【作者】 任延广；

【导师】 杨宝俊；

【作者基本信息】 吉林大学 ， 地球探测与信息技术， 2004， 博士

【摘要】 油气生成、运移、聚集和保存与沉积盆地的形成、演化和改造密切相关，对盆地油气资源远景、油气分布规律和富集区带的认识准确与否，很大程度上取决于对盆地形成、演化和改造过程的认识程度。本论文试图将沉积盆地分析与油气地质研究有机结合，应用现代地质理论和勘探技术最新进展，从基础地质研究出发，把握油气生、运、聚和保存条件，达到指明勘探方向和有利勘探目标的目的。为此选择资料条件较好、勘探进展缓慢的松辽盆地西家围子断陷为研究对象，开展了地层、构造、沉积和含油气系统等方面的研究工作，对盆地特征和天然气聚集规律有了全新的认识，取得了多项创新性成。徐家围子断陷地质特征依据地震和钻井资料综合分析，徐家围子地区泉头组以下地层中可识别出五个级别的层序界面，用9个区域分布的高级别的层序界面和2个重要洪泛面为界，重新厘定了徐家围子地区组、段级地层的层序，确定地层层序为白垩系下统火石岭组（一、二段，新划分段）、沙河子组（一、二）、营城组（一、二、三、四段，新划分段）、登娄库组（一、二、三、四段）和泉头组下部（一、二段）。营城组具四分性，火石岭组在中性火山岩之下存在含煤碎屑岩地层，整体上徐家围子断陷地层由三套火山岩和四层碎屑岩构成。断陷内地层空间分布格局复杂。徐家围子断陷是由徐西、宋西两条边界断裂控制的箕状断陷，控陷断裂NNW向延伸部位控制了断陷的沉降中心 ，形成安达、杏山和薄荷台三个坳陷中心。控陷断裂NE向转折部位沉降量相对较小 ，形成分割沉降中心的宋站低隆起和丰乐低隆起。沙河子组末期和营一段末期二次构造运动形成了升平—兴城断弯褶皱 、榆西断展褶皱和一系列反转构造挤压构造单元 。徐家围子断陷经历了三个构造演化阶段 ，火石岭组沉积时期是断陷的孕育阶段 ，沙河子组沉积时期是断陷发展阶段；营城组沉积时期是断陷的萎缩阶段。大规模伸展断陷作用发生在早白垩世沙河子组沉积时期，是在左行走滑应力背 <WP=144>景下形成的，由宋西断裂南段、徐西断裂北段南部、徐西断裂南端构成的平面上北北东向斜列的深凹陷。沙河子组末期和营一段末期发生了二次区域性的挤压改造作用，使先期形成的伸展盆地构造格局复杂化。徐家围子地区深层包括了断陷期含火山岩、煤系沉积建造和坳陷早期以河流和浅水湖泊为特征的碎屑岩建造。断陷期地层中以形成于潮湿的气候条件下和较缓的斜坡边缘、牵引流作用为主的辫状平原扇、辫状三角洲厚层砾岩沉积为特色，坳陷早期地层以各种类型的河流沉积较常见。沙河子组沉积时期是断陷沉积最繁荣的时期，发育广阔的断陷湖盆，沉积了厚层深—半深湖相泥岩，夹煤层，以发育于断陷东部的辫状平原扇向西的进积充填作用为主。2、天然气成藏条件徐家围子断陷烃源岩以沙河子组湖相泥岩和煤层为主，火石岭组一段和营城组二、四段也有一定的生烃能力，登娄库组二段生烃潜力较小，基底古生界也有一定贡献。沙河子组、火石岭组泥岩均达到好气源岩标准，具有比较大的原始生气潜力，有机质类型以Ⅲ型为主，少部分为Ⅰ型和Ⅱ型，各套烃源岩均处于高成熟-过成熟阶段。天然气以烃类气体为主，主要是干气，湿气含量很少，具有一定量的无机成因气体，天然气成因类型以煤型气和混合气为主，并有油型气和无机气存在。徐家围子断陷火山岩好储层以裂缝－孔隙组合型为主，其次为纯裂缝型。火山岩原始储集性能受岩性和岩相控制，后来的构造运动形成的裂缝和风化、淋滤作用改善储层，成岩充填作用使储层物性减损。爆发相和溢流相上部亚相火山岩储集性最好，营城组一段火山岩分布广泛，是本区最重要的储集层段，有利储层沿宋西和徐西二条控陷断裂成带分布。松辽盆地深层碎屑岩储层主要为登娄库组和泉头组下部，包括冲积扇、砾质辫状河成因的砾岩，各种河流和三角洲成因的砂岩，成岩作用强，属致密储层，局部层段存在次生孔隙，对改善储层物性至关重要。本区致密砂、砾岩储层中次生孔隙主要为胶结物浊沸石溶孔，其次为长石粒内溶孔，酸性流体是浊沸石次生孔隙的成因，据浊沸石内少量气液包裹体均一温度推算，形成于青山口组沉积时期。在纵向上，浊沸石溶孔发育深度范围在2300-3200m之间，平面上升平—汪家屯地区和昌德地区浊沸石溶孔最发育。松辽盆地烃源岩的主要生排气期在早白垩纪晚期和晚白垩纪，与天然气成藏期基本吻合 。火石岭组泥岩生气高峰分别出现在距今120Ma和 80Ma ，分别相当于登娄库组初期和嫩江组末期，沙河子组生气高峰期以距今80Ma为主 。火石岭组和沙河子组煤层的总排气期主要为130～100Ma 。徐家围子断陷火山岩次生包裹体均一温度反映深层天然气的成藏期次一般不超过2期，火石岭组天然气的主要成藏期为距今110-70Ma ，营城组天然气的主要成藏期100-65Ma（相当于q-m沉积期）。虽然各地区成藏时间有差别， <WP=145>但天然气主体成藏时间晚于90Ma，成藏持续时间大于15Ma。将徐家围子地区划为徐家围子断陷含油气系统，将与之相邻德古中央隆起区单独作为一个复合含油气系统。以古流体势为主要依据，将徐家围子断陷含油气系统划分为安达坳陷北部、宋深1、昌德东、兴城、榆西、薄荷台坳陷?更多还原

