Petrophysical and acoustic assessment of carbonate rocks, Zahle area, central Lebanon

Abstract

Transport and acoustic measurements have been conducted on fifteen rock samples collected from central Lebanon to characterize the rock properties and to assess the impact of lithology, pore types, pore sizes, and textural parameters on the storage capacity and elastic characteristics. The spontaneous imbibition of selected samples was examined by detecting the moving capillary front across a sample. The coefficient of capillarity derived from the spontaneous imbibition is positively correlated with permeability. Seismic velocities in the studied rocks vary widely and are positively correlated with the rock density. Matrix-supported rocks with a larger proportion of micropores have lower seismic wave velocities, whereas the grain-supported carbonates exhibit low to moderate porosity and higher acoustic velocities. The elastic properties of the studied carbonates indicate a granular, rather than a crystalline, texture for the majority of the studied rocks. The widely variable elastic behavior of basically carbonate rocks implies that seismic reflection profiles in carbonate sequences may contain seismic reflections that do not result from non-carbonate intercalations but which result mainly from variable porosity, pore types, and shapes in the carbonate rocks themselves. This study provides important information on the textural, petrophysical, and elastic properties of carbonate rocks which are crucial for the assessment and understanding of the seismic reflection sections in subsurface carbonate reservoirs.