碳酸盐岩古暗河油藏是由深部暗河、浅层暗河以及高角度裂缝共同组成的缝洞储集体,且以大尺度溶洞为储集空间,为塔河油田三大主要油藏类型之一。以TK440井区剩余油的认识和挖潜为例,通过缝洞结构的精细刻画、生产动态综合分析和水淹特征的系统梳理,总结了古暗河油藏剩余油分布的4种模式和可行性挖潜手段。研究认为：采用大泵排液实现井间提液引流,改变压力场分布,可启动浅层暗河未动用剩余油;逆水侵方向水驱,利用暗河高度差可有效地动用深部暗河井间高部位剩余油;基于油、气密度差异,采用重力分异原理形成人工气顶纵向置换,可高效挖潜单井井周阁楼油和暗河盲端剩余油。最终形成了不同剩余油分布模式下的可行挖潜手段,现场实施取得了较好的效果,进一步验证了古暗河油藏剩余油分布模式的可靠性和挖潜对策的有效性,可为同类型油藏剩余油的有效挖潜提供技术支撑。

Carbonate palaeo-subterranean river reservoirs are fractured-vuggy reservoirs composed of deep main rivers, shallow branch and high-angle fractures, with large-scale karst caves as the storage space, belonging to the three main reservoir types in Tahe oilfield. Taking the knowledge of remaining oil and tapping potential in TK440 well area as an example, through the fine characterization of the fracture-cave structure, comprehensive analysis of production dynamics, and systematic analysis of water flooding characteristics, four patterns of remaining oil distribution and feasible potential tapping methods are summarized..The results show that: using large pump for the well drainage and changing the distribution of pressure field, can excavated the remaining oil in shallow underground river. Water flooding in reverse direction, with the advantage of the height difference, can effectively excavate the remaining oil in deep underground river. Based on the difference of oil and gas density, the vertical displacement of artificial gas cap formed of the principle of gravity differentiation can effectively recovery the attic oil around single well and the remaining oil in the blind side of underground rivers. Feasible means of potential tapping under different distribution patterns of remaining oil has been found, and good results have been achieved in the field implementation, which further validates the reliability of remaining oil distribution patterns and the effectiveness of tapping the potential of the reservoir, and provides technical support for the effectively potential tapping of remaining oil in the similar reservoir.