A technique to quickly determine the asphaltene onset pressure (AOP) of a crude oil from low-volume, nonequilibrium measurements is presented. The pressure at which the optical signature indicative of asphaltene aggregation is first detected in recombined crude oils is found to decrease strongly with the rate of depressurization and can be well-described with a modified power law. This technique exploits this rate dependence and uses two separate decompressions at highly disparate depressurization rates to determine the AOP. Benchmarking with this technique was performed with recombined crude oils that were characterized with conventional pressure/ volume/temperature analysis. Using this technique, measurements enabling the determination of the AOP of a live crude oil can be obtained in minutes with a nominal uncertainty of 500 psi. This is a significant reduction in time compared with the multihour process used for conventional equilibrium-based measurements. Onset-time data from these studies are consistent with conventional aggregation theories, but there is insufficient range to differentiate between reaction-limited aggregation (RLA) and diffusion-limited aggregation (DLA).

提出了一种通过小体积非平衡测量快速确定原油的沥青质起始压力（AOP）的技术。发现在重组原油中首先检测到指示沥青质聚集的光学特征的压力随降压速率而大大降低，并且可以用改进的幂定律很好地描述。该技术利用了这种速率依赖性，并以高度不同的降压速率使用两个单独的压缩来确定AOP。该技术的基准测试是通过常规压力/体积/温度分析表征的重组原油进行的。使用这种技术，可以在数分钟内获得测定活性原油AOP的测量值，标称不确定度为500 psi。与传统的基于平衡的测量相比，这需要花费数小时的时间，因此可大大减少时间。这些研究的发病时间数据与常规聚集理论一致，但是没有足够的范围来区分反应受限聚集（RLA）和扩散受限聚集（DLA）。