Technology Focus: EOR Performance and Modeling (January 2016)
Authors: Gurpinar Omer 
Published: December 2016

Technology Focus

Efforts to increase recovery factors in all types of oil reservoirs keep increasing, regardless of the fluctuations in oil prices. It is a historical fact that, when oil price drops, industry’s focus turns to produce/recover more oil where the oil is already found. In my career, this is the sixth oil-price crush I have seen, and the same behavioral change is happening again. The only difference between now and my first experience, in the 1980s, is that the need for enhanced-oil-recovery (EOR) applications today is a must, not a luxury. Luckily, activity in the world of EOR is continuing and for the better.

Recovery-optimization efforts of the national oil companies are expanding with larger and well-designed EOR pilots and even with offshore chemical EOR projects. It is worth mentioning here that the EOR experience gathered by the international oil companies and service companies over the decades is definitely finding its way to provide a stable foundation to those new EOR projects. Additionally, new EOR projects are getting the benefit of the significant enhancements in reservoir characterization and evaluation, flow physics, EOR chemicals, modeling capabilities, conformance capabilities, and monitoring and control systems. All those are happening; therefore, it is safe to say the new EOR projects will be significantly more successful compared with the older ones from 1980s.

Mitigating declining pressures in the 1970s and 1980s was basically handled by injection of water with simple vertical injectors with limited design. Now, companies think about low-salinity (LoSal) options every time pressure maintenance with water is considered. Alternatively, companies can design reliable water-alternating- gas (WAG) -injection schemes by placing the right-trajectory wells in the right locations of heterogeneous reservoir systems, which were already illuminated sufficiently with advanced reservoir characterization. Placing in-situ sensors and digital feedback mechanisms enables companies to optimize the new recovery process significantly. To start with, instead of just going with pressure maintenance, smart EOR screening systems that might have already been used may be more promising EOR options. Accessibility to fast EOR pilots suitable for the heterogeneity of the reservoir could be used, and the decision for field expansion takes place much faster and more reliably than it did in the 1980s. More-reliable modeling capabilities, coupled with cloud computing, are providing an environment in which refining EOR decisions in the presence of the uncertainties of the reservoirs is now possible. Limited design capability, smaller number of field tests, and lack of monitoring and control were the reasons most EOR projects did not perform in the past. All those issues are history now.

Over the last year, irrespective of the inclement times in our industry, fundamental sciences, EOR physics, numerical modeling, monitoring and controlling capabilities, and EOR chemicals all demonstrated advancements. Ironically, fast exploitation of the unconventional liquids is considered to be one of the key reasons for the drop in oil prices; there are efforts to identify EOR potential for those reservoirs. The efforts consist of advancements in reservoir characterization suitable to those unique reservoir systems, smarter fracturing fluids, and EOR pilots.

As a result of the continuing momentum in EOR efforts, many excellent technical papers were developed and, once again, selecting only a few was rather difficult. The following pages provide some insights on how EOR is being tested for “tight/light” reservoirs, CO2/LoSal WAG experimentation, and giant-field EOR applications. JPT

Recommended additional reading at OnePetro: www.onepetro.org.

SPE 173322 A Four-Phase-Flow Model To Simulate Chemical EOR With Gas by Mohammad Lotfollahi, The University of Texas at Austin, et al.

SPE 174648 Novel Visualization of Chemical EOR Flooding Using a Lab-on-a- Chip Setup Supported by an Extensive Rheological Characterization by J. Wegner, Clausthal University of Technology, et al.

SPE 173205 Reduced-Order Models for Rapid EOR Simulation in Fractured Carbonate Reservoirs by S. Agada, Heriot-Watt University, et al.