锦州20-A构造沙二段储层成岩特征及异常高孔带成因

DIAGENETIC CHARACTERISTICS AND ORIGIN OF ABNORMAL HIGH-POROSITY BELT IN E_2S_2 RESERVOIR OF STRUCTURE JINZHOU 20-A

综合利用薄片、扫描电镜、X衍射、阴极发光、物性等资料,对锦州20-A构造沙河街组二段储层的岩石学特征、成岩作用、超压成因、次生孔隙成因等进行了研究。结果表明:锦州20-A构造沙二段砂岩岩石类型主要为长石砂岩、岩屑质长石砂岩,可溶组分含量较高;成岩作用主要有压实作用、胶结作用、交代作用和溶蚀作用,以早期碳酸盐胶结和后期溶解为典型特征,成岩演化处于中成岩A期,较研究区整体成岩演化滞后;沙二段地层压力连线与静水压力线平行,且压力系数随深度减小,为连通传递超压,超压封存箱内碳酸盐胶结物的溶蚀再分配以及超压对黏土矿物转化的抑制是深部高孔带形成的主要控制因素。

Comprehensively utilizing the data of cast thin section, scanning electron micrograph （ SEM ） , X-ray diffraction, cathodoluminescence/cathodeluminescence and physical properties, the petrological characteristics, di- agenesis, overpressure and secondary pore geneses and so on are figured out for Member 2 reservoir of Shahejie For- mation （ E2s2 ） in Structure Jinzhou 20-A. The results show that the sandstone types are mainly feldspathic sand- stone and lithic-feldspar sandstone, which have abundant content of preferring solution; the diageneses main refer to compaction, cementation, metasomatism and dissolution, which are typically characterized by early-stage carbon- ate cementation and later dissolution, the diagenetic evolution is within middle-A stage, which is lagging behind comparing the regional diagenetic evolution; the pressure sure and moreover the pressure coefficient decreases with line of E2s2 formation is parallel to the hydrostatic pres- the depth increases, as a overpressure connecting trans- mission. The dissolution ＆ redistribution of the carbonate cements in the overpressure mothballing box and the re- tardation of the clay minerals by the overpressure are the main controlling factors of the generation of the high-poros-ity belts in the deep part.