油气幕式成藏的矿物学和地球化学记录——以准噶尔盆地西北缘油藏为例

报道了记录油气幕式成藏事件的含油环带状方解石等自生矿物及其地球化学特点。这种矿物发现在准噶尔盆地西北缘一些油气藏的油源断裂附近,方解石(或SiO₂裂隙填充物)内发育十余条或更多的烃类环带,与之相间生长的方解石的成分也频繁变化。地球化学示踪分析表明,含油气流体主要来源于深部二叠系,具有富含Fe和Mn等元素的特征,因此与油气充注密切相关的含油方解石明显富含Fe和Mn,使得环带状方解石的Fe,Mn和Mg等元素发生显著的波动特点,真实记录了含油气流体幕式充注的周期性过程。

Mineralogy and geochemical records of episodic reservoiring of hydrocarbon: example from the reservoirs in the northwest margin of Junggar basin

Authigenic minerals,such as calcite and etc.with oil-bearing girdles that recorded the traces of episodic reservoiring event and their geochemical characteristics,are studied in this paper.The calcite(also called SiO_2 the fissure filler),consisting of various components and interweaving with a dozen or more oil-bearing girdles inside them,is likely to be found near the source faults of some reservoirs in the northwest margin of Junggar basin.Geochemical tracing analysis suggests that the hydrocarbon-bearing fluids were mainly sourced from the deep of the Permian and had carried with them such elements as Fe,Mn,and etc..Therefore,the oil-bearing calcite in close relation to hydrocarbon charging is rich in Fe and Mn and the contents of Fe,Mn,and Mg in the calcite girdle fluctuate remarkably.This phenomenon honestly recorded the periodic process of the episodic charging of hydrocarbon-bearing fluids.