Desorption of Asphaltenes from Silica-Coated Quartz Crystal Surfaces in Low Saline Aqueous Solutions

The quartz crystal microbalance (QCM) was used to study desorption of asphaltenes from silica-coated quartz crystals upon exposure to various aqueous low saline solutions of different salt concentrations and cationic valency. Ultraviolet (UV) spectroscopy measurements confirmed desorption in selected experiments. The amount of desorption was related to the type and concentration of electrolyte and the sequence of injecting the electrolyte solutions. Initial desorption upon exposure to solutions with high ionic strength was likely due to repulsion between negatively charged sites acquired at the silica and the asphaltenes. During the injection of low saline aqueous solutions, a critical expansion of the diffuse double layer was required for desorption to occur. Comparatively lower desorption of asphaltenes was observed in the CaCl₂ solutions than in NaCl and seawater solutions.     

Protein foam application for enhanced oil recovery

Protein foam was explored as a foaming agent for enhanced oil recovery application in this study. The influence of salinity and oil presence on bulk stability and foamability of the egg white protein (EWP) foam was investigated. The results were compared with those of the classical surfactant sodium dodecyl sulfate (SDS) foam. The results showed that the EWP foam is more stable than the SDS foam in the presence of oil and different salts. Although, the SDS foam has more foamability than the EWP foam, however, at low to moderate salinities (1–3 wt% NaCl), both foam systems showed improvement in foamability. At a NaCl concentration of 4.0 wt% and above, foamability of the SDS foam started to decrease drastically while the foamability of the EWP foam remained the same. The presence of oil has a destabilizing effect on both foams but the EWP foam was less affected in comparison to the SDS foam. Moreover, increasing the aromatic hydrocarbon compound percentage in the added oil decreased the foamability and stability of the SDS foam more than EWP foams. This study suggests that the protein foam could be used as an alternative foaming agent for enhanced oil recovery application due to its high stability compared to the conventional foams.     

Origin and Recharge Altitude of the Thermo-Mineral Waters of the Eastern Pyrenees

The thermo-mineral waters of the axial zone of the Eastern Pyrenees form a geochemically homogeneous group. They emerge in granite or orthogneiss and all have a sodium sulphide chemistry. Principal component analysis of their physico-chemical parameters has distinguished three types of fluid, 1) hot water that has evolved in a closed system and whose chemistry may reflect that of deep water, 2) water that is also of unmixed origin, but whose chemical composition has been modified during cooling by conduction, and 3) water cooled by mixing with surface water.

Stable isotope (¹⁸O, ²H) contents indicate that all the waters are of meteoric origin (from oceanic and/or Mediterranean precipitation). No heavy isotope enrichment has been found that would indicate evaporation or a geothermal effect between water and the host rock.

The differences in isotope contents between surface and thermo-mineral waters are attributed to a difference in recharge altitude; altitude gradients in ¹⁸O and ²H, estimated by two independent methods, are respectively 0.24‰ and 1.84° per 100m. They may, however, be lower when precipitation is in the form of snow. Applying these calculated gradients to thermo-mineral waters, taking mixing effects into account, has given an estimate of the minimum altitude of recharge of 110 springs in the Eastern Pyrenees.     

Nachruf Prof. Hübner

Abstract

Representative water samples were collected from different oases in the western desert of Egypt to examine characteristics of Egyptian groundwater. Chemical data recognized two basic groundwater types; alkali bicarbonate and alkali chloride, where sodium has the highest concentration. For each region the median SD, δ¹⁸ 0 and ionic strength of water calculated from their chemical analyses are recorded and plotted.

Generally, the results of isotopic content measurements of the groundwaters from the different oases in the western desert indicate the fossile origin of these waters. The values of δD and δ¹⁸ 0 of the western desert oases' waters are characteristic of old paleowaters from the Nubian sand aquifer. Modern sparse rainfall data suggest that any precipitation will exhibit moderate to large positive isotopic content enrichments and cannot be a source for these waters. They have been in no connection with the Nile water, moreover the change in isotopic composition is due to evaporation which is now ineffective at deeper levels.     

A 6.5-year continuous record of sea surface salinity and seawater isotopic composition at Harbour of Ishigaki Island,southwest Japan

We produced continuous records of sea surface salinity and isotopic composition from 1998 to 2004 at Ishigaki Island, southwest Japan, and found clear seasonal variations in salinity and oxygen isotopic composition and increasing trends of them after 1999. These increasing trends could be principally due to the decreasing difference between local precipitation (P) and evaporation (E), as a result of the reduction of horizontal vapour transport from adjacent oceans. When samples collected in heavy rainfall events were excluded, the average Δδ¹⁸O/Δ salinity slope was obtained as 0.31, 0.35 in summer and 0.28 in winter. Estimated E/P ratios based on the isotopic box model are in good agreement with the ratios of independently estimated E to observed P.     

