The permanent abandonment of oil and gas wells creates a subsurface containment system that must function without active management for decades or, in carbon capture and storage (CCS) applications, for centuries. Evidence from regulatory monitoring and field-scale integrity assessments consistently show that the dominant cause of containment failure is not error at the abandonment stage itself, but deficiencies introduced during drilling and well construction — in casing centralization, cement placement, material selection, and barrier configuration — that become irreversible once the well is completed. This thesis investigates how five categories of construction-stage decisions — well trajectory, casing grade and setting depth, mud weight and conditioning, cement slurry formulation, and monitoring architecture — govern the long-term integrity of abandoned wells, and develops a structured framework for evaluating these decisions against abandonment performance.