南海礼乐盆地新生代构造层序界面特征及油气地质意义

礼乐盆地是中国南海深水领域一个重要的含油气盆地,具有较好的油气资源前景。应用沉积学和层序地层学的原理和方法,结合区域构造演化特征,详细研究了礼乐盆地新生代沉积充填过程中关键构造层序界面(S100、S70、S50)在钻井岩性、测井曲线、古生物及地震剖面上的特征。结果表明,构造层序界面为岩性、电性的突变面,在构造层序界面附近,古生物演化过程中存在标志生物种属和数量的突变。在地震剖面上,构造层序界面是区域性的不整合界面,表现为明显的上超、下超或削截特征。进而详细论述了这3个构造层序界面形成的油气地质意义,具体表现为:(1)反映了关键时期礼乐盆地性质的转化;(2)有利于形成优质储集空间;(3)层序不整合面既是油气横向长距离运移的重要通道,也是礼乐盆地油气藏成藏的关键。

Cenozoic tectonic sequence boundary and petroleum geological significance of the Lile Basin, South China Sea

The Lile Basin is a major petroliferous basin with great potential of petroleum resources in the deep-water sea domain of the South China Sea. The key tectonic sequence boundaries S100, S70 and S50 generated during the Cenozoic deposition and filling are discussed in detail in lithology, well logs, palaeontology and seismic reflection profiles in the light of the principles and methods of sedimentology and sequence stratigraphy, and regional tectonic evolution. The tectonic sequence boundaries cited above are considered as the lithologic and electric abrupt surfaces. There are also the saltatory evolution in the biospecies and numbers in the palaeontological evolution at or near the tectonic sequence boundaries. In the seismic reflection profiles, the tectonic sequence boundaries appear as the regional unconformities characteristic of onlap, downlap or truncation. The tectonic sequence boundaries represent the transition of the Lile Basin during the major tectonic evolutionary stages, benefit to the formation of the high-quality reservoir spaces, and serve as the pathways for the long-distance oil and gas migration and the sites of hydrocarbon accumulation in the Lile Basin.