An Evaluation of Phase Behaviors of the Oil-Gas-Water System in the Displacement of Crude Oil with CO2

CO₂ dissolution into an aqueous phase and water evaporation into a gaseous phase takes place during CO₂ injection into an oil reservoir. This study aims to evaluate the phase behaviors of the oil-gas-water system in the displacement of crude oil by CO₂. The composition of the JL oilfield in the northeast of China is taken as an example. The flash calculation of the oil-gas-water system was performed, based on the method presented by Li and Nghiem. The research re...     

建场测深法在新疆布尔津盆地油铀勘探中的应用

为明确位于新疆北部的布尔津盆地的资源状况,以实际采集数据为基础,采用建场测深法成果剖面研究了该盆地的地层地质结构,并对深层油气及浅部砂岩型铀矿进行评价。通过利用已知测井电阻率曲线模拟计算不同深度的电磁信号频率响应,论证了该方法探测从浅层第三系到深部石炭系的采集参数和工作方案;在数据处理成果的基础上,结合研究区已知地层物性特征,推断沿线的地质结构,揭示了布尔津凹陷的结构及下二叠统卡拉岗组、上石炭统哈尔加乌组、上石炭统恰其海组地层的分布,认为哈尔加乌组是本区有潜力的烃源岩。同时利用电阻率及双频相位属性对研究区浅部第三系砂岩型铀成矿条件进行分析,其结果与附近已知矿点情况吻合。本文提出的方法可为类似地区进行多种矿产资源勘探提供技术参考。     

2021年圣克鲁斯群岛MS 6.0地震PKPPKP震相识别

采用云南省地震局3个有人值守国家测震台和5个无人值守国家测震台记录到的2021年11月25日圣克鲁斯群岛M_S 6.0地震波形,运用测震学分析方法,对此次地震进行分析,提出其常见震相的一般性特征,并且重点总结了PKPPKP震相的特征,以免误将该震相分析为1个新地震的P波,分析结果表明PKPPKP震相在震中距约为70°时明显。     

含气软黏土的不排水抗剪强度计算模型

含气软黏土广泛分布在世界五大洲,大量离散气泡的存在对软黏土的不排水抗剪强度具有强化或损伤作用,然而目前仍缺乏能综合考虑气相强化与气相损伤竞争机制的含气土不排水剪切强度解析表达式。结合临界状态土力学理论,基于笔者提出的含气土屈服函数,建立了v-lnp¢ 空间下临界状态线截距与土体含气特性(u_{w 0},y₀)的数学关系,进而推导了含气软黏土在三轴应力状态下不排水抗剪强度s_u的理论显式表达式。同时,采用所提出的含气软黏土不排水抗剪强度理论计算公式,分别对比了3种典型的含气软黏土在不同含气特性下的不排水抗剪强度理论预测与试验结果,包括马来西亚高岭土、Combwich 黏土和高岭黏土。另外,对比分析了4种不同的含气软黏土不排水抗剪强度理论计算模型的预测误差百分比,证明了提出的基于改进的含气软黏土本构模型的不排水抗剪强度理论计算式的合理性,能够更加准确地同时考虑含气软黏土的气相强化与气相损伤双重效应。     

Grampian migmatites in the Buchan Block,NE Scotland

Rocks exposed along the Scottish coast between Fraserburgh and Inzie Head contain information critical to understanding the evolution of the Buchan Block, the type locality for low‐P, high‐T regional metamorphism, and its relationship with the rest of the Grampian terrane, one of the major tectonostratigraphic components of the Scottish Caledonides. The ~8 km long section traverses a regional network of shear zones and, at the highest grades around Inzie Head, passes into the core of the Buchan Anticline, a large‐scale open fold that is commonly regarded as a late structure, post‐dating metamorphism. The metasedimentary rocks increase in grade from upper amphibolite to granulite facies and preserve unequivocal evidence for partial melting. The diatexite migmatites around Inzie Head, along with other gneissose units within the Buchan Block, have been regarded as allochthonous Precambrian basement rocks that were thrust into their current position during the Grampian orogenesis. However, field observations show that the onset of in situ partial melting in metapelitic rocks, which was associated with the formation of garnet‐bearing aplites and associated pegmatites, occurred around Fraserburgh, where shear fabrics are absent. Thus, the rocks preserve a continuous metamorphic field gradient that straddles the shear zone network. This observation supports an alternative interpretation that anatexis was the result of mid‐Ordovician (Grampian) metamorphism, rather than an older tectonothermal event, and that the Inzie Head gneisses are autochthonous. Using an average mid‐Dalradian pelite as a plausible representative protolith, phase equilibria modelling satisfactorily reproduces the observed appearance and disappearance of key minerals providing that peritectic garnet produced with the first formed melts (represented by the garnet‐bearing aplites) depleted the source rocks in Mn. The modelled metamorphic field gradient records a temperature increase of at least 150 °C (from ~650 °C near Fraserburgh to in excess of 800 °C at Inzie Head) but is isobaric at pressures of 2.7–2.8 kbar, suggesting the Buchan Anticline developed synchronous with partial melting. The Buchan Anticline is likely an expression of crustal thinning and asthenospheric upwelling, which produced voluminous gabbroic intrusions that supplied the heat for Buchan metamorphism.     

