Abstract
Background: Carbonate reservoirs are widespread and geologically complex, making their development a persistent challenge for the oil and gas industry. Low-permeability formations typically exhibit strong heterogeneity and a fractured–porous matrix, which hinder uniform oil displacement during conventional waterflooding. In such settings, reservoir pressure maintenance often results in early water breakthroughs along high-permeability zones and reduced sweep efficiency. Aim: This study reports injectivity profile alignment (IPA) in a carbonate reservoir in Kazakhstan to optimize waterflooding and enhance displacement efficiency. Materials and methods: The study covers the reservoir’s geological and petrophysical characteristics, the selection of water-blocking formulations based on laboratory results, and the criteria for identifying candidate injection wells. Effectiveness was evaluated from injectivity profile changes and production responses of nearby wells. Results: IPA treatments were implemented in six injection wells, with 100–150 m³ of water-blocking formulation injected per well. Logging confirmed improved injectivity profiles and flow contribution from previously inactive intervals. Sweep efficiency increased by an average of 14%. Field monitoring showed stable performance, with each treatment yielding about 1.2 thousand tonnes of incremental oil. Conclusion: The results confirm that IPA is effective for stabilizing reservoir pressure maintenance and enhancing oil recovery in complex fractured–porous media.