Residual-Oil Zone: Paleo-Oil Characterization and Fundamental Analysis
- Ahmed Aleidan (Saudi Aramco) | Hyung Kwak (Saudi Aramco) | Hendrik Muller (Saudi Aramco) | Xianmin Zhou (Saudi Aramco)
- Document ID
- Society of Petroleum Engineers
- SPE Reservoir Evaluation & Engineering
- Publication Date
- May 2017
- Document Type
- Journal Paper
- 260 - 268
- 2017.Society of Petroleum Engineers
- oil characterization, ROZ, paleo oil
- 4 in the last 30 days
- 451 since 2007
- Show more detail
- View rights & permissions
|SPE Member Price:||USD 12.00|
|SPE Non-Member Price:||USD 35.00|
In most reservoirs around the world, paleo oil exists below the free-water level (FWL) and is considered residual oil to natural/geological waterflood. This nontrivial resource of residual oil will not flow by primary- or secondary-recovery means but requires carefully designed enhanced-oil-recovery (EOR) methods to mobilize it. To date, there is no detailed analysis of paleo oil in the literature simply because it is difficult to obtain a reservoir sample.
This study provides a comprehensive paleo-oil analysis for samples obtained from reservoir sponge cores. The oil in the sponge core was extracted, analyzed, and compared with mainpay-zone (MPZ) oil. Critical data have been unveiled on paleo-oil characterization through fundamental studies on oil quality, fingerprint, filling history, available hydrocarbon components and compounds, and molecular-level characterization. It was found that the global composition and overall quality of paleo oil are very similar to those of the MPZ oil. However, the differences between the two oils were only apparent when the study was extended further to include molecular-level analysis and available hydrocarbon components and compounds. These differences may define the appropriate EOR methods to mobilize this oil and explain trapping mechanisms caused by fluid properties.
Gas-chromatography (GC) studies revealed that paleo-oil extracts have the same pristane/phytane ratio as the MPZ oil, suggesting that they are of the same origins and share the same source rock. Further analysis showed a good match of the terpane biomarkers between paleo-oil extracts and MPZ oil but with slightly lower maturity levels. Paleo-oil quality was compared with MPZ oil by use of pyrolytic oil-productivity index (POPI) analysis which indicated the same °API range as the MPZ oil and the same light volatile, thermally distilled, and cracked components. Paleo and MPZ oils were also analyzed with low-field nuclear magnetic resonance (NMR) to qualitatively test the similarity of the oil components and to measure their apparent viscosities. Both oils have shown very comparable viscosity measurements and NMR signatures. The simulated distillation analysis showed that lighter components in paleo oil are less abundant than in MPZ oil, whereas medium-to-heavy components are relatively similar. A Fourier transform ion cyclotron resonance (FT-ICR) study, which zoomed into the heavier components, revealed that paleo oil has less aromaticity than MPZ oil and lacks aromatic sulfur and disulfur compounds, a negligible amount of nitrogen compounds, and no resin-type components.
This study provides in-depth information about oil extracted from the residual-oil zone (ROZ), which does not flow by primary or secondary recovery means. To our knowledge, there is no available information in the literature that explains the components, compounds, quality, and behavior of this oil because it is difficult to obtain reservoir samples. These data shed light on a possible trapping mechanism caused by fluids in place. The study also used several methods and tools to confirm the conclusions and to ensure repeatability of results.
|File Size||671 KB||Number of Pages||9|
Aleidan, A. A., Zhou, X., Kwak, H. et al. 2014. A Laboratory Study to Investigate CO2 Potential to Mobilize Paleo Oil. Presented at the SPE Improved Oil Recovery Symposium, Tulsa, 12–16 April. SPE-169113-MS. https://doi.org/10.2118/169113-MS.
Buiting, J. J. 2011. Upscaling Saturation-Height Technology for Arab Carbonates for Improved Transition-Zone Characterization. SPE Res Eval & Eng 14 (1): 11–24. SPE-125492-PA. https://doi.org/10.2118/125492-PA.
Carnegie, A. J. G. 2007. Understanding the Pressure Gradients Improve Production From Oil/Water Transition Carbonate Zone. Presented at the SPWLA 48th Annual Logging Symposium, Austin, Texas, USA, 3–6 June. SPWLA-2007-DDD.
