【作者】 沈艳杰；

【导师】 程日辉；

【作者基本信息】 吉林大学 ， 矿产普查与勘探， 2012， 博士

【摘要】 随着松辽盆地营城组深层火山油气藏勘探的成功实践，火山岩（包括火山碎屑岩）作为储层的研究日益得到极大的关注。火山碎屑岩是火山熔岩与沉积岩之间的过渡岩性，其相-结构研究对于储层地质特征（包括物性特征）具有重要意义。松辽盆地东南缘出露的火山岩露头，提供了盆地火山碎屑岩相-结构研究的良好剖面。与徐家围子断陷营城组火山碎屑岩的比较性研究，以及为由此建立的火山碎屑岩相结构模式为盆地火山碎屑岩储层研究提供了研究平台。本文以松辽盆地南缘露头区出露的火山熔岩和火山碎屑岩为研究对象，通过火山岩样品年代学研究，建立了营城组1-10Ma尺度的年代地层格架。利用地球化学分析，对比了火山碎屑岩地层，为划分火山旋回和火山喷发期次提供了元素地球化学的证据；对于同一冷凝单元内部的“热基浪相-热碎屑流相-空落相”给出了以K2O为代表的主量元素含量变化规律。结合年代学和元素地球化学，讨论了营城组形成的盆地构造背景，认为松辽盆地营城期为造山期后的伸展盆地。通过对破火山口岩性序列重建和火山口发育过程恢复，形成两种火山口发育模式，即①酸性岩浆活动形成的“蒸气爆发-蒸气岩浆爆发”火山口模式和②中基性岩浆活动形成的“爆炸-喷溢”-“爆炸-溢流”-“岩浆侵出”火山口模式。结合运用粒度分析、筛分分析和碎屑组成等方法，研究了营城组原发火山碎屑岩堆积和再搬运火山碎屑堆积，建立了原发火山碎屑堆积相结构模式（包括热基浪堆积、热碎屑流堆积、空落堆积）和再搬运火山碎屑堆积相结构模式（包括河流-冲积平原和三角洲-湖泊上的热碎屑流堆积、热基浪堆积、火山泥石流堆积以及熔积岩沉积）。根据火山碎屑岩相结构模式，分析了徐家围子断陷火山熔岩-火山碎屑岩储层与岩性和岩相的关系，得出同一冷凝单元内，热碎屑流相的储集性能好于热基浪相和空落相。近火山口-火山斜坡堆积的火山碎屑岩储层物性好于火山斜坡-过渡环境中的火山碎屑堆积。具体的研究成果和认识有7个方面：1．确定了营城组火山旋回时限，建立了营城组年代地层格架确定的松辽盆地营城组沉积时限与火山旋回时限为，营一段沉积时限为120-134Ma，火山旋回时限为2.34-7.0Ma；营二段沉积时限为115-120Ma，火山旋回时限为1.25Ma；营三段沉积时限为110.7-115Ma，火山旋回时限为1.0-1.3Ma。由此建立了松辽盆地营城组1-10Ma尺度的年代地层格架。2．实现了元素地球化学的火山碎屑岩地层对比，确定了松辽盆地营城组时期为造山后伸展构造背景建立了营城组火山碎屑岩剖面主量元素氧化物Na2O、K2O、Al2O3和SiO2含量曲线，实现了火山碎屑岩地层的对比，给出了同一冷凝单元内“热基浪-热碎屑流-空落”以K2O为代表的主量元素含量规律。确定了营城组时期盆地构造背景为造山期后的裂谷伸展环境。3．建立了火山口相结构模式建立的火山口发育模式有两类，①“蒸气爆发-蒸气岩浆爆发”火山口模式，火山口由酸性岩浆活动形成，堆积岩性为蒸气爆发的集块、角砾岩-蒸气岩浆爆发的角砾熔岩和凝灰夹熔岩-侵出和侵入作用形成的珍珠岩和隐爆角砾岩。②“爆炸-喷溢”-“爆炸-溢流”-“岩浆侵出”火山口模式，火山口由中基性岩浆活动形成，堆积岩性为集块/角砾岩与熔岩互层。4．建立了火山斜坡相结构模式建立了“热基浪-热碎屑流-空落”结构的冷凝单元模式。热基浪具2相结构，下部为爆发角砾岩堆积；中上部为玻屑/晶屑/岩屑凝灰岩堆积；热碎屑流具3相结构，下部为角砾岩堆积，中部为熔结凝灰岩，上部为玻屑凝灰岩；空落具2相结构，底部为弹射坠落的火山角砾岩，顶部为喷射降落的含角砾凝灰岩、岩屑/玻屑凝灰岩。5．建立了再搬运相结构模式建立的再搬运火山碎屑岩相结构模式有两类，①在河流-冲积平原和三角洲-湖泊上的热碎屑流、热基浪相模式，相序与斜坡堆积相似，但火山碎屑具再搬运特征。②火山泥石流堆积相模式，包括同喷发期垮塌成因模式和喷发期后剥蚀成因模式。6．确定了有利储层的火山碎屑岩相在徐家围子断陷，同一冷凝单元内热碎屑流相的储集性能好于热基浪相、空落相和热碎屑流与空落的混合相。受空落物质影响，含有细粒空落物质降低岩相的储层物性。7．确定了有利储层的火山碎屑岩性在徐家围子断陷，确定的有利储层的岩性为热碎屑流相堆积的流纹质岩屑晶屑凝灰岩，热基浪相堆积的含角砾岩屑晶屑凝灰岩，空落相堆积的流纹质角砾凝灰岩。更多还原

