前石炭纪古地貌对铝土岩气藏控制作用——以鄂尔多斯盆地庆阳古隆起为例  

Control of Pre-Carboniferous palaeogeomorphology on bauxite gas reservoirs:A case study of Qingyang palaeohigh in Ordos Basin

作　　者：曹茜 李涵[1,2] 潘星 封莉[3] 刘宣妤 侯芳 李辉 CAO Qian;LI Han;PAN Xing;FENG Li;LIU Xuanyu;HOU Fang;LI Hui(Research Institute of Exploration and Development,Changqing Oilfield Company,PetroChina,Xi’an 710018,China;National Engineering Laboratory for Exploration and Development of Low-Permeability Oil&Gas Fields,Xi’an 710018,China;Exploration Division,Changqing Oilfield Company,PetroChina,Xi’an 710018,China)

机构地区：[1]中国石油长庆油田公司勘探开发研究院,陕西西安710018 [2]低渗透油气田勘探开发国家工程实验室,陕西西安710018 [3]中国石油长庆油田分公司勘探事业部,陕西西安710018

出　　处：《天然气地球科学》2024年第8期1396-1410,共15页Natural Gas Geoscience

基　　金：中国石油“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：鄂尔多斯盆地含铝土岩系地层较为发育,近年来针对该地层的铝土岩气藏的勘探开发取得重大突破,并提出了“古地貌控储、煤岩近源供烃、岩性构造控藏”的成藏模式,进一步揭示了铝土岩具有近源规模成藏的规律。为明确古地貌对铝土岩气藏的控制作用,以鄂尔多斯盆地陇东地区石炭纪太原组为例,通过印模法恢复前石炭纪古地貌形态特征,并结合钻井、测录井、地震、野外露头观察及分析化验等资料分析古地貌对陇东地区太原组铝土岩气藏的控制作用。研究表明:太原组沉积期古地貌主要发育高地、斜坡、洼地3个二级古地貌单元,斜坡又可分为潜坑、阶地及沟槽3个三级古地貌单元,主要以岩溶斜坡为主,古地貌整体趋势走向为西南高、东北低。古地貌对研究区前石炭纪铝土岩气藏的控制作用如下:①古地貌控制表,生期淋滤作用的时间和强度;②古地貌控制沉积相态的展布,沉积于古陆边缘及潮坪相的铝土岩厚度较大;③古地貌控制铝土岩厚度和孔隙发育,古地貌潜坑、阶地铝土岩厚度大,溶孔与裂缝发育;④上部广覆式煤系源岩生烃,生烃动力驱动向下运移至表生期发育的铝土岩储层聚集成藏,多孔状铝土岩是制约天然气成藏的关键地质要素。Bauxite series strata are well developed in the Ordos Basin.In recent years,significant progress has been achieved in the exploration and development of bauxite gas reservoirs within these strata.A reservoir-forming model has been proposed,emphasizing the role of paleogeomorphology in controlling reservoir formation,the contribution of coal rock in supplying hydrocarbons near the source,and the influence of lithology and structure in reservoir development.This model sheds light on the near-source scale reservoir-forming potential of bauxite.In order to elucidate the influence of paleogeomorphology on bauxite gas reservoir,this study focuses on the Permian Taiyuan Formation in the Longdong area of the Ordos Basin.Using the impression method,the paper reconstructs the paleogeomorphology characteristics of the Pre-Carboniferous Taiyuan Formation.By integrating drilling,logging,seismic,outcrop observation,analysis,and actual production data,the study analyzes the impact of paleogeomorphology on bauxite gas reservoirs in the Taiyuan Formation of the Longdong area.The study reveals that:(1)The Taiyuan Formation exhibits three primary palaeogeomorphology units,namely highland,slope,and depression,along with three secondary micro-palaeogeomorphology units,which include buried pit,terrace,and groove.Specifically,the palaeogeomorphology of the Taiyuan Formation predominantly features karst slopes,with a general trend of higher elevations in the southwest and lower elevations in the northeast.The paleogeomorphology plays a crucial role in controlling the pre-Carboniferous bauxite gas reservoirs in the area by influencing the timing and intensity of supergene leaching.(2)The thickness of bauxite in buried pits and terraces is largely controlled by paleogeomorphology,where dissolved pores and fractures are well developed.(3)Additionally,the distribution of sedimentary facies is influenced by paleogeomorphology,leading to thick bauxite deposits in the margins of ancient land and tidal flat facies.(4)The development of reservoi

关 键 词：古地貌 古地貌恢复 铝土岩气藏 鄂尔多斯盆地 

分 类 号：TE122.2[石油与天然气工程—油气勘探]