大孔道识别特征及形成机理研究——以胡12块油田沙三中段为例

大孔道是疏松砂岩油藏长期注水冲刷形成的次生高渗条带,极易造成注水低效循环。大孔道的形成严重影响了油田可采油的动用程度,而且增加了开发成本。因此必须加强对大孔道的识别及其形成机理的研究。以胡12块油田为例,通过对大孔道在吸水剖面、电性、静态等方面的特征分析,进而分析了大孔道的形成机制。胡12块油田大孔道的形成受储层的岩石学特征和成岩程演化度控制。成分成熟度高,填隙物含量少,碳酸盐胶结物少,成岩演化程度低,压实作用中等-弱的储层在后期长时间大规模注水加剧了大孔道的形成发育,是形成大孔道的直接原因。

Characteristics and Formation Mechanism of Large Pores, with the Middle Part of Shahejie Formation in the Hu12 Block Oilfield as an Example

Large pores widely spread in water flooding field,which make the circulation of water flooding very inefficient,and will greatly affect flooding effectiveness.Once large pores come into being,the water which was pumped into reservoir would hardly circulate,which not only affects the extent of petroleum that can be extracted,but also increases the cost of exploitation.So it is important to study the mechanism of their formation and how to identify them.This paper, with the Hu12 block oilfield as an example,studies the large pore characteristics in the injection profile,electrical properties and static state features,and then the formation mechanism of large pores.The formation of large pores is controlled by the reservoir rock characteristics and the evolution of diagenesis.Because of the large- scale water injection,the reservoir of high compositional maturity,with less matrix materials,less carbonate cement,and low level of diagenetic evolution and of middle-weak compaction degree,will directly induce the formation of large pores.