埕岛油田古生界地层特征及其构造意义

Paleozoic Stratigraphic Characteristics and Its Tectonic Significance in Chengdao Oilfield

中国东部断陷盆地基底古生界潜山具有良好的成藏条件,是基岩油藏重要的勘探领域。渤海湾盆地埕岛油田基底古生界沉积厚度大、岩石类型多、地层残留复杂、构造应力不同,决定了储层物性的平面及纵向差异性,进而影响了油气成藏的差异性,因此开展地层残留规律的研究是区域古生界油气勘探的关键。以往对地层残留的研究多依据钻井揭示与地震解释的表象研究,缺乏成因过程的深入分析。基于井、震资料分析,开展了地层发育序列、残留规律研究,在此基础上探讨了研究区地层残留特征的构造意义。主要取得了以下认识:(1)研究区古生界主要发育了寒武系、下-中奥陶统、中-上石炭统及二叠系;(2)古生界整体呈现出现今南高北低、东高西低的特征。受负反转构造控制,潜山带构造低部位地层残留少;(3)从地层展布规律分析了其经历的主要风化剥蚀期次,推测了地质历史时期的构造特征,佐证了区域构造演化过程;为东部叠合盆地基底古生界地层特征研究及构造演化提供了参考依据。

The Paleozoic buried hills which have favourable reservoir forming conditions in basement of the rifted basins in east China are important areas for hydrocarbon reservoirs exploration. Reservoir physical properties and hydrocarbon accumulation are different in the plane and the vertical for the great thickness of the sedimentary formation,varieties of rock types,complex residual formation and different tectonic stresses of the Paleozoic basement of Chengdao oilfield in Bohai Bay basin. Therefore,study of the law of residual formation is a key of oil and gas exploration of the Paleozoic. Residual formation has been studied shallowly before based on drilling results and seismic interpretation,and analysis of the genetic development is lacked. In this study,stratigraphic sequence and development law of residual formation are studied based on well and seismic analysis. And some results and understandings are achieved as follows： Firstly,Cambrian,Lower-Middle Ordovician,Middle-Upper Carboniferous and Permian strata are developed from the bottom up in the study area. Secondly,from north to south and from east to west,the residual Palaeozoic strata today change from high to low. And the residual Palaeozoic strata are less on lower location of the buried hill structural zone because of the inversion structures. Finally,main weather denudation stages are analyzed and the structural features of geological history are speculated from the stratigraphic distribution characteristics. And the regional tectonic evolution process is furtherproved. This study provides a reference for research of the stratigraphic features and tectonic evolution of basement of the Paleozoic in the superposed basin in east China.