含煤盆地煤储层后期改造形式及对煤层气选区影响--以华北克拉通选区为例

阐述了改造型含煤盆地煤储层被改造的两种形式；煤体结构的改造及构造煤的形成原因；后生充填物对煤层孔隙的改造及形成原因。提出了以构造煤发育程度作为改造型含煤盆地改造强度的一个指标。概述了华北克拉通盆地由中生代剪压应力转化为新生代剪张应力和拉张应力，而在盆地内形成以挤压构造为主到伸展构造为主的演化历程，及不同构造类型的区域分布，指出这种演化极易形成构造煤和后生充填物。提出将华北克拉通含煤盆地分为3种改造类型及其分布区域，分析了各自区域的煤储层物性及对煤层气开发选区的影响。提出应重视鄂尔多斯盆地侏罗纪煤层的煤层气．研究与开发．     

Application of AVO Analysis to Seismic Data for Detection of Gas below Methane Hydrate Stability Zone in Nankai Trough Area

Abstract. For the purpose of development of methane hydrate, occurring in the deep marine subsurface, as a resource, the most important issue is to understand the methane hydrate system (generation, migration and accumulation) as well as to delineate the methane hydrate reservoir properties. We have applied the Amplitude Versus Offset (AVO) analysis to the seismic data acquired in the Nankai Trough, offshore Japan, in order to confirm the occurrence of gas just below the methane hydrate-bearing zone, assuming that gas will show a so-called Class-3 AVO response. Knowledge of the amount and occurrence of gas in the sediment below methane hydrate-bearing zone is one of the keys to understand the methane hydrate system.
We have utilized the qualitative analysis of AVO methodology to delineate how gas is located below the BSR, which is thought to be the reflection event from the interface between the methane hydrate-bearing zone and the underlying gas-bearing zone. In the region of MITI Nankai Trough Well PSW-3, we observe two BSRs separated by 25 ms. After AVO modeling using well data, we applied AVO attribute analysis and attribute crossplot analysis to the seismic data. Finally we applied an offset-amplitude analysis to CMP gather data at specific locations to confirm the results of AVO attribute analysis. The AVO analysis shows that there is very little gas located in the underlying sediment below methane hydrate-bearing zone. This result supports the fact that we could not obtain any clear evidence of gas occurrence just below the methane hydrate-bearing zone in the Nankai Trough well drilling.     

Interpretation of radon anomalies in seismotectonic and tectonic-gravitational settings: the south-eastern Crati graben (Northern Calabria, Italy)

The study area is located in the south-eastern part of the Crati valley (Northern Calabria, Italy), which is a graben bordered by N–S trending normal faults and crossed by NW–SE normal left-lateral faults. Numerous severe crustal earthquakes have affected the area in historical time. Present-day seismic activity is mainly related to the N–S faults located along the eastern border of the graben. In this area, much seismically induced deep-seated deformation has also been recognised.In the present paper, radon concentrations in soil gas have been measured and compared with (a) lithology, (b) Quaternary faults, (c) historical and instrumental seismicity, and (d) deep-seated deformation.The results highlight the following:

(a) There is no evidence of a strong correlation between lithology and the radon anomalies.

(b) A clear correlation between the N–S geometry of radon anomalies and the orientation of main fault systems has been recognised, except in the southernmost part of the area, where the radon concentrations are strongly affected by the superposition of the N–S and the NW–SE fault systems.

(c) Epicentral zones of instrumental and historical earthquakes correspond to the highest values of radon concentrations, probably indicating recent activated fault segments. In particular, high radon values occur in the zones struck by earthquakes in 1835, 1854, and 1870.

(d) Deep-seated gravitational deformation generally coincides with zones characterised by low radon concentrations.

In the studied area, the anisotropic distribution of radon concentrations is congruent with the presence of neotectonic features and deep-seated gravitational phenomena. The method used in this study could profitably contribute towards either seismic risk or deep-seated gravitational deformation analyses.     

Localization of mining-induced horizontal fractures along rock layer interfaces in overburden: field measurements and prediction

The locations of mining-induced horizontal fractures along rock interfaces in the overburden of Donetsk Coal Basin were identified using an original experimental device. The device traps methane from horizontal fracture zone (100–fold coal seam thickness) over an active longwall mining excavation. Presence or absence of horizontal fractures along rock layer interfaces is correlated with physical characteristics of the overburden, such as thickness, uniaxial compressive strength of overburden rock layers, location of rock layer interfaces and thickness of extracted coal seams. As a result, a combined criterion based on these physical characteristics is proposed to predict the presence of overburden horizontal fracturing in coal mine operations.     

