Residual or capillary trapping is one of the key trapping mechanisms for geological storage of CO₂. Yet, very few studies so far have attempted to estimate the residual trapping and the related characteristic parameter, residual saturation, in situ. At Heletz, a pilot CO₂ injection site in Israel a single-well push-pull experiment to estimate residual gas saturation in situ was carried out during autumn 2016. The main characterization method was hydraulic withdrawal tests. The residually trapped zone was also created by means of fluid withdrawal, by first injecting CO₂ and then withdrawing fluids leaving behind the immobile residual CO₂. This paper presents the first model interpretation of the experimental results. Numerical modeling with TOUGH2/ECO2N was carried out to model the entire test sequence, the focus being in matching the collected pressure, temperature and flow data as well as observations of gas content in the borehole. The experimental results could be well fitted with the model that also is in agreement with previously collected petro-physical data. The results indicate a somewhat lower residual gas saturation than that measured in the laboratory, the estimated maximum residual saturation from the field experiment being 10% and the corresponding value from the core 20%. The results also indicate that most of the CO₂ entered the upper reservoir layer, thus actually giving an estimate of the effective residual trapping in that layer. Overall, pressure response gave a clear signal and was an effective method in getting an estimate of the effective residual trapping in the interval tested.

残留或毛细管捕集是CO ₂地质封存的关键捕集机制之一。但是，到目前为止，很少有研究尝试就地估计残留陷井和相关的特征参数，即残留饱和度。在以色列的Heletz CO ₂试点注入场，于2016年秋季进行了单井推挽实验，以估计现场残留的天然气饱和度。主要表征方法是水力抽采测试。残留的捕获区域也通过流体抽出产生，方法是先注入CO ₂然后再抽出留下固定的残留CO _2的流体。本文介绍了实验结果的第一个模型解释。用TOUGH2 / ECO2N进行了数值建模，以模拟整个测试程序，重点是匹配收集的压力，温度和流量数据以及对井眼中气体含量的观测。实验结果可以很好地拟合该模型，该模型也与先前收集的石油物理数据一致。结果表明残留气体饱和度比实验室测量的要低一些，现场试验估计的最大残留饱和度为10％，岩心的相应值为20％。结果还表明，大多数CO ₂进入上部储层，因此实际上给出了该层中有效残留捕集的估算值。总体而言，压力响应给出了清晰的信号，并且是获得对测试间隔中有效残留捕集量的估计的有效方法。