【Abstract】 The generation, migration, accumulation and gas are associated with the formation, evolution and reformation of the basin, on which the prediction of resource prospect, distribution law and abundance zone depends mostly. In order to point out the exploration direction and the potential exploration targets it is attempted to combine the sedimentary basin analysis with the oil and gas geology study, and to apply the modern geological theory and the new exploration techniques to recognize the conditions of generation, migration and preservation of the oil and gas based on the basic geology study in this dissertation.So we selected Xujiaweizi depression with good data and slowly exploration pace as the object to study the stratum,sedimentary and pretroleum system and so on,and we have obtained the completely new knowledge about the geological features and the gas accumulations,as well as many qther creative achievements in the basin.Geological Features of Xujiaweizi Fault Depression There are 5 levels sequence boundaries recognized from the integrated seismic and well data below the Quantou Formation in Xujiaweizi fault depression.The lower Cretaceous are separated on the level of member and bed by 9 regional higher level sequence boundaries and 2 significant flooding surfaces, including Huoshiling Formation (Member 1and 2 recognized again), Shahezi Formation (Member 1and 2), Yingcheng Formation (Member 1,2,3,4 recognized again), Denglouku (Member 1,2,3,4),and Lower Quantou Formation (Member 1,2).The Yingcheng Formation is also divided into 4 members.And the intermediate volcanic rock bed is overlain the coal-bearing clastic rock bed in the Huoshiling Formation.The formations of Xujiaweizi fault depression are consisted of three sets of volcanic rocks and four sets of clastic rocks.The spatial distribution of the formations is complex in the depression.The Xujiaweizi fault depression is a halfgraben-like fault depression controlled by two <WP=147>boundary faults of Xuxi and Songxi, which extend to NNW and control the subsiding center in the depression, furthermore, to form the three depression centers: eastern Shengping, Xingshan and Bohetai. The turning point of the downchasm-dominated faults to the northeast, which resulted in the formation of the Songzhan low uplift and the Fengle low uplift to separate the subsiding center. The tectonic movements caused the formation of Shengping-Xingcheng fault extend fold belt, Yuxi fault bend fold and reverse structures in the late depositing periods of the Shahezi and the Member 1 of Yingcheng.The Xujiaweizi fault depression has been subjected to three tectonic evolution stages:the fault-subsiding stage whichis the Huoshiling Formation depositing period,the down-wraping stage which is the Shahezi Formation depositing period,the shrinking stage which is the Yingcheng Formation depositing period.The large scale expanding and faulting activities occur in the Early Cretaceous when the Shahezi Formation is depositing under the background of left-lateral strike-slip fault.The deep depression is obliquely located to NNE from the horizontal view which is constituted by the southern segment of the Songxi fault,the south of the northern segment of the Xuxi fault and the southern segment of the Xuxi fault.The two regional compressing and reforming tectonic movements make the initial tectonic framework of the expanding basin complex in the late depositing period of the Shahezi Formation and the late depositing period of the Member 1 of Yingcheng Formation.Xujiaweizi fault depression contains the formation bearing volcanic rocks and coals of the fault-subsiding stage and the formation bearing clastic rocks characterized by fluvial facies and lacustrine facies in the early down-wrapping stage.The conglomerates of the braided plain fan and braided delta are the strata characteristics of the faulting-subsiding stage,which are formed in the wet climate condition by the traction on the edge of the low-angle slope.But the sediments of various fluvial facies are more common in the str更多还原