微生物碳酸盐岩储层特征及主控因素——以塔里木盆地阿克苏地区下寒武统肖尔布拉克组上段为例

Characteristics and main controlling factors of microbial carbonate reservoir: a case study of upper member of Lower Cambrian Xiaoerbulake Formation in Akesu area, Tarim Basin

通过野外露头观察,室内薄片鉴定以及物性分析,详细分析了塔里木盆地阿克苏地区下寒武统肖尔布拉克组上段微生物碳酸盐岩储层特征及其主控因素。研究认为肖上段主要发育微生物礁和微生物层这两种巨观构造,其中前者包括凝块石礁和表附菌礁,后者包括凝块石层、表附菌层、叠层石层、层纹石层和泡沫绵层。微生物碳酸盐岩具有多种与微生物相关的孔隙,同时也具有非微生物储集空间。凝块石礁和泡沫绵层是最有利的微生物储层,表明不同类型的微生物岩储层具有较大的物性差别。于提希剖面和苏盖特布拉克剖面对比发现,相同类型的微生物岩储层亦具有较大的差异,这是因为微生物碳酸盐岩储层的形成与保存受控于沉积相分布、古地貌特征、成岩作用以及微生物结构的缘故。

Through observation of field outcrops, identification of thin section and physical property analysis, the characteristics and main controlling factors of microbial carbonate reservoir in the upper member of Lower Cambrian Xiaoerbulake Formation in Akesu area, Tarim Basin have been examined in detail. It is concluded through the study that two kinds of megascopic structures are developed, including microbial reef and microbial layer in this member; the former includes thrombolite reef and Epiphyton reef, and the later contains thrombolite, Epiphyton, stromatolite, laminite and spongiostromata biostromes. The microbial carbonate contains a variety of pores related to microbes and also non-microbial reservoir space. Thrombolite reef and spongiostromata biostrome are the most favorable microbial reservoirs, indicating different types of microbialite reservoirs differ widely in physical properties. The comparison of Yutixi profile with Sugetbulak profile shows that even the same type of microbialite reservoirs differ considerably. This is because the formation and preservation of microbial carbonate reservoirs are affected by the distribution of sedimentary facies, ancient landform features, diageneses and microbial structures.