Gas breakthrough pressure of tight rocks: A review of experimental methods and data

Breakthrough pressure is a key parameter of the caprock sealing ability for gas reservoirs. It has also become an important parameter for gas production from tight reservoirs, such as shale gas reservoirs, as water in these tight formations may require gas to overcome the breakthrough pressure before being produced. Laboratory measurement is essential to obtain the breakthrough pressure because no field methods can accurately estimate it. In this review article, the definition, the experimental methods, and experimental data for breakthrough pressure on tight rocks are reviewed. The advantages and issues of each experimental method are discussed. Furthermore, the relationships between breakthrough pressure and rock properties, especially its permeability, are investigated. It is found that breakthrough pressure has a close relationship with pore structure and most of the experimental data show that it has a power law relationship with absolute permeability. Moreover, water saturation, gas type, and effective stress are all found to have an impact on the breakthrough pressure. Finally, future research topics are proposed, including investigating sample length on breakthrough pressure measurement and developing more theoretically based models for breakthrough pressure with regards to absolute permeability or other measurable rock properties.