Estimation of the Permeability of an Unconventional Formation Core by History-Matching the Saturation with CO2

摘要

Unconventional resources are of great importance in the global energy supply. However, the ultralow permeability, which is an indicator of the producibility, makes the unconventional production challenging. Therefore, the permeability is one of the critical petrophysical properties for formation evaluation, along with the rock porosity and compressibility. There are many existing approaches to determine permeability in the laboratory using core analysis. The methods can be divided into two categories: steady-state and unsteady-state approaches. The steady-state approach is a direct measurement using Darcy’s law. This approach suffers from the accuracy in the measurement of low flow-rate and the long run-time. The unsteady-state approach includes pulse decay, oscillating pressure, and GRI methods. These approaches are complicated in terms of set-ups and interpretations. Both steady-state and unsteady-state approaches typically have a constraint on the maximum differential pressure.