大安北地区扶杨油层储层致密化因素研究

Study on Densification Factors of Fuyang Reservoir in Daanbei Area

大安北地区扶杨油层储层为特低—超低渗、低—特低孔储层,为了更好地研究其储层特征,利用铸体薄片、扫描电镜、岩心和测井等各种资料以及恒速压汞等技术,对储层致密化因素进行分析。研究结果表明:研究区主要岩石类型为长石质岩屑砂岩,成分成熟度较低。孔隙类型以原生粒间孔为主,其次为粒间溶孔,喉道类型以细—微细喉不均匀型微喉道和片状喉道为主。储层主要为三角洲平原分流河道及三角洲前缘水下分流河道砂体;砂岩厚度一般较薄,其内又常被多个非储层段分隔。储层特征受沉积作用和成岩作用综合影响,水下分流河道是形成有利储层的主要相带。碎屑颗粒中长石、岩屑等不稳定组分及杂基含量较高,压实成岩作用使原生孔隙大大降低,而后期次生孔隙不发育,导致储层致密化。

Results of predecessors＇ research show that the sand in Daanbei area belongs to very low - ultra - low permea- bility, low- very low hole. To better study the reservoir characteristics, analysis of reservoir densification factors be- comes extraordinary necessary. Through rock thin section identification, scanning electron microscope, X -ray diffrac- tion analysis, core and logging data, etc. this paper systematically studies the densification factors of Fuyang reservoir in Daanbei area with the technology of constant -rate intruding mercury. The results show that the main rock types of the study area are feldspathic litharenite sandstones with low maturity for component. Primary intergranular pore is the main pore type, and the second is intergranular dissolved pore, and fine -fine heterogeneous micro throat and flake throat have absolute predominance in the throat types. The reservoirs in the study area are mainly delta plain distributary chan- nel sand body and delta front underwater distributary channel sand body. The sand body has small individual layer thick- ness, divided by several non reservoir sections. The reservoir characteristics are controlled by sedimentation and diagen- esis, favorable reservoir is mainly distributed in the central channel. The unstable components like feldspar and debris and the mixed base content clastic particles are high, compaction diagenesis makes primary pore greatly reduced, togeth- er with the undevelopment of late secondary pore lead to reservoir densification.