Abstract
<jats:title>Abstract</jats:title> <jats:p>Waterflooding is widely implemented as a secondary recovery technique; however, its efficiency is frequently compromised by premature water channeling within the reservoir. Over the past 17 years, both near-wellbore and in-depth conformance-improvement technologies have been deployed across ten (10) Colombian fields to enhance waterflood performance and maximize oil production. Polymer gel-based channeling control measures, first introduced in 2008, have delivered consistently favorable results. San Francisco Field commenced oil production in 1985 and has been under waterflood since 1992, achieving an average recovery factor of 34.41% OOIP. Due to relatively low recovery and pronounced reservoir heterogeneity, four injection patterns were selected in early 2025 for a gel-based conformance-control treatment. Candidate patterns were identified based on multiple criteria, including high water intake with low oil recovery, early water breakthrough, high water cut, uneven injection profiles, and high injectivity.</jats:p> <jats:p>A comprehensive laboratory evaluation was conducted to confirm gel performance, stability, and compatibility under reservoir and operational conditions. The treatments were executed in three stages: (1) pre-flush with water to assess injectivity before gel injection, (2) main gel injection followed by a polymer push, and (3) water over-flush. Injection pressures were continuously monitored to ensure they remained below formation fracture limits. Innovative strategies were implemented during the pre-flush and post-flush stages, and their impacts were evaluated in this study.</jats:p> <jats:p>Approximately four months after treatment, oil production from the four patterns began to increase steadily. In early 2026, the average incremental production reached 80 barrels of oil per day (BOPD), accumulating nearly 20,000 barrels for the campaign. This improvement was accompanied by a 54% reduction in water production, thereby significantly improving the field's economic performance. Based on current projections, these treatments are expected to yield an average cumulative oil production per pattern of 15,000 barrels (P10 case), 22,000 barrels (P50 case), and 33,000 barrels (P90 case) over five years. Patterns that incorporated customized surfactant formulations in both the pre-flush and post-flush stages exhibited superior gel injectivity and incremental oil recovery.</jats:p> <jats:p>The results provide valuable insights for optimizing the planning and execution of conformance control campaigns. They also offer practical guidelines for tailoring treatment designs to specific reservoir conditions, thereby supporting improved technical and economic decision-making. The campaign was executed following a standardized, surveillance-driven conformance workflow, enabling consistent design, execution, and performance evaluation across multiple injection patterns.</jats:p>