Evaluation of lithological and mechanical characteristics of Ilam Formation

The Ilam Formation has a special place in the oil industry as one of the most important oil reservoirs and as a construction site in projects, so knowing its engineering geological characteristics is very important.In order to comprehensively investigation of the Ilam formation, the type section of the formation was studied in Ilam, Lorestan and Kermanshah provinces. Based on the studies of 110 samples, 7 types of microfacies were identified and were classified in 4 groups Mudstone, Wackestone, Wackestone-Packstone and Packstone by Dunham method. The physical properties of rocks including density, porosity, water absorption and p-wave velocity and mechanical properties including uniaxial compressive strength and point load index were measured.The results show that the average porosity and water absorption of mudstone samples are higher than the other types of rocks tested, which is due to the finer grain of the texture. P-wave, point load index and uniaxial compressive strength in Packstone samples are higher than other types of samples, which is due to the presence of more grains in the texture and as a result its higher strength.The results of the statistical tests show that there is a statistically significant relationship between the independent variables and the dependent variable. In addition, the relationship between point load index and uniaxial compressive strength was linear. The correlation coefficient of uniaxial compressive strength with porosity and point load index is higher than other parameters, and as a result, they provide a suitable estimation of the strength of Ilam limestones.