构造—古地貌对沉积的控制——以L工区古近系沙三段为例

Control of Tectonic-paleogeomorphology on Deposition:A case from Es3 in L project

综合利用地震、测井和录井资料,恢复了L工区沙三段的构造—古地貌,并分析了构造—古地貌对沉积体系的控制作用。沙三段沉积时期,同沉积断裂较少,且规模较小,差异沉降相对较弱,受不同走向断层的控制,总体上其构造—古地貌可划分为14个构造—古地貌单元,3个凸起带、西北部1个稳定剥蚀带、西南部1个深洼带、3个浅洼带、3个斜坡带、2个水下低凸起带及分散在斜坡带上的沟谷(如图2)。受构造—古地貌控制,在斜坡带及浅洼带识别出辫状河三角洲、滨浅湖混合滩、滨浅湖钙质滩坝及滨浅湖砂质滩坝,在靠近控凹断层的深洼带识别出扇三角洲。辫状河三角洲、扇三角洲及滨浅湖砂质滩坝砂岩丰富,可形成地层—岩性圈闭,是油气勘探的重要区域。

Based on the tectonic-paleogeomorphology and the seismic of the Es3 in the L project,we restore the tectonic-paleogeomorphology of Es3 in the L project and study on the control of tectonic-paleogeomorphology on deposition.In Es3,synsedimentary fault is less,and on a smaller scale,the differential settlement is relatively weak.Controlled by different strike fault,its overall structure-the ancient landform can be divided into 14tectonic-paleogeomorphology,three bump southwest,northwest stable denudation,deep depression belt,three shallow depression belt,three slope belt,two underwater low convex belt and dispersed in the slope belt in valleys.Controlled by the the tectonic-paleogeomorphology of Es3 in the L project,In the slope belt and shallow depressions the braided river delta,the littoral and shallow lake foreshore,the littoral and shallow lake calcium dam and littoral and shallow lake sand dam were formed.fan deltas were formed near the fault which control the deep depression.In the braided river delta,fan delta and littoral and shallow lake sand bar,sandstone is rich.It can form lithologic trap formation that is an important area of oil and gas exploration.