酒西盆地原油溶解气中稀有气体同位素特征研究

对酒西盆地青西坳陷青西油田和南部隆起鸭儿峡油田8个原油样品进行了稀有气体测试分析,探讨了原油中氦的来源问题。青西油田4口井和鸭儿峡油田527井、702井原油3He/4He (Rc)为10-8量级,推测其原油中稀有气体是壳源放射性成因的,同时也说明与青西油田和鸭儿峡油田527井、702井有关的推覆断层的切割深度限于地壳范围内。鸭儿峡油田501井、114井原油样品3He/4He (Rc)达10-7量级,说明有少量幔源氦的混入,而与这两口井有关的推覆断层的切割深度可能已达地幔。酒西盆地大地热流值较低,平均50.9 mWm-2(6),表明其大地构造活动性较我国东部盆地弱。

PROBING RESEARCH OF CRUDE OIL NOBL GAS FROM THE JIUXI BASIN

The noble gas isotope of 8 crude oil samples of the Qingxi oil field in the Qingxi depression and Yaerxia oil field in the Southern uplift in the Jiuxi basin was measured. He source of the crude oils was discussed. The　3He/4He(Rc)ratios of the crude oil noble gases from 4 wells in the Qingxi oil field, the 527 well and the 702 well in the Yaerxia oil field reach an order of 10-8,indicating a crust radioactive source. This shows that the overthrusts related to the Qingxi oil field and the 527 well and the 702 well in the Yaerxia oil field cut into the depth of the crust. The　3He/4He(Rc)ratios of the crude oil noble gasesfrom the 501 well and the 114 well in the Yaerxia oil field is up to an order of 10-7, showing the input of a minor amount of mantle-derived helium and the cutting depth of the overthrusts associated with the two wells into the mantle. The geothermal flow of the Jiuxi basin is lower than that of the basins of eastern China, displaying that the basin has weak tectonic activity.