基于流体活动属性的高精度煤层气甜点区识别
High accurate identification on coalbed methane sweet-spot based on fluid flow attribute
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摘要: 基于常规叠后地震反演能够识别煤层,但无法预测煤层的含气性,利用地震波衰减理论的流体活动因子能够有效表征储层的含气性,识别含气煤储层,提出将流体活动因子与高精度匹配追踪算法相结合,在高精度地震信号时频分解的基础上,建立含气煤层与地震波衰减的联系,求取流体活动性属性,实现高精度煤层气甜点区识别。研究结果表明:匹配追踪方法相比于其他时频分析方法可克服窗函数的限制,能在时间域和频率域同时精细表征信号特征。流体活动属性与高精度时频分析相结合的流体检测方法能够提高流体识别的精度,预测结果与气测录井吻合,由数据驱动,结果与地震数据吻合,不受构造及层序解释的影响,能客观反映煤层的含气性。Abstract: The conventional post-stack seismic inversion could indentify the coal seam, but could not predict the gas content of the seam. The fluid flow factor of the seismic wave attenuation theory could be applied to effectively characterize the gas content of the reservoir, to indentify the gas bearing coal reservoir and to provide the fluid flow factor applied to combine with the high accurate matching tracing algorithm. Based on the high accurate time frequency analysis of the seismic signals, a relationship between the gas content seam and the seismic wave attenuation was established to seek the fluid flow attribute and to realize the high accurate identification on the coalbed methane sweet-spot. The study results showed that the matching tracing methane could overcome the limit of the window function in comparison with the other time frequency analysis methods and could finely characterize the signal features both in the time domain and the frequency domain. The fluid detection method combined with the fluid flow attribute and the high accurate time frequency analysis could improve the accuracy of the fluid identification. The prediction results were fitted with the gas logging. Due to the data driven, the results were faithful to the seismic data and were not affected by the structure and the stratigraphic sequence interpretation and could objectively reflect the gas content of the seam.