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281.
282.
为恢复延兴盆地城子河组的古环境,对研究区zk6井钻井岩芯系统取样进行地球化学特征分析,结果显示下部含煤岩段Sr/Ba比值为0.20~0.75,平均值为0.41,上部湖泊泥岩段Sr/Ba比值为0.12~0.36,平均值为0.21,反映城子河组整体以淡水沉积为主,且下部含煤岩段较上部湖泊泥岩段盐度高。城子河组所有样品V/(V+Ni)比值为0.72~0.84,Cu/Zn比值为0.10~0.55,Th/U比值为0.28~3.60,δEu值为0.4~0.84,Ceanom值为-0.04~0.09,表明城子河组沉积时期水体为还原环境;下部含煤岩段Sr/Cu比值为5.87~24.12,平均值为11.21,B元素含量为232.60×10-6~721.00×10-6,平均值为425.75×10-6。上部湖泊泥岩段Sr/Cu比值为3.56~10.50,平均值为6.00,B元素含量为23.69×10-6~119.00×10-6,平均值为78.36×10-6,结合Rb/Sr及孢粉化石分析,表明城子河组下部含煤岩段气候干旱,湖泊泥岩段气候湿润,总体上气候自下而上具有由干旱向湿润变化的规律。 相似文献
283.
284.
准噶尔盆地吉木萨尔凹陷二叠系梧桐沟组作为一套重要的储集岩,具有良好的油气成藏前景,但对其层序划分及地层沉积样式的认识一直存在争议。在构造背景分析的基础上,结合岩芯、测井及地震资料,对研究区梧桐沟组层序地层划分及地层沉积样式研究表明,梧桐沟组沉积时期构造强度较弱,地形较为平缓,地层在全区稳定分布;中晚二叠世盆地发生造山运动,吉木萨尔凹陷东南边缘区域经过构造抬升,上部地层遭受不同程度的剥蚀,形成了现今"底平顶削"的地层样式。以凹陷中部少数地层保存较全的井的地层叠加样式分析为基础,通过井-震结合识别不同类型界面,特别是最大湖泛面,建立了区域层序地层格架,即梧桐沟组为一个完整的长期基准面旋回(三级层序),并在其内部识别出5个中期旋回。梧桐沟组地层在不同的层序发育时期表现出不同的旋回叠加样式:下段沉积时期,即最大湖泛面以下,随着可容纳空间的增大,地层表现为明显的退积叠加样式;上段沉积时期,即最大湖泛面以上,随着可容纳空间的减小,地层表现为明显的进积叠加样式,符合沉积物体积分配原理。 相似文献
285.
Coalbed methane (CBM) resources in No.15 coal seam of Taiyuan Formation account for 55% of the total CBM resources in southern Qinshui Basin (SQB), and have a great production potential. This study aims at investigating the CBM production in No.15 coal seam and its influence factors. Based on a series of laboratory experiments and latest exploration and development data from local coal mines and CBM companies, the spatial characteristics of gas production of No.15 coal seam were analyzed and then the influences of seven factors on the gas productivity of this coal seam were discussed, including coal thickness, burial depth, gas content, ratio of critical desorption pressure to original coal reservoir pressure (RCPOP), porosity, permeability, and hydrogeological condition. The influences of hydrological condition on CBM production were analyzed based on the discussions of four aspects: hydrogeochemistry, roof lithology and its distribution, hydrodynamic field of groundwater, and recharge rate of groundwater. Finally, a three-level analytic hierarchy process (AHP) evaluation model was proposed for predicting the CBM potentials of the No.15 coal seam in the SQB. The best prospective target area for CBM production of the No.15 coal seam is predicted to be in the districts of Panzhuang, Chengzhuang and south of Hudi. 相似文献
286.
《Proceedings of the Geologists' Association. Geologists' Association》2021,132(6):657-666
The thickest section of Early Jurassic strata known from onshore Ireland (total Jurassic thickness 566 m) is reported from the Ballinlea-1 well (Rathlin Basin) situated on the north coast of Northern Ireland. A biostratigraphical and palaeoenvironmental assessment is presented for this section largely based on calcareous benthic microfossils (foraminifera and ostracods). The Early Jurassic Waterloo Mudstone Formation (Lias Group) of Northern Ireland has previously received little micropalaeontological attention, therefore this work provides an opportunity to enhance palaeogeographic and palaeoenvironmental understanding for the Early Jurassic of the province, and this paper illustrates the key microfossil taxa of this age from Ireland for the first time. The records, based on ditch-cuttings samples, demonstrate a stratigraphical range from Hettangian to Early Pliensbachian, consistent with other wells and boreholes in this basin. The assemblage compositions are comparable to those elsewhere in the European boreal Atlantic realm. Hettangian to earliest Sinemurian microfossil assemblages are generally of low diversity and are numerically dominated by metacopid ostracods with occasional influxes of foraminifera. Gradually, foraminiferal abundance (often dominated by species of the Lagenida) come to exceed those of the ostracods in the Early Sinemurian reaching their greatest diversity in the Late Sinemurian. The sediments are considered to represent an inner to mid-shelf environment throughout while the record thickness for this region indicates ongoing syn-sedimentary fault movement along the basin margins within this period. 相似文献
288.
