Prediction of Oil Recovery Factor in Stratified Reservoirs after Immiscible Water-Alternating Gas Injection Based on PSO-, GSA-, GWO-, and GA-LSSVM

In this study, we solve the challenge of predicting oil recovery factor (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>RF</mi></mrow></semantics></math></inline-formu...

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Main Authors: Pål Østebø Andersen, Jan Inge Nygård, Aizhan Kengessova
Format: Article
Language:English
Published: MDPI AG 2022-01-01
Series:Energies
Subjects:
Online Access:https://www.mdpi.com/1996-1073/15/2/656
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author Pål Østebø Andersen
Jan Inge Nygård
Aizhan Kengessova
author_facet Pål Østebø Andersen
Jan Inge Nygård
Aizhan Kengessova
author_sort Pål Østebø Andersen
collection DOAJ
description In this study, we solve the challenge of predicting oil recovery factor (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>RF</mi></mrow></semantics></math></inline-formula>) in layered heterogeneous reservoirs after 1.5 pore volumes of water-, gas- or water-alternating-gas (WAG) injection. A dataset of ~2500 reservoir simulations is analyzed based on a Black Oil 2D Model with different combinations of reservoir heterogeneity, WAG hysteresis, gravity influence, mobility ratios and WAG ratios. In the first model MOD1, RF is correlated with one input (an effective WAG mobility ratio <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mi>M</mi><mo>*</mo></msup></mrow></semantics></math></inline-formula>). Good correlation (Pearson coefficient −0.94), but with scatter, motivated a second model MOD2 using eight input parameters: water–oil and gas–oil mobility ratios, water–oil and gas–oil gravity numbers, a reservoir heterogeneity factor, two hysteresis parameters and water fraction. The two mobility ratios exhibited the strongest correlation with RF (Pearson coefficient −0.57 for gas-oil and −0.48 for water-oil). LSSVM was applied in MOD2 and trained using different optimizers: PSO, GA, GWO and GSA. A physics-based adaptation of the dataset was proposed to properly handle the single-phase injection. A total of 70% of the data was used for training, 15% for validation and 15% for testing. GWO and PSO optimized the model equally well (<i>R</i><sup>2</sup> = 0.9965 on the validation set), slightly better than GA and GSA (<i>R</i><sup>2</sup> = 0.9963). The performance metrics for MOD1 in the total dataset were: RMSE = 0.050 and <i>R</i><sup>2</sup> = 0.889; MOD2: RMSE = 0.0080 and <i>R</i><sup>2</sup> = 0.998. WAG outperformed single-phase injection, in some cases with 0.3 units higher RF. The benefits of WAG increased with stronger hysteresis. The LSSVM model could be trained to be less dependent on hysteresis and the non-injected phase during single-phase injection.
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spelling doaj.art-c6795bde3ad74e9b900bd68604bf28482023-11-23T13:39:58ZengMDPI AGEnergies1996-10732022-01-0115265610.3390/en15020656Prediction of Oil Recovery Factor in Stratified Reservoirs after Immiscible Water-Alternating Gas Injection Based on PSO-, GSA-, GWO-, and GA-LSSVMPål Østebø Andersen0Jan Inge Nygård1Aizhan Kengessova2Department of Energy Resources, Faculty of Science and Technology, University of Stavanger, 4021 Stavanger, NorwayBouvet, 4020 Stavanger, NorwayDepartment of Energy Resources, Faculty of Science and Technology, University of Stavanger, 4021 Stavanger, NorwayIn this study, we solve the challenge of predicting oil recovery factor (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>RF</mi></mrow></semantics></math></inline-formula>) in layered heterogeneous reservoirs after 1.5 pore volumes of water-, gas- or water-alternating-gas (WAG) injection. A dataset of ~2500 reservoir simulations is analyzed based on a Black Oil 2D Model with different combinations of reservoir heterogeneity, WAG hysteresis, gravity influence, mobility ratios and WAG ratios. In the first model MOD1, RF is correlated with one input (an effective WAG mobility ratio <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msup><mi>M</mi><mo>*</mo></msup></mrow></semantics></math></inline-formula>). Good correlation (Pearson coefficient −0.94), but with scatter, motivated a second model MOD2 using eight input parameters: water–oil and gas–oil mobility ratios, water–oil and gas–oil gravity numbers, a reservoir heterogeneity factor, two hysteresis parameters and water fraction. The two mobility ratios exhibited the strongest correlation with RF (Pearson coefficient −0.57 for gas-oil and −0.48 for water-oil). LSSVM was applied in MOD2 and trained using different optimizers: PSO, GA, GWO and GSA. A physics-based adaptation of the dataset was proposed to properly handle the single-phase injection. A total of 70% of the data was used for training, 15% for validation and 15% for testing. GWO and PSO optimized the model equally well (<i>R</i><sup>2</sup> = 0.9965 on the validation set), slightly better than GA and GSA (<i>R</i><sup>2</sup> = 0.9963). The performance metrics for MOD1 in the total dataset were: RMSE = 0.050 and <i>R</i><sup>2</sup> = 0.889; MOD2: RMSE = 0.0080 and <i>R</i><sup>2</sup> = 0.998. WAG outperformed single-phase injection, in some cases with 0.3 units higher RF. The benefits of WAG increased with stronger hysteresis. The LSSVM model could be trained to be less dependent on hysteresis and the non-injected phase during single-phase injection.https://www.mdpi.com/1996-1073/15/2/656water-alternating-gas (WAG)physics-informed machine learningleast square support vector machine (LSSVM)particle swarm optimization (PSO)dimensionless numbershysteresis
spellingShingle Pål Østebø Andersen
Jan Inge Nygård
Aizhan Kengessova
Prediction of Oil Recovery Factor in Stratified Reservoirs after Immiscible Water-Alternating Gas Injection Based on PSO-, GSA-, GWO-, and GA-LSSVM
Energies
water-alternating-gas (WAG)
physics-informed machine learning
least square support vector machine (LSSVM)
particle swarm optimization (PSO)
dimensionless numbers
hysteresis
title Prediction of Oil Recovery Factor in Stratified Reservoirs after Immiscible Water-Alternating Gas Injection Based on PSO-, GSA-, GWO-, and GA-LSSVM
title_full Prediction of Oil Recovery Factor in Stratified Reservoirs after Immiscible Water-Alternating Gas Injection Based on PSO-, GSA-, GWO-, and GA-LSSVM
title_fullStr Prediction of Oil Recovery Factor in Stratified Reservoirs after Immiscible Water-Alternating Gas Injection Based on PSO-, GSA-, GWO-, and GA-LSSVM
title_full_unstemmed Prediction of Oil Recovery Factor in Stratified Reservoirs after Immiscible Water-Alternating Gas Injection Based on PSO-, GSA-, GWO-, and GA-LSSVM
title_short Prediction of Oil Recovery Factor in Stratified Reservoirs after Immiscible Water-Alternating Gas Injection Based on PSO-, GSA-, GWO-, and GA-LSSVM
title_sort prediction of oil recovery factor in stratified reservoirs after immiscible water alternating gas injection based on pso gsa gwo and ga lssvm
topic water-alternating-gas (WAG)
physics-informed machine learning
least square support vector machine (LSSVM)
particle swarm optimization (PSO)
dimensionless numbers
hysteresis
url https://www.mdpi.com/1996-1073/15/2/656
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