Schlumberger DBR Technology Center, Edmonton, AB, T6N 1M9, Canada.
Lab Chip. 2012 Nov 7;12(21):4381-7. doi: 10.1039/c2lc40706j.
A novel microfluidic device designed for analyzing phase diagrams of gas-liquid systems (PVT or pressure-volume-temperature measurements) is described. The method mimics the phase transition of a reservoir fluid as it travels through the wellbore from the formation to the surface. The device consists of a long serpentine microchannel etched in a silicon substrate. The local pressure inside the channel is measured using membrane-based optical pressure sensors positioned along the channel. Geometrical restrictions are placed along the microchannel in order to nucleate bubbles when nucleation conditions are met, thus preventing the development of a supersaturation state in the channel. We point out that a local equilibrium state between gas and liquid phases is achieved, which implies that equilibrium properties can be directly measured on the chip. We analyze different mixtures of hydrocarbon systems and, consistently with the preceding analysis, obtain excellent agreement between our technique and conventional measurements. From a practical viewpoint (important for the relevance of the technology), we observe that the measurement time of thermodynamic properties of gas-liquid systems is reduced from hours to minutes with the present device without compromising the measurement accuracy.
本文介绍了一种用于分析气液系统相图（PVT 或压力-体积-温度测量）的新型微流控装置。该方法模拟了储层流体从地层到地表通过井筒时的相变过程。该装置由刻蚀在硅衬底上的长蛇形微通道组成。通过沿通道放置的基于膜的光学压力传感器测量通道内的局部压力。在微通道中设置几何限制，以在满足成核条件时成核气泡，从而防止通道中出现过饱和度状态。我们指出，实现了气-液相间的局部平衡状态，这意味着可以直接在芯片上测量平衡性质。我们分析了不同烃类系统的混合物，并与前面的分析一致，我们的技术与传统测量方法之间具有极好的一致性。从实际角度来看（对于技术的相关性很重要），我们观察到，使用当前装置可以将气-液系统热力学性质的测量时间从数小时缩短到数分钟，而不会影响测量精度。
