Identification and Prediction of Allo-Source Overpressure Caused by Vertical Transfer: Example from an HTHP Gas Reservoir in the Ledong Slope in the Yinggehai Basin
The Yinggehai Basin is a typical high temperature and high pressure (HTHP) gas-bearing basin. The pressure coefficient exceeds 2.2 in deeply-buried Miocene reservoirs in the Ledong Slope, a nondiapir zone in the Yinggehai Basin. Determining the overpressure mechanisms and predicting the pore pressur...
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| Format: | Article |
| Language: | English |
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Wiley
2021-01-01
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| Series: | Geofluids |
| Online Access: | http://dx.doi.org/10.1155/2021/6657539 |
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| author | Caiwei Fan Changgui Xu Chao Li Aiqun Liu Hu Li Jingxian Hou Xiaoying Zhang Bin Lu Jun Li |
| author_facet | Caiwei Fan Changgui Xu Chao Li Aiqun Liu Hu Li Jingxian Hou Xiaoying Zhang Bin Lu Jun Li |
| author_sort | Caiwei Fan |
| collection | DOAJ |
| description | The Yinggehai Basin is a typical high temperature and high pressure (HTHP) gas-bearing basin. The pressure coefficient exceeds 2.2 in deeply-buried Miocene reservoirs in the Ledong Slope, a nondiapir zone in the Yinggehai Basin. Determining the overpressure mechanisms and predicting the pore pressure are key issues for natural gas exploration and development in the Ledong Slope. In this paper, overpressure mechanisms were investigated according to the analysis of vertical effective stress-logging responses and geological evaluations, and the pore pressure was predicted using the Bowers method. The loading-unloading crossplots indicated that the overpressure that existed in reservoirs mainly consists of two types: neighbor-source and allo-source overpressure. The neighbor-source overpressure is mainly caused by the pressure transmission from the adjacent mudstone to the reservoir, with a pressure coefficient less than 1.5 ~ 1.6. The high-magnitude overpressure points with pressure coefficients greater than 1.6 show a typical unloading response, indicating elevated sandstone pressures rather than in situ mudstone pressures, which are most likely to be generated by overpressure vertical transfer. The high-magnitude overpressure fluid generated by the high mature ultradeep buried N1s source rock migrated to the shallower reservoirs via hidden faults/microfractures, which led to the vertical transfer of overpressure. Vertically transferred overpressure was generated at 1.5 ~0.2 Ma, which is beneficial for the preservation of overpressure in lenticular sandbodies. The estimated pore pressure by the Bowers method is in good agreement with the measured pressure and provides a meaningful reference for predrilling pressure prediction in nondiapir or diapir zones in the Yinggehai Basin. |
| format | Article |
| id | doaj-art-788b8d9ab69e41b8a04ab83d721cc773 |
| institution | Kabale University |
| issn | 1468-8115 1468-8123 |
| language | English |
| publishDate | 2021-01-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geofluids |
| spelling | doaj-art-788b8d9ab69e41b8a04ab83d721cc7732025-02-03T06:46:11ZengWileyGeofluids1468-81151468-81232021-01-01202110.1155/2021/66575396657539Identification and Prediction of Allo-Source Overpressure Caused by Vertical Transfer: Example from an HTHP Gas Reservoir in the Ledong Slope in the Yinggehai BasinCaiwei Fan0Changgui Xu1Chao Li2Aiqun Liu3Hu Li4Jingxian Hou5Xiaoying Zhang6Bin Lu7Jun Li8Zhanjiang Branch of China National Offshore Oil Corporation Ltd., Zhanjiang 524057, ChinaZhanjiang Branch of China National Offshore Oil Corporation Ltd., Zhanjiang 524057, ChinaKey Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, ChinaZhanjiang Branch of China National Offshore Oil Corporation Ltd., Zhanjiang 524057, ChinaZhanjiang Branch of China National Offshore Oil Corporation Ltd., Zhanjiang 524057, ChinaZhanjiang Branch of China National Offshore Oil Corporation Ltd., Zhanjiang 524057, ChinaDimue Technologies Limited, Wuhan 430071, ChinaDimue Technologies Limited, Wuhan 430071, ChinaSchool of Earth Resources, China University of Geosciences (Wuhan), Wuhan 430074, ChinaThe Yinggehai Basin is a typical high temperature and high pressure (HTHP) gas-bearing basin. The pressure coefficient exceeds 2.2 in deeply-buried Miocene reservoirs in the Ledong Slope, a nondiapir zone in the Yinggehai Basin. Determining the overpressure mechanisms and predicting the pore pressure are key issues for natural gas exploration and development in the Ledong Slope. In this paper, overpressure mechanisms were investigated according to the analysis of vertical effective stress-logging responses and geological evaluations, and the pore pressure was predicted using the Bowers method. The loading-unloading crossplots indicated that the overpressure that existed in reservoirs mainly consists of two types: neighbor-source and allo-source overpressure. The neighbor-source overpressure is mainly caused by the pressure transmission from the adjacent mudstone to the reservoir, with a pressure coefficient less than 1.5 ~ 1.6. The high-magnitude overpressure points with pressure coefficients greater than 1.6 show a typical unloading response, indicating elevated sandstone pressures rather than in situ mudstone pressures, which are most likely to be generated by overpressure vertical transfer. The high-magnitude overpressure fluid generated by the high mature ultradeep buried N1s source rock migrated to the shallower reservoirs via hidden faults/microfractures, which led to the vertical transfer of overpressure. Vertically transferred overpressure was generated at 1.5 ~0.2 Ma, which is beneficial for the preservation of overpressure in lenticular sandbodies. The estimated pore pressure by the Bowers method is in good agreement with the measured pressure and provides a meaningful reference for predrilling pressure prediction in nondiapir or diapir zones in the Yinggehai Basin.http://dx.doi.org/10.1155/2021/6657539 |
| spellingShingle | Caiwei Fan Changgui Xu Chao Li Aiqun Liu Hu Li Jingxian Hou Xiaoying Zhang Bin Lu Jun Li Identification and Prediction of Allo-Source Overpressure Caused by Vertical Transfer: Example from an HTHP Gas Reservoir in the Ledong Slope in the Yinggehai Basin Geofluids |
| title | Identification and Prediction of Allo-Source Overpressure Caused by Vertical Transfer: Example from an HTHP Gas Reservoir in the Ledong Slope in the Yinggehai Basin |
| title_full | Identification and Prediction of Allo-Source Overpressure Caused by Vertical Transfer: Example from an HTHP Gas Reservoir in the Ledong Slope in the Yinggehai Basin |
| title_fullStr | Identification and Prediction of Allo-Source Overpressure Caused by Vertical Transfer: Example from an HTHP Gas Reservoir in the Ledong Slope in the Yinggehai Basin |
| title_full_unstemmed | Identification and Prediction of Allo-Source Overpressure Caused by Vertical Transfer: Example from an HTHP Gas Reservoir in the Ledong Slope in the Yinggehai Basin |
| title_short | Identification and Prediction of Allo-Source Overpressure Caused by Vertical Transfer: Example from an HTHP Gas Reservoir in the Ledong Slope in the Yinggehai Basin |
| title_sort | identification and prediction of allo source overpressure caused by vertical transfer example from an hthp gas reservoir in the ledong slope in the yinggehai basin |
| url | http://dx.doi.org/10.1155/2021/6657539 |
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