A Novel Semianalytical Model for the Relationship between Formation Pressure and Water Saturation in Coalbed Methane Reservoirs
The accuracy of the relationship between formation pressure and water saturation has a direct impact on predicting the production performance of coal reservoirs. As a result, researchers are becoming more interested in this connection. The most commonly used method to evaluate this connection is the...
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| Natura: | Articolo |
| Lingua: | English |
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MDPI AG
2023-01-01
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| Serie: | Energies |
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| Accesso online: | https://www.mdpi.com/1996-1073/16/2/875 |
| _version_ | 1827626276731486208 |
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| author | Long Yang Yizhong Zhang Maolin Zhang Bin Ju |
| author_facet | Long Yang Yizhong Zhang Maolin Zhang Bin Ju |
| author_sort | Long Yang |
| collection | DOAJ |
| description | The accuracy of the relationship between formation pressure and water saturation has a direct impact on predicting the production performance of coal reservoirs. As a result, researchers are becoming more interested in this connection. The most commonly used method to evaluate this connection is the semianalytic method, but it disregards the impact of coal matrix shrinkage on pore compressibility, resulting in inaccurate water saturation estimations for coal reservoirs. A material balance equation that considers the effect of coal matrix shrinkage on cleat porosity and pore compressibility, as well as the gas–water relative permeability curve, is used for the first time in this study to establish a model between pressure and water saturation. Furthermore, this study extends the proposed pressure–saturation model to predict cumulative gas production and gas recovery, resolving the difficult problem of calculating recovery for coalbed methane reservoirs. To verify its accuracy, this study compares the proposed method with numerical simulations and previous methods; the results of the comparison show that the water saturation under formation pressure calculated by the method proposed in this study is closer to the results of the numerical simulation. Sun’s model ignores the effect of matrix shrinkage on pore compressibility, resulting in larger calculation results. The findings of this study indicate that the effect of coal matrix shrinkage on pore compressibility cannot be ignored, and that the proposed method can replace numerical simulation as a simple and accurate method for water saturation evaluation, which can be applied to predict cumulative gas and recovery estimation for closed coalbed methane reservoirs. The proposed method increases the accuracy of the semianalytical method and broadens its application. It is critical for the prediction of coal reservoir production performance and forecasting of production dynamics. |
| first_indexed | 2024-03-09T12:52:29Z |
| format | Article |
| id | doaj.art-f80074c8334d40febd3e6fe1d444dcb4 |
| institution | Directory Open Access Journal |
| issn | 1996-1073 |
| language | English |
| last_indexed | 2024-03-09T12:52:29Z |
| publishDate | 2023-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Energies |
| spelling | doaj.art-f80074c8334d40febd3e6fe1d444dcb42023-11-30T22:05:21ZengMDPI AGEnergies1996-10732023-01-0116287510.3390/en16020875A Novel Semianalytical Model for the Relationship between Formation Pressure and Water Saturation in Coalbed Methane ReservoirsLong Yang0Yizhong Zhang1Maolin Zhang2Bin Ju3School of Petroleum Engineering, Yangtze University, Wuhan 430113, ChinaSchool of Petroleum Engineering, Yangtze University, Wuhan 430113, ChinaSchool of Petroleum Engineering, Yangtze University, Wuhan 430113, ChinaSchool of Oil and Gas Engineering, Southwest Petroleum University, Chengdu 610500, ChinaThe accuracy of the relationship between formation pressure and water saturation has a direct impact on predicting the production performance of coal reservoirs. As a result, researchers are becoming more interested in this connection. The most commonly used method to evaluate this connection is the semianalytic method, but it disregards the impact of coal matrix shrinkage on pore compressibility, resulting in inaccurate water saturation estimations for coal reservoirs. A material balance equation that considers the effect of coal matrix shrinkage on cleat porosity and pore compressibility, as well as the gas–water relative permeability curve, is used for the first time in this study to establish a model between pressure and water saturation. Furthermore, this study extends the proposed pressure–saturation model to predict cumulative gas production and gas recovery, resolving the difficult problem of calculating recovery for coalbed methane reservoirs. To verify its accuracy, this study compares the proposed method with numerical simulations and previous methods; the results of the comparison show that the water saturation under formation pressure calculated by the method proposed in this study is closer to the results of the numerical simulation. Sun’s model ignores the effect of matrix shrinkage on pore compressibility, resulting in larger calculation results. The findings of this study indicate that the effect of coal matrix shrinkage on pore compressibility cannot be ignored, and that the proposed method can replace numerical simulation as a simple and accurate method for water saturation evaluation, which can be applied to predict cumulative gas and recovery estimation for closed coalbed methane reservoirs. The proposed method increases the accuracy of the semianalytical method and broadens its application. It is critical for the prediction of coal reservoir production performance and forecasting of production dynamics.https://www.mdpi.com/1996-1073/16/2/875coalbed methane reservoirsformation pressure and water saturationpore compressibilityrecoverymaterial balance |
| spellingShingle | Long Yang Yizhong Zhang Maolin Zhang Bin Ju A Novel Semianalytical Model for the Relationship between Formation Pressure and Water Saturation in Coalbed Methane Reservoirs Energies coalbed methane reservoirs formation pressure and water saturation pore compressibility recovery material balance |
| title | A Novel Semianalytical Model for the Relationship between Formation Pressure and Water Saturation in Coalbed Methane Reservoirs |
| title_full | A Novel Semianalytical Model for the Relationship between Formation Pressure and Water Saturation in Coalbed Methane Reservoirs |
| title_fullStr | A Novel Semianalytical Model for the Relationship between Formation Pressure and Water Saturation in Coalbed Methane Reservoirs |
| title_full_unstemmed | A Novel Semianalytical Model for the Relationship between Formation Pressure and Water Saturation in Coalbed Methane Reservoirs |
| title_short | A Novel Semianalytical Model for the Relationship between Formation Pressure and Water Saturation in Coalbed Methane Reservoirs |
| title_sort | novel semianalytical model for the relationship between formation pressure and water saturation in coalbed methane reservoirs |
| topic | coalbed methane reservoirs formation pressure and water saturation pore compressibility recovery material balance |
| url | https://www.mdpi.com/1996-1073/16/2/875 |
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