松辽盆地长岭断陷无机成因CO_2气成藏条件分析

随着深层天然气勘探的进展,在松辽盆地长岭断陷的多个气田中发现了含量不等的CO2气体。通过天然气的CO2碳同位素值和3He/4He值,分析了长岭断陷CO2气体的成因类型,认为长深2、长深4、长深6井区以及松南气田的CO2气体为幔源无机成因为主,而东岭气田的CO2气体为有机成因,这主要受控于断陷内的深大断裂的分布。盆地内地幔隆起导致地壳减薄而发育的低速高导岩浆房、长岭断陷深层"网状结构"的构造拆离带和基底深大断裂则是长岭断陷无机成因CO2气藏形成的有利条件。

Inorganic carbon dioxide gas reservoir formation in Changling Fault Depression,Songliao Basin

With the development of deep gas exploration, some huge, enriched zones of CO₂ have been found in the Changling Fault Depression of the Songliao Basin. The origin of the CO₂ was analyzed for carbon isotope values of and the 3He/4He ratio was determined. The CO₂ gas in the Changshen2, 4, 6 well blocks and the Songnan gas field is mainly inorganic gas sourced from the mantle, while that in the Dongling gas field is organic gas. The type was controlled by the distribution of deep fractures in the fault depression. The low-speed and high-conductivity magma chambers resulted from crustal thinning during mantle uplift, the "mesh structure" tectonic detachment belt in the deep Changling Fault Depression and the deep and extensive faults on the basement are the advantageous conditions for the formation of inorganic CO₂ reservoirs.