The development and application of novel apparatus for relative permeability measurement

Abstract

Relative permeability plays a crucial role in understanding the characteristics of gas and water seepage in porous media and in establishing production schedules in practical engineering applications. However, accurately determining water saturation in the relative permeability measurement is challenging due to the minimal detectable amount of movable water in ultra-low-permeability rocks. This chapter introduces a novel method to determine water production during relative permeability measurement. We developed an apparatus that combines a separator with a high-precision differential pressure transducer (DPT) to measure the variation in water production during the experiment. The repeatability of measurements using this apparatus was tested, and the results demonstrated high stability. In addition, we used this apparatus to investigate the gas−water relative permeability in high-rank coal. The results indicate that the effect of displacement pressure on the relative permeability properties depended on the type of gas. The carbon dioxide–water system exhibited a significantly larger two-phase flow span compared to the helium–water or methane–water system at the same displacement pressure. Moreover, the relative permeability of the carbon dioxide–water system showed a higher sensitivity to the displacement pressure compared to the helium–water and methane–water systems.