Mechanical Tests on Digital Samples of Carbonates Obtained Using X-Ray Microtomography

Drilling and the development of oil and gas production in carbonate reservoirs have presented serious operational problems in the Brazilian Offshore oil fields. These problems are partly caused by difficulties in the characterization of carbonates whose structures have complex spatial distributions. This paper proposes to integrate the processing and analysis of digital images acquired from X-ray micro-CTs and the development of finite element meshes for numerical simulation in order to predict elastic properties and correlates this with the rock microstructure. Digital images of samples of outcrops (travertine) were used, considered as analogous to carbonate rock reservoirs. The results were compared to the actual test results and data found in the literature indicating the potential and current limitations of this technique. It is concluded that the value of Young's modulus obtained from numerically simulated tests is affected by the spatial distribution of the pores and the microporosity of the rock. The values found in the virtual test tended to be higher than those obtained in actual tests. This difference is due to the difficulty of inserting, in the microstructure numerical model, the contacts between the grains, as well as more compressible regions not determined by the acquisition of the images. It is concluded that this technique has the potential to assist the analysis of relevant aspects of the microstructure of elastic properties of carbonate rocks.