基于传质扩散理论的高渗油藏窜流通道量化方法

海上高渗砂岩油藏胶结疏松，注入水冲刷作用对储层改造作用明显，其窜流通道在平面上呈“纺锤形”，垂向上有明显“贼层”特征。目前窜流通道的时间域、空间域连续量化方法存在数学模型和求解过程过于复杂的缺陷。考虑窜流通道平面、垂向特征，建立降维方法，将高渗油藏注采井间窜流通道三维物理模型变为平面和剖面两个二维物理模型的叠加；根据注入水在平面上纺锤形分布和注入化学剂浓度分布的相似性，及注水倍数、含水饱和度和渗透率变化倍数的单调相关性，提出了基于“饱和度差异”的“等效扩散系数”概念，建立了包含产出端含水率的平面数学模型；针对“贼层”是无效水循环主要通道的特征，定义了稀释倍数，实现了产出端含水率的解析求解，建立了窜流通道厚度、渗透率级差和等效扩散系数的快速量化方法。矿场算例应用结果显示，暴性水淹井和快速水淹井窜流通道厚度分别为0.04 m、0.38 m，渗透率级差分别为22、8，和示踪剂解释结果吻合；解释得到的等效扩散系数同时表征了储层微观非均质性和油水黏度比导致的指进程度及窜流通道波及面积的大小。

Quantitative method of channeling-path by diffusion theory in high permeability reservoir

As high permeability reservoir is interconnected poorly, it is usually thought that there is strong washing action when water fooding. The channeling-path generated from this action looks like spindle in plane and extreme heterogeneity in vertical. Therefore, it results in the current quantitative method and corresponding mathematical model are so complex that they are regularly solved with numerical approach, generally in which includes geological model establishment and discretization in time and space domain, rather than analytical method. Based on the new method proposed in this paper, the 3-D channeling-path physical model of channeling-path in interwell is equivalent with superposition between a horizontal model and vertical model respectively. Consequently, there is a new 3-D mathematical model which is the combination between a horizontal model with equivalent diffusion coeffcient which represents horizontal spindle shape, and a vertical model with dilution coeffcient which represents extreme vertical heterogeneity. Based on the above proper descending dimension simplifcation, the outlet water cut could be solved analytically. The proposed method has applied in channeling-path quantifcation of 3 wells by typical water cut curves characteristics matching. The obtained parameters, including channeling-path thickness ratio, heterogeneity coeffcient and equivalent diffusion coeffcient, reasonable agree with tracer interpretation results. Furthermore, the sensitivity analysis gives physical meaning of equivalent diffusion coeffcient that could characterize the effect of fnger advance in early term and sweep area in late term.