四川盆地元坝气田超深层礁滩气藏储层气水识别技术

四川盆地元坝地区二叠系长兴组发育大型的台地边缘生物礁滩气藏,具有埋藏深、储层空间展布复杂多变、一礁或一滩为一个气藏、气水分布极其复杂的特点,给勘探开发带来了很大的风险。为了精细刻画元坝气田生物礁滩气藏储层及气水的展布特征,提高探井成功率,集成创新了储层气水识别技术:采用了叠前道集优化技术提高了道集的信噪比;利用小角度叠前反演技术解决了超深层弹性参数的求取;最后从岩石物理参数分析入手,综合实验室岩石物理测试分析及测井、试气成果统计分析结果,明确了气水识别的敏感参数;在此基础上进一步利用坐标旋转技术构建新的高灵敏度识别因子,从而提高了叠前敏感参数反演的识别能力和精度。在该地区Ⅰ区块实际应用的结果表明,该技术有效刻画出了元坝气田气区、水区以及气水过渡区,预测结果与后期实际钻井揭示的规律相一致。

Gas water identification technologies for ultra deep reef reservoirs in the Yuanba Gas Field,Sichuan Basin

Large platform margin reef gas reservoirs were discovered to be deep, one reef one reservoir, in the Permian Changxing – Feixianguan Fm in the Yuanba area, Sichuan Basin. The exploratory drilling reveals that their spatial distribution is complex and changeable and their gas water distribution is extremely complicated, which brings about a high risk in exploration and exploitation there. In order to improve the success ratio of exploratory wells, it is necessary to finely describe the characteristics of reef and beach gas reservoirs and gas water distribution in this study area. Therefore, technologies of gas water identification were integrated and innovated. First, pre stack gathers optimization techniques were used to improve the SNR. Then, the small angle stack inversion technology was employed to calculate the elastic parameters. Finally, based on the analysis of petrophysical parameters from laboratory, logging and well test data, those sensitive gas water parameters were clearly identified. On this basis, the coordinate rotation technology was applied to build a new highly sensitive identification factor, thereby to improve the identification ability and accuracy of pre stack inversion of sensitive parameters. The application result from Block I in this study area indicated that the gas zone, water zone, and gas water transition zone were precisely described, which is in good agreement with the later actual drilling data.