百色盆地中三叠统兰木组孤立残余灰岩岩溶特征及演化

Karst characteristics and evolution of isolated residual limestone of the Middle Triassic Lanmu Formation in the Baise Basin

中三叠统兰木组灰岩潜山油藏是百色盆地油气勘探的重要领域。基于野外剖面及扫描电镜、阴极发光、普通薄片、铸体薄片等资料,对百色盆地中三叠统兰木组残余灰岩岩溶特征进行了研究。结果表明,兰木组现今残余灰岩呈孤立块状不均匀分布,上法地区灰岩分布范围较大,灰岩最大厚度450 m左右。残余灰岩主要为亮晶砂屑灰岩、泥晶及亮晶生屑灰岩、生物丘和礁灰岩。灰岩内部广泛发育溶蚀孔洞、裂缝,可划分出垂向上的风化残积表生带、渗流带和潜流带,横向上形成多个岩溶斜坡—岩溶高地—岩溶斜坡交替分布的格局。通过分析兰木组灰岩从印支晚期—燕山—喜山运动早期的长期隆升及差异剥蚀特征,建立了兰木组残余灰岩岩溶地貌及演化模式。研究结果可以为类似残余灰岩岩溶的研究提供新的思路,并对研究区有利储层预测提供指导。

The limestone-buried hill reservoir of the Middle Triassic Lanmu Formation is an important area of oil and gas exploration in the Baise Basin.Based on field profiles and data from scanning electron microscopy,cathodoluminescence,and ordinary and cast thin sections,it was studied the karst characteristics of the residual limestone of the Middle Triassic Lanmu Formation in the Baise Basin.The results show that the current residual limestone of the Langmu Formation is unevenly distributed in isolated blocks,with a maximum limestone thickness of about 450 m in the Shangfa area.The residual limestone is mainly sparry arenaceous limestone,micritic bioclastic limestone,and bioherm limestone.According to the extensive development of dissolution pores and fissures within the limestones,the limestones can be divided into weathering residual epigenetic zones,seepage zones,and subduction zones in the vertical direction,and multiple karst slope-karst highland-karst slopes in the horizontal direction in an alternating pattern.By analyzing the long-term uplift and differential denudation of the limestones of the Lanmu Formation from the late Indosinian-Yanshan-Early Himalayan movement,it was established a model of karst geomorphology and evolution of the residual limestones of the Lanmu Formation.The study results can provide new ideas for the study of similar residual limestone karst and guides for the prediction of favorable reservoirs in the study area.