四川盆地威远龙马溪组页岩气甜点区地震定量预测

摘要

Sweet spots in the shale reservoirs of the Lower Silurian Longmaxi Formation in Block Weiyuan 201 of Sichuan Basin were predicted quantitatively using seismic data and fuzzy optimization method.First,based on seismic and petrophysical analysis,the petrophysical features of reservoir rock were determined,and elastic parameters sensitive to high gas content shale were selected;second,high resolution data volumes of the elastic parameters were obtained from prestack simultaneous inversion,and the planar distribution of key parameters of shale gas evaluation were calculated based on the results of petrophysical analysis;third,the fuzzy evaluation equation was established by fuzzy optimization method with test and logging data of horizontal wells with similar operation conditions;fourth,key parameters affecting the productivity of horizontal wells were sorted out and the proportions of them in the sweet spot quantitative prediction were worked out by fuzzy optimization to set up a sweet spot evaluation system.Three classes of shale gas reservoirs and 2 kinds of sweet spots were predicted with the above procedure,and the sweet spots have been predicted quantitatively by combining the above prediction results with the testing production.The testing results of 7 verification wells proved the reliability of the prediction results.%应用模糊优化方法,对四川盆地威远201区块下志留统龙马溪组页岩气甜点区进行地震定量预测.首先以地震岩石物理分析为基础,确定储集层岩石物理特征,优选高含气页岩敏感弹性参数;通过叠前同时反演获得高精度弹性参数反演数据体,并根据岩石物理分析结果求取页岩气关键评价参数的平面分布;选取施工条件基本相同的水平井测试及测井数据,应用模糊优化的方法,构建模糊评价方程;经过模糊优化确定影响水平井产量的关键参数及各参数在甜点区定量预测中的权重,建立甜点区定量预测评价体系.经上述过程共预测出3类页岩气储集层、2类甜点区,并将预测结果采用测试产量标定,实现了甜点区定量预测,7口验证井的测试结果证实了预测结果的可靠性.