济阳坳陷渤南洼陷沙四上亚段碎屑岩成岩作用及其孔隙演化

Diagenesis and Porous Development of Clastic Rock in Upper Part of 4^(th) Member of Shahejie Formation in Bonan Sag of Jiyang Depression

为揭示济阳坳陷渤南洼陷沙四上亚段碎屑岩成岩作用及其对孔隙演化的定量影响,寻找有利储集体,应用铸体薄片、扫描电镜、黏土矿物X射线衍射分析等实验测试资料对其进行了研究。结果表明:渤南洼陷沙四上亚段碎屑岩储集体成岩作用包括压实作用、胶结作用、溶蚀作用及交代作用;受成岩早期膏岩层产生的碱性流体和中后期烃源岩排出的有机酸影响,膏岩层段储集体经历了先碱性后酸性的成岩环境;由成岩环境控制,碎屑岩储集体在早成岩阶段以胶结减孔为主,到中成岩阶段发生溶蚀增孔现象;基于不同深度、不同层位的大量分析化验资料,初步形成了孔隙演化的定量表征方法;低位体系域次生孔隙发育的碎屑岩储集体分布于渤南洼陷南部及北部扇三角洲前缘、东部扇三角洲平原,原生孔隙较发育的碎屑岩储集体分布于砂岩滩坝;高位体系域次生孔隙发育的碎屑岩储集体分布于渤南洼陷北部近岸水下扇扇端和南部扇三角洲平原,原生孔隙较发育的碎屑岩储集体分布于扇三角洲前缘。

To analyze diagenesis of clastic rock in upper part of the 4^(th) member of Shahejie Formation(Es4~s) in Bonan sag of Jiyang depression and its quantified influence on porous development and find favorable reservoirs, casting slices, scan electronic microscope and X-ray diffraction are used to study the relevant data. The results indicate that compactness, cementation, dissolution and metasomatism occurred in the clastic rock reservoir of Es4~s in Bonan sag. Influenced by alkali fluid from early–stage gypsum and organic acid from latestage hydrocarbon source rock, the gypsum reservoir experienced the alkali and acid diagenetic environment. Controlled by the diagenetic environment, there were mainly cementing pores in the clastic rock reservoir in the early diagenesis and dissolving pores occurred in the middle diagenesis. Based on a large amount of analytic and testing data about different depths and horizons, the quantitative characterization method of pore development is established for the time being. The clastic rock reservoir in the low-level system domain, with development of secondary pores, is distributed in the southern and northern delta frontal area and eastern fan delta plain of Bonan sag, while the clasitc rock reservoir with development of primary pores is distributed on sandstone beach bar. The clastic rock reservoir in the high-level system domain, with development of secondary pores, is distributed in the end of the northern near-bank underwater fan and southern fan delta plain of Bonan sag, while the clastic rock reservoir with development of primary pores is distributed in the frontal area of fan delta.