波阻抗反演在南海北部神狐海域天然气水合物勘探中的应用

Impedance Inversion and Its Application in Gas Hydrate Exploration in Shenhu Area,Northern South China Sea

针对神狐海域的地质构造和天然气水合物的赋存特征,以重点测线三维地震数据为基础,分析讨论了基于宽带约束的模拟退火波阻抗反演方法、流程和关键技术问题,定量获得了含天然气水合物沉积物的波阻抗特征。结果表明:基于宽带约束的模拟退火波阻抗反演数据具有较高的有效垂向分辨率和较好的横向连续性;神狐海域高波阻抗异常反映了含天然气水合物沉积层,而不连续异常低波阻抗层是水合物层之下游离气的表现,这与钻探结果吻合。由此可见,基于宽带约束的模拟退火波阻抗反演可为天然气水合物层识别和预测、勘探目标圈定、钻探井位选择提供重要依据。

Impedance inversion is one of the means for oil-gas reservoir prediction.In view of the complicated geology and formation-distribution features of gas hydrate,based on the 3D seismic data collected by Guangzhou Marine Geological Survey,the method,process and key technology of broadband-based simulated annealing impedance inversion had been discussed,and the impedance data for the hydrate-bearing sediments of Shenhu area,Northern South China Sea were revealed in this paper.It is showed that the results of broadband-based simulated annealing impedance inversion are of high vertical valid resolution and horizontal continuity.The very high impedance layer shows the hydrate-bearing sediments and relatively lower one corresponds with the free gas in Shenhu area,which coincide with the gas hydrate drilling results.Therefore,the broadband-based simulated annealing impedance inversion may provide one of basis for gas hydrate recognition and prediction,exploration target confirmation and drilling site selection.