六盘山盆地构造样式与油气分布

STRUCTURAL PATTERNS AND HYDROCARBON DISTRIBUTION IN LIUPANSHAN BASIN

六盘山盆地是在早古生代秦、祁、贺三叉裂谷系交叉带发育起来的复合—叠加型盆地,经历了印支、燕山、喜山多幕构造运动、多期改造及后期调整的过程,尤其是中新生代以来的拉张走滑、逆冲推覆和反转作用,造成盆地中、新生界构造层内构造样式多样化。通过对六盘山盆地钻井和地震资料的综合分析,对盆地的构造样式进行分析和归类,厘定3种主要构造样式,即挤压、伸展和反转构造样式,挤压构造样式是盆地最重要的构造样式,而反转构造则是区域构造背景发生转化的产物。不同的构造样式伴生有不同的油气圈闭类型,结合勘探实践分析认为盆地山前构造带深层局部构造和坳陷带的低凸起带是下部油气勘探的重点领域。

The Liupanshan Basin is a composite-superimposed basin developed in the early Paleozoic as a rift system at the trident juncture of the Qinling,Qilian and Helan Mountains.Multi-phases of tectonic movements,namely,Indo-China,Yanshan and Himalayan tectonic movements,multi-phase reconstruction and later adjustment,especially the Mesozoic and Cenozoic extensional strike-slip,thrust,overthrust,and structural reverse resulted in a variety of structural patterns in the Mesozoic and Cenozoic tectonic layers in the Liupanshan Basin.Through comprehensive analysis of drilling and seismic data,three major structural patterns were recognized,namely,compressive,extensional and inverted structure patterns,of which the compressive is the most important one,and the inverted structure is the result of the regional tectonic background.Upon the different structural patterns,there are different types of traps.It is proposed that future hydrocarbon exploration should focus more on regional deep structure along the piedmont zone as well as the low salient part of the depression zone in the Liupanshan Basin.