【作者】 黄耀综；

【导师】 刘树根；

【作者基本信息】 成都理工大学 ， 矿产普查与勘探， 2010， 硕士

【摘要】 米仓山隆起地处扬子地台(四川盆地)向北凸出的边缘,跨四川、陕西两省,西侧为碧口微地块和北东向的龙门山冲断带,北邻东西向秦岭造山带,东侧为北西向大巴山冲断带,南侧是四川盆地。本次研究主要是针对整个米仓山隆起周缘的下古生界地层,进行系统勘测和采样,从而对本区的烃源岩基本地质条件和有机质特征进行了解和分析。重点是本区的两套烃源岩层位,即:下寒武统的筇竹寺组(∈1q)和上奥陶统五峰组——下志留统龙马溪组。寒武系筇竹寺组烃源岩在米仓山隆起西北部和东南部出露完整,发育齐全,隆起的西南部和东北部则出露差一些。该组烃源岩下部主要为黑色中薄层页岩,含炭质粉砂质页岩。中下部主要为黄灰色薄板状钙质粉砂岩,风化后薄板状特征明显。中上部为黄灰——灰黑色中薄层泥岩,含粉砂质泥岩夹黄灰色中薄层泥质粉砂岩。上部是深灰——黄灰色中厚层钙质含泥质细——粉砂岩,偶夹灰岩透镜体。有效烃源岩厚度通常不超过80米。上奥陶统五峰组——下志留统龙马溪组的烃源岩在西北部零星出露,南部则连续分布。本组一段为黑色中薄层页岩、炭质页岩夹含放射虫生物化石硅质岩。底部为黄绿色中薄层含粉砂质页岩;中部为黑色薄层页岩;上部为黑色薄层含炭质页岩,水平层理发育。二段为黄绿——深灰色中薄层页岩夹泥质粉砂岩,下部为黄绿——黄灰色中薄层页岩夹泥质粉砂岩条带;中部为黄绿——灰绿色页岩;上部为深灰色薄层页岩夹薄层条带状粉砂岩。一般厚度在几十米至百米。下寒武统筇竹寺组TOC平均含量为2.29%,属好烃源岩。70%以上样品的残余热解生烃潜力S1+S2低于0.1mg/g,最大值不超过0.3 mg/g,平均值0.071 mg/g,已不能反映其原始生烃潜力。上奥陶统五峰组——下志留统龙马溪组TOC平均含量为0.11%,属非烃源岩。其热解生烃潜力低,64%样品的S1+S2分布在0.1～0.2%,这同样已不能反映该套烃源岩的原始生烃潜力。下寒武统筇竹寺组烃源岩样品的有机质类型指数超过90%,多数在97%以上,达到I型干酪根(类型指数>80)的标准,因此本区下寒武统筇竹寺组烃源岩的有机质类型为I型。米仓山隆起寒武系筇竹寺组烃源岩样品50%以上的等效镜质体反射率Ro(%)均超过2.0%,处于过成熟状态。本组样品的热解峰温大都高于490OC,意味着有机质成熟度处于生干气阶段,即RO>2。上奥陶统五峰组——下志留统龙马溪组烃源岩样品的热解峰温几乎均大于460 OC,即有机质成熟度处于高成熟——过成熟阶段,以产湿气和干气为主。饱和烃色谱图中大多数样品以单峰型为主,主碳数多为后碳型。烃源岩样品主峰碳多在18～24之间,而沥青样品的主峰碳则多为16。所取样品正构烷烃的后碳型主要与其处于过成熟阶段有关。整个米仓山隆起所采集样品的OEP和CPI值分别比较接近,除桥亭的一个样品(QT-64,上奥陶统——下志留统)外,测值均靠近1左右,无明显的奇偶优势,反映了本区烃源岩成熟度具有演化到较高程度的特点。所有样品的Pr/Ph均低,分布在0.24～0.93之间,以植烷占优势,反映了本区源岩的沉积特征以还原环境为主。通过分析米仓山隆起震旦系灯影组沥青和烃源岩样品的三环萜烷/ C30藿烷值、伽玛蜡烷/ C30藿烷值、重排甾烷/规则甾烷值,证明本区震旦系沥青与寒武系烃源岩具有亲缘关系,而不是来自上奥陶统——下志留统烃源岩。本区样品的规则甾烷表现出两种类型,分别是“V”字型和斜“L”型。其明显特征是以C27占优势,说明该区源岩生物主要来自低等的水生生物,存在于具有一定盐度的还原环境之中。米仓山隆起震旦系灯影组储层有着较好的烃源岩条件,地层封盖作用良好,自身储集性优越,具有一定的保存条件。故该区震旦系灯影组具有较好的油气勘探价值。米仓山隆起寒武系筇竹寺组页岩与美国Fort Worth盆地Barnett页岩在诸多方面具有一定的相似性,部分特征极为接近,预测该筇竹寺组页岩气藏有着广阔的发展远景。更多还原

