A new method for calculating gas saturation of low-resistivity shale gas reservoirs
The Jiaoshiba shale gas field is located in the Fuling area of the Sichuan Basin, with the Upper Ordovician WufengâLower Silurian Longmaxi Fm as the pay zone. At the bottom of the pay zone, a high-quality shale gas reservoir about 20Â m thick is generally developed with high organic contents and gas...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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KeAi Communications Co., Ltd.
2017-09-01
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| Series: | Natural Gas Industry B |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2352854017301274 |
| _version_ | 1797281807032385536 |
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| author | Jinyan Zhang Shurong Li Libin Wang Fang Chen Bin Geng |
| author_facet | Jinyan Zhang Shurong Li Libin Wang Fang Chen Bin Geng |
| author_sort | Jinyan Zhang |
| collection | DOAJ |
| description | The Jiaoshiba shale gas field is located in the Fuling area of the Sichuan Basin, with the Upper Ordovician WufengâLower Silurian Longmaxi Fm as the pay zone. At the bottom of the pay zone, a high-quality shale gas reservoir about 20Â m thick is generally developed with high organic contents and gas abundance, but its resistivity is relatively low. Accordingly, the gas saturation calculated by formulas (e.g. Archie) using electric logging data is often much lower than the experiment-derived value. In this paper, a new method was presented for calculating gas saturation more accurately based on non-electric logging data. Firstly, the causes for the low resistivity of shale gas reservoirs in this area were analyzed. Then, the limitation of traditional methods for calculating gas saturation based on electric logging data was diagnosed, and the feasibility of the neutronâdensity porosity overlay method was illustrated. According to the response characteristics of neutron, density and other porosity logging in shale gas reservoirs, a model for calculating gas saturation of shale gas was established by core experimental calibration based on the density logging value, the density porosity and the difference between density porosity and neutron porosity, by means of multiple methods (e.g. the dual-porosity overlay method by optimizing the best overlay coefficient). This new method avoids the effect of low resistivity, and thus can provide normal calculated gas saturation of high-quality shale gas reservoirs. It works well in practical application. This new method provides a technical support for the calculation of shale gas reserves in this area. Keywords: Shale gas, Gas saturation, Low resistivity, Non-electric logging, Volume density, Compensated neutron, Overlay method, Reserves calculation, Sichuan Basin, Jiaoshiba shale gas field |
| first_indexed | 2024-03-07T17:02:46Z |
| format | Article |
| id | doaj.art-4761f38f088340bd843a03a54fba81e8 |
| institution | Directory Open Access Journal |
| issn | 2352-8540 |
| language | English |
| last_indexed | 2024-03-07T17:02:46Z |
| publishDate | 2017-09-01 |
| publisher | KeAi Communications Co., Ltd. |
| record_format | Article |
| series | Natural Gas Industry B |
| spelling | doaj.art-4761f38f088340bd843a03a54fba81e82024-03-03T03:12:42ZengKeAi Communications Co., Ltd.Natural Gas Industry B2352-85402017-09-0145346353A new method for calculating gas saturation of low-resistivity shale gas reservoirsJinyan Zhang0Shurong Li1Libin Wang2Fang Chen3Bin Geng4Corresponding author.; Well Logging Company of Sinopec Shengli Oilfield Service Corporation, Dongying, Shandong 257096, ChinaWell Logging Company of Sinopec Shengli Oilfield Service Corporation, Dongying, Shandong 257096, ChinaWell Logging Company of Sinopec Shengli Oilfield Service Corporation, Dongying, Shandong 257096, ChinaWell Logging Company of Sinopec Shengli Oilfield Service Corporation, Dongying, Shandong 257096, ChinaWell Logging Company of Sinopec Shengli Oilfield Service Corporation, Dongying, Shandong 257096, ChinaThe Jiaoshiba shale gas field is located in the Fuling area of the Sichuan Basin, with the Upper Ordovician WufengâLower Silurian Longmaxi Fm as the pay zone. At the bottom of the pay zone, a high-quality shale gas reservoir about 20Â m thick is generally developed with high organic contents and gas abundance, but its resistivity is relatively low. Accordingly, the gas saturation calculated by formulas (e.g. Archie) using electric logging data is often much lower than the experiment-derived value. In this paper, a new method was presented for calculating gas saturation more accurately based on non-electric logging data. Firstly, the causes for the low resistivity of shale gas reservoirs in this area were analyzed. Then, the limitation of traditional methods for calculating gas saturation based on electric logging data was diagnosed, and the feasibility of the neutronâdensity porosity overlay method was illustrated. According to the response characteristics of neutron, density and other porosity logging in shale gas reservoirs, a model for calculating gas saturation of shale gas was established by core experimental calibration based on the density logging value, the density porosity and the difference between density porosity and neutron porosity, by means of multiple methods (e.g. the dual-porosity overlay method by optimizing the best overlay coefficient). This new method avoids the effect of low resistivity, and thus can provide normal calculated gas saturation of high-quality shale gas reservoirs. It works well in practical application. This new method provides a technical support for the calculation of shale gas reserves in this area. Keywords: Shale gas, Gas saturation, Low resistivity, Non-electric logging, Volume density, Compensated neutron, Overlay method, Reserves calculation, Sichuan Basin, Jiaoshiba shale gas fieldhttp://www.sciencedirect.com/science/article/pii/S2352854017301274 |
| spellingShingle | Jinyan Zhang Shurong Li Libin Wang Fang Chen Bin Geng A new method for calculating gas saturation of low-resistivity shale gas reservoirs Natural Gas Industry B |
| title | A new method for calculating gas saturation of low-resistivity shale gas reservoirs |
| title_full | A new method for calculating gas saturation of low-resistivity shale gas reservoirs |
| title_fullStr | A new method for calculating gas saturation of low-resistivity shale gas reservoirs |
| title_full_unstemmed | A new method for calculating gas saturation of low-resistivity shale gas reservoirs |
| title_short | A new method for calculating gas saturation of low-resistivity shale gas reservoirs |
| title_sort | new method for calculating gas saturation of low resistivity shale gas reservoirs |
| url | http://www.sciencedirect.com/science/article/pii/S2352854017301274 |
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