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松辽盆地烃类气和CO2大量共存,已发现多个高含CO2气藏;CO2具有无机、有机和混合3种成因,但以无机成因为主。从已发现含CO2天然气和区域地质综合分析出发,探讨了松辽盆地潜在的CO2气源及其脱气模式。研究表明,松辽盆地主要有幔源岩浆、火山岩、碳酸盐岩和有机质4种潜在的气源,结晶基底的幔源岩浆是松辽盆地最重要的气源,特别是新生代碱性玄武岩浆;沉积盖层的火山岩是松辽盆地另一种重要的气源,营城组和登娄库组的中酸性火成岩很有可能就是昌德东CO2气藏的主力生气层;变质基底的石炭系—二叠系碳酸盐岩是今后勘探中值得关注的气源;沉积盖层和变质基底中有机质丰富,但对高含量CO2气藏的形成贡献有限。气源不同导致有利的脱气模式亦不同:幔源CO2进入沉积盆地中具有沿岩石圈断裂直接脱气模式、热流底辟体脱气模式和壳内低速高导岩浆房—基底断裂组合脱气模式;火山岩最主要的脱气模式是火山岩吸附气后期脱气;碳酸盐岩接触变质作用和动力变质作用下脱气有利于CO2气成藏。
In the Songliao Basin, hydrocarbon gas and CO2 coexist abundantly, and a number of high-CO2 gas reservoirs have been discovered. CO2 has three types of inorganic, organic and mixed, but mainly inorganic. Based on the comprehensive analysis of CO2-bearing natural gas and regional geology, the potential source of CO2 gas and its degassing mode in Songliao Basin are discussed. The study shows that the Songliao Basin is mainly composed of mantle-derived magma, volcanic rock, carbonate rock and organic matter. The mantle-derived magma of crystalline basement is the most important gas source in the Songliao Basin, especially the Cenozoic alkaline basalt The volcanic rocks in the caprock are another important source of gas in the Songliao Basin. The moderate-acid igneous rocks in Yingcheng Formation and Denglouku Formation are likely to be the main gas-bearing layers of the Changde East CO2 gas reservoir. The metamorphic carboniferous The Carboniferous-Permian carbonate rocks are the gas sources of interest in future exploration. The organic matter is abundant in the sedimentary cover and metamorphic basement, but the contribution to the formation of high-CO2 gas reservoirs is limited. Different sources of gas result in favorable degassing modes: the mantle source CO2 enters the sedimentary basin with degassing patterns along the lithosphere faults, degassing patterns from the thermal flow diagenesis, and degassing of low-velocity and high-permeability magmatic chamber-basement fractures in the crust Mode. The most important degassing mode of volcanic rocks is deglazing of the later stage of volcanic adsorption gas. The degassing of carbonate rocks under metamorphism and dynamic metamorphism is favorable for CO2 gas accumulation.