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571.
准噶尔盆地石南31井区AVO多属性储层及流体预测 总被引:1,自引:1,他引:1
针对石南31井油藏评价过程中存在的问题,首先通过AVO正演证明AVO多属性预测砂体空间展布的可行性,其次优选提取出的AVO属性,对每种属性建立对应的检验标准,采用多数据体、多方法综合标定技术准确标定层位.利用P波数据体以层序地层学的方法原理为指导,建立地层和沉积格架;利用泊松比道积分确定砂体内部物性变化,利用流体检测数据体分析砂体含油气情况,最终综合分析以上3个数据体的结果进行油藏评价.通过以上研究说明在含钙泥岩发育地区,利用AVO多属性储层预测是常规方法的有效补充,而AVO油气检测则存在一定多解性. 相似文献
572.
This paper has made a study of the relationship between the phases of seismic activities from 1966 to 1976 in the region of
the North China Block and the temporal and spatial evolution of temperature anomalies from February 1960 to January 1979 of
the greater North China. The main conclusions are: (1) The temperature variation from February 1960 (rise) to January 1977
(drop) and the temperature rises of September 1975 and February 1976 are connected with the beginning and conclusion of phases
of seismic activity. (2) The relation between the time-duration and the extent of temperature anomaly and that between these
two parameters and the energy released by an earthquake have high credibility. (3) If the time period of 16.5 years between
February 1960 and July 28, 1976, the occurrence time of the the great Tangshan earthquake, is divided into 18 time intervals
according to 0.618N, the earthquakes in this phase of seismic activity and temperature rises fall just into the same intervals.
The Chinese version of this paper appeared in the Chinese edition ofActa Seismologica Sinica,15, 76–82, 1993. 相似文献
573.
574.
陈伯舫 《地震地磁观测与研究》1994,15(5):18-21
本文分析了拉萨台长周期成分的感应尺度C值。周期范围从0.3-67d,超过两个量级。用Monte-Carlo法对所得的Cre(T)和Cim(T)结果进行反演计算,反演结果给出了深部电导率结构可能的多解范围和最佳拟合的电性模型。所谓最佳拟合是指目标函数值最小的一种拟合。 相似文献
575.
Chloritoid and staurolite stability: implications for metamorphism in the Archaean Yilgarn Block, Western Australia 总被引:2,自引:0,他引:2
Abstract The stability of quartz-chloritoid-staurolite-almandine-cordierite and aluminium silicates is used to constrain both metamorphic conditions and pressure-temperature trajectories for two localities within the 2700 Ma Archaean Yilgarn Block in Western Australia. Available experimental data are used to calculate thermodynamic data for a self-consistent set of equilibria between these minerals. A lower amphibolite facies locality from the margin of a lower strain area contains assemblages including quartz-chloritoid-staurolite-garnet-biotite with altered cordierite replacing chloritoid, quartz-staurolite-andalusite, and quartz-cordierite-andalusite-biotite. This locality was heated to 530–560°C in the andalusite field, at 4.2 kbar. A sample from a mid- to upper-amphibolite facies, highly strained locality contains relict staurolite enclosed by andalusite, in turn replaced by cordierite and muscovite with biotite and sillimanite in the matrix. The assemblage was heated isobarically from conditions near the maximum experienced by the lower grade locality of 560°C at 4.2 kbar to temperatures in excess of the andalusite-sillimanite transition but within the quartz plus muscovite stability field (600–650°C). The higher grade locality is close to a granitoid dome and sections based on gravity profiles reveal that this locality is underlain by granitoid at shallow depths. The higher grade metamorphism apparently reflects superposition of the thermal aureole on regional metamorphic conditions similar to those in the lower grade areas. 相似文献
576.
Indirect determination of weighted joint density (wJd) by empirical and fuzzy models: Supren (Eskisehir, Turkey) marbles 总被引:1,自引:0,他引:1
Correct block size assessment is the most important stage for rock quarry management. Although volumetric joint count (Jv) and weighted joint density (wJd) were proposed for this purpose, simple prediction method for these indices is not encountered in literature. Due to the fact that some rock masses such as marbles contain less discontinuity, collection of representative amount of data from in situ line surveys for statistical assessments is highly difficult. For this reason, the main targets of the present paper are to apply photoanalysis approach for collecting additional discontinuity data and to obtain some simple statistical and fuzzy models for predicting weighted joint density to evaluate block size in engineering practice for marbles around Supren (Eskisehir, Turkey). In addition, a new and simple approach to predict volumetric decrease caused by chemical weathering is introduced. For these purposes, extensive field and photoanalysis studies were performed and the data obtained from both field and photoanalysis studies were assessed by regression and fuzzy approaches. The results revealed that the prediction performance of the fuzzy inference system is higher than that of the regression equation. 相似文献
577.
