【作者】 张明学；

【导师】 卢双舫； 冯志强；

【作者基本信息】 大庆石油学院 ， 油气田开发工程， 2009， 博士

【摘要】 本文以层序地层学、构造地质学、沉积学、含油气系统和油气成藏动力学理论为指导,运用地震、测井、录井、岩芯等资料,在对乌尔逊凹陷构造格局、构造样式和断裂系统进行深入研究的基础上,对大磨拐河组地层的层序地层格架、沉积相、构造圈闭、地层岩性圈闭、储层和油气藏分布规律及控制因素进行了深入细致的分析和研究。乌尔逊坳陷自下而上可划分为断陷构造层(铜钵庙组-南屯组)、断-坳转化构造层(大磨拐河组-伊敏组)和坳陷构造层(青元岗组);发育伸展构造样式(陡坡铲式扇、滚动背斜、缓坡断裂坡折带、同向断阶和反向断阶)、扭动构造样式和反转构造样式(断层式反转、褶皱式反转和混合式反转)3大类8亚类构造样式,其中陡坡铲式扇、缓坡断裂坡折带和扭动-反转叠加的构造带控制大磨拐河组油富集。平面上乌尔逊凹陷南北以苏仁诺尔断裂带、乌21井附近的隆起带及巴彦塔拉转换带为界可划分为4个不同构造活动区(扎和庙地区、苏仁诺尔地区、乌南和巴彦塔拉地区)。不同地区受不同走向断层控制形成相应的半地堑(地堑)结构。乌尔逊凹陷发育下部断层系(铜钵庙组-南屯组断层系)和上部断层系(大磨拐河组-伊敏组断层系);断裂的强活动时期在铜钵庙组～南屯组时期、伊敏组时期和青元岗组时期。铜钵庙组～南屯组时期,在NW-SE方向的引张应力场作用下形成下部断层系;伊敏组时期,受近EW向的拉张应力场控制形成上部断层系;伊敏组末期～青元岗组时期,受到近EW向弱挤压应力场作用下形成部分断层式反转构造、褶皱式反转构造以及混合式反转构造。综合地震、测井、岩芯及化验分析等资料,将大磨拐河组地层划分为15个四级层序,并构成一个完整超层序的五个沉积时期,由下至上,首先为辫状河三角洲-较浅水湖泊-扇三角洲低水位沉积时期,包括一个四级层序(DⅠ1层序);其次为辫状河三角洲-较深水湖泊-扇三角洲水进沉积时期,包括两个四级层序(DⅠ2、DⅠ3层序);接下来为曲流河三角洲-较深水湖泊-辫状河三角洲高水位早期沉积时期,包括两个四级层序(DⅠ4和DⅠ5层序);再接下来为曲流河三角洲-较浅水湖泊-辫状河三角洲高水位中期沉积时期,包括四个四级层序(DⅡ1至DⅡ4层序);最后为网状河三角洲-浅水湖泊-曲流河三角洲高水位晚期沉积时期,包括六个四级层序(DⅡ5至DⅡ10层序)。其中低水位期、水进期和高水位中期三个时期砂地比值高、砂岩发育;高水位早期和高水位晚期两个时期砂地比值低、砂岩不发育。根据各种地质资料结合储层地震反演技术,在层序地层格架内对研究区目的层进行了油气藏成藏研究,并分析了成藏控制因素。分析表明,乌尔逊坳陷大磨拐河组共发育17个主要的断裂密集带,具有走滑、斜拉和泥岩水平拆离等多种成因机制,由长期继承性活动的断裂(油源断层)和上部断裂系统构成的密集带,构造破碎,圈闭密集发育,控制大磨拐河组油富集。大磨拐河组纵向上划分为4套储盖组合,乌南地区的油主要分布在储盖组合Ⅱ和Ⅲ中;乌北地区的油主要分布在储盖组合Ⅰ中。主要为断层-岩性油藏和断块油藏。大磨拐河组自身烃源岩多为差-中等烃源岩,生烃潜力差,油主要来自南屯组暗色泥岩,且与南屯组一段关系密切。乌北地区的油与南屯组油同源同期成藏,成藏关键时刻为伊敏组沉积晚期,为原生油藏:乌南地区的油与南屯组同源不同期,GOI和原油成熟度变化表明南屯组存在古油藏,大磨拐河组油有调整早期南屯组油,为次生油藏的可能,成藏时期为伊敏组沉积晚期-青元岗组沉积时期。大磨拐河组有利于油富集砂体具有累积厚度大于10m、砂地比大于20%、孔隙度大于10%,渗透率高于0.2md四个典型特征;大磨拐河组油成藏主控因素为:在南屯组有效烃灶范围内,油源断层与砂体正交匹配,构造-岩相带控制大磨拐河组油富集。存在3种类型的成藏模式:Ⅰ型模式为陡坡断阶带-扇三角洲相油垂向运移后向陡坡侧向运移断层遮挡聚集成藏模式;Ⅱ型模式为断裂坡折带-三角洲前缘相油垂向运移后短距离侧向运移砂体边界遮挡聚集成藏模式;Ⅲ型模式为走滑-反转构造带-三角洲前缘相油垂向运移后短距离侧向运移受晚期断层和砂体边界遮挡聚集成藏模式。更多还原

