A brief review of dynamic capillarity effect and its characteristics in low permeability and tight reservoirs

摘要

Capillary pressure plays a fundamental role for the characterization and development of oil and gas reservoirs. Traditionally, the capillary pressure measured in equilibrium state is adopted for the investigation of the multiphase flow in porous media. However, the actual multiphase flow in the underground reservoirs is dynamic (transient) at most time, which is affected by the dynamic capillarity effect. This review offers an overview of studies on the mechanisms, experiments and models of the dynamic capillarity effect, with particular emphasis on the dynamic capillarity effect in low permeability and tight reservoirs. The review initially discussed the controlling parameters of the dynamic capillarity effect, including fluid viscosity, heterogeneity, domain scale, wettability et al., among which conclusions on the influence of the properties of porous media and wettability are consistent. The second part of the review outlined the development of the porous media permeability and the experimental conditions for the dynamic capillarity effect experiments. In the third section, the dynamic capillarity effect models were concluded, namely the continuum models used in production prediction and the pore scale models mainly used to explore the physics of multiphase flow. In addition, an overview of the influence of the dynamic capillarity effect on low permeability and tight reservoirs was provided, and methods (e. g. adding surfactants) to optimize the behavior of dynamic capillarity effect were discussed. Finally, the criteria to consider the dynamic capillarity effect in a porous medium are proposed. This study can help for a better understanding of multiphase flow in porous media.