161 / 2022-02-27 20:43:50

重力流-底流共同作用下的海底扇朵叶沉积构型特征 ——以东非某深水研究区为例

Gravity flow, Bottom current, Submarine lobe, Reservoir architecture, Connectivity feature

Submarine fan deposits have great potential for oil and gas resources, and the study of their sedimentary architecture is essential for the development of deep-water reservoirs. The research on the submarine fan lobe architecture is mostly limited to gravity flows individually. Whereas the bottom currents are often accompanied by deep-water deposition, there is rare research on the architecture characteristics of the submarine fan lobe under the gravity flows and bottom currents. In this paper, we study on a deep-water area in East Africa under the environment of gravity flows and bottom currents as an example, including architecture of the submarine lobe, and different overlapping patterns and connectivity features of different hierarchy lobes by using core, logging and seismic data. Then, the sedimentary architecture pattern of submarine lobes under the gravity flows and bottom currents is established. The main conclusions include: 1) the lobe complex and the single lobe show unidirectional southward stacking pattern, which is opposite to the direction of bottom current, and the single lobe presents an asymmetric shape with thicker lobes margin on bottom current side; the mudstone between the lobe complex is thick and continuous, and the mudstone between single lobe is thin and discontinuous. 2) The lobe layers inside the single lobe display vertical accumulation, which shows no obvious relationship with bottom currents; there are few mudstone interlayers in a single lobe, and the mudstone interlayers gradually increase from the proximal the distal of the lobe. 3) The influence of the bottom current on the lobes is mainly manifested in the fact that the single lobe in the early stage deposited thicker vertically of the lobe margin along the bottom current side, so that the followed single lobe deposit on lower position of the previous topography, showing the migration opposing bottom current. Comparing the effects of the bottom current on the channel, their migration directions are all opposite to bottom current; For submarine lobe, there is no obvious asymmetry with large-scope horizontal drift deposits on the bottom current side. Instead, the single lobe margin is thicker vertically on the bottom current side, which shows the asymmetry that the main body of the lobe is biased to the bottom current side. The research is of great significance to the theory of deep-water sedimentary architecture and the planning of gas reservoir development.