Evaporation Stage of Paleo-saline Lake in the Sichuan Basin, China: Insight from Fluid inclusions in Halite

Sichuan Basin is one of the most important marine–salt forming basins in China. The Simian and Triassic have a large number of evaporites. The Triassic strata have found a large amount of polyhalite and potassium-rich brine. However, no soluble potassium salt deposit were found. In this study, the halite in well Changping 3 which is located at the eastern part of the Sichuan basin was studied using the characteristics, hydrogen and oxygen isotopes of the fluid inclusion in halite to reconstruct the paleoenvironment. The salt rocks in well Changping 3 can be divided into two types: grey salt rock and orange salt rock. The result shows that the isotopic composition of the halite fluid inclusion is distinct from the global precipitation line reflecting that the salt formation process is under strong evaporation conditions and the climate is extremely dry. At the same time, compared with the hydrogen and oxygen isotopes of brine in the Sichuan Basin and the hydrous isotope composition of the inclusions in the salt inclusions of other areas in China, it is shown that the evaporation depth of the ancient seawater in the Sichuan Basin was high and reached the precipitation of potassium and magnesium stage.     

OCS,H2S,and CS2 fluxes from a salt water marsh

The diurnal-to-monthly behavior of the fluxes of OCS, H₂S, and CS₂ from a mixed-Spartina grass-covered site in a Wallops Island salt water marsh was determined through a series of experiments in August and September, 1982. Absolute flux values were determined for OCS and H₂S, while only relative values were determined for CS₂. The rates of emission of OCS and H₂S were observed to vary diurnally and to be strongly influenced by tides. The time-averaged flux values show that such mixed-Spartina stands are insignificant ( 1%) global sources of H₂S or CS₂ and insignificant contributors to the global OCS cycle (< 1%). These results demonstrate that some marsh regions play a minor role in the global sulfur budget and, consequently, that the inclusion of such areas in extrapolations of measurements of more productive regions could lead to an overestimate of the role of salt water marshes in the global sulfur budget.     

Oxidation of sulphur compounds in the atmosphere: I. Rate constants of OH radical reactions with sulphur dioxide,hydrogen sulphide,aliphatic thiols and thiophenol

The reactions of OH radicals with SO₂, H₂S, thiophenol, and a series of aliphatic thiols (1–5 C-atoms) have been investigated in 201 and 381 reaction chambers at 1 atm total pressure and 300 K using a competitive kinetic technique. Initially, OH radicals were produced by photolysis of CH₃ONO/NO mixtures in air. Applying this OH source rate constants for OH with SO₂, H₂S, and thiophenol in synthetic air were determined to be (1.1±0.2)×10^-12, (5.5±0.8)×10^-12 and (1.1±0.2)×10^-11 cm³ s^-1, respectively. However, when this method was applied to the aliphatic thiols the rate constants obtained were found to be dependent on the partial pressures of O₂ and NO. These effects have been attributed to the built-up of a radical species, not yet identified, which leads to uncontrolled chain reactions in the system. Using the photolysis of H₂O₂ at wavelengths greater than 260 nm as the OH source in 1 atm N₂, rate constants for the 1–5 aliphatic thiols in the range 2.9 to 5.6×10^-11 cm³ s^-1 were obtained. The rate constants obtained in the present study are compared with recent literature values.     

塔里木盆地油田水文地球化学

塔里木盆地油田水总矿化度６０ｇ／Ｌ－３２０ｇ／Ｌ，与氯离子浓度呈正相关，总体上受铝酸盐矿物的成岩改造影响甚小。油田水主要为部分贫镁型和完全耗镁型两种。部分贫镁水型被认为来自方解石的白云石化作用和斜长石的溶解作用；氧同位素值，Ｌｉ，Ｂ和Ａｌ浓度随埋深而增大，高的锶浓度指示了水－铝硅酸盐矿物反应是受温度控制的Ｍｇ－Ｌｉ可指示古地温。     

Water—Rock Interaction in Tarim Basin：Constraints from Oilfield Water Geochemistry

Olifeld waters from Cenoxoic and Mesozoic terrestrial and Paleozoic marine environments in the Tarim Basin show no obvious difference in water chemistry except Br and isotopic compositions.The Paleozoic marine strata have higher Br concentrations than the terrestrial sediments,and the lack of obvious relationship between Br and I suggests that Br is not,for the most part,derived from the degradation of organic matter.The oilfield waters are characterized by high TDS(total dissolved solids),ranging from 120000mg/L to 320000mg/L relatively low Mg,high Ca,Sr,and CF relative to Br of evaporating seawater,suggestive of enhanced water-rock interaction,OAA(organic acid anions)concentrations are generally lower than 1500mg/L with high values occurring over the temperature range from 95℃ to 140℃,in the Cambrian to Jurassic systems,and nearby unconformities.Organic acids are considered to be generated mainly from thermal maturation of kerogens during progressive burial of the Jurassic-Triassic and Cambrian-Ordovician systems,biodegradation of crude oils nearby unconformities,and thermochemical sulfate reduction in part of the Cambrian and Ordovician strata.High Al concentrations up to 3mg/L to 5.5mg/L tend to occur in the waters of high OAA or petroleum-bearing intervals,suggesting the presence of organic complexing agents.Calculation by SOLMINEQ.88 with updated database shows that AlAc^2 may account for more than 30% of the total Al.Isotopic measurements(δD,δ18O)provide evidence for the following types of waters:diagenetically-modified connate meteoric water from the Jurassic and Triassic strata;diagenetically-modified connate marine water from the Cambrian and Ordovician strata;subaerially-evaporated water from the Cenozoic and Cretaceous strata;and mixed meteoric-evaporated or/and diagenetically modified connate water from the Carboniferous strata and reservoirs adjacent to the J/C and T/C unconformities.Those waters with very negative δD values from -51.30‰to-53.80‰(SMOW) and positive δ18O values from 2.99‰to 4.99‰(SMOW)in the continuous burial of the Cambrian-Ordovician system are explained to have resulted from hydrocarbon-water and water-rock interactions.     

