摘要
为揭示塔里木盆地石炭系A油藏水驱开发末期剩余油潜力，综合利用水驱过程的CT扫描检测、高温高压条件下水驱后含油薄片观察和高温高压微观刻蚀模型水驱油实验3种实验手段，揭示了西部某A油藏石炭系底部的海相储层剩余油形成机理，明确了水驱开发末期的剩余油类型及潜力分布，并提出了三次采油建议。研究结果表明：受注入水剥离作用、突进分隔作用、绕流作用和捕获作用影响，剩余油分布呈现整体分散、局部斑块状富集的特点；剩余油类型可划分为孔喉充填型、孔内半充填型、孔壁油膜型、分散油滴型、喉道滞留型和角隅型6种。其中，水驱中水洗区域的孔内半充填型和分散油滴型剩余油，呈分散状，占65.4%，潜力最大；水驱未波及区域内的孔喉充填型剩余油，呈斑块状富集，占21.0%，潜力次之。建议用表面活性剂驱或天然气驱进行挖潜。
Abstract
Three experiments including CT scanning during flooding, post-flooding observation of oil-bearing thin sections under high temperature and pressure, and water flooding under high temperature and pressure by microscopic etching model, are utilized to disclose the formation mechanisms of remaining oil, their types and distribution at the end of water flooding in the marine A reservoir at the bottom of the Carboniferous system, western Tarim Basin, and strategies of enhanced oil recovery (EOR) are proposed. The results show that the remaining oil is in dispersed distribution as a whole and features patchy enrichment, due to the stripping, fingering, by-passing and capturing effects; accordingly, the remaining oil can be categorized into 6 types including pore throat filling, pore half-filling, oil film on pore walls, dispersed oil droplets, throat retention and pore corner retention. Among others, the pore half-filling type and dispersed oil droplet type in the flooded areas, account for 65.4% of the total, the highest in production potential, followed by pore throat filling type in non-swept zones, which features patchy enrichment, accounting for 21%, with lower production potential. In this regard, the surfactant or gas flooding is suggested to enhance oil recovery.
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