【Abstract】 Guided by the theories of sequence stratigraphy, structural geology, sedimentology and petroleum system and oil and gas pool forming dynamics, using seismic data, borehole log, logging curves and cores, based on the deeply study of structural framework, structural style and fault system in Wuerxun depression, detailed research and analysis on the sequence framework, sedimentary facies, structural trap, stratigraphic and lithologic trap, reservoir, hydrocarbon distribution and its controlling factors in the Damoguaihe group in Hailaer Basin have been carried out in the paper.The stratum in Wuerxun depression can be divided into 3 structural layers from bottom to top: fault depression structural layer (Tongbomiao group and Nantun group), fault-depression structural layer (Damoguaihe group and Yimin group) and depression structural layer (Qingyuangang group). There are 3 categories and 8 sub-categories of structural styles: stretch structural pattern (steep slope listric fan, rolling anticline, fault slope break on gentle slope, synthetic fault bench and antithetic fault bench), shear structural pattern and inversed structural pattern (fault inversion, folding inversion and mixed inversion), where steep slope listric fan, fault slope break belt on gentle slope and shear summed inversed structural belt controls hydrocarbon concentration in Damoguaihe group.Taking Surennuoer fault zone, the uplift zone beside Well Wu 21 and transform zone in Bayantala as boundary, Wuerxun depression can be divided into four structural active areas on plane and different areas develop different half grabens or grabes due to faults with different strikes in each area. Wuerxun depression develops two fault systems, which are lower fault system (in Tongbomiao and Nantun Group) and upper fault system(in Damoguaihe and Yimin group ) The lower fault system is formed in Tongbomiao and Nantun group deposition period when depression is controlled by NW-SE direction tension stress. The upper fault system is formed in Yimin group deposition period when depression is controlled by EW direction tension stress. After that stage depression is controlled by EW direction feebleness compress stress and forms some fault inversed structure, folding inversed structure and mixed inversed structure from the end of Yimin group to Qingyuangang group deposition period.Combined seismic data, well logging data, cores with chemical examination data, we divided Damoguaihe group into fifteen fourth-order sequences, which form an entire super sequence with five deposition stages, the first sequence (D I 1) is the stage of braided river delta, comparable shallow lake and fan delta deposition of lowstand system tracts(LST) period; The second and third (D I 2, D I 3)sequences are the stages of braided river comparable deep lake and fan delta deposition of transgressive system tracts(TST) period. The fourth and fifth ((D I 4, D I 5) sequences are the stages of meandering river delta, comparable deep lake braided river delta facies of early stage of highstand system trarcts(HST) period. The sixth-tenth (D II 1-D II 4) sequences are the stages of meandering river delta, comparable shallow lake braided river delta facies of middle stage of HST period. The eleventh -fifteenth (D II 5-D II 10) sequences are the stages of anastomosed stream delta, shallow lake braided river delta of the end stages of HST period. Sandstone is well developed with a higher sand-land ratio in the stages of LST, TST and middle stage of HST, while sand is not well developed in the rest of the two stages.According geologic data combined with reservoir seismic inversion technique, the research on hydrocarbon accumulation in the formation of interest and analysis of its control factor has been finished. It is shown that there are 17 main fault zones which have the mechanism of strike-slip, slanting stretch and horizon decoupling. The long term inherit developed faults (oil source faults) and their upper layer fault system forms dense fault zones, which control hydrocarbon accumulation in Damoguaihe group. From bottom to top Damoguaihe group develops four reservoir and capping sets. Hydrocarbon mainly distributes in set II and III in Wunan area while distributes in set I in Wubei area. Oil reservoir at here is mainly fault-lithologic reservior and fault blocks reservoir.The quality of hydrocarbon source rocks in Damoguaihe group is mainly bad-middle class, lack of hydrocarbon generate potential. Oil mainly comes from the dark shale affected by segment one of Nantun Group. The source and accumulation period of oil in Damoguaihe Group in Wubei area are the same as oil in Nantun Group. Crucial period of crude oil accumulation is the end of Yimin Group. On the other hand, the situation in Wunan area is different. Variation of GOI and crude oil maturity show that there is paleo-oil pool in Nantun group. Oil in Damoguaihe group is probably secondary oil pool due to the adjustment of oil in Nantun formation. The crucial period of crude oil pool accumulation is from the end of Yimin group to Qingyuangang group.The preferred oil accumulation sandstone in Damoguaihe group has four characteristics: the accumulative thickness is more than 10 meters and sand percentage is higher than 20% in stratum with more than 10% porosity and permeability higher than 0.2md. The main control factors of oil accumulation in Damoguaihe group are oil source faults and sand body orthogonal matched in hydrocarbon kitchen of Nantun group, structural and lithofacies belt control oil accumulation in Damoguaihe group. Thus there are three types of oil accumulation modes:①oil in fan delta in abrupt slope fault step zone, after vertical movement, migrates laterally towards abrupt slope then shielded by fault and finally forms accumulation in reservoir;②oil in delta front in gradient break fault zone, after vertical movement, migrates laterally in a short distance then shielded by the border of sand body and finally forms accumulation in reservoir;③oil in delta front in strike slip inversed structure belt, after vertical movement, migrates laterally in a short distance then shielded by late period fault plane and sand body border and finally forms accumulation in reservoir mode.更多还原