鄂北什股壕地区下石盒子组沉积微相及展布特征

SEDIMENTARY MICROFACIES AND DISTRIBUTION CHARACTERISTICS OF XIASHIHEZI FORMATION IN THE SHIGUHAO REGION,NORTH ORDOS BASIN

鄂北什股壕地区下石盒子组作为重要的油气产层,一直以来都是油气勘探研究的重要层位,本文通过对鄂北什股壕地区伊字号、锦字号等30余口井的测井资料的详细分析,结合J1井等23口钻井岩心观察描述,根据岩性特征、沉积相及研究区内东西、南北向沉积剖面结构特征的识别,将什股壕地区下石盒子组划分为冲积扇和辫状河沉积相,并可进一步识别出泛滥平原、心滩等4类沉积微相。在下石盒子沉积演化过程中,砂体具有东西向分带,南北向展布的特征,盒1段以冲积扇沉积为主,储集砂体厚度大,河道发育规模大;盒2、3段为辫状河沉积,砂体较盒1段薄,河道规模也不断变小。研究成果为进一步储层分布规律研究和油气勘探提供了主要的基础地质资料。

The Xiashihezi Formation of Shiguhao region in Ordos basin is the most important oil and gas production horizon. Through the analysis of logging data and drilling cores of Meng 1, Meng 2,ShiE1,YI,Jin in Shiguhao area in Ordos basin, combined with the flag characteristics of lithologic features and sedimentary structure in Jinl etc 23 drilling across the South-North and East-West,the Shiguhao region is classified into alluvial fan and braided river sedimentary facies, and 5 sedimentary microfacies, such as riverbed runway resort and channel bar. On the basis of characteristics sedimentary microfacies, correlation of microfacies for single-well and among wells,the distribution map of sedimentary microfacies of Xiashihezi Formation in research region is presented. The evolution of vertical and horizontal distribution of 8 sedimentary microfacies is described in details. In the process of sedimentary evolvement, the sedimentary systems were allu- vial fan in He 1 Member,with thick reservoir sandstone, well developed river channel. The sedi- mentary systems of He 2 Member and He 3 Member were braided river with thin sandstone and small scale river channel.