川西地区上三叠统地层古压力形成与演化的数值模拟

MATHEMATICAL MODELLING ON THE DEVELOPMENT AND EVOLUTION OF THE PALEO-FORMATION-PRESSURE IN THE UPPER TRIASSIC, WEST SICHUAN BASIN

徐国盛 刘中平

Xu Guosheng Lin Zhongping

成都理工学院石油系 610059

Chengdu Inctitute of Technology

本文将川西上三叠统地层孔隙裂缝的发展变化─-有机质的成熟过程─-原始地层压力的形成演化当作一个整体系统来研究,探索了三者在时间和空间上相互匹配、相互制约的关系。研究认为上三叠统原始地层压力的形成演化以喜山期构造运动为界分为早晚两期:早期在其多种成因机制中,烃类的生成是原始地层压力形成演化的最主要因素,表现为循序渐进的增压过程,并以此定量计算了喜山运动前各阶段原始地层压力的增长情况;晚期主要表现为喜山期强烈的侧向挤压应力对先期形成的地层压力进行改造,通过对该区构造应力场的模拟,半定量地说明了侧向挤压应力对原始地层压力的改造程度,并确认喜山期构造运动的差异改造是造成目前地层压力分布不一致的直接原因。

The evolution of pores and fractures, the maturation of organic matter and the development of original formation pressure (OFP) were considered in a contect, and the spatial and temproal relationships among these three aspects were discussed in this paper. It was proposed that the development and evolution of OFP could be divided into two periods, i.e. the earlier period (pri-Himalayan) and the later period (since-Himalayan). Athough there were many factors contributing to OFP during the earlier period, the hydrocarbon generation was the most important mechanism and OFP increased progressively. Accordingly, the increment of OFP in each stage was calculated. In the later.period,the great lateral squeering force in Himalayan strongly affected OFP formed in the earlier period.Therefore, the Variation of OFP by structural squeeze was semi-quantitatively represented through modelling on tectonic stress field, and the difference of the present OFP in area could be directly related to the extent of tectonic activity in Himalayan.

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https://doi.org/10.11781/sysydz199601117