【Abstract】 With the successful practices in volcanic oil and gas reservoir exploration of Yingcheng formationin Songliao basin, the volcanic reservoir rock (including pyroclastic rock) has drown more attention.Pyroclastic rock is a transitional rock developed between lava and sedimentary rocks, and the faciesand archateture of pyroclastic rock is an important part in the reservoir study. There are a large numberof volcanic outcrops in the south-eastern margin of Songliao basin, providing profiles for studying thevolcanic clastic rock facies and archateture.Volcaniclastic rock facies models are built up basedon the study of the outcrops, and these models provide a platform for analysis the volcanicclastic rockreservoir.Based on geochronology study of those main studying objects, which are pyroclasticrocks and lava rocks in the south eastern margin of songliao basin, the chronostratigraphic frameworkof Yingcheng formation with a 1-10Ma scale is built up.Using of geochemical analysis correlates ofthe two pyroclastic rocks outcroped sections，and provides proofs for dividing of volcanic eruptioncycles and stages. The changing laws of the major elements as represented by K2O, is given in a＂base surge-pyroclastic flow-airfall＂cooling unit. The tectonic setting of the basin in Yingcheng stagewas a rifting-extension basin related to post-orogenic geological processes discussed in isotopicgeochronology and geochemistry. Two models of the crater developing process are given, byreconstructing the lithologic sequences and the development process of the craters, which are①＂vapour explosion-vapour magma explosion＂crater model of acidic magmation, and②＂explosion-effusion＂-＂explosion-effluence＂-＂magma extrusion＂crater model ofintermediate-basic magmation.The original erupting and re-worked sediments are studies through the outcrop studycombining with grian size analysis, sieve analysi and detrital component analysis, and the pyroclastic deposits models of facies and architecture (including base surge, pyroclastics flow and airfallsediments) and re-worked sediments models of facies and architecture (including base surge,pyroclastics flow and airfall on fluvial plain and delta-lacustrine, lahar and peperite sediments). Therelationship between lithology-facies and lava-volcaniclastic rock reservoir is discused in Xujiaweizifault depression after those facies and architecture models mentioned above. The conclusion is obtainedthat the reservoir performance of pyroclastic flow is better than base surge and airfall, and pyroclasticsediments on the crater and nearby volcano slope are better than those on the volcano slope -transitional environment. There are 7 main achievements as fellows:1.Determined the volcanic cycle geochronology of Yingcheng formation, and built upchronostratigraphic framework of Yingcheng formationThe sedimengtary geochronology of Yingcheng formation is 110.7-134Ma. Elevenvolcanic/sedimentary cycles in three members of Yingcheng formation. Ages are as following：120-134Ma (Member 1),115-120Ma (Member 2) and 110.7-115(Member 3). Based on thesegeochronology, the chronostratigraphic framework in 1-10Ma scale of Yingcheng formation isestablished.2.Attained pyroclastic rock strata correlation by element geochemistry，determined thetectonic setting in the stage of Yingcheng formation as rifting-extension related to post-orogenicgeological processesThe content curves of Na2O, K2O, Al2O3and SiO2of Yingcheng pyroclastic rocks are received,and strata correlation of pyroclastic rocks is attained. A regularity of K2O content of pyroclastic rocksin the cooling unit with＂base surge- pyroclastic flow-airfall＂is taken. The tectonic setting in the stageof Yingcheng formation was rifting-extension related to post-orogenic geological processes.3.Established the crater model of facies and architectureThere are two types of crater facie and architecture models.①is＂vapour explosion-vapourmagma explosion＂crater model caused by the acidic magmation, and accumulation of lithologyincluding volcanic agglomerate and breccia( production of vapour explosion), agglomerate lava andtuff interbeded with lava (production of vapour lava explosion), and Pearlite and breccia withcryptoexplosive structure (production of intrusion and extrusion);②is＂explosion-effusion＂-＂explosion-effluence＂-＂magma extrusion＂crater model caused by the intermediate-basic magmation,and accumulation of lithology is of alternate layers of agglomerate/ breccia and lava.4.Established the volcano slopes model of facies and architectureEstablished the cooling unit model of archetacture with " base surge-pyroclastic flow -airfall".Base surge model has a two- facies archetacture, the lower is composed of explosion breccia , themiddle-upper is composed of vitric,crystal and debris tuffs. Pyroclastic flow has a three- facies archetactur, the lower is composed of coarse fragment deposition of breccia/ breccia-bearing, themiddle is composed of ignimbrite.and the upper is composed of vitric tuffs in which pumice is enriched.Airfall has a two-facies archetacture. In the bottom there are catapult airfall deposits composed ofbreccia, breccia lava, breccia-bearing tuff. In the top there are ejection airfall deposits ofbreccia-bearing tuff, crystal,debris, vitric tuff.5.Established re-worked pyroclastics model of facies and architectureThere are two types of re-worked architecture models.①is pyroclastic flow and base surge onfluvial plain and delta–lake, and lithofacies sequence is similar to that on volcanic slopes, however thepyroclastics are re-worked in a certain part.②is lahar deposit including the genetic model of collapsedaccumulation at the same time with the eruption and the genetic model of erosion- accumulation afterthe eruption.6.Determined the pyroclastic rock facies of the favorable reservoirWith in a cooling unit，reservoir propertiy of the pyroclastic flow is better than base surge, airfalland mixture of base surge and airfall in Xujiaweizi fault depression. But reservoir performance hasbeen reduced with addtion of fine airfall material.7.Determined the pyroclastic Lithology of the favorable reservoirThe pyroclastics rocks of the favorable reservoirs includs rhyolitic lithic crystal tuff in pyroclasticflow, lithic crystal tuff with breccias in base surge sediments and rhyolitic breccia tuff in airfallsediments in Xujiaweizi fault depression.更多还原