Comparison of Mud Pressures Predicted with Different Constitutive Models in Anisotropic Shale Rocks

Depleted oil and gas fields are good targets for gas storage both in offshore and onshore environments. Carbon capture and sequestration (CCS) must repurpose existing rigs to drill new wells cost-effectively. The integrity of the well is crucial for successful carbon dioxide sequestration. During the drilling phase, well integrity involves preventing not uniform wellbore wall geometry induced by local rock failures and ensuring that cave-ins and washouts do not occur. The post-drilling experience in depleted fields can undoubtedly help selecting mud pressures to avoid instability when drilling new wells. The cap of most depleted fields is composed of shale rock that often exhibits variation in strength properties along and across the lamination planes and has been responsible for the major source of instability Carey Mehrabian et al., 2019. The mechanical properties of shale at significant depths are hard to ascertain Steiger Vales et al. 2004; Aoki et al., 1993; Holt et al. 2014; Detournay Deangeli Tran et al., 2022. All the previous considerations evidenced the difficulty and uncertainties related to the prediction of mud pressures in wellbore drilled in transversely isotropic shales. To reduce uncertainties on mud pressure prediction, there is the need of properly investigate the mechanical response of anisotropic shales during drilling operations. By integrating multiple models, engineers can gain a deeper understanding of the complex interactions between different factors influencing shale behavior. This enables them to anticipate potential challenges and hazards during drilling and wellbore operations, leading to more proactive risk mitigation strategies.