Enhanced Oil Recovery in Liquid-Rich Shale Reservoirs: Laboratory to Field
- Najeeb Alharthy (Colorado School of Mines) | Tadesse Teklu (Colorado School of Mines) | Hossein Kazemi (Colorado School of Mines) | Ramona Graves (Colorado School of Mines) | Steven Hawthorne (Energy and Environmental Research Center (EERC)) | Jason Braunberger (Energy and Environmental Research Center (EERC)) | Basak Kurtoglu (Marathon Oil Company)
- Document ID
- Society of Petroleum Engineers
- SPE Annual Technical Conference and Exhibition, 28-30 September, Houston, Texas, USA
- Publication Date
- Document Type
- Conference Paper
- 2015. Society of Petroleum Engineers
- 5.4 Enhanced Recovery, 1.6 Drilling Operations, 5.8.4 Shale Oil, 6 Health, Safety, Security, Environment and Social Responsibility, 6.7 Fundamental Research in HSSE, 5 Reservoir Desciption & Dynamics, 1.6.9 Coring, Fishing, 5.7 Reserves Evaluation, 5.4 Enhanced Recovery, 3 Production and Well Operations, 4.6 Natural Gas, 5.3.6 Chemical Flooding Methods (e.g., Polymer, Solvent, Nitrogen, Immiscible CO2, Surfactant, Vapex), 4.6 Natural Gas, 5.8 Unconventional and Complex Reservoirs, 5.7.2 Recovery Factors
- Enhanced Oil Recovery, Super-critical Huff and Puff, Liquid Rich Shale Reservoirs, Oil Mobilization
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Production of tight oil from shale reservoirs in North America reduces oil imports and has better economics than natural gas. Consequently, there is a strong interest in oil production from Bakken, Eagle Ford, and Niobrara. However, oil recovery factor for Bakken remains low, which is about four to six percent of the oil in place. Even with this low oil recovery factor, Bakken recoverable reserves are estimated to be 7.4 billion barrels; thus, a large volume of oil will remain unrecovered. This low level of oil recovery was the motivation to investigate the feasibility of enhanced oil recovery (EOR) in liquid-rich shale reservoirs such as Bakken.
In this paper, we will present both laboratory and numerical modeling of EOR in Bakken cores using CO2, C1-C2 mixture, and N2. The laboratory experiments were conducted at the Energy and Environmental Research Center (EERC). The experiments recovered 90+ percent oil from several Middle Bakken cores and nearly 40 percent from Lower Bakken cores. To decipher the oil recovery mechanisms in the experiments, a numerical compositional model was constructed to match laboratory oil recovery results. We concluded that solvent injection mobilizes matrix oil by miscible mixing and solvent extraction in a narrow region near the fracture-matrix interface, thus promoting counter-current flow of oil from the matrix instead of oil displacement through the matrix. Specifically, compositional modeling results indicate that the main oil recovery mechanism is miscible oil extraction at the matrix-fracture interface region. However, the controlling factors include re-pressurization, oil swelling, viscosity and interfacial tension reduction, diffusion-advection mass transfer, and wettability alternation.
We scaled up laboratory results to field applications via a compositional numerical model. For field applications, we resorted to the huff-and-puff protocol to assess the EOR potential for a North Dakota Middle Bakken well. We concluded that long soak times yields only a small additional oil compared to short soak times, and re-injecting wet gas, composed of C1,C2, C3, and C4+, produces nearly as much oil as CO2 injection.
|File Size||7 MB||Number of Pages||29|
Hawthorne, S. B., Gorecki, C. D., Sorensen, J. A., Steadman, E. N., Harju, J. A., Melzer, S., 2013. Hydrocarbon Mobilization Mechanisms from Upper, Middle, and Lower Bakken Reservoir Rocks Exposed to CO2. SPE 167200, SPE Unconventional Resources Conference Canada, 5-7 November, Calgary, Alberta, Canada.