对产自河北围场下白垩统九佛堂组的65件鲎虫化石标本进行研究。根据其形态特征,认为这些鲎虫化石属于三角围场鲎虫(Weichangiops triangularisYang et Hong, 1980)。有观点认为,具有上肛板的鲎虫为冷水型鲎虫,而不具上肛板的鲎虫为暖水型鲎虫。河北围场采集的鲎虫化石有的具上肛板,有的不具上肛板,目前没有任何证据表明其为冷水型鲎虫与暖水型鲎虫混生的产物。通过研究,对三角围场鲎虫的特征进行了适当修正,认为围场地区的鲎虫化石具1对复眼,因此依据单个复眼而建立的新亚科——围场鲎虫亚科(Weichangiopsinae)不成立,应予以摒弃。三角围场鲎虫存在明显的性双形现象,雄性个体尾部具有上肛板,雌性个体不具有上肛板,这对于鲎虫化石分类研究具有重要的科学价值,可避免在生物分类时发生同物异名现象。 相似文献
289.
Shangbin Chen Zhuo Gong Xueyuan Li Huijun Wang Yang Wang Yingkun Zhang 《地学前缘(英文版)》2021,12(6):192-208
Fine characterization of pore systems and heterogeneity of shale reservoirs are significant contents of shale gas reservoir physical property research.The research on micro-control factors of low productivity in the Qiongzhusi Formation(Fm.)is still controversial.The lower Cambrian Qiongzhusi Fm.in the Qujing,Yunnan was taken as the object to investigate the influence of mineral compositions on the phys-ical properties of the reservoir and the heterogeneity of shale,using the algorithm to improve the char-acterization ability of Atomic Force Microscopy(AFM).The results showed that:(1)The pores are mainly wedge-shaped pores and V-shaped pores.The pore diameter of the main pore segment ranges from 5 to 10 nm.Mesopores are mainly developed in the Qiongzhusi Fm.shale in Well QD1,with the average pore diameter of 6.08 nm.(2)Microscopic pore structure and shale surface properties show strong hetero-geneity,which complicates the micro-migration of shale gas and increases the difficulty of identifying high-quality reservoirs.(3)The increase of clay mineral content intensifies the compaction and then destroys the pores.Conversely,brittle minerals can protect pores.The support and protection of brittle minerals to pores space depend on their content,mechanical properties and diagenesis.(4)Compression damage to pores,large microscopic roughness and surface fluctuations and strong pore structure heterogeneity are the reasons for the poor gas storage capacity of the Qiongzhusi Fm.,which will lead to poor productivity in the Qiongzhusi Fm. 相似文献
290.
Jianhua Zhang 《Geological Journal》1996,31(3):201-215
The Lower to Middle Ordovician Guniutan (Kuniutan) Formation in the eastern Yangtze Gorges, China has been demonstrated to be similar to the ‘Orthoceratite Limestone’ in Baltoscandia with respect to facies, stratigraphic development and conodont biostratigraphy. Thus the ‘Orthoceratite Limestone’ appears to be a much more widely distributed and characteristically Ordovician facies than has hitherto been assumed. Five lithostratigraphic subdivisions of the Guniutan Formation are here defined in ascending order as the Nanya, Puxi, Wuguixi, Daping and Niangjiafang members. It is shown that these members, which represent considerable spans of time as indicated by their conodont stratigraphy, may be fairly thin but nevertheless regionally extensive. A new conodont zone, with Eoplacognathus crassus as the zonal fossil, is established to accommodate the precise dating of the Wuguixi and Puxi members. Microfacies data from the Guniutan Formation, available for the first time, show that its dominant component particles are sand-sized echinoderm and arthropod debris, as in the Baltoscandian ‘Orthoceratite Limestone’. 相似文献