Study of Additives for Self-Healing of Cement Stone Under Hydrocarbon Gas Migration Conditions
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 self-healing 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 Natural Rubber (NR) additives, in solid and liquid forms, were tested as modifying agents. The key requirement was their ability to block channels larger than 0.3 mm, with agglomeration and activation prevented by treatment with hydrophobizing agents and dry cement. Building on previous success with oil-swelling additives, the study shifts focus to gas and gas condensate reservoirs. A custom testing stand was developed to simulate downhole conditions, creating artificial channels in cement with diameters of 0.8 mm. The setup demonstrated that certain additives could seal these channels within 3 to 7 days. The findings contribute to understanding additive performance and offer a step toward replicating wellbore conditions in the lab. This technology has the potential to enhance zonal isolation, reduce remediation costs, and improve safety in challenging reservoir environments.