Texture development of mesophase in reservoir pyrobitumen and the temperature-pressure converting of the gas reservoir in the Chuanzhong Uplift, Southwestern China  

作　　者：Cheng-Yu Yang Mei-Jun Li Tie-Guan Wang Ning-Ning Zhong Rong-Hui Fang Long Wen 

机构地区：[1]State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum,Beijing,102249,China [2]Oil&Gas Survey,China Geological Survey,Beijing,100083,China [3]The Key Laboratory of Unconventional Petroleum Geology,China Geological Survey,Beijing,100083,China [4]Exploration and Development Research Institute of Southwest Oil&Gasfield Company,PetroChina,Chengdu,Sichuan,610041,China

出　　处：《Petroleum Science》2023年第2期721-732,共12页石油科学（英文版）

基　　金：funded by the National Natural Science Foundation of China for Young Scholars(No.41903059).

摘　　要：The Neoproterozoic-Lower Paleozoic dolostone gas reservoirs in the Chuanzhong Uplift in Southwestern China contain the mesophase pyrobitumen (pyrobitumen with mesophase). The mesophase in the pyrobitumen is mostly composed of a mixture of condensed macromolecule polycyclic aromatic hydrocarbons (PAH), and has been mostly converted to various grain, flow, and domain textures. The volcanic activity nearby the Chuanzhong Uplift may have generated very hot (over 300 °C) hydrothermal fluid, with migration of the fluid into the dolostone reservoir transforming the hydrocarbons in the reservoir into an anisotropic carbon by-product, which formed under high temperature and pressure conditions;over 300 °C and 200 MPa according to fluid inclusion analysis. The high temperature-pressure in reservoir was caused by sudden devolatilization of the hydrocarbons due to hydrothermal heating, which formed the unusual texture of the mesophase. The elliptical mesophase grains (EG), the honeycomb structure of pyrobitumen, and the occurrence of polarized classes of mesophase in single pyrobitumen deposits are all unusual textures. This study investigates the texture development of this pressure-affected pyrobitumen. Observation and study of the mesophase suggest that the class of mesophase in pyrobitumen is determined by temperature, while pressure (assessed from associated fluid inclusions) significantly affected the texture. Analysis of the texture of the pyrobitumen in conjunction with previous thermometry results from methane inclusions suggests that the high class mesophase of the pyrobitumen could be applied as a temperature indicator for geological conditions. Furthermore, the unusual textures of the pyrobitumen including elliptical mesophase grains (EG), the honeycomb structure of pyrobitumen, and the occurrence of polarized classes of mesophase in single pyrobitumen could reflect the abnormal high formation pressure.

关 键 词：PYROBITUMEN MESOPHASE Optical texture Pressure affect Oil reservoir Chuanzhong Uplift 

分 类 号：TE344[石油与天然气工程—油气田开发工程]