Assessing Mechanical Integrity of Cementitious Materials: Microbial-Induced Precipitation vs Oil-Well Cement

Over the past decades, the oil-well cement (OWC) has been used in sealing the wellbore-casing or inter-casing annular spaces. The Microbial-induced precipitation (MIP), on the other hand, is an emerging biomineralization cement system that can be utilized in energy, construction, mining, and other industries. However, understanding the mechanical integrity and peak strength of these cement systems are important for improving their applicability at varying in-situ-pressure and temperature conditions. Here, we experimentally investigated the mechanical integrity of the microbial-induced precipitation and the oil-well cement and their applicability to plugging of leakage pathways. We utilized 2 core samples from a sedimentary sequence with artificially induced fractures along the longitudinal axis of the cores, and treated the induced-fractures in these cores with the cementations from the MIP and OWC, respectively. We compared the mechanical properties of the cement seals in these cores to assess their mechanical integrities and applications. Our results show that the OWC is more efficient than MIP in sealing in-situ macro-fractures and provided a relatively greater mechanical integrity for the wellbore-casing or inter-casing annular spaces. In addition, although OWC has higher mechanical integrity over MIP, the MIP has an edge in its application for sealing of microfractures and mini-aperture of casing-cement or cement-formation delamination. We envisage that our study will advance the understanding of these methods and their applications for the enhancement of wellbore integrity for drilling operations, enhanced geothermal systems (EGS), geologic CO₂ storage (GCS), and mining operations.