构造抬升是异常高压的成因吗?

IS TECTONIC UPLIFTING THE GENESIS OF ABNORMAL HIGHPRESSURE?

夏新宇 曾凡刚 宋岩

XIA Xin-yu ZENG Fan-gang SONG Yan

中国石油 勘探开发研究院, 北京 100083 2. 中国人民大学 环境学院, 北京 100872

Research Institute of Petroleum Exploration and Development, CNPC, Beijing 100083, China 2. School of Environment and Resources, Renmin University of China, Beijing 100872, China

国内诸多文献认为构造抬升是异常高压的成因,这种看法忽略了抬升过程中流体温度降低和孔隙体积反弹对流体压力的影响。计算表明,这两个因素不能全部忽略。构造抬升倾向于形成异常低压而不是形成异常高压。由于抬升过程中负载和温度的降低使得不均衡压实作用等因素趋于停止,构造挤压往往是抬升区超压最主要的成因。在晚近期发生过构造抬升的地区,利用地震法预测异常压力分布需要谨慎。构造抬升使得某些盆地(例如鄂尔多斯盆地)含气层系古超压消失,主要原因在于抬升引起的流体状态的变化,而不只是烃源岩的供气量小于天然气的散失量。

In many articles and works in China,tectonic uplifting was regarded as the genesis of abnormal highpressure.This opinion omitted the effects on fluid pressure by the decrease of fluid temperature and the rebound of pore volume in the process of uplifting.Calculations show that neither of the two factors can be neglected completely.Tectonic uplifting inclines to forming abnormal lowpressure rather than abnormal highpressure.Since the decrease of load and temperature in the process of uplifting makes unisostatic compaction and other factors tend to stopping,tectonic compression often becomes the most principal genesis of overpressure in uplifted areas.Therefore,caution is needed when using the seismic method to predict the distribution of abnormal pressure in the areas where tectonic uplifting happened in later and recent periods.Tectonic uplifting resulted in the disappearance of paleooverpressure in the gas bearing measures of some basins(for example,the Ordos Basin).This is mainly because of the fluid state changes caused by uplifting,not only because the gas suppling amount of hydrocarbon source rock was less than the dispersed amount of natural gas.

国家自然科学基金(40102011).

https://doi.org/10.11781/sysydz200206496