震測逆推結合古構造復原之三維地層孔隙壓力梯度分析

Analysis of 3D Formation Pore Pressure Gradient by Integrating Seismic Inversion and Structural Restoration

傅式齊(S. C. Fuh) ； 楊育良(Y. L. Yang) ； 李健平(C. P. Lee) ； 馮力中(L. C. Feng)

《鑛冶：中國鑛冶工程學會會刊》 55卷2期 (2011/06) Pp. 21-30

https://doi.org/10.30069/MM.201106.0002

摘要

本研究結合構造復原與震測逆推方法，在古構造深度域，以Kan and Swan（2001）文獻中的方法，建立系統化三維地層壓力及其梯度預測新技術，大幅改善過去一維地層壓力梯度預測的限制，及局部井測趨勢線不一致造成地層壓力梯度預測不適用的缺失。應用於台灣西南部藤寮、關仔嶺、龍船、新市及永康地區的高壓層預測系統，建立新市及永康地區地層壓力及其梯度三維模型。研究結果在古構造深度域，以Kan and Swan方法建立台灣西南部地層壓力梯度與聲波走時趨勢差值（Δt）關係式: P（z）/z=10.3 Kpa/M+0.018127*Δt+0.000115*（Δt）^2。整體而言，估算誤差的來源有以下幾種：（1）.震測資料振幅保幅的程度；（2）.井測資料的不準度：井測資料施測年份差大時，測勘儀器精準度不同造成的井測資料基值不同。井測資料針對井崩區段所作之修正，修正不夠或修正過多的誤差；（3）.井測地層壓力資料之誤差及資料點的缺乏；（4）.構造上舉量估算的誤差。新市及永康地區建立之三維地層孔隙壓力及梯度模型顯示，新市一號井鳥嘴層鑽遇之高壓層，向西南分布至永康地區。

並列摘要

In this study, structure restoration and seismic inversion were integrated to construct Kan and Swan (2001) geopressure model to overcome the multi P-sonic trend problem occur red in the southwestern foothill of Taiwan. The geopressure model systematically predict the pseudo 3D pore fluid pressure gradient in Hsinshi and Yunkung area. P-sonic logs from 9 wells were used to estimate the amount of uplift at the well locations. Pressure data from 5 wells were used to perform the multi-linear regression of pressure gradient prediction equations in the paleo-depth domain: P(z)/z =10.3 Kpa/M+0.018127*Δt+0.000115*(Δt)^2. The pseudo 3D pore fluid pressure gradient determined in this study showed that the over pressured zone in the Niaotsui formation penetrated by the HSS-1 well extends southwestward to the Yunkung area.