断陷湖盆储集砂体发育的主控因素——以辽河西部凹陷古近系为例

断陷湖盆是我国东部新生代发育的主要含油气湖盆,探讨这类盆地储集砂体发育主控因素,对油气储层预测具有重要的实践意义。运用沉积—构造地质学和地球物理理论与技术,对辽河断陷西部凹陷古近系砂体发育特征进行研究,结果表明:沉积环境、古地貌、基准面和湖平面变化是断陷湖盆储集砂体发育的主要控制因素。除了沉积环境,构造运动造就的古地貌影响最大。西部凹陷古近纪古地貌包括古隆起、古沟谷、古台地、古坡折和古断槽等单元类型,它们不同程度地控制着沉积体系的展布和砂体的发育。根据构造特征,古坡折分为断阶型、陡崖型和陡坡型,它们分别对应于冲积扇-扇三角洲-远岸浊积扇沉积体系、冲积扇-近岸浊积扇沉积体系、冲积扇-扇三角洲和冲积扇-近岸浊积扇沉积体系等的发育。

The Main Control Factors of Sandbody Reservoir Development in Rift-Subsidence Lake Basin: An Example from the Paleogene West Sag of Liaohe Basin

Rift-subsidence lake basins are important oil-bearing basin of Eocene in the eastern China.The research of the main controlling factors of sandbody development has great practical significances for the prediction of hydrocarbon reservoirs.The characteristic research of the Paleogene sandbody distribution in west sag of Liaohe Basin shows that sedimentary environment,palaeogeomorphology and lake surface and base level fluctuation are the dominant controlling factors of sandbody development,among which the palaeogeomorphology is the most obvious one except for the sedimentary environment.The palaeogeomorphology of west sag includes palaeo-high,palaeo-ditch and valley,palaeo-platform,palaeo-break in-slope and palaeo-trough fault,which affect the distribution of depositional system and the development of sandbodies.The palaeo-break in-slope is divided into three types,i.e.faulted terrace type break in-slope,faulted scarpe type break in-slope and steep slope type break in-slope.Alluvial fan,fan-deltas and far-shore turbidite fan are developed on faulted terrace type break in-slope;Alluvial fan and nearshore turbidite fan are developed on faulted scarp type break in-slope;Alluvial fan,fan-deltas and nearshore turbidite fan are developed on steep slope type break in-slope.