Avaliação geomecânica preliminar de rochas para armazenamento geológico de carbono

Abstract

In the face of advancing global warming, carbon capture and geological storage (CCS) technology has emerged as a solution to mitigate emissions and even remove carbon from the atmosphere. Engineering projects of this nature alter the natural stress state of subsurface rocks, which may compromise the integrity of the structure—something that is fundamental for CCS projects aiming to ensure the permanent trapping of the gas. In this context, it is essential to investigate the rocks involved in each case, as well as at different stages—before, during, and after the implementation of the activity. These investigations are preferably empirical, through in situ or laboratory measurements, making it fundamental to characterize the rock matrix in terms of all aspects that may influence its mechanical behavior. Thus, the present work aimed to assess, from a geomechanical point of view, rocks from outcrops in Northeastern Brazil and rocks collected from outcrops in the United States in a preliminary way, that is, in their original state before the development of CCS activities. For this purpose, porosity and permeability measurements were conducted, along with uniaxial compressive strength and indirect tensile tests. Based on the parameters obtained and the developed analysis, it was concluded that two sandstones which showed the best storage capacities demonstrated insufficient mechanical performance. Meanwhile, one sandstone from Northeastern Brazil and one from the U.S. presented a better balance, with good storage capacity and medium mechanical strength. Finally, a diabase sample was also analyzed, which showed excellent mechanical performance combined with minimal porosity and permeability, highlighting its potential application as a caprock.