摘要:为了揭示低可容纳空间三角洲沉积背景下层序发育及砂体分布特征，运用层序地层学的相关理论和方法，结合岩心、测井、录井和地震等资料，以珠江口盆地白云凹陷北坡珠江组下段为例进行了层序地层和控砂模式的研究。识别出强制海退和正常海退造成的暴露侵蚀不整合面、与暴露侵蚀界面相对应的整合面、海泛面、最大海泛面、强制海退底面和最大海退面等6种界面，将研究区珠江组下段划分为一个半三级层序；并指出低可容纳空间三角洲沉积背景下沉积界面与基准面一致或略低于基准面，准层序以与海泛面对应的暴露侵蚀面为界面，且主要形成于基准面上升半旋回，区域基准面相对海平面的下降是控制层序边界形成的主要因素；平面上砂体赋存在三角洲前缘和下三角洲平原的沉积地区，新增可容纳空间的形成速率及剩余可容纳空间的原有规模是控制砂体横向连续分布的关键因素；垂向上砂体分布在SQ1层序基准面缓慢上升到下降之前形成的高位体系域和SQ2层序基准面下降最低点到缓慢上升至最大海退面形成的低位体系域，这两套砂体横向连续性较好，存在良好的生储盖组合和油气输导条件，是形成大型油气藏的有利部位。
关键词: 控砂模式/
层序地层/
三角洲沉积/
低可容纳空间/
白云凹陷北坡
Abstract:The sequence stratigraphy and sandbodies control pattern of the lower-member in Zhujiang Formation of the northern Baiyun Depression in the Pearl River Mouth Basin have been studied in order to reveal the sequence evolution and the sandbodies distribution of the delta which has a low accommodation space with the help of the theory and method of sequence stratigraphy in combination of the comprehensive utilizing of core, logging information, and 3D seismic data. There are six sequence boundary types which have been recognized, they are exposed erosional unconformity which is caused by forced regression and normal regression, conformity surface corresponding to the unconformity, flooding surface, maximum flooding surface, bottom surface of forced regression and maximum regression surface. Based on the sequence boundary, the lower-member of Zhujiang Formation in the research area has been divided into one and a half third-order sequences. Meanwhile, the sedimentary boundaries of the delta with a low accommodation space coincides with or is slightly lower than the base level , the boundary of the parasequence which formed mainly during the semi-cycle of the rising base level is the exposed erosional surface corresponding to the flooding surface, and the formation of the sedimentary boundaries is predominantly controlled by the fall of relative sea level. The sandbodies are distributed in the delta front and lower delta plain horizontally and the lateral continuity of the sandbodies is deeply affected by the formation rate of new accommodation and the prevenient size of residual accommodation. The sandbodies locate longitudinally in both the highstand systems tract of the SQ1 and the lowstand systems tract of the SQ2, further the highstand systems tract formed from when the base level rises slowly to drop and the lowstand systems tract formed from when the base level drops to the lowest point to a slow rise to maximum flooding surface. For the better lateral continuity, the excellent source-reservoir-cap rock association and the favorable migration pathways, those sandbodies might be favorable area for oil-gas reservoir.
Key words:Sandbodies controlled pattern/
Sequence stratigraphy/
Delta deposit/
Low accommodation space/
Northern Baiyun Depression
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