准噶尔盆地东北部二叠系平地泉组凝灰岩类成岩作用研究及其对孔隙的影响

发布时间：2018-04-24 20:41

本文选题：准噶尔盆地 + 二叠系平地泉组　；参考：《西北大学》2017年硕士论文

【摘要】：新疆准噶尔盆地东北部二叠系平地泉组形成于陆内裂谷背景下还原-弱氧化的咸化湖泊环境,沉积时期受火山活动和碱性岩浆-热液活动的影响,形成了一套与火山喷发和热液活动密切相关的特殊岩类。受大量偏碱性凝灰物质以及火山喷溢-喷流活动影响,研究区烃源岩局部温度场、压力场和化学场改变,热作用及加烃催化加速了湖相有机质的成熟和演化,使研究区平地泉组烃源岩具有早成熟、早运移、早成藏等特征。本文在综观研究区区域构造背景和沉积环境的基础上,结合岩石薄片显微镜下观察、扫描电子显微镜(SEM)、电子探针、X衍射、阴极发光等分析方法认为研究区的岩石类型主要有凝灰岩、沉凝灰岩、(含)凝灰质泥晶云岩等受岩浆-热液活动影响的凝灰岩类以及泥晶云岩、灰岩、陆源碎屑岩等正常沉积的岩类。研究区凝灰岩类的成岩作用总体是以碱性成岩环境为背景的,既有酸性成岩作用(长石、方沸石、碳酸盐矿物的溶蚀)的特征,也有碱性成岩作用的特征(石英溶蚀、碳酸盐沉淀、方沸石、碱性粘土矿物、自生钠长石等),呈现酸碱交替的特点,并表现出独特的成岩演化序列和成岩相(方沸石胶结成岩相,方沸石、长石溶蚀成岩相,碳酸盐矿物胶结成岩相等)。根据岩石组构特征、镜质体反射率、最大热解峰温等确定研究区凝灰岩类的成岩阶段处于中成岩A期;分析了碱性凝灰物质、岩浆-热液活动以及凝灰岩类成岩的成岩作用对孔隙类型和孔隙演化的影响。早成岩期早期具有碱性成岩特征,生成的方解石和方沸石胶结物,起到抗压实作用,保留了部分原生孔隙,早成岩中期受持续喷发而沉积的凝灰质所携带大量的热与催化加烃作用,有机质低熟生油,油较早进入岩石并占据孔隙,使储层岩石具有一定的抗压实性,较多的原生孔隙得以保留,且伴随产生的C02及有机酸在一定程度上溶蚀早期的方沸石、方解石胶结物使得次生孔隙含量增高,而由于有机酸和碳酸溶蚀碳酸盐矿物及其他矿物的同时自身也受到消耗,储层在早成岩晚期孔隙介质逐渐由酸性向碱性转变,即再次进入碱性成岩环境;中成岩A期,随着埋藏加深,岩石温度和压力发生变化,岩石中的有机质达到生烃门限,开始大量生成烃类并释放有机酸,对岩石中的碱性矿物进行溶解,形成次生孔隙,此时岩石再次进入酸性成岩环境。研究区这种特殊的酸碱交替成岩作用控制下产生多期次孔隙的特点,可能会对储层的孔隙产生重要的影响,同时也能为油气勘探提供新的方向和思路。
[Abstract]:The Permian Pingdiquan formation in the northeastern Junggar Basin, Xinjiang, was formed in the reduction-weakly oxidized saline lacustrine environment in the context of intracontinental rift. The sedimentary period was influenced by volcanic activity and alkaline magmatic hydrothermal activity. A special set of rocks closely related to volcanic eruptions and hydrothermal activity has been formed. Under the influence of a large amount of alkaline ash and volcanic spilling-jet activities, the local temperature field, pressure field and chemical field of the source rock in the study area are changed, the thermal process and hydrocarbon addition catalysis accelerate the maturation and evolution of the organic matter in the lacustrine facies. The source rocks of Pingdiquan formation in the study area are characterized by early maturity, early migration and early accumulation. In this paper, based on the regional tectonic background and sedimentary environment of the study area, the scanning electron microscope (SEM) and electron probe X ray diffraction (EPXRD) are used to study the structure and sedimentary environment of the area. The methods of catholuminescence analysis show that the main types of rocks in the study area are tuff, tuff, melitic dolomite, etc., which are affected by magma hydrothermal activity, and mudstone, limestone, etc. Normally deposited rocks, such as continental clastic rocks. The diagenesis of tuff in the study area is generally based on alkaline diagenesis, which is characterized by both acidic diagenesis (feldspar, analcite, dissolution of carbonate minerals) and alkaline diagenesis (quartz dissolution). Carbonate precipitation, analcite, alkaline clay minerals, authigenic albite and so on, show the characteristics of acid-base alternation, and show unique diagenetic evolution sequence and diagenetic facies (diagenetic facies formed by analite gel, analcite, feldspar dissolution diagenetic facies, etc.) Carbonate mineral glue forms lithofacies etc. According to the characteristics of rock fabric, vitrinite reflectance and maximum pyrolysis peak temperature, the diagenetic stage of tuff in the study area is in the middle diagenesis A stage. The effect of magma hydrothermal activity and diagenesis of tuff on pore type and pore evolution. In the early diagenetic stage, it is characterized by alkaline diagenesis, and calcite and donalite cementation play a role of anti-compaction and retain some primary pores. The tuff deposited in the middle of the early diagenetic period is carrying a large amount of heat and catalytic hydrocarbon addition, and the organic matter is low mature and the oil enters the rock earlier and occupies the pores, which makes the reservoir rock have certain compaction resistance. A large number of primary pores were preserved, and with the formation of CO2 and organic acids to some extent corrosion of the early zeolite, calcite cementation made the secondary pore content increased, As organic acids, carbonate minerals and other minerals are also consumed, the pore media of the reservoir gradually changes from acidic to alkaline in the late stage of early diagenesis, that is, it enters the alkaline diagenetic environment again, and the middle diagenesis stage A, With the deepening of burial, the rock temperature and pressure change, and the organic matter in the rock reaches the threshold of hydrocarbon generation, and begins to produce a large number of hydrocarbons and release organic acids, dissolving the alkaline minerals in the rocks and forming secondary pores. At this time, the rocks enter the acidic diagenetic environment again. This special acid-base alternant diagenesis, which produces multi-stage pores, may have an important impact on the porosity of the reservoir, and it can also provide a new direction and train of thought for oil and gas exploration.
【学位授予单位】：西北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P618.13

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