Liquid-Rich Shale Versus Conventional Depletion Performance
- Curtis Hays Whitson (Norwegian University of Science & Technology) | Guowen Lei (FMC Technologies) | Nan Cheng (Statoil)
- Document ID
- Society of Petroleum Engineers
- SPE/EAGE European Unconventional Resources Conference and Exhibition, 25-27 February, Vienna, Austria
- Publication Date
- Document Type
- Conference Paper
- 2014. Society of Petroleum Engineers
- 4.1.5 Processing Equipment, 1.2.3 Rock properties, 5.5.8 History Matching, 5.5 Reservoir Simulation, 5.8.4 Shale Oil, 5.2.1 Phase Behavior and PVT Measurements, 5.6.9 Production Forecasting, 5.3.2 Multiphase Flow, 5.2.2 Fluid Modeling, Equations of State, 5.1.1 Exploration, Development, Structural Geology, 5.8.8 Gas-condensate reservoirs, 4.1.2 Separation and Treating, 4.6 Natural Gas, 3.2.3 Hydraulic Fracturing Design, Implementation and Optimisation, 5.7.2 Recovery Factors
- Depletion Performance, Numerical Simulation, Liquid-Rich Shale, Unconventional versus Conventional
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This paper describes the major differences in production performance between liquid-rich shale reservoirs (LRSRs) and conventional reservoirs undergoing depletion recovery. We “map” the transition from conventional depletion performance (oil recovery and producing GOR) to “shale” depletion performance in terms of permeability. The recent research showed that depletion performance for LRSRs is fundamentally different from conventional reservoirs, which is well documented in the literature. This paper attempts to answer the questions - what differentiates conventional from (ultra-tight) shale depletion performance, and when is conventional performance invalid?
Our understanding of LRSRs depletion performance is only now being understood, based on modeling studies and field performance. Quantifying differences in LRSRs depletion performance from conventional reservoirs is important for proper engineering and development of these new resources. Production forecasting and recovery enhancement is a direct result of quantified depletion performance.
Results,Observations, and Conclusions
In this study we compare depletion performance for permeabilities ranging from 10nD to 10D, with PVT and rock properties being the same for all cases. We define a similar “economic” well performance for each permeability-case studied. Our results show that conventional reservoir performance, depending somewhat on initial fluid system, is observed for k>0.5md, while ultra-tight “shale” performance is found for k<1000nD (0.001md), with a gradual transition between these permeability values and shale-like depletion performance appearing already at 0.01md.
Significance of subject matter
Oil recovery factor is a highly ambiguous term for LRSRs with k<0.001md because the (arbitrarily) assigned drainage volume is inversely proportional with recovery factor, even though increasing drainage volume has almost no impact on oil rate or long-term cumulative oil produced; average reservoir pressure is also ambiguous for the same reasons.
|File Size||1 MB||Number of Pages||25|