渤海中部高含CO气藏天然气成因及成藏主控因素——以秦南凹陷A气藏为例

The Natural Gas Origin and Key Control Factors on Gas Reservoir with High Contents CO in Middle Bohai Offshore

王粤川 王昕 李慧勇 杨海风

WANG Yuechuan WANG Xin LI Huiyong YANG Haifeng

中海石油(中国)有限公司天津分公司, 天津塘沽 300452

Tianjin Branch of CNOOC Ltd., Tianjin Tanggu, 300452, China

秦南凹陷A气藏是渤海海域中部古近系首个百亿方天然气发现,并且其CO2超过50%。基于天然气组分、稳定碳同位素、氦同位素、流体包裹体组分和均一温度等资料,分析了天然气的成因,并对天然气成藏主控因素进行了总结。结果表明,CO2的成因类型为火山幔源型无机成因气,烃类气为来自邻近洼陷沙河街组的油型气。A气藏的形成主要与晚期快速充注成藏有利于天然气的保存以及新近系强烈活动的凸起边界断裂控制了CO2的运聚有关。今后勘探中应重视深大断裂活动性对CO2含量分布的影响。

The QN-A gas reservoir in Qingnan Depression is the first discovery in the middle part of Bohai Sea, with ten billion cu-bic meters of gas reserves and has high CO2 contents over 50%. The natural gas origin and key control factors have been analyzed through analysis of gas components, stable carbon isotope, helium isotope and fluid inclusion components and homogenization tem-peratures. The results showed that CO2 was identified as volcanic mantle-source inorganic gas, and hydrocarbon gas is oil-type gas from Es Formation in adjacent depression. The key control factors of gas reservoir include the quick gas accumulation and strong ac-tivity Neogene boundary fault of uplift, which was beneficial to gas preservation and controlled the CO2 migration and accumulation separately. In future exploration we should pay attention to the change of CO2 contents controlled by fault activity.

https://doi.org/10.3969/j.issn.1008-2336.2013.02.028