石笋流体包裹体中的惰性气体及其在重建长江中游古温度变化中的作用

文中讨论了一种评估古气温变化的新方法。我们成功地利用石笋流体包裹体所捕获的Xe/Ar比值,重建了末次冰盛期以来盛行东亚季风的长江中游地区的气候演化。一种表达成ln(CXe/CAr)的对数式被证明与冷暖周期变化具有密切的关系。从研究的石笋中所提出的δ13C与Mg/Ca曲线一般随区域古气温波动而变化,但不能排除其中有另类气候信号的叠加。我们的工作则明确地指出,流体包裹体所记录的Xe/Ar在各种反映温度变化的替代指标中可能是最好的一种。整体而言,ln(CXe/CAr)曲线与那些基本随暖期和冷期振荡的曲线保持一致。将稀有气体曲线与δ13C和Mg/Ca信号整合对比之后,我们在研究区划分出末次冰盛期以来8组暖/冷旋回。整合后的气温变化模式合理地解释了过去20000年里的区域环境变化。     

Improved Platinum-Group Element Extraction by NiS Fire Assay from Chromitite Ore Samples Using a Flux Containing Sodium Metaphosphate

Many chromite-rich rocks contain relatively high concentrations of the platinum-group elements (PGE). In many cases, the phases carrying PGE occur as either platinum-group minerals (PGM) or as base metal sulfides in solid solution in sulfides. In some cases, such as the UG-2 unit of the Bushveld Complex, the PGM are occluded inside chromite grains. Chromites are notably difficult to dissolve in most fluxes and if the chromite contains some PGM the possibility exists that not all the PGE will be recovered during fusion. In this work, shortcomings in published methods of analysis based on the nickel sulfide fire assay procedure were investigated and a new procedure developed based on the addition of sodium metaphosphate to the fusion mixture. Optimum composition of the fusion mixture was found to be 10 g sodium metaphosphate and 9 g silica to 10 g sample, 15 g sodium carbonate, 30 g lithium tetraborate, 7.5 g nickel and 4.5 g sulfur to achieve complete dissolution of chromite grains. The new flux mixture was evaluated by the analysis of reference material CHR-Pt+ (which is known to contain PGM inside chromite grains) and no undissolved chromite grains were found in the glassy slag. Analysis of the nickel sulfide beads from this fire assay using neutron activation analysis showed similar results for Rh and Ru when compared with published conventional true (or accepted) values, while Au, Ir, Os, Pd and Pt values determined here were 10 to 30% higher than the corresponding published conventional true values. It was concluded that the addition of sodium metaphosphate improved chromite dissolution in the flux and appears to improve PGE recovery.     

An Overview of Dissolved and Suspended Matter Fluxes in the Loire River Basin: Natural and Anthropogenic Inputs

The spatial and temporal distributions of major elements were investigated in the surface waters and in associated suspended matter at two sites of the upper Loire basin (Orleans and Brehemont) between 1995 and 1998.According to geochemical and isotopic patterns, the dissolved load appears to result from a process of mixing rainwater inputs, weathering processes of carbonate and silicate bedrock, and agricultural and urban inputs. Natural inputs influence 60% of water chemical composition at both sites. Annual dissolved fluxes were estimated to be 1300 10³ t/y at Orleans and 1620 10³ t/y at Brehemont. Major elements are transported mainly in the dissolved fraction. After correcting for atmospheric and anthropogenic inputs, the silicate specific export rate was calculated to be 11 t/y/km² throughout the basin and the carbonate specific export rate to be from 47 t/y/km² at Orleans to 23 t/y/km² at Brehemont.The suspended load appears to result from at least two particle reservoirs: a silicate reservoir and a carbonate reservoir. The silicate reservoir has a detrital origin, mainly during periods of high flow, while the carbonate reservoir has a detrital origin during periods of high flow and an authigenic origin during periods of low flow. Of the total annual flow of suspended matter, this authigenic material represents 16% at Orleans, 25% at Brehemont and 37% in the fluvial part of the estuary. After correcting authigenic inputs, the specific export rate due to mechanical weathering was estimated to be 8 t/y/km² throughout the Loire basin.     

气相色谱仪单机测试矿物包裹体中的气相成分与精密切换系统设计

用气相色谱法测试矿物包裹体中的气相成份时,难以实现一次性多组分全分析。在采用单机双柱串联方式时,则需要精确的柱间切换,分时操作。显而易见,正确地选择切换时机是实现单机测试的关键。为此,我们设计了一个微机控制的精密切换系统,与普通的气相色谱仪连接后,可以精确地找到切换时间,并实现自动切换。该系统也适用于其它需要分时操作的场合。     

我国页岩气资源及影响因素

在世界面临能源短缺的背景下,页岩气作为油气勘探的一个新领域,越来越得到世界各国的重视。我国页岩气资源丰富,许多盆地或地区具有页岩气大规模成藏的地质条件,对页岩气的研究显得尤为重要。该文介绍了我国页岩气资源储量、分布及开采面临的问题,概述了页岩气地质特征。在此基础上探讨了我国页岩气的影响因素,认为我国页岩气主要受有机碳含量、成熟度、裂缝的发育程度、地层压力的控制;页岩气与煤层气同属于非常规天然气,其赋存形态、成因类型、富集规律具有很多相似之处,因此可将页岩气与煤层气进行对比研究。     

非线性支持向量机在油气预测中的应用

油气预测的传统方法通常是基于经验风险最小化准则,但在有限样本情况下,预测效果并不理想.研究引入基于结构化风险最小化准则的非线性支持向量机方法,通过对推广误差界的最小化达到最大的泛化能力和全局最优,时于小样本数据,该方法具有可靠的预测能力.在对四川观音场构造面新统上部碳酸盐岩储层数据处理中.通过实例试算,结果表明该方法有效可靠,预测精度高,与已知结果吻合较好.