塔里木盆地碳酸盐岩大油气区特征与主控因素

Characteristics and controlling factors of the large carbonate petroleum province in the Tarim Basin,NW China

成藏地质条件与典型油气藏综合研究表明,塔里木盆地以奥陶系碳酸盐岩非构造油气藏群为主体,形成大面积复合连片的环满加尔碳酸盐岩大油气区。碳酸盐岩大油气区多类型岩性-地层油气藏纵向叠置、横向连片,沿古隆起斜坡广泛分布;储集层非均质强、大面积展布,沿不同级别层序界面近层状分布;油气相态与物性多样,呈"下气上油"的分布特性;碳酸盐岩油气水产出变化大、递减快,20%～30%的高效井支撑70%以上油气产量。稳定的古隆起、广泛发育的非均质储集层与多期成藏等3大要素的配置控制了塔里木盆地碳酸盐岩大油气区的形成与分布。邻近烃源灶的古隆起长期稳定发育,是大油气区储集层发育的地质基础与油气运聚的指向区;储集层特性造成不规则的缝洞型油气藏群大面积断续分布,油气的富集受控于储集层,储集层是大油气区形成与富集的关键;碳酸盐岩多期油气充注与调整具有普遍性,造成含油气的广泛性与油气性质的多样性。

A comprehensive analysis of hydrocarbon accumulation conditions and typical reservoirs reveals that a large carbonate petroleum province is formed around the Manjiaer depression in the Tarim Basin and it consists of Ordovician non-structural petroleum reservoirs.Multi-type litho-stratigraphic reservoirs are stacked vertically and connected laterally along the paleo-uplift slopes,with a large area.Reservoirs are intensively heterogeneous,extensively developed and distributed in layers along the top of different-scale sequence boundaries.Hydrocarbon phase and physical properties are diverse and the distribution pattern is ＂lower gas,upper oil＂.The oil/gas/water output alters greatly and declines quickly,and 20%–30% high-efficiency wells provide more than 70% of the production.The stable paleo-uplift,widely developed heterogeneous reservoir,multi-stages of hydrocarbon accumulation are the basic forming and distribution conditions of the large carbonate petroleum province.The paleo-uplift near the hydrocarbon kitchen is developed stably and controls the reservoir distribution,migration and accumulation.The special characteristics of carbonate reservoirs result in the wide and discontinuous distribution of irregular fracture-cavity hydrocarbon pools.The enrichment of hydrocarbon is controlled by reservoirs,which are the main controlling factors of the formation and distribution of the large petroleum province.Multi-stages of accumulation and adjustment of hydrocarbon are universal and result in the wide distribution and diversity of oil and gas.