Paragenesis and Formation Mechanism of the Dolomite-Mottled Limestone Reservoir of Ordovician Ma4 Member, Ordos Basin
Despite the discovery of high-producing natural gas reservoirs in the low-permeability dolomite-mottled limestone (DML) reservoir of the fourth Member (Ma4) of the Majiagou Formation in the Ordos Basin, the current understanding of the processes responsible for reservoir formation are still superfic...
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| Format: | Article |
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MDPI AG
2023-09-01
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| Series: | Minerals |
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| Online Access: | https://www.mdpi.com/2075-163X/13/9/1172 |
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| author | Zeguang Yang Aiguo Wang Liyong Fan Zhanrong Ma Xiaorong Luo Xinghui Ning Kun Meng |
| author_facet | Zeguang Yang Aiguo Wang Liyong Fan Zhanrong Ma Xiaorong Luo Xinghui Ning Kun Meng |
| author_sort | Zeguang Yang |
| collection | DOAJ |
| description | Despite the discovery of high-producing natural gas reservoirs in the low-permeability dolomite-mottled limestone (DML) reservoir of the fourth Member (Ma4) of the Majiagou Formation in the Ordos Basin, the current understanding of the processes responsible for reservoir formation are still superficial, which extremely restricts the effectiveness of deep petroleum exploration and development in the basin. Therefore, this study analyzed the paragenesis process of the DML reservoir through systematic petrographic and geochemical measurements. The DML consists of burrows and matrix. The burrows are mainly filled with dolomite with a small amount of micrite, calcite cement, and solid bitumen. The matrix mainly consists of wakestone or mudstone. The DML has experienced multiple diagenetic events, including seepage-reflux dolomitization, compaction, calcite cement CaI cementation, micrite recrystallization, dissolution, hydrocarbon charging, calcite cement CaII cementation, and dolomite progressive recrystallization. Dolomitization is critical to the DML reservoir formation. The pore created by dolomitization is the hydrocarbon-migrated pathway and storage space. Due to the difference in Mg<sup>2+</sup>-rich fluid supply, the degree of dolomitization decreases from west to east, which causes the difference in diagenetic evolution of the western and eastern parts of the study area. The high dolomitization degree led to strong anti-compaction ability in the west, contrary to the east. Thus, the reservoir quality of the west is better than the east. |
| first_indexed | 2024-03-10T22:26:18Z |
| format | Article |
| id | doaj.art-9e7ac103bb56401f8a4595ed38492943 |
| institution | Directory Open Access Journal |
| issn | 2075-163X |
| language | English |
| last_indexed | 2024-03-10T22:26:18Z |
| publishDate | 2023-09-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Minerals |
| spelling | doaj.art-9e7ac103bb56401f8a4595ed384929432023-11-19T12:05:20ZengMDPI AGMinerals2075-163X2023-09-01139117210.3390/min13091172Paragenesis and Formation Mechanism of the Dolomite-Mottled Limestone Reservoir of Ordovician Ma4 Member, Ordos BasinZeguang Yang0Aiguo Wang1Liyong Fan2Zhanrong Ma3Xiaorong Luo4Xinghui Ning5Kun Meng6State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi’an 710069, ChinaState Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi’an 710069, ChinaNational Engineering Laboratory of Low Permeability Oil and Gas Field Exploration and Development, Xi’an 710018, ChinaExploration Department, PetroChina Changqing Oilfield Company, Xi’an 710018, ChinaState Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi’an 710069, ChinaState Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi’an 710069, ChinaState Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi’an 710069, ChinaDespite the discovery of high-producing natural gas reservoirs in the low-permeability dolomite-mottled limestone (DML) reservoir of the fourth Member (Ma4) of the Majiagou Formation in the Ordos Basin, the current understanding of the processes responsible for reservoir formation are still superficial, which extremely restricts the effectiveness of deep petroleum exploration and development in the basin. Therefore, this study analyzed the paragenesis process of the DML reservoir through systematic petrographic and geochemical measurements. The DML consists of burrows and matrix. The burrows are mainly filled with dolomite with a small amount of micrite, calcite cement, and solid bitumen. The matrix mainly consists of wakestone or mudstone. The DML has experienced multiple diagenetic events, including seepage-reflux dolomitization, compaction, calcite cement CaI cementation, micrite recrystallization, dissolution, hydrocarbon charging, calcite cement CaII cementation, and dolomite progressive recrystallization. Dolomitization is critical to the DML reservoir formation. The pore created by dolomitization is the hydrocarbon-migrated pathway and storage space. Due to the difference in Mg<sup>2+</sup>-rich fluid supply, the degree of dolomitization decreases from west to east, which causes the difference in diagenetic evolution of the western and eastern parts of the study area. The high dolomitization degree led to strong anti-compaction ability in the west, contrary to the east. Thus, the reservoir quality of the west is better than the east.https://www.mdpi.com/2075-163X/13/9/1172Ordos BasinMa 4 Memberparagensisdolomitizationbioturbation |
| spellingShingle | Zeguang Yang Aiguo Wang Liyong Fan Zhanrong Ma Xiaorong Luo Xinghui Ning Kun Meng Paragenesis and Formation Mechanism of the Dolomite-Mottled Limestone Reservoir of Ordovician Ma4 Member, Ordos Basin Minerals Ordos Basin Ma 4 Member paragensis dolomitization bioturbation |
| title | Paragenesis and Formation Mechanism of the Dolomite-Mottled Limestone Reservoir of Ordovician Ma4 Member, Ordos Basin |
| title_full | Paragenesis and Formation Mechanism of the Dolomite-Mottled Limestone Reservoir of Ordovician Ma4 Member, Ordos Basin |
| title_fullStr | Paragenesis and Formation Mechanism of the Dolomite-Mottled Limestone Reservoir of Ordovician Ma4 Member, Ordos Basin |
| title_full_unstemmed | Paragenesis and Formation Mechanism of the Dolomite-Mottled Limestone Reservoir of Ordovician Ma4 Member, Ordos Basin |
| title_short | Paragenesis and Formation Mechanism of the Dolomite-Mottled Limestone Reservoir of Ordovician Ma4 Member, Ordos Basin |
| title_sort | paragenesis and formation mechanism of the dolomite mottled limestone reservoir of ordovician ma4 member ordos basin |
| topic | Ordos Basin Ma 4 Member paragensis dolomitization bioturbation |
| url | https://www.mdpi.com/2075-163X/13/9/1172 |
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