Compositional and Geomechanical Effects in Huff-n-Puff Gas Injection IOR in Tight Oil Reservoirs
- Deepen Gala (The University of Texas at Austin) | Mukul Sharma (The University of Texas at Austin)
- Document ID
- Society of Petroleum Engineers
- SPE Annual Technical Conference and Exhibition, 24-26 September, Dallas, Texas, USA
- Publication Date
- Document Type
- Conference Paper
- 2018. Society of Petroleum Engineers
- 5.2.1 Phase Behavior and PVT Measurements, 5.1 Reservoir Characterisation, 5.2 Fluid Characterization, 5.1.10 Reservoir Geomechanics, 0.2 Wellbore Design, 5.4 Improved and Enhanced Recovery, 5.8.4 Shale Oil, 5.2.2 Fluid Modeling, Equations of State, 5.2 Reservoir Fluid Dynamics, 5.5 Reservoir Simulation, 5.4.2 Gas Injection Methods, 5 Reservoir Desciption & Dynamics, 0.2.2 Geomechanics
- Huff-n-Puff Gas IOR, liquid rich shale reservoirs, fracturing, Compositional reservoir simulation, Geomechanics
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Lab experiments, field pilots and numerical modeling focusing on fluid flow aspects have indicated that gas injection in tight oil reservoirs is technically feasible. Several operators have conducted pilot tests in the Eagleford and Bakken shales for a Huff-n-Puff IOR strategy with mixed results. Our objective in this work was to study the impact of geomechanical effects, such as permeability changes and opening and closure of fractures during injection and production, on such huff-n-puff processes. We developed a fully coupled geomechanical compositional reservoir simulator to model Huff-n-Puff gas injection for improving liquid recovery in tight oil reservoirs. The simulator solves component mass balances, a suitable equation of state and pressure equations which are coupled with rock deformation and calculates stress changes due to both poroelastic (pressure changes) and mechanical (fracture opening and closing) effects. The phase behavior of the injected gas with a specified composition (which is different from the in-situ reservoir fluid) is accounted for using phase stability and flash calculation algorithms.
We present results from simulations using representative rock and fluid data from an unconventional reservoir and observe the following trends using our simulation studies: (a) Selection of the gas injection rate is very important in order to achieve a substantial pressure increase during the injection period. (b) Geomechanical effects, permeability decrease during increasing effective stress and permeability increase during decreasing effective stress has a significant impact on overall oil recovery. (c) Huff-n-Puff IOR will be more successful in certain reservoirs than in others depending on the composition of the reservoir fluid, saturation pressure, producing GOR and geomechanical reservoir rock properties. Our simulation results provide operators with significant new insights on the design of gas injection IOR processes. It is shown that geomechanical effects during huff-n-puff cycles have a significant impact on oil recovery, particularly if natural fractures and planes of weakness are present. Specifically, several design questions can be answered such as (a) gas injection rates and volumes (b) impact of injection fluid and reservoir fluid composition (c) selection of candidate reservoirs (d) impact of operating bottomhole temperature and pressure.
|File Size||1 MB||Number of Pages||24|
Chhatre, S. S., Sinha, S.,Braun, E. M.,Esch, W. L.,Determan, M. D.,Passey, Q. R. and Kudva, R. A. (2014). Effect of Stress, Creep, and Fluid Type on Steady State Permeability Measurements in Tight Liquid Unconventional Reservoirs. URTEC 1922578-MS. Presented at Unconventional Resources Technology Conference, 25-27 August, Denver, Colorado, USA.
Fragoso, A.,Selvan, K., & Aguilera, R. (2018). An Investigation on the Feasibility of Combined Refracturing of Horizontal Wells and Huff and Puff Gas Injection for Improving Oil Recovery from Shale Petroleum Reservoirs. SPE 190284-MS. Presented at SPE Improved Oil Recovery Conference, 14-18 April 2018, Tulsa, Oklahoma, USA.
Kim, T. H., Park, S. S., & Lee, K. S. (2015). Modeling of CO2 Injection Considering Multi-Component Transport and Geomechanical Effect in Shale Gas Reservoirs. SPE 176174-MS. Presented at SPE/IATMI Asia Pacific Oil & Gas Conference and Exhibition, 20-22 October 2015, Nusa Dua, Bali, Indonesia.
Orangi, A.,Nagarajan, N. R.,Honarpour, M. M., & Rosenzweig, J. J. (2011). Unconventional Shale Oil and Gas-Condensate Reservoir Production, Impact of Rock, Fluid, and Hydraulic Fractures. SPE 140536-MS. Presented at SPE Hydraulic Fracturing Technology Conference, 24-26 January 2011, Woodlands, Texas, USA.
Yu, W.,Zhang, Y.,Varavei, A.,Sepehrnoori, K.,Zhang, T.,Wu, K., & Miao, J. (2018). Compositional Simulation of CO2 Huff-n-Puff in Eagle Ford Tight Oil Reservoirs with CO2 Molecular Diffusion, Nanopore Confinement and Complex Natural Fractures. SPE 190325-MS. Presented at SPE Improved Oil Recovery Conference, 14-18 April 2018, Tulsa, Oklahoma, USA.