一种识别储层非均质性的双示踪剂方法

根据非均质多孔介质渗流与示踪剂迁移理论,提出一种识别储层非均质性的双示踪剂方法,通过构建考虑层间绕流的非均质单管模型,对双示踪剂方法进行试验验证。该方法利用两种扩散系数存在明显差别的示踪剂(离子型化学示踪剂溴化钾KBr和颗粒型荧光标记示踪剂荧光碳纳米颗粒Cdot)分别反映非均质多孔介质的总孔隙体积和非均质多孔介质内流动区的孔隙体积,识别储层非均质性和评价注入水的波及状况。结果表明:均质条件下KBr和Cdot的穿透曲线基本重合,而非均质条件下KBr和Cdot的穿透曲线产生分离,且KBr和Cdot在多孔介质中的流体置换率或改变率fv值相差较大;在一定的注入速率条件下,通过分析KBr和Cdot的产出规律及其fv值的变化规律,可识别储层非均质性和评价注入水的波及状况,验证了双示踪剂方法的可行性和有效性。

A dual-tracer method for assessment of reservoir heterogeneity

A dual-tracer method for the assessment of reservoir heterogeneity was proposed in this study based on the theory of fluid flow and tracer transport in heterogeneous porous media. Experiments were conducted using a single tube packed with sands simulating heterogeneous layers in order to validate the method. An ionic chemical tracer (KBr) and a fluorescent nano-particle tracer (Cdot) with different diffusion coefficient were used to indicate the total pore volume and flowing pore volume of the heterogeneous porous media, and thus to identify the reservoirs heterogeneity and to evaluate the water flooding effect. The results show that the breakthrough curves of KBr and Cdot under homogeneous conditions are almost coincident with each other, while obvious difference between the breakthrough curves can be observed under heterogeneous conditions. There is a significant difference for the fluid replacement or change rate (the f_v value) in porous media between KBr and Cdot tracers, which can be used to identify the reservoirs heterogeneity by analyzing the output of KBr and Cdot and the variation of their f_v values at a certain injection rate when considering the crossflow characteristics between the heterogeneous layers. These results can validate the feasibility and effectiveness of the dual-tracer method.