滨里海盆地肯基亚克地区中、下石炭统碳酸盐岩储层特征与成岩作用

利用岩心、岩矿薄片、扫描电镜、孔渗和地化等多种资料,对滨里海盆地肯基亚克地区A井取心段中、下石炭统碳酸盐岩岩石类型、储集空间和成岩作用进行了研究。研究揭示:中、下石炭统碳酸盐岩为纵向上非均质性强的开阔台地相颗粒灰岩和泥晶灰岩储层,可划分为以粒间溶孔-粒内溶孔为主的Ⅰ类好储层和以晶间孔-晶间溶孔为主的Ⅱ类中等或差储层。胶结作用和溶蚀作用是控制两类储层形成的主要成岩作用,前者主要包括正常海水叶片状-纤维状方解石胶结作用、埋藏期镶嵌状、粒状、半自形方解石胶结作用,后者主要包括大气淡水溶蚀作用和埋藏期溶蚀作用。其中,埋藏期溶蚀作用是形成Ⅰ类储层的关键,Ⅱ类储层则具胶结作用发育的特征。

Diagenesis and reservoir characteristics of the Lower-Middle Carboniferous carbonates in Kenkyak area, Pre-Caspian Basin

By using core,thin section,SEM,porosity,permeability and geochemical data,this paper studied rock types,reservoir spaces and diagenesis of the Lower-Middle Carboniferous carbonate rocks in the coring interval of well A in Kenkyak area,Pre-Caspian Basin.The Lower-Middle Carboniferous carbonate reservoirs are grainstones and micrites of open platform facies with strong vertical heterogeneity and can be divided into two types,ClassⅠand ClassⅡ.The Class I is high quality reservoir with intergranular dissolved pores and intragranular dissolved pore as the main pore types.In contrast,the ClassⅡis moderate to poor reservoirs with pores dominated by intercrystalline pores and intercrystalline dissolved pores.Cementation and dissolution are the main diagenesis processes controlling the two types of reservoirs.The cementation mainly includes bladed-fibrous calcite cementation in normal seawater diagenetic environment and mosaic-granular-subhedral calcite cementation in burial diagenetic environment.The dissolution includes meteoric dissolution and burial dissolution,with the latter being critical for the formation of classⅠreservoir.The cementation is well developed in the classⅡ reservoir.