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71.
Pier Paolo Bruno 《Bulletin of Volcanology》2004,66(4):342-355
Digital marine seismic reflection data acquired in 1973 in the Bay of Pozzuoli, and recently reprocessed, were used to study the volcanological evolution of the marine sector of Campi Flegrei Caldera during the last 37 ka. In order to gain more information, interpretation also involved estimation of the "pseudo-velocity" and the "pseudo-density" from the resistivity logs of two onshore deep exploration wells. The main results are: (1) discovery of ancient pre-18 ka and post-37 ka submarine and mainly effusive volcanic activity, along coeval emission centers located at the edges of Campi Flegrei Caldera; (2) confirmation that the caldera collapse in the marine sector of Campi Flegrei seems strongly controlled by regional NE–SW and NW–SE structural discontinuities; (3) the finding of at least two episodes of collapse in the bay; and (4) identification of a post-18 ka volcanic deflation phase that has caused about 150–200 m of subsidence in the central sector of the Bay of Pozzuoli in the last 18 ka.Editorial responsibilty: T. Druitt 相似文献
72.
本文研究了用于测井相分析识别岩性的人工神经网络(ANN)模型设计并在SUN工作站上用基于距离D-KohonenNN、D-BPNN两个网络建立了ANN自动测井相分析系统。在实际应用中对比了AW岩相识别和传统多元统计岩相识别的效果,证明了ANN模式识别技术用于测井相分析的可行性和优越性。 相似文献
73.
Jacek?Majorowicz Jan??afanda Torun- Working Group 《International Journal of Earth Sciences》2008,97(2):307-315
High-precision temperature measurements were carried out up to a depth of 2,930 m in the 5.5-km-deep well Torun-1, 26 years
after completion of drilling. The temperature log provides equilibrium thermal state information for the Polish Lowland at
the western margin of the Precambrian craton. Geothermal gradient calculated from the equilibrium temperature log, together
with estimates of thermal conductivity from ‘net rock’ geophysical well logging analysis and available core measurements,
yields heat flow in the range 50–60 mW/m2 below 2-km depth. Heat flow of 50 mW/m2 plus ∼10 mW/m2 generated within thick sediments and highly metamorphosed sedimentary wedge is typical for the western margin of the Precambrian
East European craton. Heat-flow variations with depth can be explained by a model of surface-temperature changes >10°C (glaciation
to Holocene).
Torun-1 Working Group: Marta Wróblewska, Jacek Majorowicz, Jan Szewczyk, Jan Šafanda, Vladimír Cermák 相似文献
74.
M. Teresa Mariucci Simona Pierdominici Luca Pizzino Fabrizio Marra Paola Montone 《Journal of Volcanology and Geothermal Research》2008
A 350 m deep borehole was drilled in the Colli Albani volcanic district (Central Italy) in order to: understand the shallow crust structure beneath the volcanic complex; characterize the rock physical properties especially through in-situ measurements and, afterward, laboratory experiments; assess the local present-day stress field; install a broad-band seismometer at depth. The borehole is located adjacent to the western rim of the Tuscolano–Artemisio caldera, where several phenomena of unrest recently occurred. In 1989–90 a seismic swarm affected this area and a related uplift was recognized. In addition, high gas concentrations (mainly CO2 and H2S), in aquifers and soils, caused illnesses and casualties among inhabitants and animals in the past. 相似文献
75.
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77.
本文利用射线展开理论、割线积分技术及留数定理,研究了裸眼井声波全波测井中纵波和斯通利波的性质。下面简要说明数值计算方法。 计算方法 考虑在无限大均匀地层中,有一充满流体的深井。在井轴上放一点状声源,则在井轴上离声源距离为z处的声压为 相似文献
78.
