川中大安寨段致密油储层储集特征研究

Reservoir Characteristics of the Tight Oil Reservoir of the Da'anzhai Member in Central Sichuan Basin,SW China

通过岩芯观察、铸体薄片鉴定、SEM扫描电镜等方法对川中地区下侏罗统大安寨段致密油储层储集空间特征进行研究,发现川中大安寨段致密油储层发育大量微裂缝,储集空间则以溶蚀孔洞、粒间溶孔、粒内溶孔、晶间微孔、有机质孔等次生孔隙为主,原生孔隙几乎均为微米—纳米级微孔。利用CT扫描技术建立大安寨段致密灰岩储层微观储集空间三维模型,发现该段致密灰岩基质内部存在大量能够赋存油气的储集空间,同时认为,大安寨段孔喉系统可大致分为孤立孔型和孔缝型两种。根据该段储集空间特征及孔缝配置关系将大安寨段储层分为孔隙型、孔缝型、裂缝型3类储层,其中,孔缝型储层分布较广,裂缝型储层初期产能最高,孔隙型储层具有长期稳产的特点,具有开发潜力。

Through methods such as core observation, cast thin section identification, and scanning electron microscopy, the reservoir space characteristics of the tight oil reservoir of the Lower Jurassic Daanzhai Member in the Middle Sichuan region were studied. It is found that there are numerous microfractures in the tight oil reservoir, and the reservoir space mainly compris- es of secondary pores, such as dissolution pores, intergranular dissolution pores, intragranular dissolution pores, intercrystalline micropores, and organic pores. Almost all primary pores are micro/nano pores. A three-dimensional microscopic model of the reservoir space in the dense limestone of the Daanzhai Member was established using computed tomography （CT） scan- ning technology. Plenty of reservoir space that can store oil and gas is noted inside the dense limestone matrix. Further, it is believed that, in general, the pore-throat system of the Daanzhai Member can be classified into two types： isolated-porous and fractured-porous. According to the reservoir space characteristics and pore/fracture configuration relationship, the reser- voir of the Daanzhai Member is divided into three types： porous, fractured-porous, and fractured reservoirs. Among them, the fractured-porous reservoirs are more widely distributed. The early-stage productivity of the fractured reservoirs is the highest. The porous reservoirs are characterized by their long-term steady productivity and have good potential for exploitation.