川西地区燕山期的发展演化及油气勘探

YENSHANIAN OIL/GAS GENERATION AND EVOLUTION IN WEST SICHUAN AND ITS OIL/GAS EXPLORATION PROSPECTS

燕山期是川西上三叠统源岩生烃高峰期,该期的构造演化对油气聚集有着重要意义。根据构造背景和沉积特点,燕山期川西的构造演化可分为隆拗发展、挤压褶皱、萎缩沉降三个阶段。其中隆升活动对川西气藏的分布有着重要影响。根据现今构造展布及燕山期的演化特点,可将川西划分为东部龙泉山断褶带、南部隆升断褶区、西部龙门山前陡坡断褶带和中部凹陷区四个区带。其中,燕山期存在的隆起或斜坡及与断褶区、带的叠合部位,是油气的有利勘探区。

Since the Yenshanian movement is a peak stage for oil/gas generation of the Triassic source rocks in west Sichuan, the tectonic evolution in this stage would be significant for oil/gas accumulation in the area. On the basis of tectonic settings and sedimentary characters, the tectonic evolution in west Sichuan can be divided into three developing stages of upliftings and depressions, compressional foldings and shrinking subsidence, among which the upliftings play a significant part in the distribution of gas pools in west Sichuan. The west Sichuan Area then can be grouped by different structural belts of the Longquanshan fault-folded belt in east, the uplifting fault-folded belt in south, the steep-slope fault-folded belt in front of the Longmenshan in west and the depressional zone in the central part based on the present-day tectonic framework and the characters of the Yenshanian tectonic evolution. The superimposed areas between the upliftings or slope and the fault-folded belts mentioned above developed in the Yenshanian Period are most promising prospects for oil/gas exploration.