【Abstract】 Micangshan uplift develops on the margin at the north in yangtsensis platform, and extends Sichuan province and Shanxi province. The west of Micangshan uplift is Bikou microblock and Longmenshan thrust belt, and at the north of it is Qinling orogenic zone, and to the east is Dabashan thrusted belt, while at the south is Sichuan basin.The aim of research is to study lower Palaeozoic strata in this region, collect samples to analyse and discern the geologic features of source rocks. Lower Cambrian Qiongzhusi formation and upper Ordovician- lower Silurian are the main source rocks in Micangshan uplift area.The source rocks of Qiongzhusi formation are much more integrated and better in northwest and southeast than in southwest and northeast. At the ease of this formation is the black median laminaed shale and some silty shale, with silicious lunker.The lower-middle of it is grey-yellow calcareeous siltstone, laminated which is much conspicuous after weathered. The middle-upper of it is yellow-black median laminaed mudstone and some argillaceous siltstone. The upper is grey-yellow medium siltstone with limestone lentes.The effective thickness of Source Rocks is not more than eighty metres.The Source Rocks of the upper Ordovician- lower Silurian is few in the northwest, while outcroping well in the south. The first fraction of this formation is black median lamina shale with the siliceous rocks of radiolarite. The bottom of it is yellow-green median laminaed silty shale. The middle of it is a black thin shale. The upper of it is a black thin shale, horizontally stratified. The second fraction of this formation is grey-yellow median lamina shale and pelitic siltstone. The bottom of it is yellow-green shale with silty bands,and the middle is green- grey shale. The upper of it is the deeply grey thin shale with rheoglyphs. The effective thickness of it is usually from dozens to one hundred metres.The average TOC of the lower Cambrian Qiongzhusi formation is 2.29 percent, which means that this formation could be good source rocks. The latent capacity of pyrolysed hydrocarbon in more than 70 percent of these samples is less than 0.1mg/g, and even the largest one is no more than 0.3mg/g. The average value of the samples is only 0.07mg/g, which can not represent the latent capacity.The average TOC of upper Ordovician- lower Silurian is 0.11 percent, which is very low. The latent capacity of pyrolysed hydrocarbon is very low and 64 percent of these samples are between 0.1 and 0.2mg/g, which is also not the criterion of the latent capacity.The index number of organic material in source rocks of the lower Cambrian Qiongzhusi formation is more than 90 percent, most samples of which are no less than 97 percent. According to this data, we can see that the type of organic material in Qiongzhusi formation belongs to type I.The vitrinite reflectance of more than 50 percent samples is over 2 percent in the lower Cambrian Qiongzhusi formation. This means that the formation is over matured. The maximal temperature of thermal decomposition in Qiongzhusi formation is higher than 490 degrees centigrade, which shows that the maturity of organic material is in dry gas phase.The upper Ordovician- lower Silurian is over matured, as the peak temperature thermolysis is moer than 460 degree. This formation mainly produces combination gas and dry gas.On the chromatogram pictures of satisfied hydrocarbons, most of the samples show unimodality and the main number of carbon is no less than 22. The main number of carbon in source rocks is between 18 and 24, and 16 in samples of bitumen. This feature is connected with post mature peroid inseparablely.The OEP and CPI of those samples in Micangshan uplift are much close with each other, which are almost 1, except one sample(QT-64). This reflects that the maturity of organic material in this region is in upper peroid. The Pr/Ph of all samples is very low ,which is between 0.24 and 0.93. This indicates that phytane gains ground, which indicates that the depositional feature is oxygen free environment.According to analyse the ratio of tricyclic terpane to hopanoid, the ratio of gammacerane to hopanoid and the ratio of diasteranes to regular gonane in source rocks and bitumen in Sinian Dengying formation, we see that the bitumen in Sinian is relative to source rocks in Cambrian, but not from upper Ordovician- lower Silurian.The types of regular gonane are‘V’and angular‘L’. The prominent feature is that the number of carbon is 27 in preponderance. This indicates that the organism producing the source rocks were mainly from ordinary aquatic life and in reducing environment with some solt.The reservoir Sinian Dengying formation bitumen in Micangshan uplift has mang advantage features, such as good source rocks, excellent sealing gland, superior reservoir strata and effective conservation. So Sinian Dengying formation is worthy of exploration.The Cambrian Qiongzhusi formation shale in Micangshan uplift has similar characteristic to the Barnett shale in Fort Worth basin in America. It is suggested that the Qiongzhusi formation shale gas pool may have good future.更多还原