塔里木盆地北部寒武──奥陶系碳酸盐岩的深部溶蚀作用

Deep dissolution of Cambrian-Odovician carbonates in the Northern Tarin Basin

塔里木盆地寒武－奥陶系碳酸盐岩深部溶蚀的主要特征是非组构选择性、多沿缝合线及裂隙发育。深部溶蚀的主要依据是，溶蚀了晚期成岩组构或溶蚀沿晚期成岩组构（缝合线及裂隙）进行，其中充填烃类或其他晚期成岩矿物，同时不仅在地腹区，而且在早期连续沉降（∈－Ｐ１）、后期抬升成陆（Ｐ２－Ｑ）的柯坪露头区具此特征。本区深部溶蚀作用主要与生油岩有机质热成熟过程中产生的二氧化碳所形成的酸性水有关。

Cambrian-Odovician carbonate rocks are one of the main reservoirs in the Northern Tarim Basin. Deep dissolution has important role in the formation of effective porosity of the reservoir rocks. The main characterstics of deep dissolution in the region are non-fabric selective dissolution, and dissolution developed mainly along stylolites and fractures. The main evidence for deep dissolution are: 1.The dissolution of late stage diagenetic fabrics or the dissolution developed along late stage diagenetic fabrics (such as stylotes and fractures) ;2. The dissolution pores filled with hydrocarbon or other late stage diagenetic minerals;3. NOt only the covered region, but also the Kepin outcrop region (continuous depression in early stage -from cambrian to early Permian, uplift in late stage - from late Permian to present) have above characteristics.Based on preliminary analysis, this paper considers that the deep dissolution is mainly related to CO2bearing acid water produced by organic matter thermal evolution of source rock.