松辽盆地长岭凹陷中部上白垩统砂岩成岩作用及成岩相带

DIAGENESIS AND FAVORABLE DIAGENETIC FACIES OF UPPER CRETACEOUS SANDSTONES IN THE MIDDLE OF CHANGLING DEPRESSION IN SONGLIAO BASIN

松辽盆地长岭凹陷中部上白垩统储层砂岩主要类型为岩屑长石砂岩,经历的成岩作用主要有以机械压实为主的压实作用,碳酸盐、粘土矿物、硅酸盐及硅质胶结为主的胶结作用,以长石、岩屑等不稳定组分溶解为主的溶蚀作用和局部发育的交代作用。研究区储层孔隙类型以粒间孔隙、粒内溶孔和铸模孔为主,其中粒间孔隙最为发育。储层砂岩成岩演化阶段处于早成岩B期—中成岩B期,主要为中成岩A期。结合沉积相和成岩作用特征,深入探讨了适合本区的成岩相的划分方案,划分的主要成岩相类型为压实成岩相、碳酸盐胶结相、不稳定组分溶蚀相、硅质胶结相和钠长石成岩相,成岩相决定储层的性能,不稳定组分溶蚀相和钠长石成岩相构成了本区的有利成岩相带。

Upper Cretaceous sandstones in the middle of Changling Depression of Songliao Basin mainly belong to lithic arkose,which experienced mechanical compaction, carbonate cementation, clay mineral cementation, silicate cementation, silicic cementation, dissolution of unstable compo- nents and local metasomatism. A variety of pore types in studied region include intergranular pores,intragranular pores,moldic pores, as well as a negligible amount of micro-pores and over- sized pores. Among the pores, the intergranular pores are dominant. Two stages of oil inclusions in the Hua 5 （the first Member of Nenjiang Formation） were recognized. Hydrocarbon injection of the first period has low maturity, while the second B period possesses little hydrocarbon injection. Based on the diagenetic events, the diagenetic stages of the studied area are diversified from the early eodiagenesis B to the mesodiagenesis B,with the principal diagenetic stage being the mesodi- agenesis A. The classification of diagenetic facies in the area is discussed on t]he basis of sedimen- tary facies and diagenesis. Diagenetic facies can be classified into five types, they are compaction diagenetic facies, carbonate-cementation facies, unstable components dissolution facies, siliceous cementation facies and albite diagenetic facies. The unstable components dissolution facies and al- bite diagenetic facies constitute the favorable diagenetic facies in the studied region.