The Liangshan and Qixia formations in the Sichuan Basin of central China were formed in the earlier middle Permian. Based on outcrop observation of the Changjianggou section at Shangsi, Guangyuan region and 3rd-order sequence division in typical drillings, one-dimensional spectrum analysis has been used to choose the better curve between the natural gamma ray spectrometry log(ln(Th/K)) in Well-Long17 and the gamma ray log(GR) in Well-Wujia1, respectively, for identifying Milankovitch cycles in Sequence PSQ1 which comprises the Liangshan and Qixia formations, and then to identify the variation in the Milankovitch cycle sequences. On this basis, the system tract and 4th-order sequence interfaces in Sequence PSQ1 were found via two-dimensional spectral analysis and digital filtering. Finally, a high-frequency sequence division program was established. Among these cycles, long eccentricity (413.0 ka) and short eccentricity (123.0 ka) are the most unambiguous, and they are separately the major control factors in forming 4th-order (parasequence sets) and 5th-order (parasequences) sequences, with the average thicknesses corresponding to the main cycles being 11.47 m and 3.32 m in Well-Long17, and 14.21 m and 3.79 m in Well-Wujia1, respectively. In other words, the deposition rate in the beach subfacies is faster than that of the inner ramp facies. The ln(Th/K) curve is more sensitive than the GR as the index of relatively ancient water depth in carbonate deposition. One-dimensional spectrum analysis of ln(Th/K) curve could distinguish the Milankovitch cycle sequences that arose from the Precession cycle (20.90 ka), with a much higher credibility. Sequence PSQ1 in Well-Long17 contains 10 4th-order sequences, and the growth span of Sequence PSQ1 consisting of the Liangshan and Qixia formations is about 4.13 Ma. The single deposition thickness of the long eccentricity cycle sequence has the characteristics of thinning and then thickening in the two-dimensional spectrum, which could be used to identify the system tract interface of the 3rd-order sequence. The precession sequence thickness remains stationary. As a result, the early deposition rate in the mid-Permian of the Sichuan basin was very slow, remaining nearly stationary, and this reflects a sustained depositional environment. Whole-rock carbon and oxygen isotope curves could also prove this point. Milankovitch cycle sequence studies provide a basis for paleoenvironmental analysis and, as such, can be used to analyze ancient climate change, calculate deposition rate and deposition time, and carry out fine isochronous stratigraphic correlation. 相似文献
79.
The Eocene Niubao Formation of the Lunpola Basin, a large Cenozoic intermontane basin in central Tibet, is an important potential hydrocarbon source and reservoir unit. It represents ∼20 Myr of lacustrine sedimentation in a half-graben with a sharply fault-bounded northern margin and a low-angle flexural southern margin, resulting in a highly asymmetric distribution of depositional facies and sediment thicknesses along the N-S axis of the basin. An integrated investigation of well-logs, seismic data, cores and outcrops revealed three third-order sequences (SQ1 to SQ3), each representing a cycle of rising and falling lake levels yielding lowstand, transgressive, and highstand systems tracts. Lowstand systems tracts (LST) include delta and fan delta facies spread widely along the gentle southern margin and concentrated narrowly along the steep northern margin of the basin, with sublacustrine fan sand bodies extending into the basin center. Highstand systems tracts (HST) include expanded areas of basin-center shale deposition, with sublacustrine fans, deltas and fan deltas locally developed along the basin margins. Sequence development may reflect episodes of tectonic uplift and base-level changes. The southern margin of the basin exhibits two different structural styles that locally influenced sequence development, i.e., a multi-step fault belt in the south-central sector and a flexure belt in the southeastern sector. The sedimentary model and sequence stratigraphic framework developed in this study demonstrate that N2 (the middle member of Niubao Formation) exhibits superior hydrocarbon potential, characterized by thicker source rocks and a wider distribution of sand-body reservoirs, although N3 (the upper member of Niubao Formation) also has good potential. Fault-controlled lithologic traps are plentiful along the basin margins, representing attractive targets for future exploratory drilling for hydrocarbons. 相似文献
80.
应用滑动窗关联维计算方法对鲁北济阳坳陷某钻井剖面石炭系-二叠系陆表海沉积层段GR测井响应数据进行了分形维数计算,结果表明海侵体系域关联维数一般较小,且维数曲线振荡变化较弱,而高水位体系域则相反.这与海侵体系域形成时海平面上升的主控因素压制或掩盖了其他因素的显现有关,同时也证明测井序列分形分析能从另一个新的视角观察识别测井序列中所包含的地质信息.随着分形方法应用研究的不断开展,必将从测井数据中挖掘出更多的有用信息,指导油气等资源勘探与开发,丰富及完善测井地质学理论.相信将来分形会成为地质数据分析的标准工具. 相似文献