中国西部地区方沸石胶结相与碎屑岩次生优质储集层形成机制

含油气盆地碎屑岩次生优质储集层的发育,除了与广泛发育的方解石胶结相有关外,在中国西部还有一类与沸石族自生矿物胶结的成岩相有关,其中以溶蚀方沸石胶结相形成的次生优质储集层与油气聚集成藏又有十分密切的关联。经实例分析:与自生方沸石胶结有关的成岩相主要受控于扇(辫状河)三角洲前缘相带、火山岩物源和成岩早期的碱性环境;次生优质储集层的形成在时间上主要处于成岩中期A阶段,在空间上受控于邻近的烃源岩、圈闭和输导体的沟通。方沸石矿物在物理性质上具有抗压易溶(有机酸)作用,较其他常见的自生矿物(胶结物)相对优越,就方沸石易于溶蚀的特点而言是较为理想的自生矿物(胶结物)。其溶蚀对孔隙度的贡献率在50％～75％之间,发育几率占绝对优势。所以,在方沸石发育的相带中寻找以粒间溶蚀孔为主的优质储集层,具有可靠的操作性和现实性。

Analcite cementation facies and forming mechanism of high-quality secondary clastic rock reservoirs in western China

In petroliferous basin,the generation of high-quality secondary clastic reservoirs are linked with calcite cementation facies; and in western China,it is also related to another cemented diagenetic facies of authigenetic zeolite,of which the high-quality secondary formed by the corroded analcite facies is closely connected with the hydrocarbon accumulation. It is showed by the examples that the diagenetic facies of analcite texture is controlled by the fan(braid river)-delta front,volcanic cinder and the alkaline condition in an eogenetic stage. The high-quality secondary clastic reservoirs were formed in stage A of middle diagenetic period. The distribution is decided by the source rocks nearby,traps and the connection of channel systems. The characters of analcites pressure resistance,erodibility(organic acid)are super to that of other authigenes minerals(cements). Therefore analcite is the ideal place for the development of induced porosity,and the ratio of emposieu to the porosity is 50％～75％. It is real and workable to prospect high-quality secondary emposieu-oriented reservoirs formed by intergranular dissolution pores in the environment of analcite distributed area.