坎波斯盆地ABL区块水道化朵叶演化模式

Evolutionary Model of Hydrochemical Lobes in the ABL Block of Campos Basin

阴国锋

YIN Guofeng

中国石化上海海洋油气分公司, 上海 浦东新区 200120

Shanghai Offshore Oil & Gas Company, SINOPEC, Pudong New Area, Shanghai 200120, China

作为海底扇沉积体系的重要组成部分，深海水道和朵叶体受到了沉积学界的广泛关注，然而，关于两者之间过渡部分“水道—朵叶体过渡带”以及其所对应的“水道化朵叶体”的研究却尚不充分。以巴西坎波斯盆地深水区ABL区块为例，利用三维地震资料以及钻测井资料，识别出了砂质水道、泥质水道及席状朵叶等不同沉积单元，进而明确了工区内水道化朵叶体的广泛发育；在此基础上，对水道化朵叶体的总体沉积特征以及内部沉积构型进行了表征，分析了相关的影响因素，并最终建立了它的发育演化模式。ABL区块内水道化朵叶体的总体沉积特征在不同位置表现出明显变化，近物源一端朵叶体的水道化程度明显较高。整个水道化朵叶体可以划分为3个朵叶单元，按照时间顺序从北向南依次发育。朵叶单元1在次要物源的影响下发育大量分支水道，使其水道化程度相对较高；朵叶单元2在主物源影响下沿着主供给水道展布，受地形坡度向下游逐渐变缓的影响，其水道化程度向下游逐渐变弱；朵叶单元3主要受到主供给水道中重力流活动的影响，在主供给水道的一系列弯曲带处，重力流从主水道中剥离出来并发生快速沉积，从而形成了水道化程度较弱的朵叶单元3。

As the major components of submarine fan systems, submarine channels and lobes receive much attention from the sedimentological community. However, studies about the“channel-lobe transitional zone”and the associated channelized lobes are still not enough. This study takes the Block ABL in deep-water areas of Campos Basin of Brazil as the example and recognizes different depositional elements of sandy channels, muddy channels, and sheet lobes, which suggests that channelized lobes are widely developed within the study area. We then characterize the overall deposition and internal architecture of channelized lobes, analyze the associated controlling factors, and establish the evolution model. The results suggest that the overall deposition of channelized lobes show significant variations between different locations; compared with the deposition in southern and downdip area, lobes in northern and proximal areas are more channelized. About the internal architecture, the channelized lobes could be divided into 3 lobe elements, which developed from north to south in terms of sequence. Lobe element 1 was mainly controlled by the source from north, which developed lots of distributaries and was more channelized. Controlled by the main source, Lobe element 2 was oriented along the major feeder channel; due to the gradual decreasing of topographic gradient, the degree of channelization of Lobe element 2 decreased. Lobe element 3 was mainly controlled by the behavior of gravity flow in the major feeder channel; around the bend of major feeder channel, gravity flows were stripped and deposited rapidly, which caused the formation of Lobe element 3 with relatively weak degree of channelization.

10.11885/j.issn.1674-5086.2024.09.04.01