斜坡带小型岩性油藏滚动评价——以吐哈盆地台北凹陷葡萄沟—葡北构造带为例

斜坡背景上叠置了局部背斜或鼻状凸起岩性圈闭,有利于截获从斜坡低部位运移上来的油气而聚集成藏。通常在凹陷的鼻状凸起或横梁斜坡,大型三角洲砂体较为发育,油气聚集受鼻状凸起或脊状构造控制,低幅度构造圈闭、岩性圈闭和构造-岩性圈闭为油气聚集的主要场所,储集层砂体、沟通断裂和不整合面为油气输导的主要通道。葡萄沟—葡北构造带发育的岩性油藏远离生油凹陷区,具有构造隐蔽、单井控制储量小、圈闭落实难度大等特点,正确认识各种成藏要素及其配置关系,对该区岩性油藏的滚动评价具有重要意义。该区储集层横向变化快,非均质性强,油水关系复杂,制约了油田高效开发。通过对构造、油藏及储集层发育特征进行综合分析,总结了研究区油气聚集规律,建立了研究区储集层沉积及油气成藏模式。

Rolling Evaluation on Small Lithologic Reservoirs in Slope Zones: A Case Study on Putaogou-Pubei Structural Zone of Taibei Sag in Turpan-Hami Basin

The trap with lithologic reservoirs in the structural slope zone superimposes local anticlines or nose-like swells on the slope, which is helpful in blocking oil and gas migrating from the lower part of the slope and making them accumulate in the reservoirs. Usually in nose-like swells or cross-beam slopes in a sag, large delta sand bodies are relatively developed, oil and gas accumulation are controlled by the nose-like swell or ridge-like structure. Low-relief structural traps, lithologic traps and structural-lithologic traps are primary places for oil and gas accumulation. Sandstone reservoirs, connected faults and unconformities are primary channels for oil and gas migration. The lithologic reservoirs developed in the Putaogou-Pubei structural zone are far away from the oil-generating sag and are characterized by subtle structure, small amount of well controlling reserves and difficulties in trap identification. To fully understand various accumulation factors and their relationships is of great significance for rolling evaluation on the lithologic reservoirs in the study area. The reservoirs show rapid lateral changes, strong heterogeneity, and complex OWC, which restrict efficient oilfield development. After comprehensive analysis on the structures, oil reservoirs and reservoir physical properties, the laws of hydrocarbon accumulation are summarized, and the hydrocarbon accumulation model is established for the study area.