Quantitative analyses of porosity evolution in tight grainstones: A case study of the Triassic Feixianguan formation in the Jiannan gas field,Sichuan Basin,China |
| |
| Institution: | 1. College of Earth Science and Engineering, Shandong University of Science and Technology, Qingdao 266590, China;2. Laboratory for Marine Mineral Resources, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266590, China;3. School of Geoscience, China University of Petroleum, Qingdao 266580, China;4. State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Changping, Beijing 102249, China;1. State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 10083, China;2. Beijing Research Institute of Uranium Geology, Beijing 100029, China;1. State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China;2. College of Geosciences, China University of Petroleum, Beijing 102249, China;3. School of Energy Science and Engineering, Henan Polytechnic University, Jiaozuo, Henan 454000, China;1. Northwest Oilfield Company, SINOPEC, Urumuqi, Xinjiang, 830011, China;2. Petroleum Exploration & Production Research Institute of Northwest Oilfield Company, SINOPEC, Urumuqi, Xinjiang, 830011, China;3. Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, 100029, China;1. Key Laboratory of Orogenic Belts and Crustal Evolution, School of Earth and Space Science, Peking University, Beijing 100871, China;2. Institute of Geophysics, Research Institute of Exploration and Development, PetroChina Xinjiang Oilfield Company, Xinjiang 830013, China;3. PetroChina Research Institute of Petroleum Exploration and Development, Beijing 100083, China;1. Key Laboratory of Tectonics and Petroleum Resources (China University of Geosciences), Ministry of Education, Wuhan, 430074, China;2. China University of Petroleum (Huadong), Qingdao, Shandong, 266580, China;3. Research Institute of Petroleum Exploration and Development, PetroChina, Beijing, 100083, China;4. China University of Petroleum, Changping, Beijing 102249, China;1. State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, PR China;2. China University of Petroleum, Beijing 102249, PR China;3. China National Petroleum Corporation, Beijing 100007, PR China;4. Oil and Gas Exploration and Development Institute of Tarim Oilfield, Korla 841000, PR China |
| |
| Abstract: | Tight grainstones, although widespread throughout the Lower Triassic Feixianguan Formation in the Sichuan Basin, have received little attention, in part, due to their lower porosity and greater heterogeneity relative to their dolostone counterparts. Based on data from cores and thin sections, as well as petrophysical properties, the Feixianguan grainstones, representing a major gas reservoir in the Jiannan gas field were systemically analysed to better understand porosity evolution in tight carbonates that have experienced original oil accumulation and subsequent thermal cracking during progressive burial. The grainstones were divided into two types according to whether pyrobitumen was present, and their porosity evolutions were quantitatively reconstructed. Taking 40% as the original porosity, the grainstones without pyrobitumen, which were ineffective palaeo-oil reservoirs, lost 21.94% and 3.13% of their porosities through marine and burial calcite cementation, respectively, and 13.34% by compaction, and have a current porosity of 1.59%, thus allowing them to serve as major present-day gas reservoirs. Comparatively, pyrobitumen-bearing grainstones, which were once palaeo-oil reservoirs, lost 23.96% and 2.36% of their porosities through marine and burial calcite cementation, respectively; 11.4% by compaction, and 1.44% by pyrobitumen and have a current porosity of 0.84%, thus making them ineffective gas reservoirs. This study provides a quantitative understanding of the close association between porosity evolution and reservoir effectiveness for the palaeo-oil charge and present-day gas accumulation with respect to diagenetic history, which is useful for the future exploration in tight gas limestone reservoirs. |
| |
| Keywords: | Tight grainstone Porosity evolution Diagenesis Feixianguan formation |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
