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- Title
四川盆地涪陵气田白马向斜五峰组—龙马溪组 页岩气成藏地质条件及成藏模式.
- Authors
万云强; 陈践发; 陈 聪; 刘 超; 马 勇; 梁佳宝
- Abstract
At present, the breakthrough of shale gas exploration in China is mainly concentrated in the medium and shallow overpressured shale gas reservoir. With the deepening of research, shale gas exploration gradually goes to the deep layer. The Baima block of Fuling shale gas field is a deep overpressured gas reservoir with great exploration potential. Based on the well logging data and test analysis data of Wufeng-Longmaxi formations in well J148-1, the gas bearing characteristics and influencing factors of Wufeng-Longmaxi formations are analyzed in this paper, and the formation and enrichment mechanism of shale gas and the accumulation model of shale gas are discussed. The shale gas content of Wufeng-Longmaxi formations ranges from 1.09 to 6.81 m³/t (with an average of 3.15 m³/t), and increases with increasing depth. The average gas content of small formations 1-3 is 5.35 m³/t, which is a favorable shale gas interval. The total organic matter content, mineral composition, reservoir properties and preservation conditions all have a certain control effect on the gas content of the shale.TOC of the Wufeng-Longmaxi formations is between 1.29% and 5.50%(with an average of 2.75%), and increases with the increase of burial depth. Quartz content is 17.2%-64.7% (average 36.1%), feldspar content is 2.7%-14.5% (average 8.0%), carbonate mineral content is 2.0 %-56.6% (average 12.6%), pyrite content is 1.4%-6.7% (average 3.4%) . The clay mineral content is 17.2%-54.3% (average 40.1%) . The porosity of 1-4 layers is between 2.38% and 5.64% (average 4.06 %), the porosity of 8-9 layers is between 1.95 % and 2.75% (average 2.24%), and the permeability of 1-4 layers is between 0.03×10-3 and 16.43×10-3 μm² (average 0.75×10-3 μm²) . The permeability of 8-9 small layer ranges from 0.05×10-3 to 55.63×10-3 μm² (the average is 2.31×10-3 μm²), and the total organic matter content, brittle mineral content and porosity are positively correlated with the gas content. There are three types of pores in the shale: inorganic pores, organic pores and micro-fractures, mainly organic pores. The study area is far from the main fault, regional cap layer is developed, top and bottom lithology is dense, preservation conditions are good, free gas is abundant, and the reservoir formation model is broad and slow syncline. The shale of Wufeng-Longmaxi formations in the study area was immature from the end of Ordovician to the Late Silurian, entered the mature stage in the late Silurian, entered the high mature stage in the Middle Jurassic, entered the over-mature stage in the Late Jurassic, and stopped thermal evolution in the Middle Cretaceous.
- Subjects
SHALE gas reservoirs; CARBONATE minerals; NATURAL gas prospecting; OIL shales; GAS-lubricated bearings; SHALE gas; SHALE oils
- Publication
Natural Gas Geoscience, 2024, Vol 35, Issue 9, p1656
- ISSN
1672-1926
- Publication type
Article
- DOI
10.11764/j.issn.1672-1926.2024.01.003