Christiansen, R. L., Heymans, M. J., Fanchi, J. R. et al. 1999. Transition Zone Characterization With Rock-Fluid Property Measurements. Presented at the International Symposium of the Society of Core Analysts, Golden, Colorado, USA, 1–4 August. SCA-9939.
Christiansen, R. L., Heymans, M. J., and Fanchi, J. R. 2000. Estimating Oil Reserves in Oil-Water Transition Zones. Presented at the SPE Asia Pacific Conference on Integrated Modelling for Asset Management, Yokohama, Japan, 25–26 April. SPE-59403-MS. https://doi.org/10.2118/59403-MS.
Dobitz, J. K. and Prieditis, J. 1994. A Stream Tube Model for the PC. Presented at the SPE/DOE Improved Oil Recovery Symposium, Tulsa, Oklahoma, 17–20 April. SPE-27750-MS. https://doi.org/10.2118/27750-MS.
Efnik, M. R. S., Hafez, H. H., Abdulla, F. et al. 2006. Producing Dry Oil From a Transition Zone: Should This Be Called a Wedge Zone?. Presented at the Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, 5–8 November. SPE-101471-MS. https://doi.org/10.2118/101471-MS.
Fanchi, J. R., Christiansen, R. L., and Heymans, M. J. 2000. An Improved Method for Estimating Oil Reserves in Oil/Water Transition Zones. Presented at the SPE/DOE Improved Oil Recovery Symposium, Tulsa, 3–5 April. SPE-59352-MS. https://doi.org/10.2118/59352-MS.
Honarpour, M. M., Nagarajan, N. R., Grijalba Cuenca, A. et al. 2010. Rock-Fluid Characterization for Miscible CO2 Injection: Residual Oil Zone, Seminole Field, Permian Basin. Presented at the SPE Annual Technical Conference and Exhibition, Florence, Italy, 19–22 September. SPE-133089-MS. https://doi.org/10.2118/133089-MS.
Jackson, M. D., Valvatne, P. H., and Blunt, M. J. 2002. Prediction of Wettability Variation and Its Impact on Waterflooding Using Pore- to Reservoir-Scale Simulation. Presented at the Annual Technical Conference and Exhibition, San Antonio, Texas, USA, 29 September–2 October. SPE-77543-MS. https://doi.org/10.2118/77543-MS.
Jones, P. J. and Tobey, M. H. 1999. Pyrolic Oil-Productivity Index Method for Characterizing Reservoir Rock. US Patent No. 5,866,814.
Koperna, G. J., Melzer, L. S., and Kuuskraa, V. A. 2006. Recovery of Oil Resources From the Residual and Transitional Oil Zones of the Permian Basin. Presented at the SPE Annual Technical Conference and Exhibition, San Antonio, Texas, 24–27 September. SPE-102972-MS. https://doi.org/10.2118/102972-MS.
Masalmeh, S. K. and Oedai S. 2000. Oil Mobility in Transition Zones. Presented at the International Symposium of the Society of Special Core Analysis, Abu Dhabi. SCA 2000-02.
Melzer, L. S., Kuuskraa, V. A., and Koperna, G. J. 2006. The Origin and Resource Potential of Residual Oil Zones. Presented at the SPE Annual Technical Conference and Exhibition, San Antonio, Texas, 24–27 September. SPE-102964-MS. https://doi.org/10.2118/102964-MS.
Parker, A. R. and Rudd, J. M. 2000. Understanding and Modeling Water Free Production in Transition Zones: A Case Study. Presented at the SPE Asia Pacific Conference on Integrated Modelling for Asset Management, Yokohama, Japan, 25–26 April. SPE-59412-MS. https://doi.org/10.2118/59412-MS.
Reed, R. N. and Wheatley, M. J. 1984. Oil and Water Production in a Reservoir With Significant Capillary Transition Zone. J Pet Technol 36 (9): 1559–1566. SPE-12066-PA. https://doi.org/10.2118/12066-PA.
Skauge, A. and Surguchev, L. 2000. Gas Injection in Paleo Oil Zones. Presented at the SPE Annual Technical Conference and Exhibition, Dallas, 1–4 October. SPE-62996-MS. https://doi.org/10.2118/62996-MS.
Vinegar, H. 1995. NMR Fluid Properties. SPWLA Short Course on Nuclear Magnetic Resonance Logging, ed. D. T. Georgi, SPWLA, Paris, Section 3