Effect of pore type on porosity, permeability and pore volume compressibility of geological formations due to in-situ stress change

Understanding the behavior of reservoir rocks under various in-situ stress conditions is important for compaction evaluation, reserve estimation, production forecasting, pressure maintenance, and casing collapse diagnosis. Such a behavior can be affected by change in rock porosity, permeability and pore volume compressibility which are all functions of rock pore type under various stress magnitudes. Thus, in this study the significance of pore type in determination of porosity, permeability and pore volume compressibility under different hydrostatic stresses were investigated. Twelve carbonate samples with four different pore types including touch vug, non -touch vug, porous matrix and tight matrix were tested hydrostatically. Samples with touch vug and tight ma-trix pores revealed the minimum and maximum porosity and permeability effects under various effective pres-sures, respectively. Also, samples with touch vug pore demonstrated a sharp reduction in their pore volume compressibility at the initial steps of measurement while the pore volume compressibility of samples with non -touch vug pore resulted in a fluctuated trend and less reduction compared to the samples with touch vug pore. Finally, it was noted that the samples with tight matrix pore type are deemed to have the lowest pore volume compressibility.

Automated summary

This study investigates the influence of different pore types on the porosity, permeability, and pore volume compressibility of rocks. Samples with touch vug and tight matrix pores exhibit the most significant changes in porosity and permeability, while samples with touch vug pores also show significant changes in pore volume compressibility. Samples with tight matrix pores have the lowest pore volume compressibility.