Abstract
This study addresses the long-standing issue of cement sheath integrity in oil and gas wells, a challenge that persists despite over 40 years of research.The focus is on selfhealing cement systems, which can repair cracks either autogenously (through unhydrated cement particles reacting with water) or autonomously (using additives like swelling agents or bacteria).However, limitations such as crack size and material compatibility require tailored solutions.Rubber and NR additives, in solid and liquid forms, were tested as modifying agents.