An Approach to Oil Production Forecasting in a WAG Process Using Natural CO2

Ligero, Eliana Luci; Mello, Samuel Ferreira de; Mazo, Eduin Orlando Muñoz; Schiozer, Denis José

doi:10.2118/157680-ms

All Days 2012

DOI: 10.2118/157680-ms

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An Approach to Oil Production Forecasting in a WAG Process Using Natural CO2

Eliana Luci Ligero

Samuel Ferreira de Mello

Eduin Orlando Muñoz Mazo

et al.

Abstract: The water-alternating-gas process (WAG) was originally proposed to improve sweep efficiency during gas injection and it combines the advantages of gas and water flooding, better microscopic displacement efficiency and improved macroscopic sweep, respectively. Carbon dioxide is an attractive gas to be used in the Enhanced Oil Recovery (EOR) process, mainly, when the oil in place contains some dissolved CO2 which is produced in the gas phase. The WAG-CO2 can be an attractive recovery method in reservoirs with oi… Show more

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Cited by 2 publications

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Construction of Single-Porosity and Single-Permeability Models as Low-Fidelity Alternative to Represent Fractured Carbonate Reservoirs Subject to WAG-CO2 Injection Under Uncertainty

Menezes

Santos

et al. 2022

SPE EuropEC - Europe Energy Conference Featured at the 83rd EAGE Annual Conference &Amp; Exhibition

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Fractured carbonate reservoirs are typically modeled in a system of dual-porosity and dual-permeability (DP/DP), where fractures, vugs, karsts and rock matrix are represented in different domains. The DP/DP modeling allows for a more accurate reservoir description but implies a higher computational cost than the single-porosity and single-permeability (SP/SP) approach. The time may be a limitation for cases that require many simulations, such as production optimization under uncertainty. This computational cost is more challenging when we couple DPDP models with compositional fluid models, such as in the case of fractured light-oil reservoirs where the production strategy accounts for water-alternating-gas (WAG) injection. In this context, low fidelity models (LFM) can be an interesting alternative for initial studies. This work shows the potential of compositional single-porosity and single-permeability models based on pseudo-properties (SP/SP-P) as LFM applied to a fractured benchmark carbonate reservoir, subject to WAG-CO2 injection and gas recycle. Two workflows are proposed to assist the construction of SP-P models for studies based on (i) nominal approach and (ii) probabilistic approach of reservoir properties. Both workflows begin with a parametrization step, in which the pseudo-properties are optimized for a base case in order to minimize the mismatch between forecasts of the SP/SP-P and DP/DP models. The new parametrization methods proposed in this work showed to be viable for the construction of the SP/SP-P models. For studies under uncertainties, the workflow proposes obtaining pseudo-properties by robust optimizations based on representative models from a DP/DP ensemble, which proved to be an effective method. The case study is the benchmark UNISIM-II-D-CO with an ensemble of 197 DP/DP models and two different production strategies. The risk curves for production, injection and economic indicators obtained from DP/DP and SP/SP-P ensembles showed good match and the computational time spent on simulations of the SP/SP-P ensemble was 81% faster than DP/DP models, on average. Finally, the responses obtained from both ensembles were validated in a reference model (UNISIM-II-R) that represents the true response and is not part of the ensemble. The results indicate the SP/SP-P modeling as a good LFM for preliminary assessments of highly time-consuming studies. Besides, the workflows proposed in this work can be very useful for assisting the construction of SP/SP-P models for different case studies. However, we recommend the use of the high-fidelity models to support the final decision.

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Construction of Single-Porosity and Single-Permeability Models as Low-Fidelity Alternative to Represent Fractured Carbonate Reservoirs Subject to WAG-CO2 Injection Under Uncertainty

Menezes

Santos

et al. 2022

SPE EuropEC - Europe Energy Conference Featured at the 83rd EAGE Annual Conference &Amp; Exhibition

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Experimental Study on Injection Strategy of CO2 Near-Miscible Flooding in Low Permeability Reservoirs with High Water Cut

Chen

Yang

Liu³

et al. 2016

Day 1 Mon, November 14, 2016

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Lack of gas source and poor physical properties of oil are two key problems for the application limitation of CO2 miscible flooding in China. However, in Jilin oilfield, the discovery of natural gas reservoir with different CO2 content (5%-98%) make it possible, especially for some low permeability blocks. MMP determined by slim tube test is 23.5MPa. Reservoir pressures after prolonged waterflood development are maintained at 23 MPa to 24.5 MPa. Thus, CO2 near miscible flooding for these oilfields is of great potential. Advanced CO2 injection is proposed for the undeveloped blocks and WAG is proposed for the high water cut blocks. Long core (~1m) test shows that CO2 injection before oil production can ease the fast decline of reservoir pressure for this low permeability reservoir. Oil and CO2 has more time to contact then miscibility can be fully developed, fingering improved and oil damage of depleted development can be avoided. Recovery incremental is about 6.7%. In addition, injection rate, injection opportunity, injection pressure, water gas ratio (WGR), water cut, gas oil ratio and oil recovery were all considered to optimize the parameters of WAG in waterflooded reservoirs with different water cut (30%, 50%, 75%, and 90%). Results show that the optimum WGR is 1:2, and the optimum gas slug is 0.1 PV. Channeling and bypassing were concluded to be the main reason for the early breakthrough and low oil recovery considering the low transmissibility. However, slow gas injection rates, may fail to maintain pressures and oil rates. Thus, the optimum injection rate is 0.05 cc/min for both water and CO2. Also, it was found that the earlier the WAG conducted, the faster the water cut and oil production response, and the more obvious the water cut decline and oil recovery increase. Results show that more than ~30 % of the residual oil after water flooding could be recovered, which indicates that CO2 near miscible flooding, including advanced CO2 flooding and WAG, could be feasible in some blocks of this low permeability reservoir. The results of this study should contribute to our understanding of the mechanisms and injection strategy of CO2 near miscible flooding in water drive reservoirs and support the ongoing research, development and application of CO2 tertiary oil recovery process in Jilin Oilfield.

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An Approach to Oil Production Forecasting in a WAG Process Using Natural CO2

Cited by 2 publications

References 14 publications

Construction of Single-Porosity and Single-Permeability Models as Low-Fidelity Alternative to Represent Fractured Carbonate Reservoirs Subject to WAG-CO2 Injection Under Uncertainty

Construction of Single-Porosity and Single-Permeability Models as Low-Fidelity Alternative to Represent Fractured Carbonate Reservoirs Subject to WAG-CO2 Injection Under Uncertainty

Experimental Study on Injection Strategy of CO2 Near-Miscible Flooding in Low Permeability Reservoirs with High Water Cut

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