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Harbour Energy is the largest London-listed independent oil and gas company with interests in Indonesia, Vietnam and Mexico, as well as a leading position in the UK. One of its assets is a producing block located in offshore Natuna Sea delivering gas into Singapore since 2000. The block was developed through a combination of platforms and subsea tiebacks, and consists of seven producing fields with highly laminated reservoirs, diverse reservoir quality and complex fault block systems. This complexity creates challenges to optimise production in order to maintain gas supply sustainability in response to buyers’ demand.

Responding to challenges created by the complexity of the field, a Production System Optimization process involved establishing a multidisciplinary team to generate production opportunities and priorities in a holistic manner with associated values and the enablers. Several factors have been considered to achieve this objective. First was the crucial understanding of the subsurface attributes. This involved comprehending how the reservoir operated to assure effective production. Secondly was the importance of evaluating the current well stock including its design, performance characteristics (such as rates and pressures), well condition and integrity. Thirdly was the essence of optimizing the infrastructure design including production, artificial lift, and export systems. Fourthly was the necessity of implementing flow assurance philosophies and strategies to manage multiphase flow behavior, hydrates, wax, sand, and other solids production, as well as addressing materials and production chemistry issues, including chemical injection requirements. Fifthly was the vital consideration of the overarching limits of the entire system, in addition to its components. And finally, the importance of having the right people and organization, both onshore and offshore to assure successful delivery of the optimization process.

The process of Production System Optimization involved identifying the current key threats to production and implementing controls and mitigations to minimize or eliminate production losses. This included assessing the existing systems and identifying any areas for improvement. Operational activities that could enhance production with minimal expenditure
were also considered, such as optimizing operating parameters, implementing best practices, and improving maintenance procedures. Additionally, opportunities for production enhancement in the reservoir, wells, and facilities were explored, which might require additional investment. This could involve implementing new technologies, conducting infill activities, or expanding the asset’s value through further investment opportunities. Lastly, to
progress any of the aforementioned items, additional required work and/or technology were identified, such as conducting further research, implementing advanced monitoring systems, or adopting innovative production techniques.

A comprehensive evaluation has identified and assessed a range of opportunities associated with wells and reservoirs optimization, well management, facilities optimization, operational excellence, infill drilling opportunity, near-field exploration drilling and commercial opportunities. The priority of these opportunities was clearly established, taking into account their respective value and cost, providing a roadmap for production optimization. This alignment has facilitated consistent planning of project sequencing, resource optimization, and the resolution of commercial issues. The team has successfully identified potential opportunities that could potentially add approximately 10 MMBOE resources to the Natuna Block A and have made consistent progress in pursuing these opportunities and have already delivered 1.5 MMBOE in 2023.