A new type of interaction between generalized Chaplygin gas and dark matter

In this paper, we investigate the model with a new type of interaction between generalized Chaplygin gas (GCG) and dark matter. It is shown that there exists a stable scaling attractor, which provides the possibility to alleviate the coincidence problem. The equation of state (EoS) of GCG approaches the attractor phase from either w _g >?1 or w _g w _g w _g w _g >?1), and next cross again the phantom divide (the transition from w _g >?1 to w _g Q can change its sign from Q<0 to Q>0 as the universe expands, which is different from the usual interaction. Moreover, we investigate the model from statefinder viewpoint. The statefinder diagnostic can not only discriminate the model with different coupling constant but also distinguish the model from other dark energy models.     

Study on Effects of Low Viscosity Fluid Pre-injection on Hydraulic Fracture Complexity in Tight Heterogeneous Glutenite Reservoirs

Tight heterogeneous glutenite reservoir is typically not easy to form complex hydraulic fracture (HF) due to its poor physical properties, poor matrix seepage capacity, and small limit discharge radius and undeveloped natural fracture system. To improve the HF complexity and the stimulated reservoir volume (SRV), a novel stimulation technology called CO₂ miscible fracturing has been introduced and its fracturing mechanism has been studied. The CO₂ miscible fracturing modifies the in situ stress field by injecting low viscosity fluid to increase the HF complexity and SRV. Therefore, a series of numerical simulations based on a hydro-mechanical-damage model were carried out to study the effects of low viscosity fluid pre-injection on pore pressure, stress field, and fracturing effect in tight heterogeneous glutenite reservoirs. The results indicate that the low viscosity fluid injection can effectively increase the pore pressure around the wellbore and reduce the effective stress of the glutenite. The FCI and SRV increase with the increase of the pre-injection amount of the low viscosity fluid. The HF complexity and SRV can be improved by pre-injecting low viscosity fluid to transform the in situ stress field. The field application of this technology in a well of Shengli Oilfield showed that low-viscosity fluid pre-injection can effectively increase the width of the fractured zone, improve the SRV, and optimize the fracturing effect.

     

鄂西宜昌地区页岩气勘探发现对MVT铅锌矿成矿的指示意义

油气成藏和有机质参与金属成矿的内在联系是近年来国内外地学界关注的热点问题.根据流体包裹体岩相学观察和激光拉曼光谱分析,在鄂西宜昌地区震旦系陡山沱组和下寒武统牛蹄塘组页岩储层及震旦系灯影组MVT（Mississippi Valley type）铅锌矿床中发现了高密度甲烷包裹体,并利用甲烷包裹体的甲烷拉曼散射峰v₁计算了甲烷包裹体的密度;同时采用Rb-Sr、Sm-Nd同位素定年确定了MVT铅锌矿成矿年代.鄂阳页1井陡山沱组页岩石英脉和何家坪MVT铅锌矿方解石样品中甲烷包裹体密度分别为0.237~0.278 g/cm3和0.213~0.271 g/cm3,属于高密度甲烷包裹体.何家坪铅锌矿共生矿物闪锌矿和方铅矿的Rb-Sr等时线年龄为189.1±1.8 Ma,方解石的Sm-Nd等时线年龄为189.9±2.0 Ma,指示铅锌矿形成于燕山早期的构造挤压运动;共生矿物的初始87Sr/86Sr值（0.711 92）和方解石的初始87Sr/86Sr值（0.712 03~0.712 27）指示何家坪铅锌矿成矿流体的Sr同位素主要来源于页岩层.何家坪铅锌矿中捕获的以流体包裹体形式存在的高密度甲烷流体最有可能来源于陡山沱组页岩和/或牛蹄塘组页岩内高密度超压甲烷流体.页岩气层和MVT铅锌矿中高密度甲烷包裹体的发现及MVT铅锌矿成矿时间的确定为探讨有机质参与MVT铅锌矿成矿提供了新证据.      

Late Ordovician high-Mg adakitic andesite in the western South China block: evidence of oceanic subduction

The Early Palaeozoic was an important period in the geologic evolution of the South China block (SCB), marking the intracontinental orogen in the Wuyi-Yunkai region. One salient feature of the western SCB is the absence of Early Palaeozoic oceanic subduction-related magmatism. Here, we report the first known occurrence of Late Ordovician andesites from the Shimian area, western SCB. Zircon SHRIMP U–Pb dating reveals that the andesites formed at ca. 451 Ma. They have geochemical features of high-Mg adakitic andesite (HMAA) and are characterized by low K₂O (1.09–2.24 wt.%) and Th (2.50–5.65 ppm) and high MgO (4.02–6.91 wt.%) and Mg# (56–71). Furthermore, their zircon grains display positive ε_Hf(t) (+11.4 to +19.6) and low δ¹⁸O (4.72–6.20‰) values. The andesites are interpreted to have been derived from partial melting of a peridotitic mantle wedge in an oceanic subduction setting and subsequent fractional crystallization. Integrating previous studies of the Qinling-Dabie orogenic belt with the data presented in this contribution, we suggest that the SCB was probably involved in the Early Palaeozoic Andean-type orogeny along the Gondwanan proto-Tethyan margin.     

