With operators investing increasingly in hard-to-reach hydrocarbons, a greater emphasis has been placed on recovery optimization. Technological advances have made economical the additional recovery of identified reserves, the planning for which should be considered as early as possible in the life of a reservoir.

Buoyant oil prices, the growing international demand for oil, and declining oilfield productivity all highlight the need for improved and accelerated recovery. The global average oilfield recovery factor is approximately 40%. This results in large volumes of unproduced yet identified hydrocarbons.

For decades the industry has been employing a number of different EOR techniques, but generally only in large land fields that can support a large infrastructure and justify a major investment. Although the fundamental physics of EOR – how to mobilize oil within the pore system – are well known, we are now seeing significant advances in other enablers such as reservoir characterization, reservoir-scale monitoring, well placement, smart completions, and new EOR agents. All of these developments provide the opportunity to make EOR more successful.

North America has the largest number of EOR projects today, but operators in the oil-rich Middle East are launching similar schemes. In addition, giant oil fields are now being considered for EOR earlier in their life cycles. This is an important point: Rather than considering EOR as part of a reactive, late-life field strategy, consideration is being given to the most suitable EOR methodology during the earliest stages of field development. This proactive approach will save money, boost ultimate recovery, and ensure maximum return on investment.

Making the right selection when it comes to EOR techniques is crucial. There are a number of different choices in this regard, including chemical methods, miscible and immiscible gas flooding, and thermal recovery methods. The correct choice of EOR strategy goes a long way toward optimizing eventual recovery.

Advanced reservoir simulation software is the most reliable approach in selecting the best EOR technique for a particular field. A predictive reservoir model is a must for understanding the dynamic behavior of reservoir fluids, including EOR agents, and for optimizing injection and production options. Three-phase 3-D simulations are used to model EOR techniques. The Petrel E&P software platform and ECLIPSE reservoir simulation software can be used to create multiscale reservoir models that deliver greater predictive and analytical power. This improved reservoir characterization is essential for optimal EOR technique planning.

Running through different EOR scenarios digitally is an ideal way to mitigate the risks associated with these decisions and will increase confidence in reservoir strategy and recovery planning. Major unknowns such as formation heterogeneity can be evaluated using multiple iterations with different parameters. It is possible to compare expected costs and project economics with the base case of continued production without EOR. If the simulation indicates that the project meets technical and financial requirements, then it can be used to design subsequent pilot projects.

EOR projects are currently among the most complex and difficult undertakings in the upstream industry. Success lies in improving the efficiency in every step of the process by synchronizing diverse measurements, applying advanced technologies, and integrating knowledge across multiple domains. Comprehensive reservoir simulation supports efficient decision-making at every stage of the EOR workflow, from concept selection to full-field implementation.
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