吐鲁番坳陷侏罗系地下水动力与油气成藏

Groundwater hydrodynamics and hydrocarbon accumulation in the Jurassic of the Turpan Depression

楼章华 金爱民 李华明 张慧婷

Lou Zhanghua Jin Aimin Li Huaming Zhang Huiting

沉积盆地地下水动力场演化和地下水成因控制了地下水化学场的分布规律,盆地边缘大气水下渗淡化,凹陷中心泥岩压实排水淡化,越流泄水区浓缩。在离心流和向心流的流动过程中,地下水浓缩、盐化,在越流泄水区形成矿化度的相对高值区。泥岩压实离心流是沉积盆地油气运移的主要动力,在地下水的越流泄水过程中有利于大量的油气聚集;在泥岩压实离心流过程中,由于岩性、地层、断层等圈闭也使得部分油气在运移过程中聚集;在向心流的推进过程中,先前聚集的油气可能部分被破坏,另外也可能在特定的地质条件下形成水动力圈闭。

The evolution of groundwater hydrodynamic field and origin of groundwater in sedimentary basins control the distribution patterns of chemical field of ground water.At the margin of a basin,groundwater desalinates due to the downward infiltration of atmospheric water,while in the central depression,groundwater desalinates due to discharge from mudstone under compaction.In contrast,groundwater concentrates in bypassing discharge area.During centrifugal and endoeentric flow processes,groundwater concentrates and gets salinized,forming a relative high salinity zone in the bypassing discharge area.Centrifugal flow from mudstone compaction serves as the main driving force of hydrocarbon migration in sedimentary basins and provides a favorable environment for large scale hydrocarbon accumulation during the bypassing and discharging of ground water.Moreover,it also can contribute some hydrocarbons to the lithologic,stratigraphic,fault traps located on the pathway of hydrocarbon migration.The advancement of endocentric flow may destroy the earlier hydrocarbon pools and also possibly lead to the formation of hydrodynamic traps at specific geologic conditions.

10.11743/ogg20080409