Credence of Elastic Properties of Ughelli Sandstone on Microstructure

The elastic properties of sandstones depend on their geological environment. The differences in these geological structures are responsible for the challenges in establishing a common value for rock properties. The aim of this research is to obtain the Young’s modulus and Poisson’s ratio for sandstone using simulation and to compare the values with those derived from experimental Linear Variable Differential Transformers (LVDTs) method. The procedure included the determination of the Young’s modulus, Poisson's ratio and bulk modulus for samples of sandstone. The porosities of the samples were obtained because they are relevant to the productivity of oil reservoirs. The next procedure employed the use of a photo-stress tomography for the micro-measurement which describe the microstructure of the material. All tests were performed on a commonly sourced core sample from Ughelli. Next, a particle- flow-code simulation was carried out. Three types of grains having different spherical index (sphericity) where generated by simulation, and were used to develop three samples of sandstone. Model 1, model 2 and model 3 were simulated and the porosities of the samples were 0.29, 0.27 and 0.25 respectively. Model 3 is the model represented by a grain having a combination of two dissimilar sphericity and it has a good fit with the porosity of the natural sandstone. Thus, the sample exhibit a steady increase in modulus when the confined pressure induces strain into the sandstone. As the compaction of the inter-granular contacts interferes with the porosity of the rock, the material exhibit quantitative changes in the compressive strength, Young’s moduli and Poisson’s ratio. The role of the microstructure of the rock on the porosity is hereby explained. Therefore, probing the microstructure of the rock is an important procedure in the simulation of sandstone.