摘要
天然气组分和同位素不仅在成藏前受源岩类型、成熟度和成藏过程的控制,而且在成藏后还要受到次生作用如扩散作用的影响,特别是对于埋藏较浅的气藏,扩散作用的影响尤为显著;库车坳陷大宛齐油田就是受天然气扩散作用影响而形成次生油田的一个较为典型的实例。大宛齐油田埋深小于600m,其浅层溶解气组分明显偏"湿"、干燥系数为下高上低,天然气甲烷碳同位素则具有下轻上重的特征。通过对大宛齐油田和羊塔克气田的实际计算证明,扩散作用对埋藏较浅、成藏早的天然气影响很大。根据羊塔克等凝析气藏天然气中凝析油含量推算,形成大宛齐油田大致要散失(308～878)×108m3的天然气。
The components and its isotopes are controlled not only by source type, source maturity and formation process of natural gas, but also by other effect such as diffusion after pool formation. The diffusion influence on gas is bigger especially in shallow buried gas pool. Dawanqi oilfield is a secondary reservoir formed through gas diffusion, which is an example in much extreme condition. The buried depth of Dawanqi oilfield is less than 600m, with solution gas much 'wetter' in shallow layer, with dry coefficient much lower in shallow layer and much higher in deep layer, and with methane carbon isotope heavier in shallow layer and lighter in deep layer. Based on the calculation on gas diffusive content of two examples of Dawanqi oilfield and Yangtake gas condensate field, gas diffusion has very obvious effect on the gas pool which was buried shallowly and formed early. According to the condensate oil content of the discovered gas condensate reservoirs, it could be get that Dawanqi oilfield was formed with about( 308～878)×108 m3 gas being diffused.
出处
《天然气地球科学》
EI
CAS
CSCD
2003年第5期393-397,共5页
Natural Gas Geoscience
