不同沉积环境形成的储层成岩差异性研究——以东营凹陷王家岗地区红层与博兴洼陷灰层滩坝为例

Study on the Differences of Diagenetic Evolution under Different Sedimentary Environment:Take an example of the Red-beds of Wangjiagang,Dongying Sag and Oligocene Gray-beds Beach-bar of Boxing Sag

为了分析原始沉积环境对成岩作用的控制,凸显红层储层成岩作用的特殊性,综合运用薄片鉴定、扫描电镜观察、岩心常规分析、全岩矿物X-射线衍射等多种分析化验资料,对王家岗地区冲积平原红层砂体和博兴洼陷灰层滩坝砂岩进行成岩差异对比研究,定性剖析了2类砂体成岩作用特征,定量表征了2类砂体成岩产物、成岩孔隙演化过程。结果表明:灰层滩坝储层中以晚期含铁类碳酸盐胶结物为主、压实作用较强、溶蚀作用强烈;红层储层中以早期碳酸盐胶结物为主、压实作用较弱、溶蚀作用较弱。由于2类砂体经历了不同强度的成岩作用,导致储层成岩孔隙演化过程、孔隙类型差异性明显,红层储层以原生孔隙为主,滩坝砂岩储层以次生孔隙为主。最终对比分析认为2类砂体形成时的原始沉积环境不仅控制了早期成岩产物类型以及数量,并进一步影响中晚期成岩事件的发生。

To analyze the controlling influence of original sedimentary environment on diagenesis,and high- light the distinctiveness of the diagenesis of the red-bed reservoir, based on various analyses such as thin section identification, scanning electron microscope, core analysis, X-ray diffraction mineral analysis, etc. , alluvial plain of Wangjiagang and beach-bar of Boxing were selected for a comparative research between red-bed sandstone and grey-bed sandstone. The paper qualitatively analyzed the diagenetic characteristics and quantitatively calculated the diagenetic products, evolution process of diagenetic porosity with two types of sandbody. The results show that, grey-bed beach sandstones have characteristics of late ferrous- bearing carbonate cements, strong compaction, strong denudation;Red-bed reservoirs have characteristics of early carbonate cementation,weak compaction, and weak denudation. The two kinds of sandbodies experi- enced diagenesis of different intensity, resulting in the obvious difference between the diagenetic porosity e- volution and pore types of reservoir, red-bed reservoir is mainly primary pore,reservoir of beach-bar sand- stone is dominated hy secondary pores.