塔河油田缝洞型碳酸盐岩油藏剩余油分布特征

DISTRIBUTION CHARACTERISTICS OF THE REMAINED OIL IN TAHE FRACTURED-CAVE CARBONATE OIL RESERVOIRS

塔河油田缝洞型碳酸盐岩油藏储集体主要由大型溶洞、裂缝及溶孔组成，其中大型溶洞是主要的储油与产油空间。大型溶洞内流体流动为自由流，与砂岩孔隙中的流体流动具有较大的差别。溶洞内油水两相流时不存在固体介质对流体流动阻力，油水间的重力作用表现突出，油水间重力分异迅速，油水界面清晰。溶洞之间由裂缝相连通，耦合后流动更加复杂，裂缝内流体流动表现为高速达西流动，底水沿裂缝水窜速度快。结合生产动态与数值模拟研究，揭示了5种缝洞型油藏复杂介质剩余油分布类型，即井旁溶洞剩余油、溶洞顶部剩余油、缝洞剩余油、下层溶洞剩余油和裂缝上部剩余油等，为塔河油田开发调整及提高采收率提供了地质基础。

Fractured-cave carbonate reservoirs of Tahe Oilfield are mainly composed of vast karst caves, fractures and dissolved rugs, and the former is the principal space to reserve and produce oil. The liquid flow in the above kind of reservoir belongs to free one, which possesses much sharper contrast with the flow in sandstone pores and fractures. There is not any flow resistance to flow liquids for the solid media in the oil and water two-phase flow in the karst caves, the gravity between the oil and water displays well and the their gravity differentiation is fast, and moreover the interface between them is pretty clear. The caves are connected by the fractures, after the integration, the flow becomes rather complicated： the liquid flow within the fractures is characterized by high-speed Darcy flow, the water crossing of the bottom water along the fractures is rather swift. Combining with the production perform- ances and the researches of the numerical simulation, five kinds of remained oil distribution are disclosed for the fractured-cave oil reservoirs with complex media： karst-cave remained ~oil nearby the well, the oil remained on the top of the karst caves, fractured cave remained oil, the oil remained in the lower karst caves and the oil remained on the upper part of the fractures. All the achievements obtained above have provided the geological foundation for the development adjustment and recovery enhancement of Tahe Oilfield.