturation of natural gas hydrates in suspended mode. However, this method is difficult to be applied in post-stack inversion due to the complex relationship between longitudinal wave impedance and hydrate saturation. The Wood impedance method* a new method for predicting the hydrate saturation in suspended mode, was proposed in this paper. This method was formed on the basis of the simplification of the existing Wood method, and it can clearly reflect the relationship between the longitudinal wave impedance of hydrate layer and the hydrate saturation. Based on the assumption that the hydrate matrix in the sea area is composed of silt and clay, the error analysis of Wood impedance method was carried out, and the hydrate saturation predicted by Wood impedance method was close to the actual hydrate saturation. The two-dimensional application of this method was carried out according to the data of Shenhu sea area,and the results show that the hydrate saturation predicted by Wood impedance method is close to the actual saturation measurement range. Hence,this method shows a certain promotion and application value.