Thermal Evolution of Lower Silurian Longmaxi Formation in the Eastern Sichuan Basin(PDF)
《地球科学与环境学报》[ISSN:1672-6561/CN:61-1423/P]
- Issue:
- 2015年第06期
- Page:
- 22-32
- Research Field:
- 基础地质与矿产地质
- Publishing date:
Info
- Title:
- Thermal Evolution of Lower Silurian Longmaxi Formation in the Eastern Sichuan Basin
- Author(s):
- CAO Huan-yu; ZHU Chuan-qing; QIU Nan-sheng
- 1. State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China; 2. Exploration Company of SINOPEC, Chengdu 610041, Sichuan, China
- Keywords:
- thermal evolution; geothermal field; vitrinite reflectance; apatite fission track; shale gas; Lower Silurian; Longmaxi Formation; Sichuan Basin
- PACS:
- P618.130.2
- DOI:
- -
- Abstract:
- Thermal evolution of shale, which is the maturity stage in different geological times, has great importance in hydrocarbon exploration and development as well as hydrocarbon resource assessment. Thermal evolution of shale is mostly controlled by time and temperature, and especially by temperature. The thermal history in the eastern Sichuan Basin was reconstructed by geothermometer data of equivalent vitrinite reflectance and apatite fission track; the thermal evolution history of Lower Silurian Longmaxi Formation in the eastern Sichuan Basin was analyzed; the relationship between thermal evolution of shale and shale gas accumulation was discussed. The results show that the thermal state is stable from Late Proterozoic to Late Paleozoic in the eastern Sichuan Basin, and the heat flow is low (45-50 mW·m-2); the heat flow begins to increase during Hercynian, and reaches the peak (60-80 mW·m-2) in Late Permian (about 250 Ma), and then persistently decreases to the present value (45-65 mW·m-2); the maturity evolution and hydrocarbon generation process of Longmaxi Formation have two rapid maturation stages, including the crust extension of Dongwu movement in Hercynian and rapid bury of stratum since Late Triassic; the thermal evolution of Longmaxi Formation reaches the peak in Late Cretaceous (about 80 Ma), and the following intensive uplift and cooling lead to the termination of hydrocarbon generation; the thermal evolution has close relationship with shale gas accumulation, which can be divided into biogenic gas stage (250-430 Ma), pyrolysis gas stage (80-250 Ma) and uplifting and reforming stage (0-80 Ma) in Longmaxi Formation; rapid maturation and hydrocarbon generation provide the abundance of gas, and accelerate the formation of reservoir space, and the following rapid uplift and cooling improve the reservoir property of shale, and are advantageous for the preservation of shale gas.
Last Update: 2015-11-27