During the development of low or ultra-low permeability oil resources, the alternative energy supply becomes a prominent issue. In recent years, carbon dots (CDs) have drawn much attention owing to their application potential in oil fields for reducing injection pressure and augmenting oil recovery. However, carbon dots characterized of small size, high surface energy are faced with several challenges, such as self-aggregation and settling. The preparation of stably dispersed carbon dots nanofluids is the key factor to guarantee its application performance in formation. In this work, we investigated the stability of hydrophilic carbon dots (HICDs) and hydrophobic carbon dots–Tween 80 (HOCDs) nanofluids. The influences of carbon dots concentration, sorts and concentration of salt ions as well as temperature on the stability of CDs were studied. The results showed that HICDs are more sensitive to sort and concentration of salt ions, while HOCDs are more sensitive to temperature. In addition, the core flooding experiments demonstrated that the pressure reduction rate of HICDs and HOCDs nanofluids can be as high as 17.88% and 26.14%, respectively. Hence, the HICDs and HOCDs nanofluids show a good application potential in the reduction of injection pressure during the development of low and ultra-low permeability oil resources.

在低渗透率或超低渗透率石油资源开发过程中，替代能源供应成为一个突出的问题。近年来，碳点（CD）由于其在油田中的潜在应用而引起了人们的关注，可降低注入压力和提高采油率。然而，以小尺寸，高表面能为特征的碳点面临着一些挑战，例如自聚集和沉降。稳定分散的碳点纳米流体的制备是保证其在地层中的应用性能的关键因素。在这项工作中，我们研究了亲水性碳点（HICD）和疏水性碳点–吐温80（HOCD）纳米流体的稳定性。研究了碳点浓度，盐离子的种类和浓度以及温度对CD稳定性的影响。结果表明，HICD对盐离子的分类和浓度更敏感，而HOCD对温度更敏感。此外，岩心驱替实验表明，HICDs和HOCDs纳米流体的降压率分别高达17.88％和26.14％。因此，HICD和HOCD纳米流体在开发低渗透率和超低渗透率石油资源的过程中，在降低注入压力方面显示出良好的应用潜力。