塔里木盆地哈拉哈塘凹陷东西两侧海相稠油地球化学特征:以LG7井和DH1-6-9井稠油为例

Geochemical characteristics of heavy oils from the east and west sides of Halahatang Depression,Tarim Basin,China:Exemplified by Oils of LG7 and DH1-6-9

塔里木盆地哈拉哈塘凹陷东侧轮古地区有丰富的海相稠油产出,其中包括大型的塔河油田群,在凹陷的西北缘也有海相稠油发现。凹陷东侧海相稠油的地球化学成因已经有较多的研究报道,而西北缘针对海相稠油的研究工作仍然十分薄弱,其地球化学成因仍需深入探讨。本工作以哈拉哈塘凹陷东西两侧的稠油LG7井和DH1-6-9井为例,对比研究其地球化学特征,重点对比分析稠油沥青质中吸附/包裹烃类化合物的地球化学应用。研究结果表明凹陷东西两侧的稠油藏至少经历了两期油气的充注,其中第一期充注来自同一套烃源岩,后期遭受了严重的生物降解改造;第二期充注来自另一套烃源岩,其正构烷烃仍然具有完整的分布模式。凹陷两侧稠油经历了相似的后期成藏过程,在西北缘相应的构造单元中可望发现更多海相来源的油气资源。

In the east side of Halahatang Depression, the Lungu area, Tarim Basin, a lot of marine heavy oils, including Tahe oilfields have been found, and some heavy oils from the northwestern side of the Depression were found, too. Many studies have been reported concerning the heavy oils from the east side of Halahatang while little was known for the heavy oils from the northwestern side of the Depression. This work geochemical characteristics of heavy oils of LG7 （from the east side） and DH1-6-9 （from the west geochemical analyses of the compounds adsorbed/occluded inside asphaltenes of the oils. The results Depression, studied the side）, e.g. indicate that both oils experienced more than one charges of petroleum fluids. The first charge of the two sites has been derived from the same set of source rocks, which were heavily altered by the post biodegradation occurring in the oil reservoirs, whereas the later charge（s） were derived from different source rocks. The similar geochemical characteristics and accumulation processes indicate that more marine oils are expected to be found from the corresponding tectonic units in the northwestern side of Halahatang Depression.