低渗透储层成岩作用定量表征与成岩储集相——以吉林新立油田泉头组三、四段为例

Quantitative characterization of diagenesis and diagenetic reservoir facies of the low permeability reservoirs:An example from the 3rd and 4th members of the Quantou Formation in the Xinli Oil Field, Jilin

关键词:  新立油田  下白垩统  低渗透储层  成岩定量表征  成岩储集相  松辽盆地

Key words:  Xinli Oil Field  Lower Cretaceous  Low permeability reservoir  quantitative characterization  of diagenesis  diagenetic reservoir facies  Songliao Basin

摘要:

作者采用铸体薄片、阴极发光、扫描电镜等手段,统计了新立油田泉头组三、四段储层的视压实率和视胶结率,对成岩作用强度进行了定量表征。引入了成岩系数和成岩储集相的概念,并按照成岩系数大小,将储层划分为4种成岩储集相,即强溶蚀次生孔隙成岩储集相(A相),中等压实-弱、中胶结混合孔隙成岩储集相(B相),强压实-弱、中胶结混合孔隙成岩储集相(C相)和碳酸盐强胶结成岩储集相(D相)。其中以A相最有利于油气聚集,B相次之,C相较差,D相最差。分析了各类成岩储集相特征和演化,认为晚成岩A亚期的酸性水溶蚀作用形成次生孔隙是改善储层物性的关键因素。

Abstract:

The quantitative characterization of diagenesis and diagenetic reservoir facies has been made for three types of diagenesis in the low permeability reservoirs in the 3rd and 4th members of the Quantou Formation in the Xinli Oil Field, Jilin by using the techniques of quantitative statistics of cast thin-section, cathodoluminescene and SEM. The intensity of each type of diagenesis is evaluated.The types of the diagenetic reservoir facies are summarized, on the basis of lithofacies, diagenesis types and intensity, reservoir properties, including:strongly corroded secondary porosity type (Facies A), moderately compacted and weakly to moderately cemented mixed porosity type (Facies B), strongly compacted and weakly to moderately cemented mixed porosity type (Facies C), and strongly carbonate-cemented type (Facies D). Facies A is most favourable for hydrocarbon accumulation, followed by Facies B and C. Facies D is worst. The examination of the characteristics and evolution of the above-mentioned diagenetic reservoir facies shows that the secondary pores generated by acidic formation water formed during the late diagenetic stage may be considered as the key factors for the improvement of the physical properties of the reservoirs in the study area.