Comparison of Fenton,ultraviolet–Fenton and ultrasonic–Fenton processes on organics and colour removal from pre-treated natural gas produced water

Produced water (PW) from natural gas field, characterized with high organic contents, has brought high environmental concerns world widely. Fenton and enhanced Fenton technologies were considered as the potential methods to degrade the organic contaminates in the PW, but with very limited data or reference. Here, we examined the optimum conditions of Fenton on organics and colour removal from natural gas PW after coagulation pre-treatment. Simultaneously, the optimal Fenton process integrated with ultraviolet (UV) and ultrasonic (US) irradiation were applied to enhance pollutants removal efficiencies. The optimal Fenton conditions were found at 60 min with molar ratios of 6:1 and 25:1 for H₂O₂/COD and H₂O₂/Fe²⁺, respectively and the initial pH of 3. Among these the three treatment processes, chemical oxygen demand (COD), total organic carbon, 5-day biological oxygen demand (BOD₅), and colour removal efficiencies were highest during UV–Fenton (82, 73, 68, and 95%,) followed by US–Fenton (79, 70, 66, and 95%) and Fenton treatment (70, 58, 51, and 92%), respectively. High biodegradability (BOD₅/COD) was also observed after UV–Fenton process (0.76) than the others (both 0.73). The current study showed a satisfactory carbon and colour removal efficiencies from PW using different Fenton processes; however, there still is a need for final polishing such as biological treatment or low cost constructed wetland before discharge. This study can be a good reference for engineering application PW treatment.     

First observation of domoic acid and its isomers in shellfish samples from Shandong Province,China

Journal of Oceanology and Limnology - A total of 133 shellfish samples were collected in seven cities of Shandong Province, China, from May to October, 2019. The domoic acid (DA) concentrations...     

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地下储层构型表征:现状与展望

地下储层构型表征是近十几年发展起来的油气藏开发地质研究方向。与露头构型分析不同的是,地下储层构型表征主要依据地震信息和多井信息,相应地发展了两类方法,其一为地震沉积学(地貌学)方法,即通过三维地震资料地层切片等方式,利用地震成像特征研究沉积单元的分布;其二为多井模式预测方法,即通过将不同级次的定量构型模式与地下井资料(包括动态监测资料)进行拟合,分级约束并预测不同级次的构型单元的井间分布。论述了这两类方法的起源、基本原理、应用范畴及存在问题,并根据油田生产要求与技术发展提出了进一步深入研究的方向,包括三维定量构型模式的深化研究、储层构型地震响应及解释方法研究、多井模拟拟合方法的改进与创新等。     

大兴安岭南段多金属成矿带硫、铅同位素组成及其地质意义

大兴安岭南段是我国北方重要的多金属矿床成矿带,对其成矿物质来源的分析研究有利于区域成矿规律的总结。在前人的工作基础上,对典型矿床的矿石矿物进行了硫、铅同位素研究。结果表明:闪锌矿、方铅矿、毒砂、黄铜矿、辉钼矿等硫化物的δ34S值主要变化范围为-6‰～4‰,平均值为0‰,峰值出现在0‰～2‰,呈塔式分布;无明显的重硫、轻硫富集,说明硫源较单一;矿石矿物及岩石的206 Pb/204 Pb、207Pb/204Pb、208Pb/204Pb值的变化范围主要集中在18.13～18.74、15.38～15.68和37.1～38.93,其平均值分别为18.38、15.54和38.09。同时,数据结果显示:成矿带的东部与西部存在较为明显的铅同位素差异,西部矿床中铅的分布主要集中在造山带演化线附近,而东部矿床中铅主要集中分布在上地幔和造山带演化曲线附近。     

Interannual variations of North Equatorial Current transport in the Pacific Ocean during two types of El Niño

Interannual variations of Pacific North Equatorial Current (NEC) transport during eastern-Pacific El Niños (EP-El Niños) and central-Pacific El Niños (CP-El Niños) are investigated by composite analysis with European Centre for Medium-Range Weather Forecast Ocean Analysis/Reanalysis System 3. During EP-El Niño, NEC transport shows significant positive anomalies from the developing to decay phases, with the largest anomalies around the mature phase. During CP-El Niño, however, the NEC transport only shows positive anomalies before the mature phase, with much weaker anomalies than those during EP-El Niño. The NEC transport variations are strongly associated with variations of the tropical gyre and wind forcing in the tropical North Pacific. During EP-El Niño, strong westerly wind anomalies and positive wind stress curl anomalies in the tropical North Pacific induce local upward Ekman pumping and westward-propagating upwelling Rossby waves in the ocean, lowering the sea surface height and generating a cyclonic gyre anomaly in the western tropical Pacific. During CP-El Niño, however, strength of the wind and associated Ekman pumping velocity are very weak. Negative sea surface height and cyclonic flow anomalies are slightly north of those during EP El Niño.