塔河油田南部志留系油气成藏主控因素与成藏模式

Main controlling factors and models of Silurian hydrocarbon accumulation in the southern Tahe Oilfield

塔河油田南部志留系储层主要发育于柯坪塔格组上段、中段和下段,与上覆泥岩组成3套储盖组合,其油气藏类型可分为构造-地层复合油气藏、地层不整合遮挡油气藏、岩性油气藏以及地层超覆油气藏。岩心微观观察、原油地化特征、自生伊利石K-Ar测年及流体包裹体均一温度研究表明,塔河油田南部志留系以多期充注、多期成藏为特征,加里东晚期—海西期为稠油、沥青主要形成期,可动油成藏期为喜山期。油气成藏主要受古构造及其演化、断裂-砂体-不整合面组成的输导体系以及优质储层的控制,油气成藏模式可概括为"多期充注、多期调整、喜山定型、储层控富、输导控藏"。塔河油田南部志留系资源潜力可观,志留系剥蚀尖灭线附近有利于成藏。

Silurian reservoirs in the southern Tahe Oilfield develop mainly in the upper,middle and lower members of the Kepingtag Formation and constitute 3 suits of reservoir-cap rock assembles together with the overlaying shale,where types of hydrocarbon accumulation include structural-stratigraphic,unconformity barrier,lithologic and overlap reservoirs.Studies on the micro-examination of cores,geochemical characteristics of crude oils,the authigenic illite K-Ar dating and the homogenization temperature of fluid inclusions indicated that Silurian hydrocarbon reservoirs were characterized by multiphase charging and multistage accumulation.Bitumens and heavy oils were formed mainly in Late Caledonian-Hercynian,while the present movable oil accumulated in Late Himalayan.The formation and distribution of hydrocarbon pools are controlled by many factors,such as palaeo-structure and its evolution,a transport system composed of faults,sand bodies and unconformities,and high-quality reservoirs.The hydrocarbon accumulation model was characterized by ＂multiphase charging,multistage adjustment,formalization in Himalayan,hydrocarbon enrichment controlled by reservoirs and accumulation controlled by transport＂.The potential of Silurian hydrocarbon resources is considerably great in the southern Tahe Oilfield and strata adjacent to the Silurian erosional pinch-out line are favorable for hydrocarbon accumulation.