胶东金成矿区岩石氧氢同位素地球化学背景初探

本文对胶东区域与金矿有关的各主要地质体氧氢同位素组成背景进行研究，给出了燕山早期“玲珑”中粗粒二长花岗岩（滦家河型花岗岩）氧氢同位素背景值为δ１８Ｏ＝７．８％，δＤ＝－１１０‰；燕山晚期郭家岭（型）斑状花岗闪长岩背景值为δ１８）＝１０．０‰；昆嵛山复式岩基背景值为δ１８Ｏ＝８．５‰，δＤ＝－９０‰。胶东群变质岩各岩性段δ１８Ｏ＝５．１－１１．３‰，δＤ＝－８１－－９６‰，表明其源岩既有幔源中基性组     

硫化氢、相态烃和自然电位法综合测量勘查油气田方法

经近几年试验,我们提出用土壤吸附硫化氢气体作指标,勘查油气田新方法.并将它和相态烃法、自然电位法相配合,在已知油气田开展了试验,取得令人十分满意的效果.油气藏中含有大量硫化氢气体及含硫有机化合物.油气垂直微渗漏到近地表时,硫化物气体也随伴而至.运移过程中,硫化氢气体及含硫化合物在细菌及氧气作用下会发生一系列复杂的化学变化,如生成硫酸盐等,但经已知油气田试验结果表明,在油气藏上方近地表土壤中仍保留有明显的硫化氢气体异常,而且异常形态有一定的模式,有环状、半环状、片部和带状等不同形态.异常均和下伏油气藏或断裂构造相吻合,表明硫化氢气体测量法是勘查油气田的有效方法.更引人注目的是,它和相态烃、自然电位异常吻合的很好,异常均出现在油藏上方,表明综合使用这三种方法将会取得更好的找油气效果.     

Growth of monodisperse,submicron aerosol particles exposed to SO2, H2O2, and NH3

The growth of monodisperse particles (0.07 to 0.5 µm) exposed to SO₂ (0–860 ppb), H₂O₂ (0–150 ppb) and sometimes NH₃ (0–550 ppb) in purified air at 22 °C at relative humidities ranging from 25 to 75% were measured using the Tandem Differential Mobility Analyzer technique. The experiments were performed in a flow reactor with aqueous (NH₄)₂SO₄ and Na₂SO₄ droplets. For (NH₄)₂SO₄ droplets the fractional diameter growth was independent of size above 0.3 µm but decreased with decreasing size below that. When NH₃ was added the fractional growth increased with decreasing size. Measurements were compared with predictions of a model that accounts for solubility of the reactive gases, the liquid phase oxidation of SO₂ by H₂O₂, and ionic equilibria. Agreement between measured and predicted droplet growth is reasonable when the ionic strength effects are included. Theory and experiments suggest that NH₃ evaporation is responsible for the decrease in relative growth rates for small aqueous ammonium sulfate particles. The observed droplet growth rates are too slow to explain observed growth rates of secondary atmospheric sulfate particles.     

硫化氢形成与C2+气态烷烃形成的同步性研究几个模拟实验的启示

硫酸盐热还原（TSR）是高含硫天然气形成的主要原因,但是参与TSR反应的主要烃类组分仍存在争议。在对比分析湿气—硫酸镁反应体系、甲烷—硫酸钙反应体系以及重烃—硫酸镁反应体系模拟实验的基础上,通过对TSR化学反应表达式的分析以及化学动力学、热力学等理论的探讨,结合实际地质资料,认为甲烷是C₂₊烃类参与TSR反应的产物,TSR的发生与C₂₊气态烷烃的产生具有同步性,TSR的反应速率随着C₂₊气态烷烃的增加而加快,当湿气裂解为干气后,硫化氢含量几乎不再增加,从而形成干气伴生硫化氢。根据油气生成演化阶段分析,认为TSR主要发生在热裂解生凝析气阶段,原油裂解为硫化氢伴生天然气后,压力系统发生改变,天然气重新聚集成藏,如果构造环境发生改变就会进一步调整成藏。因此,天然气中硫化氢含量不仅受生成条件控制,还受运移通道、保存条件等因素控制。