鲫鲤杂交F1幼鱼耗氧率与窒息点的测定

对鲫鲤杂交F1幼鱼的耗氧率、窒息点及其影响因素进行了测定 .结果表明 :鲫鲤杂交F1是低窒息点鱼类 ,耗氧量和耗氧率随水中氧含量的下降相应地下降 ,其最高耗氧率出现在 14 :0 0到 16 :0 0之间 ,人工养殖鲫鲤杂交F1时 ,溶氧最好能维持在 5mg/L以上 ;鲫鲤杂交F1对盐度有较强的适应能力 ,比重在 1.0 10以下 4 8h未见幼鱼死亡 ;其生长发育的适宜温度为 2 0～ 2 5℃ .     

基于光谱指数的区域土壤盐分三维空间变异研究

为揭示中原黄泛区土壤盐分三维空间分布特点,以河南省封丘县为研究区域,综合应用土壤采样数据与遥感影像数据,利用光谱指数法与三维反距离权重法(IDW)对三维土壤盐分空间变异特征进行了解析与评价,显著提升了区域土壤盐分的三维预测精度。研究区域土壤电导率变异系数在0.218～0.324之间,属中等变异强度;各层土壤电导率的平均值在0.121～0.154 ds·m-1之间,土壤盐分高值区主要分布在天然渠与黄河沿线区域,研究区盐渍土剖面类型属“底聚型”,即随着深度增加土壤盐分含量逐渐增大,呈现底土积盐的趋势;该研究表明应用以光谱指数数据为基础的三维IDW方法对区域土壤盐分三维特征进行解析可以达到较高精度。该研究为中原黄泛区盐渍障碍耕地的治理利用提供了可靠技术方法。     

海洋赤潮温度盐度双参数检测技术研究

针对海洋赤潮的实时监测和预报,提出了一种通过检测海水中布里渊散射回波信号,获取海洋赤潮水体温度和盐度分布信息的双参数检测技术。通过分析布里渊散射理论,建立基于机载蓝绿激光雷达的布里渊散射信号频移量和布里渊散射信号能量与海水温度和盐度的关系模型。通过仿真计算,可由海水中的蓝绿激光布里渊散射回波信号的频移量和能量,分别得出海表及海水50 m深度以内温度和盐度的分布情况,从而可以实现海水温度和盐度的双参数实时获取,为实时判断海洋赤潮的消长过程提供理论依据。     

压力延迟渗透膜技术

压力延迟渗透膜技术是近年来备受瞩目的新型膜技术之一。它可与正渗透、反渗透等膜分离技术结合,从而在海水淡化、污水处理等领域具有广泛应用前景,而且其本身在有效获取盐差能等绿色海洋能源方面的应用潜力巨大。本文对压力延迟渗透原理、过程设计及其影响因素进行了系统总结,重点围绕压力延迟渗透膜的材料、类型、存在的问题和解决方案等最新研究进展进行详细分析和介绍,同时列举了压力延迟渗透膜技术在盐差能发电、水处理等领域的应用。     

New insights into the mechanism of wettability alteration during low salinity water flooding in carbonate rocks

There is not a consistent view about the mechanism of wettability alteration during low salinity water flooding. This paper highlights extensive wettability studies to investigate the wettability alteration on mineralogically different carbonates. Contact angle measurements were conducted to characterize wettability changes quantitatively. The results clearly revealed that wettability of carbonate rock surfaces can be altered to a more water-wet condition by lowering water salinity. The trend of the maximum change of contact angle (MCCA) variation with dolomite/calcite content in the rock is fairly linear under the same salinity, which demonstrates that carbonate minerals can affect rock wettability in a way. Also, the higher calcite content in the rock, the greater MCCA, i.e. the stronger effect of LSWF. Besides, the sensitivity of rock wettability to minerals is different under different salinity conditions. When the salinity is in the range of 2384.6?～?4769.2?mg/L, rock wettability is most sensitive to minerals. The analysis of the effect of ion composition showed that the effect of Ca²⁺ on wettability alteration is greater than that of Mg²⁺ at room temperature, and with the increase of the content of calcite in the rock, the effect of Ca²⁺ is more pronounced than that of Mg²⁺.