江陵凹陷新沟咀组下段成岩特征及高孔隙带的分布规律

江陵凹陷成岩作用明显受沉积水介质性质的控制,成岩特征呈现出淡水-半咸水介质富碳酸盐胶结与盐湖富硬石膏胶结特征,两种胶结物含量存在互为消长的关系.从分析盐湖成因角度合理解释了成岩规律,认为盐湖环境成因受控于深层卤水和古气候.淡水一半咸水环境和盐湖环境成岩作用模式的差异导致两种环境抗压实的机理存在着差异,相应的高孔隙带分布规律不同,淡水一半咸水环境的早期碳酸盐胶结物被溶蚀形成高孔隙发育带;盐湖环境的膏岩层发育区有利于形成深部异常高压的"封存箱",保存原生孔隙,从而发育高孔隙带.

Diagenetic features and distribution of high-porosity zones in lower Xingouzui Formation of Jiangling depression

Diagenesis of Jiangling depression is controlled by sedimentary water and characterized by rich carbonate cementation in fresh to semi-salt water and rich anhydrite in salt water. The abundances of the two cements show a mutual growth and decline relationship. The salt environment is controlled by the deep brine and paleoclimate. The differences of the diagenetic model between the fresh water-semisalt environment and the salt environment lead to the differences between the two environments in the mechanism of resistance to compaction and the distribution of high-porosity zones. Early carbonate cement dissolution in the fresh water-semisalt environment forms high-porosity zones, while the development zone of gypsum and anhydrite is beneficial to forming a mothballed box of overpressure at depth, thus preserving original pores and leading to the development of highporosity zones.