俄罗斯萨哈林3号V区块油气成藏条件及勘探潜力

Petroleum Accumulation Conditions and Exploration Potential of Block V of Sakhalin Project 3 in Russia

俄罗斯萨哈林3号V区块位于东萨哈林-鄂霍茨克盆地中南部,是中俄第一个油气勘探合作项目,主要勘探层系中新统发育海相三角洲沉积体系,沉积相以三角洲前缘、前三角洲以及浅海相为主,构造演化主要经历了晚白垩世-古近纪的裂谷期、渐新世中晚期-上新世早期的转换拉伸期和早上新世以后-近代的转换拉伸期3个阶段,形成了近南北走向、东西分带的"两隆三凹"的构造格局。烃源岩以达耶-胡林组硅质页岩、威宁组和奥科贝凯组暗色泥岩为主,有机质丰度高,生烃能力强。中新统两套储盖组合为油气的聚集和保存提供了有利条件。圈闭类型以断层控制的背斜和断背斜为主。研究表明,油气的生成、运移、储盖组合、圈闭形成、保存条件等成藏配置关系合理,油气主要富集于两个构造带上,分别是维尼背斜构造带和南阿雅什构造带。

Block V, located in the south-central of East Sakhalin-Okhotsk basin in Russia, has one major Eocene deltaic sedimentary systems. The main sedimentary facies include delta front, prodelta plain and shallow marine facies. Block V experienced three main tectonic evolution phases including the rifting, transformation tensile, and inversion. The tectonic framework of the Block V is characterized by NS-trending and EW-zoning ＂two uplifts and three depressions＂. The quality marine source rocks in Block V are dominated by the Dae-Khurye formation siliceous shale in Oligocene, Uyni-Dagi formation dark shale in Lower Miocene and Okobykai-Nutovian Forma- tion dark shale in Middle Miocene. They feature in high organic abundance and strong hydrocarbon potential. Moreover, two reservoir-seal cap combinations in Miocene provide favorable conditions for effective hydrocar- bon accumulation and preservation. The main trap style in Block V is anticline trap controlled by faults. Study of thermal evolution of source rocks indicates that the timing of hydrocarbon generation, migration, trap formation and reservoir--seal cap combination is rational. The potential plays of Block V mainly occur in two structural belts including Veni anticline belt and South-Ayash anticline belt.