Hosseini-Nasab S M, Zitha P L J
Delft University of Technology, Department of Geoscience & Engineering, Petroleum Engineering Group, Delft, Netherlands.
Energy Fuels. 2017 Oct 19;31(10):10525-10534. doi: 10.1021/acs.energyfuels.7b01535. Epub 2017 Aug 28.
Strong foam can be generated in porous media containing oil, resulting in incremental oil recovery; however, oil recovery factor is restricted. A large fraction of oil recovered by foam flooding forms an oil-in-water emulsion, so that costly methods may need to be used to separate the oil. Moreover, strong foam could create a large pressure gradient, which may cause fractures in the reservoir. This study presents a novel chemical-foam flooding process for enhanced oil recovery (EOR) from water-flooded reservoirs. The presented method involved the use of chemically designed foam to mobilize the remaining oil after water flooding and then to displace the mobilized oil to the production well. A blend of two anionic surfactant formulations was formulated for this method: (a) IOS, for achieving ultralow interfacial tension (IFT), and (b) AOS, for generating a strong foam. Experiments were performed using Bentheimer sandstone cores, where X-ray CT images were taken during foam generation to find the stability of the advancing front of foam propagation and to map the gas saturation for both the transient and the steady-state flow regimes. Then the proposed chemical-foam strategy for incremental oil recovery was tested through the coinjection of immiscible nitrogen gas and surfactant solutions with three different formulation properties in terms of IFT reduction and foaming strength capability. The discovered optimal formulation contains a foaming agent surfactant, a low IFT surfactant, and a cosolvent, which has a high foam stability and a considerably low IFT (1.6 × 10 mN/m). Coinjection resulted in higher oil recovery and much less MRF than the same process with only using a foaming agent. The oil displacement experiment revealed that coinjection of gas with a blend of surfactants, containing a cosolvent, can recover a significant amount of oil (33% OIIP) over water flooding with a larger amount of clean oil and less emulsion.
在含油多孔介质中可产生强泡沫，从而提高原油采收率；然而，采收率受到限制。泡沫驱采收的大部分原油形成水包油乳液，因此可能需要使用成本高昂的方法来分离原油。此外，强泡沫会产生较大的压力梯度，这可能导致储层产生裂缝。本研究提出了一种新型化学泡沫驱油工艺，用于提高水淹油藏的采收率。所提出的方法包括使用化学设计的泡沫来驱替水驱后剩余的原油，然后将被驱替的原油驱至生产井。为此方法配制了两种阴离子表面活性剂配方的混合物：(a) IOS，用于实现超低界面张力(IFT)；(b) AOS，用于产生强泡沫。使用本特海默砂岩岩心进行实验，在泡沫产生过程中拍摄X射线CT图像，以确定泡沫传播前沿的稳定性，并绘制瞬态和稳态流动状态下的气体饱和度图。然后，通过同时注入具有三种不同配方特性（IFT降低和发泡强度能力）的不混溶氮气和表面活性剂溶液，测试了所提出的提高原油采收率的化学泡沫策略。发现的最佳配方包含一种发泡剂表面活性剂、一种低IFT表面活性剂和一种助溶剂，其具有高泡沫稳定性和相当低的IFT(1.6×10 mN/m)。与仅使用发泡剂的相同过程相比，同时注入导致更高的采收率和更低的含水率。驱油实验表明，同时注入气体和含有助溶剂的表面活性剂混合物，与水驱相比，可以采出大量原油(33%原始地质储量)，产出的净油更多，乳液更少。
