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821.
含油气盆地碎屑岩次生优质储集层的发育,除了与广泛发育的方解石胶结相有关外,在中国西部还有一类与沸石族自生矿物胶结的成岩相有关,其中以溶蚀方沸石胶结相形成的次生优质储集层与油气聚集成藏又有十分密切的关联。经实例分析:与自生方沸石胶结有关的成岩相主要受控于扇(辫状河)三角洲前缘相带、火山岩物源和成岩早期的碱性环境;次生优质储集层的形成在时间上主要处于成岩中期A阶段,在空间上受控于邻近的烃源岩、圈闭和输导体的沟通。方沸石矿物在物理性质上具有抗压易溶(有机酸)作用,较其他常见的自生矿物(胶结物)相对优越,就方沸石易于溶蚀的特点而言是较为理想的自生矿物(胶结物)。其溶蚀对孔隙度的贡献率在50%~75%之间,发育几率占绝对优势。所以,在方沸石发育的相带中寻找以粒间溶蚀孔为主的优质储集层,具有可靠的操作性和现实性。 相似文献
822.
根据对渤海湾盆地沾化凹陷泥质岩、粉砂岩、砂岩和白云岩平行层面与垂直层面方向热导率差异及孔隙连通性差异特征的研究,探讨了沉积岩平行层面与垂直层面方向热导率与孔隙连通性之间的关系。热导率实验结果表明:沾化凹陷泥质岩、粉砂岩和砂岩的平行层面方向热导率大于垂直层面方向热导率;白云岩的平行层面方向热导率小于垂直层面方向热导率。沉积岩平行层面与垂直层面方向热导率差异和孔隙连通性差异之间具有正相关性。孔隙特征分析结果表明:孔隙连通性较好方向,热导率也较高;孔隙连通性较差的的方向,热导率也较低。 相似文献
823.
824.
在河北广宗勘探区深孔施工中,由于地表钻探用水水质影响及原钻井液体系不合适,造成钻井液性能指标达不到要求,性能难以控制,尤其失水量严重超标,接连发生孔内事故。针对存在的问题,经过分析和实验,采用化学方法处理钻探用水,选用聚合物钻井液,解决了深部钻孔施工存在的难点,收到了较好的效果,单孔深度达到1937.35m,并刷新了本单位及局属单位的钻探记录。 相似文献
825.
External seismic stability of vertical geosynthetic-reinforced soil walls using pseudo-static method
Analysis of external stability of vertical geosynthetic-reinforced soil (GRS) walls is very important in the seismic prone zone. The scope of this paper is to obtain required minimum reinforcement length, L min, for external seismic stability of vertical GRS walls by pseudo-static limit equilibrium method. Then, L min can be calculated to resist sliding, eccentricity, and bearing capacity failure modes. The parameters considered include both horizontal and vertical seismic coefficients (k h and k v ), surcharge load (q), wall height (H) and the properties of retained backfill, GRS, and foundation soil. Results show that L min against sliding failure mode, L min,S , increases more quickly than that against the other two failure modes with the increase in k h , q, or unit weight of retained backfill, γ b , while L min,S decreases more quickly than that against the other two failure modes with increase in friction angle of retained backfill, ? b , or unit weight of GRS, γ r . For the different failure modes, the effect of k v on L min is not identical with the change of k h , and in addition, L min/H will tend to remain unchanged with the increase in H. In general, L min against bearing capacity failure mode, L min,BC, is larger than L min against the other two failure modes. However, L min,BC will be less than L min against eccentricity failure mode, L min,E , for k h exceeding 0.35, or friction angle of foundation soil, ? f , exceeding 37°, and L min,BC will also be less than L min,S for friction angle of GRS, ? r , being no more than 26°. 相似文献
826.
Byung Sun Lee Sung-Ho Song Jin Sung Kim Jae Yeon Um Kyoungphile Nam 《Environmental Earth Sciences》2014,71(4):1521-1532
This study was conducted to identify the availability of coastal groundwater discharge (CGD), subsurface fluids flowing from inland through the coastal area to sea, as an alternative water resource for a large-scale reclaimed land. The behaviors of stable isotopes indicated that groundwater originated from inland precipitation and traveled as CGD along the coast line. Most of the groundwater samples collected from domestic wells installed along the old coast line were considered to be relatively fresh from the correlation analysis among chemical constituents. The average electrical conductivity (EC) values of the samples were identified as averaging 1,125–1,297 μS cm?1, corresponding to appropriate crop growth. A weathered-rock layer in a small catchment within the reclaimed land was proved to be a main CGD pathway, with electrical resistivity anomalies ranging from 7 to 14 Ω m. Five monitoring wells were placed in this catchment to delineate the occurrence of CGD. Long-term vertical EC profiling results for the monitoring wells indicated that CGD occurs within a depth of 30 m below the ground surface. Annual monitoring data for groundwater level and EC demonstrated that the water quality of CGD was improved by introducing fresh terrestrial groundwater. A remarkable improvement in water quality (EC decrease of 900–1,600 μS cm?1) of CGD was observed during the saline water pumping test that explains how CGD could be an alternative water resource for the reclaimed land. 相似文献
827.
