吐哈盆地火焰山中央隆起带稠油的成因机制研究

Study on Formation Mechanism of Heavy Oil in Huoyanshan Central Uplift Zone in Tuha Basin

通过对火焰山中央隆起带的石油地质和地球化学特征分析,对该区的稠油成因机理进行了研究。研究发现该区三叠系原油均有25-降藿烷和25,30-双降藿烷的存在,说明这一地区的原油普遍遭受了生物降解作用。其各个地区原油的降解程度也各不相同,其中构造低部位吐玉克地区降解程度相对较弱。英也尔地区原油的生物降解程度较高。流体包裹体的特征表明,在胜金口地区,原油充注时为正常原油,而后发生抬升和生物降解作用,从而形成稠油。玉东1井包裹体显示出现两次原油充注,稠油和正常原油。在鲁8、鲁9、鲁11、鲁2、鲁10井包裹体中,由西向东,随着埋藏深度的变低,第一期和第二期原油的充注逐渐由正常原油变为完全稠油充注。这说明原油可能在运移过程中逐渐稠化。而且鲁10井可能属于当时原油开始稠化时的关键点和开始组分散失与逸散的关键点。

The origin and formation mechanism of heavy oil have been studied by analyzing geological and geochemical characteristics of Huoyanshan central uplift zone. It has been found that 25 - norhopane and 25 - bisnorhopane and 30 - bisnorhopane are widely identified in Triassic crude oil, which indicated the petroleum biodegradation occurs in this region. The extent of biodegradation varies in different region, heavy petroleum biodegradation occurs in Yinyeer region and slight to moderate biodegradation occurs in Tuyuke region. The characteristics of fluid inclusion show the normal petroleum is filled in Shengjinkou region and thereafter petroleum is biodegraded because of rise of crust. The fluid inclusion of well Yudong 1 shows twice petroleum fillings ： normal oil and heavy oil are experienced. It is found that the petroleum filling varies from normal oil to heavy oil in Well Lu 8, Lu 9, Lu 11, Lu 2 ,Lu 10 （West to East） with the buried depth decreasing. It indicates crude oil might be thickening gradually during migration. The well Lu 10 is key point that crude oil began to thicken and components began to disperse and escape.