【作者】 张梦林；

【导师】 杨光；

【作者基本信息】 吉林大学 ， 数字地质科学， 2012， 硕士

【摘要】 苏干湖凹陷位于柴达木盆地北缘隆起（即柴北缘）西北部，面积约为7000km2，中生界主研究区面积为323km2。发育的地层为中生界的侏罗系和新生界古近系、新近系、第四系，其中中生界侏罗系仅沉积了中、上侏罗统，前者发育一套烃源岩，钻井见油气显示，但试油效果并不理想，目前成藏地质条件及成藏规律尚不清楚，本文依据地质、地震、地化及测井等基础资料，通过对生储盖组合特征的分析，研究油气藏成藏特征及油气富集规律，并建立了油气成藏模式。1、烃源岩研究研究认为该凹陷仅存在一套中侏罗统烃源岩，上侏罗统及其以上各层均为红色碎屑岩建造。烃源岩分为湖相泥岩、炭质泥岩和煤三种类型，本次对烃源岩生烃能力进行了评价，认为烃源岩以湖相暗色泥岩为主，主要发育在中侏罗统上段，有机质丰度高，类型以Ⅱ-Ⅲ为主，其中热演化特征显示大部分烃源岩的成熟度正处于生油高峰期，大多数烃源岩为好-中生油岩。2、储集层研究储集层在中、上侏罗统均有分布，物性较差，裂缝不发育，属于超低孔致密储层和低孔低渗储层，储层成岩阶段处于中成岩A期的A2亚期。储层物性受沉积作用和成岩作用的双重控制，为一套近源煤系地层沉积，导致储层杂基偏高，沉积物易受压实，在后期成岩过程中，压实作用和胶结作用不断压缩孔隙和喉道，使原生孔隙减少，虽然溶蚀作用产生的次生孔隙在一定程度上改善了储层物性，但由于储层孔隙小、喉道细，不利于酸性溶解物质的流动，因此溶蚀作用对储层的改造作用不明显。是沉积和成岩的综合作用最终导致储层致密。3、盖层评价盖层类型属于泥岩盖层，上侏罗统沉积环境较为稳定，单层泥岩厚度大，分布连续，可以作为一套局部盖层；上覆古近系发育的一套棕红、棕褐色泥岩和砂质泥岩，埋深超过1300m，泥地比均接近70%，单层最大厚度可达85m，测井和地震资料分析显示，该套盖层平面上南北向延伸超过20km，横向连续性比较稳定，可作为一套区域性盖层；通过对盖层微观参数的定量评价，认为盖层整体封闭性较好，可作为封挡石油的有利盖层，但对天然气的封挡性较差。4、成藏期次对苏参1井埋藏史进行了恢复，认为苏参1井区主要受燕山和喜山这两次比较大的构造运动的影响，引起了该区在早白垩世晚期和上新世中期的两次大规模隆升和剥蚀，前者对该区的影响较大，总剥蚀量为1440m，后者仅为319m。对中侏罗统的储层流体包裹体进行了镜下观察及测温，与烃类包裹体伴生的盐水包裹体均一温度的分布区间为64.6-89.6℃，包裹体均一温度频率呈现双主峰，主峰值区间分别为65-70℃和75-80℃，两个主峰值相差不大，在单井埋藏史图上确定油气为一期成藏，成藏时间为早白垩世晚期。5、成藏主控因素及成藏模式中生界形成了下生上储、自生自储式的生储盖组合。苏参1井相对苏探1井更靠近生烃中心，其中的岩性圈闭是油气藏形成的主要类型。早白垩世晚期是中侏罗统油气成藏的重要时期，油气生成后进入临近砂体内迅速成藏，形成自生自储的原生岩性油气藏；后期受到喜山运动影响，油气发生重新运移聚集，通过断层运移至上侏罗统底部形成下生上储的构造-岩性次生油气藏。更多还原

【Abstract】 In the regional tectonic, Suganhu depression is in Uplift of Northern Margin ofQaidam Basin, The area of Suganhu depression is7000km2. The area of the mainstudy is323km2in Mesozoic. the Through previous studies, There exists Jurassic ofMesozoic and Paleogene and Neogene and Quaternary of Cenozoic，we know thehydrocarbon source rocks were developed in the Middle and Lower Jurassic, andthere has hydrocarbon show according to the drilling, but well testing results showsnon-ideal. Formation condition analyses and reservoir-forming rule are unclear,Base on previous study，by the data on regional geology,drilling,geophysics andexperimental analysis,we had researched the characteristics of source-reservoir-sealcombinations and reservoir forming characteristics,and establish oil and gaspool-forming models of Suganhu.1、Research of source rocksBased on the logging data and the research of the past, It is concluded that thedark mudstone in the middle–lower Jurassic stratum is the only source rock of thisregion. The upper Jurassic stratum and the above one is all red clastic rocks. Thesource rock is mainly consisted of lake facies mudstone, charcoal mudstone and coal.The geochemistry characteristics is analyzed and it is concluded that the type ofsource rock in Suganhu area isⅡ-Ⅲ, the dark mudstone in the upper Jurassic stratumhas the highest abundance of organic matter, and is in a n the high evolution degree.most of them is good-middle source rocks. 2、Reservoir studyThe reservoir of Suganhu mainly distributed in J2and J3, which has poorphysical property and few Crack, it belongs to super low pore dense reservoir and lowpore low permeability dense reservoir, the stage of diagenesis of reservoir is A2, Inthe paper, sedimentation and diagenesis control the physical properties of reservoir inSuganhu, near source coal system strata sedimentary lead to the content of heterobaseis slightly higher, because of this, the sediments is easier to compaction,during theDiagenesis period, primary pore has reduced by compaction andcementation.although,the physical properties has improved by the secondary porewhich production of the dissolution, pore throat of the reservoir is too fine to flowingof the acid dissolved substances, face this kind of circumstance,the dissolution haslimited transformation effect, the comprehensive factors of sedimentation anddiagenesis ultimate lead to the present situation of the reservoir of Suganhu.3、Seal evaluationThe styles of cap rocks is mudstone seal, the sedimentary environment of upperjurassic in Suganhu is more stable,the thickness of single udstone is high andcontinuous distribution,this can be a series of local cap rock;The mudstone ofpaleogene is over1300m in buried depth, the compared of mudstone and strata isnearly70％,the large thickness of single udstone can be reach85m or73m. Accordingto the quantitative evaluation of microscopic of cap rock, the sealing property of caprock in Suganhu is good, especially for the oil,bad to gas.4、Hydrocarbon accumulation periodReconstruction of Burial History of the Suganhu, the area has twice big upliftand denudation in middle cretaceous and middle late pliocene by Yanshan movementand Xishan movement. Microscope observation and testing for fluid inclusion showsthe homogenization temperature of salt-water inclusion is between64.6℃and89.6℃,the Histogram has two main peak which are65-70℃and75-80℃, according to burialhistory and thermal history,the temperature of two main peak is close, the reservoirforming time should be just once,the time is early cretaceous period. 5、Factors controlling oil accumulation and oil and gas pool-forming modelsThe source-reservoir-cap assemblage of Suganhu has two models，they areself-generation&self-reserving lower intervals generation and upper intervalreserving.The trap in the center of Sutan1well is beneficial to the Formation of oiland gas reservoir. The stage of main oil generation is at the late period of EarlyCretaceous, the oil and gas go into the sandbodies nearby after the generation andformed a self-generate, self-reservoir reservoir swiftly. After that, by the influence ofHimalayan movement, the oil and gas migrated to the upper Jurassic formation andformed a lower-generate, upper-reservoir reservoir.更多还原