绥滨坳陷中生界层序地层特征及油气勘探远景

详细分析三江盆地绥滨坳陷的钻井资料,并结合地震解释剖面.将绥滨坳陷中生界划分为4个二级层序、8个三级层序,其中二级层序底部的三级层序发育低位体系域,其余不发育低位体系域.平衡剖面和米兰科维奇旋回分析结果表明,绥滨坳陷中生界三级以上层序主要受构造控制,米兰科维奇旋回只对高频层序(体系域)有控制作用.在上述分析基础上建立了绥滨坳陷中生界二级层序地层模式,该模式具有典型的三分性:早期的盆地充填(低位体系域),中期的盆地扩展(水进体系域)和晚期的盆地萎缩(高位体系域).并指出,二级层序发育的低位体系域上覆的水进体系域可以作为很好的封盖层,同时又可能是烃源岩,因而低位体系域应成为下一步油气勘探的目标.图9表1参9

Sequence stratigraphic characteristics and hydrocarbon prospect of Mesozoic Formation in Suibin Depression, Sanjiang Basin

According to the detailed analysis of drilling data, together with the interpretation of seismic section, the Mesozoic of Suibin Depression is divided into four second-order sequences and eight third-order sequences. The third-order sequences at the bottom of the second-order sequences develop low-stand systems tracts (LSTs), and the other sequences do not. The analysis result of the balanced section and Milankovitch cycle indicates that the Mesozoic sequences above third-order in the Suibin Depression are mainly controlled by structure, and that the Milankovitch cycle only controlls high frequency sequences (systems tracts). Base on the above analyses, the second-order sequence stratigraphy model of the Mesozoic of Suibin Depression is established. The model is of typical tripartition, the early basin fill (LST), the middle basin expansion (TST) and the late basin abortion (HST).The transgressive systems tracts (TSTs) overlying the LSTs in the second-order sequences may be good seal and source rock, so the LSTs have the potential for oil and gas.