纳米颗粒抑制CO2驱过程中沥青质沉积的研究进展

Inhibition of nanoparticles on asphaltene deposition during CO2 flooding:A review

CO2驱在低渗透油藏开发中具有易注入、易混相等优势,但其驱油过程中会带来沥青质沉积问题,导致储层孔喉堵塞、润湿性变化及渗透率降低。纳米颗粒在抑制沥青质沉积方面具有较大的潜力,有望进一步应用于提高低渗透油藏采收率。从分子结构层面讨论了纳米颗粒抑制沥青质沉积的机理,总结了近年来中外最新研究进展,指出了当前研究与应用所面临的挑战,并对其发展做出了展望。纳米颗粒主要通过吸附作用和分散作用抑制沥青质沉积,吸附作用依靠纳米颗粒的表面电荷与沥青质的强极性基团之间的静电吸引而使纳米颗粒包覆在沥青质分子表面,从而避免沥青质沉积;分散作用则主要通过接枝在颗粒表面的有机链,与沥青质分子形成范德华力或空间位阻,从而破坏沥青质分子间的自缔合作用,达到抑制沥青质沉积的效果。但该技术目前仍处于室内研究阶段,纳米流体的稳定性、经济性及其对环境影响的不确定性等因素制约了其大规模现场应用。开发出稳定性好、经济效益高、环境友好的新型纳米流体是未来研究的关键,建立更为精确的数学模型也是未来工作的重要方向。

CO2 flooding has the advantages of easy injection and miscibility in the development of low permeability reservoirs,but it will inevitably bring asphaltene deposition problems in the process of oil displacement,resulting in reservoir pore throat blockage,wettability change and permeability reduction.Nanoparticles have great potential in inhibiting asphaltene deposition,and are expected to be further used to improve oil recovery in low permeability reservoirs.In this paper,the mechanism of nanoparticles inhibiting asphaltene deposition is discussed from the molecular structure level,the latest research progress in recent years is summarized,the challenges of the research and application are pointed out,and its prospective is predicted.Nanoparticles mainly inhibit asphaltene deposition through adsorption and dispersion.Adsorption depends on the electrostatic attraction between the surface charge of the nanoparticles and the strong polar groups of the asphaltene,so that the nanoparticles are coated on the surface of asphaltene molecules and asphaltene deposition is avoided.Dispersion is mainly through the grafting of organic chains on the surface of nanoparticles to form van der Waals force or steric hindrance with asphaltene molecules,thus destroying the self-association between asphaltene molecules and achieving the inhibition of asphaltene deposition.However,the technology is still in the stage of laboratory study,and its largescale field application is restricted by factors such as the stability of nanofluids,the economy of nanomaterials,and the uncertainty to the environment,etc.The development of novel nanofluids with good stability,high economic benefits and environment-friendly is the key to future research,and the establishment of a more accurate mathematical model is also an important direction for future work.