两北地区三叠系深部碎屑岩储层特征及控制因素

Reservoir characteristics and controlling factors of the Triassic clastic rocks in the Liangbei region, Xinjiang

关键词:  储层特征  控制因素  碎屑岩  三叠纪

Key words:  reservoir characteristics  controlling factor  clastic rock  Triassic

摘要:

运用钻井岩心、铸体薄片、扫描电镜等资料,研究了两北地区三叠系深部碎屑岩储层的特征及储层发育的控制因素。研究表明,三叠系主要岩石类型为长石岩屑砂岩和岩屑砂岩,具有成分成熟度低和结构成熟度中等的岩石学特征。储集空间以粒间溶孔为主,其次为裂缝,属于中孔、中-低渗型储层。在后期成岩作用的改造下,储集性能明显变好。分流河道和河口坝砂岩具有良好储层物性,方解石、长石、岩屑在大气水和有机酸的溶蚀作用下,产生大量的溶蚀孔隙,改善了储集性能,溶蚀作用是形成优质深部碎屑岩储层的关键因素。

Abstract:

The present paper deals, on the basis of cores, cast sections and scanning electronic microscopic examination, with the reservoir characteristics and controlling factors of the Triassic clastic rocks in the Liangbei region, Xinjiang. The rock types in the Triassic clastic rocks mostly consist of feldspathic litharenite and lithic sandstone which are characterized by low compositional maturity, moderate textural maturity, abundant intergranular solution openings and minor fissures suggesting the moderate-porosity, and moderate-to lowpermeability reservoir rocks. The controlling factors of the reservoir development include sedimentary facies and diagenesis. The distributary channel and channel mouth bar sandstones are interpreted to have good porosity and permeability. Affected by meteoric water and organic acids, the dissolution of calcite, feldspar, lithclasts, quartz and matrix result in the generation of abundant solution openings, and thus are believed to be the key factors for the formation of excellent clastic reservoir rocks in the study area.