阿尔及利亚B区块上三叠统高分辨率层序及储层特征

阿尔及利亚B区块位于Oued Mya盆地东部,自奥陶纪以后该盆地多次发生隆升剥蚀,加里东运动造成志留纪和盆纪地层不同程度的缺失。海西期基底隆升,造成石炭纪和二叠纪地层的完全缺失,并在晚三叠世早期开始发育辫状河沉积。B区块晚三叠世沉积具有从早期的辫状河向中期的曲流河和晚期的盐湖演化特点,其过程较为复杂。在晚三叠世早中期发生强烈的火山喷发作用,在研究区内堆积了厚度巨大的火山岩,使研究砂体的时空展布和演化规律变得更为复杂。通过高分辨率层序分析,建立了B区块晚三叠世的等时地层格架,为恢复研究区等时条件下的古地理特征奠定了基础,并明确了层序对储层的控制规律,为该区进一步的油气勘探和开发提供了依据。

High-resolution sequences and reservoirs in the Upper Triassic strata of B block in Algeria

B block is located in the eastern part of the Oued Mya Basin in Algeria, and may have been subjected to several phases of uplift and denudation from the Ordovician onwards. The Caledonian orogeny led to the partial absence of the Silurian and Devonian strata, while the uplift of the basement during the Hercynian was responsible for the complete omission of the Carboniferous and Permian strata. The braided stream deposits were developed during the early Late Triassic. There are gradations from the early Late Triassic braided stream deposits to the middle Late Triassic meandering stream deposits and late Late Triassic saline lake deposits. In addition, the intense volcanic eruption during the early and middle Late Triassic also brought about tremendous pyroclastic rocks in the study area. According to the high-resolution isochronous stratigraphic correlation, the authors arrived at the construction of the Late Triassic stratigraphic framework and laid the foundation for the construction of the palaeogeographic framework and delineation of the targets for further hydrocarbon exploration.