台西南盆地地质构造特征及油气远景

CHARACTERISTICS OF GEOLOGIC STRUCTURE AND HYDROCARBON POTENTIAL OF THE SOUTHWEST TAIWAN BASIN

本文从盆地的基本地质特征入手,分析了台西南盆地的地层、沉积、构造特征及油气条件,在进行盆地的定性分析的基础上,对盆地内的次级构造单元进行了类比,对盆地的含油气远景进行了评价,提出了该盆地的油气勘探方向。

The Southwest Taiwan Basin is a large Mesozoic-Cenozoic sedimentary basin with an area of 73,000km2 and a sediment thickness of over 10km and located in the northeast of the South China Sea and southwest of the Taiwan Island. According to geological investigations, the basin has different strata, sedimentary facies, geologic structures and oil-generating conditions. Sediments in the basin are characterized by continental-marine facies from Mesozoic to Quaternary, indicating a complete sedimentary cycle. The sedimentation centre of the basin gradually migrated from west to east, that is, a migration from terrestrial iacies to marine facies. Because the basin is located on the continental margin of the South China Sea, fault structure is well developed in it. The basin is especially controlled by NE and NEE faults and thus divided into 4 secondary tectonic units, i. e. (1) the northern dustpan-shaped downwarp, (2) the southern graben downwarp, (3) the middle crest-shaped uplift and (4) the southern lower rise. They have different characteristics and distinction of geological structures. The Southwest Taiwan Basin has several source rock sets, well-developed reservoir beds and good trap conditions. Local structure is large in area. Up to now, many local structures have been found to have multiple source-reservoir-cap combinations. The Southwest Taiwan Basin is considered as an area with abundant petroleum potential. The middle uplift will become the target area of petroleum exploration in the very near future.