摘要
相对于有关降解原油方面的资料,有关微生物降解天然气方面的研究资料缺乏,如何确定微生物降解天然气的降解程度,尚无文献报道。通过对济阳坳陷东营凹陷八面河油田、单家寺油田和沾化凹陷孤岛油田原油、伴生天然气样品的实验分析后指出,微生物降解后的原油样品的P r/nC17、Ph/nC18、(P r+Ph)/(nC17+nC18)及C30αβ藿烷/(P r+Ph)值增加,与原油伴生的天然气的组分中甲烷含量增加,重烃含量降低,C2/C3值和C1/(C2+C3)值升高,丙烷和正丁烷的碳同位素组成明显偏重,丙烷的氢同位素组成也明显偏重,认为天然气的C1/(C2+C3)值、C2/C3值、丙烷和正丁烷的1δ3C值是判识天然气是否遭受微生物降解及其降解程度的地球化学指标,而原油的降解级别能够为识别伴生天然气的降解程度提供依据,但伴生天然气与原油的成藏时间(充注期次)应相同。
Researches on natural gas biodegradation are relatively rare compared to that on petroleum biodegradation. There is no documentation yet about how to confirm the biodegradation degree of biodegraded natural gases. Analysis on the oil and oil associated natural gas samples from the Bamianhe oil field and the Shajiasi oil field of the Dongying sag, the Gudao oil field of the Zhanhua sag of the Jiyang Depression suggests that biodegraded oil samples have the increase of Pr/nC17, Ph/nC18, （Pr＋Ph）/（nC17 ＋nC18） and C30αβ-hopane/（Pr＋Ph） ratios, and biodegraded natural gases have the increasing content of methane, decreasing contents of heavier hydrocarbons, increasing values of C2/C3 and C1/（C2＋C3） and heavier δ^13C values of propane and n-butane, as well as heavier δD value of propane. It shows that C2/C3 and C1/（C2 ＋ C3） values and δ^13C values of propane and n-butane in natural gases are geochemical parameters to distinguish biodegraded natural gases and their biodegradation degrees. When accumulated or charged at the same time, the oil biodegradation grade can provide basis for the identification of the oil associated natural gas biodegradation degree.
出处
《天然气地球科学》
EI
CAS
CSCD
2007年第5期703-708,共6页
Natural Gas Geoscience
基金
中国科学院院长奖获得者专项基金项目
国家重点基础研究发展规划项目(编号:2001CB209102)联合资助
关键词
天然气
微生物降解
碳同位素
济阳坳陷
Natural gas
Biodegradation
Carbon isotope
Jiyang depression.
