Effect of stimulation with chelating agents on carbonate rocks integrity

Well stimulation using acidic solutions was being widely used to treat the damaged carbonate formations in production and injection wells. It basically removes near wellbore damage and also creates connecting channels around the wellbore by means of dissolving clays and some parts of the carbonate rocks. Many stimulation fluids have been used such as HCl acid, acid mud, organic acids, chelating agents, etc. Wormholes that created by these fluids are very effective and can decrease the skin factor significantly; and hence results in a noticeable increase in well productivity. Despite the fact that these fluids successfully created these wormholes, diffusion of these fluids inside the rocks can create significant and permanent changes in rock mechanic properties that can eventually lead to weakening the rock strength; which may lead to future rock failure. In this paper, the effect of EDTA chelating agent on rock integrity will be investigated. The focus of the study will be on the effect of wormholes that created by these fluids. CT scan and acoustic tests will be conducted on the core samples before and while stimulation experiments.