背斜构造不同部位储集层物性差异——以库车坳陷克拉2气田为例

摘要

There are strong difference in reservoir property between the core and limbs of the Kela-2 anticline although they are in the same structure.The heterogeneity of"small-scale and east-west" in the Kuqa Depression cannot be explained by the distribution mode of compressional stress "large-scale and south-north" proposed by previous scholars.Statistics of rock constituents and characteristics shows that the differentiation of reservoir compaction between the anticlinal core and limbs of the Kela-2 anticline is clear, which is controlled by the difference of tensile stress suffered by strata over the neutral plane during fold modification.The tensile stress suffered by strata in the anticlinal core is stronger than that in the anticlinal limbs.In the Kela-2 anticline, the difference of tensile stress between the anticlinal core (Kela-201) and limbs (Kela-203 & Kela-204) is obvious.The tensile stress offsets the compaction effect caused by vertical and lateral (south-north) stresses, and it is constructive to reservoir properties.It is the major factor controlling the differentiation of reservoir compaction.%尽管处于同一构造样式内,克拉2背斜构造核部和两翼部位的储集层物性仍表现出明显的差异.前人有关库车坳陷所受构造应力的"大尺度-南北向"分布模式无法解释上述"小尺度-东西向"的储集层非均质性特征.镜下岩石组分和成岩特征统计表明,克拉2背斜褶皱核部和两翼部位的储集层表现出明显的压实分异特征,压实分异特征主要受控于中和面之上地层在褶皱变形过程中所受张应力的差异,这种张应力在背斜的轴部表现最强,向两翼方向减弱.克拉2气田背斜褶皱内部,核部储集层所受到的张性应力明显强于两翼,这种有利于保存储集层物性的张应力补偿了其他应力对储集层所造成的压实效应,成为储集层压实分异的主控因素.