The effect of rock types on pore volume compressibility of limestone and dolomite samples

Determination of porosity, permeability, and pore volume compressibility of reservoir rocks and those variations with effective stress changes are of great interest in petroleum engineering. This paper has studied the influence of pore types of carbonate reservoir rocks on pore volume compressibility as well as Klinkenberg permeability and porosity at different stress values. In the current study pore volume compressibility tests have been done on 38 limestone and 8 dolomite samples. The experiments show the importance of rock type description of the reservoir rocks. Carbonate rocks with touching vug pores have different behavior from the other studied carbonates in this paper. This complex behavior is related to the role of connecting paths closure on the characteristics of hydraulic conductivity of the rock while there is no more changes in porosity or volume change. It means that the planar connecting paths have more effect on hydraulic conductivity of this rock type, while it has not more effect on porosity. Also, in all rock types excluding touching vuggy pores limestone, increasing the initial porosity leads to increase the permeability at the same effective stress value.