鄂尔多斯盆地陇东地区太原组铝土岩系地质特征及分布预测  

Geological characteristics and distribution prediction of the Taiyuan Formation bauxite rock series in Longdong area,Ordos Basin

作　　者：王雷 李明瑞 周义军 姚志纯 姚仙洲 张苗苗 郭晓娇 WANG Lei;LI Mingrui;ZHOU Yijun;YAO Zhichun;YAO Xianzhou;ZHANG Miaomiao;GUO Xiaojiao(Geophysical Research Institute,BGP,CNPC,Xi’an 710021,China;Exploration Division of PetroChina Changqing Oil field Company,Xi’an 710018,China;National Engineering Laboratory for Exploration and Development of Low Permeability Oil and Gas Fields,Xi’an 710018,China;School of Earth Science and Engineering,Xi’an Shiyou University,Xi’an 710065,China)

机构地区：[1]中国石油东方地球物理勘探有限责任公司研究院,陕西西安710021 [2]中国石油长庆油田分公司勘探事业部,陕西西安710018 [3]低渗透油气田勘探开发国家工程实验室,陕西西安710018 [4]西安石油大学地球科学与工程学院,陕西西安710065

出　　处：《天然气地球科学》2024年第8期1375-1386,共12页Natural Gas Geoscience

基　　金：中国石油天然气股份有限公司“十四五”前瞻性基础性重大科技项目“致密气新区新领域资源潜力与富集规律研究”(编号:2021DJ2101)资助.

摘　　要：鄂尔多斯盆地陇东地区太原组铝土岩气藏是一种新的非常规气藏,具有“小而肥”的特点,勘探潜力大,但铝土岩系变化快,分布不稳定,严重限制了勘探拓展。在采用印模法恢复太原组沉积前古地貌形态的基础上,精细刻画微古地貌单元,并结合岩心、录井和测井等资料研究铝土岩系地质特征及发育模式。结果表明:陇东地区太原组沉积前岩溶古地貌发育岩溶高地、岩溶斜坡及岩溶洼地3个次级岩溶古地貌单元,对应发育潜坑、沟槽及溶蚀洼地等负向微古地貌单元;主要发育泥质铝土质+铝土岩+煤/泥岩、铁质泥岩+双铝土岩段+炭质泥岩、铁质泥岩+厚层铝土岩/泥质铝土岩+泥岩/煤及铁质泥岩+铝质泥岩+泥/灰岩4种垂向岩性组合;受岩溶古地貌、海平面变化及淋滤作用强度控制,铝土岩系形成经历了红土残积物形成、原始铝土矿层形成、负向地貌单元铝土岩堆积、淋滤改造形成多孔铝土岩及广泛海侵煤泥覆盖5个主要阶段。同时,根据铝土岩系与围岩岩性和物性差异大的特征,利用叠后地震属性及叠前反演技术,对铝土岩系分布进行了刻画及预测,结果显示陇东地区太原组铝土岩在岩溶古地貌各级地貌单元中呈孤岛状、带状、片状有序分布,铝土岩系总分布面积为613 km^(2),其中孤岛状及带状发育区是铝土岩勘探最有利区。The exploration efforts have confirmed the presence of a bauxite gas reservoir in the Taiyuan Formation within the Longdong area,Ordos Basin.This reservoir exhibits unique characteristics,is characterized by its“small and fertile”nature,and holds significant exploration potential.However,accurately predicting the thickness and variability of the bauxite rock formation poses challenges.In order to comprehend the distribution patterns of bauxite within the Taiyuan Formation in Longdong area,a variety of techniques,including drilling,logging,and three-dimensional seismic data analysis,were employed.Bauxite lithofacies types were classified,and the controlling influence and modes of karst ancient landforms on lithofacies types and distribution were investigated.Qualitative and quantitative predictions of bauxite distribution within the Longdong area,using seismic response and intersection analysis of bauxite’s rock physical properties,were conducted.The findings indicate that karst paleogeomorphology predominantly governs the lithofacies belt of bauxite in Longdong area,with subtle paleogeomorphology and sea level fluctuations directly impacting the size and lithofacies combination of bauxite rock.Four distinct types of bauxite were identified across the karst highlands and basins:reverse cyclic bauxite,bimodal bauxite,normal cyclic bauxite,and dense bauxite.By leveraging amplitude type attributes and seismic inversion techniques,more accurate predictions regarding bauxite distribution can be made.The bauxite deposits in Longdong area are primarily concentrated in the northern regions of Ningxian,Heshui County,the southwestern portion of Qingcheng County,and the Huanxian area.Taking into consideration factors such as thickness,structure,and fractures,a total of 613 km^(2) of favorable areas for bauxite exploration have been evaluated.

关 键 词：鄂尔多斯盆地 陇东地区 太原组 岩溶地貌 铝土岩系 有利区 

分 类 号：TE122.1[石油与天然气工程—油气勘探]