海相油气地质2026，Vol.31Issue(4)：341-363,23.DOI:10.3969/j.issn.1672-9854.2026.04.003
中国海相碳酸盐岩大气田天然气成因
Genesis of natural gas in large marine carbonate gas fields in China
摘要
Abstract
Marine carbonate deep oil and gas is a major field of widespread concern both domestically and internationally.Through long-term exploration practices,China has achieved significant breakthroughs in the exploration of deep/ultra-deep marine carbonate oil and gas resources in the Sichuan,Ordos,and Tarim basins.However,debates persist regarding the genesis,sources,and formation evolution of gas reservoirs.Based on fundamental geological elements and formation conditions of gas reservoirs,and utilizing 940 sample data,this study analyzes the genesis,sources,and formation processes of China's large carbonate gas fields.The results indicate that:(1)Large carbonate gas fields in the three major marine basins share certain commonalities and differences.The commonality lies in the widespread low porosity and low to ultra-low permeability characteristics of reservoirs,with gas reservoirs having proven geological reserves exceeding 100 billion cubic meters being predominantly low-pressure to normal-pressure reservoirs.However,there are notable differences in productive layer distribution,reservoir burial depth,pressure coefficients,and porosity-permeability conditions.(2)The composition and isotopic characteristics of natural gas in these large carbonate gas fields differ significantly among the three basins,suggesting differences in organic matter types and thermal maturity of the parent materials.(3)Natural gas in the three basins primarily originates from high-to-overmature oil cracking gas,supplemented by mature kerogen cracking gas.The primary source is oil-type gas,accounting for approximately 88%according to preliminary estimates,while coal-type gas serves as a secondary source,comprising 12%.These gases have generally undergone secondary alterations such as TSR(thermochemical sulfate reduction)and gas invasion.(4)The natural gas in the three basins is sourced from multiple origins,with five source systems in the Sichuan Basin,two in the Ordos Basin,and two in the Tarim Basin.(5)Four accumulation models for large marine carbonate gas fields in China:(a)In-situ oil cracking gas accumulation in paleo-oil reservoirs under high geothermal gradient conditions,(b)gas-invasion-type reservoirs under low geothermal gradient conditions,(c)dual-source mixed cracking gas accumulation,and(d)three-dimensional accumulation controlled by fault-cap coupling.关键词
碳酸盐岩大气田/天然气来源/原油裂解气/干酪根裂解气/成藏模式/中国三大海相盆地Key words
large carbonate gas fields/natural gas sources/crude oil cracking gas/kerogen cracking gas/accumulation models/three major marine basins in China分类
能源科技引用本文复制引用
国建英,李明鹏,缪卫东,崔会英,韩中喜,谢增业,李剑,王晓梅,张斌,王义凤,肖鑫,王晓波,韩维峰,田继先..中国海相碳酸盐岩大气田天然气成因[J].海相油气地质,2026,31(4):341-363,23.基金项目
本文受中国石油天然气股份有限公司前瞻性基础性科技重大项目"大气田(区)成藏规律与勘探关键技术研究"(编号:2021DJ06)、中国石油天然气集团有限公司科技项目"中国陆相烃源岩系油气形成与富集机制研究"(编号:2025DJ102)联合资助 （区）
