珠江口盆地白云凹陷早中新世深水层序模式

近年来深水勘探已成为寻找油气的重要领域,白云凹陷在早中新世经历了复杂的构造沉积环境,解剖深水层序模式有利于揭示深水沉积演化规律。通过井震结合及属性分析对白云凹陷早中新世层序地层进行研究,识别出3个层序界面:ZJSB1(23.8 Ma),ZJSB2(22Ma),ZJSB3(21Ma)。其中ZJSB1、ZJSB3为重大不整合面,ZJSB2为水道下切侵蚀面。与之对应的界面发育3套层序:ZJSQ1,ZJSQ2,ZJSQ3。由于白云凹陷构造运动及古地貌的差异性,总结了2套深水层序模式:水道—深海披覆泥层序模式与块状搬运复合体—砂质碎屑流深海扇—水道—深海泥层序模式,在不同的演化阶段,前者主要受海平面的变化控制,而后者是受构造和海平面双重影响的。而同一地质时期古地貌又控制了沉积发育,高地势区发育下切水道,而低洼区发育深海披覆泥岩。因此,深水层序模式下研究深海沉积单元,对指导深水沉积和油气勘探具有极其重要的意义。

SEQUENCE STRATIGRAPHIC MODELS OF THE EARLY MIOCENE IN BAIYUN SAG,PEARL RIVER MOUTH BASIN

The Baiyun Sag, as a deepwater sag, suffered complicated tectonic and depositional environ- ment in Early Miocene. To better understand the evolution of deep-water deposits, sequence stratigraphic models are required. Based on the integrated study of seismic data, well logs and attribute maps, we established the sequence stratigraphic framework of the Miocene in the sag. Three sequence boundaries, i. e. ZJSB1 （23.8Ma）, ZJSB2 （22Ma）, ZJSB3 （21Ma） were identified. The boundaries of ZJSB1, ZJSB3 are significant unconformities and ZJSB2 an incised channel base. With the above-men- tioned boundaries, three sequences, namely ZJSQ1, ZJSQ2, ZJSQ3 were established. Due to the di- verse tectonic movement and paleogeomorphology in the Baiyun Sag, there are two deep-water stac- king models, the model consisting of channel-deep-water drape shale and the model consisting of mass transport complexes （ MTCs）-sandy clastic flow deep sea fan-channel-deepwater drape shale. In dif- ferent evolutionary phases, the former is effected by sea level change, while the latter by both tectonic and sea level changes. Paleogeomorphy also plays significant role in sediment distribution. The incised channel usually occurs in high area and deepsea drape shale in low area.