Research on the patterns of displacement of residual natural gas by nitrogen from a depleted reservoir
The features of the final stage of gas reservoir development and methods of increasing the final gas recovery factor are characterized. Using the licensed computer program Petrel&Eclipse, the regularities of displacement of residual natural gas by nitrogen from a depleted square-shaped gas reser...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Ukrainian Geological Company (UGC)
2025-03-01
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| Series: | Мінеральні ресурси України |
| Subjects: | |
| Online Access: | https://mru-journal.com.ua/index.php/mru/article/view/422 |
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| Summary: | The features of the final stage of gas reservoir development and methods of increasing the final gas recovery factor are characterized. Using the licensed computer program Petrel&Eclipse, the regularities of displacement of residual natural gas by nitrogen from a depleted square-shaped gas reservoir with four production wells in the corners of the square and an injection well in the center were investigated. The reservoir was developed to depletion until the reservoir pressure dropped to 0.1 of the initial pressure. The achieved gas recovery factor was 90.15%. Two scenarios of nitrogen injection into the reservoir were considered: for 12 months and continuously until the nitrogen content in the production gas reached 5 % by volume. The ratio of nitrogen injection rate to gas withdrawal rate was 1, 1.25, 1.5, 1.75, 2, 2.5. The results of the study are presented in the form of tables and graphs of the dependencies of the total gas recovery factor and the residual gas recovery factor on the nitrogen injection rate and maps of pressure distribution, saturation of the porous medium with nitrogen and reserves of untapped gas at the time of cessation of nitrogen injection into the reservoir.
According to the first scenario of nitrogen injection into the reservoir, with an increase in the ratio of nitrogen injection rate to gas withdrawal rate from 1 to 2.5, the gas recovery factor increases from 91.38 to 93.679 %, and the gas recovery factor for residual gas increases from 12.517 to 35.853 %. Only in the variant with a nitrogen injection rate to gas withdrawal rate ratio of 2.5 did nitrogen break through into the production wells, but its content in the production gas did not reach 5% by volume. Under the second scenario of nitrogen injection into the reservoir, with an increase in the ratio of nitrogen injection rate to gas withdrawal rate from 1 to 2.5, the gas recovery factor decreases from 95.505 to 94.384 %, and the gas recovery factor for residual gas decreases from 54.376 to 43.003 %. However, with an increase in the ratio of nitrogen injection rate to gas extraction rate from 1 to 2.5, the total period of reservoir completion decreases from 54 to 25 months (2.16 times), and the life of wells with joint natural gas and nitrogen extraction decreases from 15 to 7 months (2.14 times). According to the results of the study, in the conditions of nitrogen injection into a depleted gas reservoir, the degree of residual gas recovery can be maximized by selecting the appropriate values of the rate and duration of nitrogen injection based on technical and economic calculations. |
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| ISSN: | 1682-721X 2707-8698 |