Block 61 Condensate Decline Management Strategy

Abstract Block 61 is gas field located in Southwest of Oman and is being operated by BP. Field has been on production under Exploration and Production Sharing Agreement since 2008. Exploration program was run between 2008 and 2013. Exploration program laid foundations for the Khazzan Phase 1 project which started up in 2017 and then Khazzan Phase 2 project started in 2020. Gas is being produced from Barik and Miqrat formations via hydraulicly fractured wells. Phase 2 enabled field to be ramped up from initial 1 Bscf to 1.5 Bscf by the mid of 2021. Khazan Phase 2 project initially targeted high CGR wells (Condensate to Gas Ratio, 40 – 80 stb/MMscf) located in the southern part of the Block. Start of the project introduced large volumes of condensate and intuitively created a desire to operate the wells at higher production rates 20 – 30 MMscf/d. However, in return higher production rates were observed to cause high condensate decline. Field was expected to have 9% to 15% (on yearly basis) managed condensate decline between 2023 and 2025. On other hand, high decline created concerns around EUR (Estimated Ultimate Recovery) per well and impact to future deliverability of the field. A structured evaluation program was launched to identify the optimal gas production rate per well, aiming to maximize cumulative condensate recovery while sustaining reservoir pressure. The methodology included reservoir simulations, well test validations, and decline curve analysis, assessing the impact of various gas rate scenarios on CGR sustainability and recoverable condensate volumes. The study produced the following key insights: Lower gas rates sustain CGR over a longer production period, enhancing overall condensate recovery.Gas rates exceeding 15 MMscf/d lead to the dew point being reached in fractures within two months, accelerating CGR decline.Producing above 15 MMscf/d negatively impacts cumulative condensate recovery, with increased condensate dropout in the reservoir.For every 5 MMscf/d increase beyond 15 MMscf/d, cumulative condensate recovery is reduced by 2–4% over a 10-year production horizon. Based on these findings, a well management strategy was implemented in 2022 to optimize condensate recovery while preserving well productivity. The strategy involved: Gas Rate Capping: High-CGR and new wells were capped at 15 MMscf/d to mitigate excessive CGR decline.Weekly Performance Monitoring: Wells exhibiting high CGR decline were identified, and operating rates were adjusted accordingly.Swing Well Utilization: Low-CGR wells (CGR <20 stb/MMscf) were designated as swing wells to accommodate gas export demand fluctuations, ensuring compliance with the Gas Sales Agreement (GSA) while preserving high-CGR wells. The implementation of the decline management strategy yielded immediate and measurable results, significantly reducing base condensate decline rates and enhancing total field condensate production beyond initial forecasts. Key performance improvements: Base condensate decline reduced from 20% in 2022 to 10% in 2023, stabilizing production profiles.Cumulative condensate production gains: 2023: +4% increase (actuals).2024: +11% increase (actuals).2025: +15% increase (forecast). The success of this data-driven well optimization approach has reinforced BP's well management strategy, setting a benchmark for efficient condensate recovery in tight gas fields. Now in 2025, the Condensate Decline Management Strategy continues to evolve with the integration of advanced data analytics tools, real-time monitoring systems, and machine learning algorithms. These innovations aim to: Refine gas rate optimization models using real-time well surveillance data.Incorporate predictive analytics for enhanced production forecasting and decline trend analysis.Explore commingled production strategies for optimizing performance across the Barik and Miqrat formations.Improve adaptive well management techniques, enabling further optimization based on evolving reservoir conditions. By leveraging continuous data-driven enhancements, BP remains committed to maximizing resource recovery, ensuring long-term field sustainability, and enhancing the overall economic value of Block 61's gas and condensate production.