Geochronology of the khondalite belt of Trivandrum Block, Southern India: Electron probe ages and implications for Gondwana tectonics 总被引:6,自引:6,他引:6
In a comprehensive U–Pb electron microprobe study of zircon and monazite from the khondalite belt of Trivandrum Block in southern Kerala, we present age data on five key metapelite locations (Nedumpara, Oottukuzhi, Kulappara, Poolanthara and Paranthal). The rocks here, characterized by the assemblage of garnet–sillimanite–spinel–cordierite–biotite–K–feldsapr–plagiocalse–quartz–graphite, have been subjected to granulite facies metamorphism under extreme thermal conditions as indicated by the stability of spinel + quartz and the presence of mesoperthites that equilibrated at ultrahigh-temperature (ca. 1000 °C) conditions. The oldest spot age of 3534 Ma comes from the core of a detrital zircon at Nedumpara and is by far the oldest age reported from this supracrustal belt. Regression of age data from several spot analyses in single zircons shows “isochrons” ranging from 3193 ± 72 to 2148 ± 94 Ma, indicating heterogeneous population of zircons derived from multiple provenance. However, majority of zircons from the various localities shows Neoproterozoic apparent ages with sharply defined peaks in individual localities, ranging between 644–746 Ma. The youngest zircon age of 483 Ma was obtained from the outermost rim of a grain that incorporates a relict core displaying ages in the range of 2061–2543 Ma.The cores of monazites also show apparent older ages of Palaeo-Mesoproterozoic range, which are mantled by late Neoproterozoic/Cambrian rims. The oldest monazite core has an apparent age of 2057 Ma. Extensive growth of new monazite during latest Neoproterozoic to Cambrian–Ordovician times is also displayed by grain cores with apparent ages up to 622 Ma. The homogeneous core of a sub-rounded monazite grain yielded a maximum age of 569 Ma, markedly younger than the 610 Ma age reported in a previous study from homogenous and rounded zircon core from a metapelite in Trivandrum Block. These younger ages from abraded grains that have undergone fluvial transport are interpreted to indicate that deposition within the khondalite belt was as young as, or later than, this range. Probability density plots indicate that majority of the monazite grain population belong to Late Proterozoic/Cambrian age (ca. 560–520 Ma) with major peaks defining sharp spikes in individual localities.The age data presented in this study indicate that the metasediments of the Trivandrum Block sourced from Archaean and Paleo-Mesoproterozoic crustal fragments that were probably assembled in older supercontinents like Ur and Columbia. The largest age population of zircons belong to the Neoproterozoic, and are obviously related to orogenies during the pre-assembly phase of Gondwana, possibly from terrains belonging to the East African Orogen. Several prominent age spikes within the broad late Neoproterozoic–Cambrian age range displayed by monazites denote the dynamic conditions and extreme thermal perturbations attending the birth of Gondwana. Our study further establishes the coherent link between India and Madagascar within the East Gondwana ensemble prior to the final assembly of the Gondwana supercontinent. 相似文献
578.
The South Indian Craton is composed of low-grade and high-grade metamorphic rocks across different tectonic blocks between the Moyar–Bhavani and Palghat–Cauvery shear zones and an elongated belt of eastern margin of the peninsular shield. The Madras Block north of the Moyar–Bhavani shear zone, which evolved throughout the Precambrian period, mainly consists of high-grade metamorphic rocks. In order to constrain the evolution of the charnockitic region of the Pallavaram area in the Madras Block we have undertaken palaeomagnetic investigation at 12 sites. ChRM directions in 61 oriented block samples were investigated by Alternating Field (AF) and Thermal demagnetization. Titanomagnetite in Cation Deficient (CD) and Multi Domain (MD) states is the remanence carrier. The samples exhibit a ChRM with reverse magnetization of Dm = 148.1, Im = + 48.6 (K = 22.2, α95 = 9.0) and a palaeomagnetic pole at 37.5 °N, 295.6 °E (dp/dm = 7.8°/11.8°). This pole plots at a late Archaean location on the Indian Apparent Polar Wander Path (APWP) suggesting an age of magnetization in the Pallavaram charnockites as 2600 Ma. The nearby St. Thomas Mount charnockites indicate a period of emplacement at 1650 Ma (Mesoproterozoic). Thus the results of Madras Block granulites also reveal crustal evolution similar to those in the Eastern Ghats Belt with identical palaeopoles from both the areas. 相似文献
579.
580.
Yuejun Wang Weiming Fan Min Sun Xinquan Liang Yanhua Zhang Touping Peng 《Lithos》2007,96(3-4):475-502
The Indosinian granites in the South China Block (SCB) have important tectonic significance for the evolution of East Asia. Samples collected from Hunan Province can be geochemically classified into two groups. Group 1 is strongly peraluminous (A/CNK > 1.1), similar to S-type granites, and Group 2 has A/CNK = 1.0–1.1, with an affinity to I-type granites. Group 1 has lower FeOt, Al2O3, MgO, CaO, TiO2 and εNd(t) values but higher K2O + Na2O, Rb/Sr, Rb/Ba and 87Sr/86Sr(t) than those of Group 2. Samples of both groups have similar LREE enriched pattern, with (Eu/Eu) = 0.19–0.69, and strongly negative Ba, Sr, Nb, P and Ti anomalies. Geothermobarometry study indicates that the precursor magmas were emplaced at high-level depth with relatively low temperature (734–827 °C). Geochemical data suggest that Group 1 was originated from a source dominated by pelitic composition and Group 2 was from a mixing source of pelitic and basaltic rocks with insignificant addition of newly mantle-derived magma. Eight granitic samples in Hunan Province are dated at the cluster of 243–235 and 218–210 Ma by zircon U–Pb geochronology. Together with recent zircon U–Pb ages for other areas in the SCB, two age-clusters, including 243–228 Ma just after peak-metamorphism ( 246–252 Ma) and 220–206 Ma shortly after magma underplating event (224 Ma), are observed. It is proposed that in-situ radiogenic heating from the over-thickened crust induced dehydrated reaction of muscovite and epidote/zoisite to form the early Indosinian granites in response to the isostatic readjustments of tectonically thickened crust. Conductive heating from the underplating magma in the postcollisional setting triggered the formation of late Indosinian granites. Such a consideration is supported by the results from FLAC numerical simulation. 相似文献