Panthi Krishna, Mohanty Kishore K
Hildebrand Department of Petroleum and Geosystems Engineering, The University of Texas at Austin, Austin, TX, United States.
Front Chem. 2024 Aug 7;12:1408115. doi: 10.3389/fchem.2024.1408115. eCollection 2024.
The residual oil left behind after water flooding in petroleum reservoirs can be mobilized by surfactant formulations that yield ultralow interfacial tension (IFT) with oil. However, finding ultralow IFT surfactant formulations is difficult for high-temperature, off-shore, carbonate reservoirs. These reservoirs are often water-flooded with seawater (with a lot of divalent ions), which is often incompatible with many surfactants at high temperatures. The goal of this research is to develop a surfactant formulation for an off-shore carbonate reservoir at 100°C previously flooded by seawater. Surfactant-oil-brine phase behavior was studied for formulations, starting from a single surfactant to mixtures of surfactants and a co-solvent. Mixtures of three surfactants and one co-solvent were needed to produce ultralow IFT formulations for the oil of interest. The surfactant system with polymer mobility control was tested in crushed reservoir rock packs. The cumulative oil recovery was >99% for the surfactant-polymer (SP) flood with an optimal salinity gradient. The constant salinity SP floods with seawater increased oil recovery significantly beyond the water flood (cumulative oil recovery >91%), even though the recovery was lower than that of the optimal salinity gradient SP flood. Our experimental work demonstrates the effectiveness of the surfactant formulation for a high-temperature carbonate reservoir at seawater salinity.
在石油储层水驱之后残留的原油，可以通过能与原油产生超低界面张力（IFT）的表面活性剂配方来实现驱替。然而，对于高温、海上碳酸盐岩储层而言，找到具有超低界面张力的表面活性剂配方是困难的。这些储层通常用海水（含有大量二价离子）进行水驱，而海水在高温下常常与许多表面活性剂不相容。本研究的目标是为一个先前已被海水驱替过的、温度为100°C的海上碳酸盐岩储层开发一种表面活性剂配方。从单一表面活性剂开始，到表面活性剂混合物以及一种助溶剂，对各种配方的表面活性剂-油-盐水相行为进行了研究。需要三种表面活性剂与一种助溶剂的混合物，才能为目标原油生产出具有超低界面张力的配方。在破碎的储层岩心中对具有聚合物流动性控制的表面活性剂体系进行了测试。对于具有最佳盐度梯度的表面活性剂-聚合物（SP）驱，累积原油采收率>99%。即使采收率低于最佳盐度梯度SP驱，但用海水进行的恒盐度SP驱显著提高了原油采收率，超过了水驱（累积原油采收率>91%）。我们的实验工作证明了该表面活性剂配方在海水盐度下对高温碳酸盐岩储层的有效性。
