摘要
四川盆地西部简阳地区二叠系火山岩储层内首次发现高密度甲烷包裹体,为火山岩气藏成因判识研究提供新的证据。笔者等以四川盆地简阳地区二叠系角砾熔岩及角砾凝灰岩的甲烷包裹体、盐水包裹体及沥青为研究对象,开展岩石学矿物学、拉曼光谱分析及包裹体测温等研究。结果表明,甲烷包裹体的甲烷拉曼位移峰为2909.78~2912.47 cm^(-1)、密度为0.21~0.34 g/cm^(3),具有高密度甲烷包裹体的特征。甲烷包裹体及焦沥青拉曼镜质体反射率(RMVRo)为3.32%~3.78%,指示储层的热演化程度较高。其中,甲烷包裹体内含C_(2)H_(6)、C_(3)H_(8)、SO_(2)等成分且储层中大量分布焦沥青,暗示气藏与古油藏裂解有关;与甲烷包裹体伴生的盐水包裹体均一温度为129.6~190.5℃(平均为165.8℃),该温度下流体包裹体P—V—T数值模拟结果表明石英和方解石内与烃类伴生的盐水包裹体的捕获压力为85.4~135.6 MPa、对应地层压力系数达1.9~2.3,反映储层具异常高压特征。简阳地区二叠系火山岩气藏中高密度甲烷包裹体为油藏裂解有关的异常高压所致,区内高密度的纯甲烷包裹体是裂解气藏富集的重要证据。综合高密度甲烷包裹体密度、组分及捕获温度可示踪裂解气藏演化过程。
Objectives:High-density methane inclusions were first discovered in Permian volcanic reservoirs in the Jianyang area of the western Sichuan Basin,providing new evidence for the genetic identification of volcanic gas reservoirs.Methods:This study utilized Raman spectroscopy to determine the density of methane inclusions.Subsequently,the reflectance of asphalt vitrinite was computed based on the results obtained from asphalt Raman spectroscopy.Furthermore,experiments were carried out to investigate the homogenization temperature in brine inclusions coexisting with hydrocarbons.Moreover,PVTsim simulations were employed to estimate the paleo-pressure of gas reservoirs in the Jianyang area.Results:The methane inclusions have a Raman shift peak ranging from 2909.78 to 2912.47 cm^(-1)and a density of 0.21 to 0.34 g/cm^(3),indicating their high-density characteristics.Furthermore,the reflectance of methane inclusions or pyrobitumen Raman vitrinite(_(RM)VR_(o))ranges from 3.32%to 3.78%,indicating a high degree of thermal evolution.The methane inclusions also contain components such as C_(2)H_(6),C_(3)H_(8),CO_(2),and a significant amount of pyrobitumen distributed throughout the reservoir,suggesting a connection between the gas reservoir and the cracking of ancient oil reservoirs.The homogenization temperature of brine inclusions in hydrothermal minerals varies from 137 to 183°C,with an average of 165.8°C.PVT simulation results show that the capture pressure of brine inclusions associated with hydrocarbons in quartz and calcite within the gas reservoir ranges from 85.4 to 135.6 MPa,corresponding to a formation pressure coefficient of 1.9 to 2.3.Conclusions:Methane contains C_(2)H_(6),C_(3)H_(8),CO_(2)and other components,with a significant amount of pyrobitumen distributed in the reservoir.This suggests that the gas reservoir is related to the cracking of the ancient reservoir.The homogenization temperature of the brine inclusions associated with methane ranges from 115 to 135.6 MPa,with the corresponding formation pressure coefficient between 1.9 and 2.3,reflecting the abnormally high-pressure characteristics of the reservoir.The formation of high-density methane inclusions in volcanic gas reservoirs in the Jianyang area is linked to reservoir cracking caused by deep burial,and high-density pure methane inclusions serve as important evidence for the enrichment of cracking gas reservoirs.Furthermore,the integration of density,composition,and homogenization temperature of high-density methane inclusions can serve as indicator for evolution pathway of cracked gas reservoirs.
作者
陈珺朗
刘小洪
谭聪
冯明友
谷志东
袁苗
李秋芬
张超
唐洪明
CHEN Junang;LIU Xiaohong;TAN Cong;FENG Mingyou;GU Zhidong;YUAN Miao;LI Qiufen;ZHANG Chao;TANG Hongming(School of Geoscience and Technology,Southwest Petroleum University,Chengdu,610500;Research Institute of Exploration and Development,PetroChina,Beijing,100083)
出处
《地质论评》
北大核心
2025年第5期1701-1715,共15页
Geological Review
基金
国家自然科学基金青年基金资助项目“火山岩储层中多种自生矿物共生机理及流体示踪意义”(编号:4120219)
中国石油天然气股份有限公司基础性前瞻性重大科技专项“叠合盆地中下组合形成演化与动力学机制研究”(编号:2023ZZ0201)的成果。
作者简介
陈珺朗,男,1999年生,硕士研究生,地质学专业,Email:1019054534@qq.com。;通讯作者:刘小洪,女,1980年生,博士,副教授,主要从事储层成岩作用研究与教学,Email:liuxiaohong_swpu@163.com。
