饱和度是估算资源量的一个重要参数,尤其是深水油气和天然气水合物共存的白云凹陷.本文利用神狐地区测井的速度、电阻率、氯离子浓度和地震反演的纵波速度异常,对该区水合物饱和度进行估算.利用二维高分辨率地震资料,分析了气烟囱、断裂、砂体、滑塌体等特殊构造对气体运移的控制作用和对水合物形成的作用.基于双相介质中纵波速度,利用迭代正演模拟反演法估算出神狐地区的天然气水合物饱和度占孔隙空间的5~30%,局部地区饱和度为44%.水合物中甲烷气体资源量达到千亿立方米,气体储量达到中等气藏的储量丰度.
Saturation is a key parameter for estimating resource amount. The Baiyun Sag in the Pearl River Mouth Basin is a zone that gas hydrate, where deep oil and gas and natural gas hydrates are in coexistence. Gas hydrate saturations were estimated by compressional velocity, resistivity and Chloride concentration based on well log data and high resolution two-dimensional seismic data in the Shenhua area. The controls of gas chimneys, faults, coarse submarine fans and slumps on fluid flow and their roles in gas hydrate formation were analyzed. Gas hydrate saturation was estimated by using the inversion of iterative forward simulation based on two-phase compressional velocities. Gas resources in gas hydrate were estimated. Our study suggested that gas hydrate saturation is estimated to account for 5~30% of the pore space in the Baiyun sag, with the highest value of 44% of the pore space. Gas resources in gas hydrates can reach 4. 732 ×10^11 ms , and gas resources can be up to reserves abundance of a middle sized gas reservoir.