Mercury (Hg) is an element of environmental and geological significance. Quantification of different Hg-binding forms is crucial to understand geological Hg provenances and associated geochemical processes during coal formation. In this study, seven coal samples were selected, according to coal rank (i.e., middle volatile bituminous, C-3; low volatile bituminous, C-2; anthracite, C-1), chemical anomalies (high S coal, IBC-105; high Cl coal, C22650) and sampling environment (fresh coal, LH; weathered coal LHW), to determine their Hg-binding forms using well-established sequential extraction procedures coupled with sink–float experiment. In the thermally metamorphosed samples C-1 and C-2, a comparative enrichment of total Hg relative to C-3 is observed. Silicate- and organic-bound Hg are the dominant Hg-binding forms in C-1, suggesting possible Hg sources from magma silicate and secondary Hg enrichment by adsorption. Sulfide- and organic-bound Hg are the most abundant Hg-binding forms in IBC-105, whereas only organic-bound Hg dominates in CC22650. Weathering processes are suggested to transform the abundant sulfide-bound Hg in LH to silicate- and organic-bound Hg in its weathering product LHW. 相似文献
828.
Statistical analysis of hydrochemistry of groundwater and its implications for water source identification: a case study 总被引:1,自引:0,他引:1
L. H. Sun 《Arabian Journal of Geosciences》2014,7(9):3417-3425
Hydrochemistry of groundwater is important for inrush water source identification in coal mines. For determining the source of inrush water from the 8101 working face in the Wolonghu coal mine, Northern Anhui Province, China, a total of 22 groundwater samples from three aquifer systems (loose layer—LA, coal bearing sandstone—CA, and the underlying limestone—TA), and eight samples from the 8101 working face were collected for analyzing major ion concentrations. The results suggest that major ion concentrations of the aquifer systems were different from each other, and they can be subdivided into Na–HCO3, Na–SO4, and Ca–SO4 types. Factor analysis indicates that their chemical compositions are mainly originated from two kinds of contributions: dissolution of soluble minerals (e.g., calcite, dolomite, and gypsum) and weathering of silicate minerals (e.g., plagioclase). Plots of factor scores and cluster analysis imply that LA was connected with CA, whereas TA was an isolated aquifer system. Moreover, the source of 8101 working face water was finally determined to be LA by using discriminant analysis. 相似文献
829.
A Study on Crack Damage Stress Thresholds of Different Rock Types Based on Uniaxial Compression Tests 总被引:7,自引:3,他引:4
Lei Xue Siqing Qin Qiang Sun Yuanyuan Wang Lee Min Lee Weichao Li 《Rock Mechanics and Rock Engineering》2014,47(4):1183-1195
When rock samples are loaded until macroscopic fractures develop, the failure process can be divided into several stages based on axial and lateral strain responses or the acoustic emission sequence during uniaxial compression tests. Several stress thresholds may be identified: the crack closure stress σ cc, crack initiation stress σ ci, crack damage stress σ cd, and uniaxial compressive strength σ ucs; these may be used as a warning indicator for rock rupture. We investigated the crack damage stress σ cd, its threshold, and a possible relationship between σ cd and the uniaxial compressive strength. The σ cd of different rock types were compiled from previous studies based on uniaxial compression tests. The results showed that the overall averages and standard deviations of σ cd /σ ucs for igneous, metamorphic, and sedimentary rocks were ~0.78 (±0.11), ~0.85 (±0.11), and ~0.73 (±0.18), respectively. There were no significant differences in σ cd /σ ucs between the different rock types, except that the sedimentary rock had a slightly larger standard deviation attributed to the variation of porosity in the samples, while the metamorphic rock had higher average σ cd /σ ucs resulting from the small statistical sample size. By excluding the higher-porosity (>10 %) rock samples, the averages and standard deviations of σ cd /σ ucs for igneous, metamorphic, and sedimentary rocks were ~0.78 (±0.09), ~0.85 (±0.09), and ~0.78 (±0.11), respectively. The results imply that the rock origin process (i.e., igneous, metamorphic, and sedimentary) has a minimal effect on σ cd /σ ucs. The ratio σ cd/σ ucs could be an essential intrinsic property for low-porosity rocks, which could be used in rock engineering for predicting the failure process. 相似文献
830.
为了研究芦山地震的孕震过程和震源区的长期构造过程以及解释实测的震后形变和重力资料, 采用分层介质模型, 利用数值模拟的方法, 考虑区域流变系数, 计算了地震引起的地表同震、震后的形变和重力变化以及区域内部分GPS与重力连续观测台站的震后形变和重力变化的时间序列.结果表明: 芦山地震的地表同震形变显示出发震断层明显的逆冲特性; 粘弹性松弛效应引起的震后地表形变和重力变化比同震形变和重力变化的范围明显扩大, 但随着粘滞系数的增加, 变化量明显减小; 观测台站的震后变化时变曲线显示震后形变和重力变化在震后50 a间变化显著, 100 a后基本平缓, 趋于稳定; 模拟计算的GPS台站中除了MEIG台和MYAN台以外, 其余台站的震后观测必须考虑粘弹性松弛的影响. 相似文献