利用声波速度测井估算海域天然气水合物饱和度

Estimating Saturation of Gas Hydrates Within Marine Sediments Using Sonic Log Data

应用针对含水合物地层的TPEM和STPBE岩石物理模型,估算神狐海域水合物钻探区SH2井的天然气水合物饱和度。利用测井和取心样品分析数据确定模型参数,分别在含水合物层段内、外选取样点数据,通过计算数据间欧氏距离定量比较模型预测的声波速度与测井数据间的差异。结果表明2个模型在含水合物地层有相当的适用性,但在不含水合物的地层中TPEM预测的声波速度更接近实测值。这2个模型估算的水合物饱和度与现场孔隙水测试分析得到的结果一致,显示出较好的实用性,TPEM模型预测的饱和度平均值为35.4%,STPBE模型预测的为29%,预测的最大值则分别为67.5%和69.4%。

Gas hydrates saturation of SH2 well in northern South China Sea is estimated by using two rock physical models, TPEM and STPBE. Models parameters are obtained from well logs and analysis data of core samples within and without gas-hydrate-bearing intervals. We test models by calculating Euclid distance between models predicted P-wave velocity and log data. The results show both models are quite practical, but TPEM do better in predicting background velocity. Gas hydrates saturation obtained from the two models are the same as that of the field measured porosity water. The average gas hydrates saturation in gas-hydrate-bearing interval is 35.4% and 29% for TPEM and STPBE respectively, and the highest values is 67. 5% and 69.4%. These are comparable to the pore water analysis results.