鄂尔多斯台地靖边潜台南部中奥陶统马五_1~2岩相古地理  

Lithofacies Paleogeography of Middle Ordovician Ma5_1~2 in Jingbian tableland,Ordos platform

作　　者：霍勇[1,2] 罗顺社[1,2] 庞秋维[1,2] 金姗姗[1,2] 罗军梅[1,2] 

机构地区：[1]油气资源与勘探技术教育部重点实验室(长江大学),湖北荆州434023 [2]长江大学地球科学学院,湖北荆州434023

出　　处：《中国地质》2012年第1期86-95,共10页Geology in China

基　　金：国家自然科学基金(41072086)资助

摘　　要：鄂尔多斯盆地中奥陶统马家沟组由于受加里东运动影响而隆起抬升遭受风化,形成良好的岩溶油气储层,对其沉积特征的研究是油气勘探的重点。本文以沉积岩石学为指导,以单因素作图为方法论,结合钻井岩心资料、测井资料的细致分析、统计,选取了地层厚度、白云岩含量、灰岩含量、膏盐含量及泥岩含量等单因素,绘制出马五21的岩相古地理图。研究表明,研究区马五12期处于一个相对的海退期,其主要发育膏云坪、云坪、泥云坪和含泥云坪。根据岩相古地理图,结合马五12地层厚度,推测研究区中部存在一个较浅的洼地,并建立了符合本区马五12的沉积模式。综合以上研究,马五21期岩相古地理特征可概括"陆外为坪,云坪广布,坪中有洼,洼中有膏"。根据本区的岩相古地理条件及区域地质特征,对良好的天然气储层的形成进行了初步的探讨。The Middle Ordovician Majiagou Formation in Ordos basin was uplifted and eroded because of the Caledonian movement,forming favorable karst reservoirs.Therefore,the study of the sedimentary characteristics is of the key importance in oil-gas exploration.Based on the methods of single factor analysis（including analysis of stratigraphic thickness proportions of dolomite,limestone,gypsum and mudstone） in combination with detailed analysis and statistics of drilling core and logging data,the authors compiled and drew the lithofacies paleogeographic maps of Ma521 submembers.The results show that Ma521 was in a relative regression stage,and developed mainly gypsum-dolomitic flat,dolomitic flat,mud-dolomitic flat and mud-bearing dolomitic flat.According to lithofacies palaeogeographic maps in combination with stratigraphic thickness of Ma 521,there may be a shallow depression in the middle of the study area,and hence the authors built the sedimentary model of Ma 521 in this area.On such a basis,the lithofacies palaeogeography of Ma521 can be summarized as ＂flats outside the lands,widespread dolomitic flats,depressions in flats,gypsum in depressions＂.According to the lithofacies paleogeography and regional geology of this area,the formation of favorable gas reservoirs has been discussed preliminarily in this paper.

关 键 词：鄂尔多斯 马家沟组 碳酸盐岩 岩相古地理 靖边 

分 类 号：P534.42[天文地球—古生物学与地层学] P531[天文地球—地质学]