Does continental crust transform during eclogite facies metamorphism?

Eclogites within exhumed continental collision zones indicate regional burial to depths of at least 60 km, and often more than 100 km in the coesite‐stable, ultra‐high pressure (UHP) eclogite facies. Garnet, omphacitic pyroxene, high‐Si mica, kyanite ± coesite should grow at the expense of low‐P minerals in most felsic compositions, if equilibrium obtained at these conditions. The quartzofeldspathic rocks that comprise the bulk of eclogite facies terranes, however, contain mainly amphibolite facies, plagioclase‐bearing assemblages. To what extent these lower‐P minerals persisted metastably during (U)HP metamorphism, or whether they grew afterwards, reflects closely upon crustal parameters such as density, strength and seismic character. The Nordfjord area in western Norway offers a detailed view into a large crustal section that was subducted into the eclogite facies. The degree of transformation in typical pelite, paragneiss, granitic and granodioritic gneiss was assessed by modelling the equilibrium assemblage, comparing it with existing parageneses in these rocks and using U/Th–Pb zircon geochronology from laser ablation ICPMS to establish the history of mineral growth. U–Pb dates define a period of zircon recrystallization and new growth accompanying burial and metamorphism lasting from 430 to 400 Ma. Eclogite facies mafic rock (~2 vol.% of crust) is the most transformed composition and records the ambient peak conditions. Rare garnet‐bearing pelitic rocks (<10 vol.% of crust) preserve a mostly prograde mineral evolution to near‐peak conditions; REE concentrations in zircon indicate that garnet was present after 425 Ma and feldspar broke down after 410 Ma. Felsic gneiss – by far the most abundant rock type – is dominated by quartz + biotite + feldspar, but minor zoisite/epidote, phengitic white mica, garnet and rutile point to a prograde HP overprint. Relict textures indicate that much of the microstructural framework of plagioclase, K‐feldspar, and perhaps biotite, persisted through at least 25 Ma of burial, and ultimately UHP metamorphism. The signature reaction of the eclogite facies in felsic rocks – jadeite/omphacite growth from plagioclase – cannot be deduced from the presence of pyroxene or its breakdown products. We conclude that prograde dehydration in orthogneiss leads to fluid absent conditions, impeding equilibration beyond ~high‐P amphibolite facies.     

富F熔体-溶液流体体系的地球化学性状及成矿效应研究进展

F既是重要的岩浆挥发分,又是重要的助熔剂和矿化剂,同时也是克拉克值较大的元素之一,并且在(铝)硅酸盐熔体中高度可溶。本文从F的常见工业矿物和主要赋存形式、分配行为的多样性、对其它元素分配行为的影响、矿化作用(即亲氟元素在热液体系中的氟化物络合形式、存在环境和沉淀机制等)、萤石和冰晶石的溶解及沉淀机制以及富F岩浆一热液体系的成矿专属性及特征6个方面探讨了F的地球化学成矿作用。结论认为:F必须有能力大量进入与花岗质或伟晶岩质熔体共存的含水流体相中才具有进一步的成矿学意义,云英岩化、钠长石化、含黄玉—萤石石英脉、具有较高F/CaO比值的残余熔体以及F在高度演化花岗质岩浆中的过饱和等因素均可能导致含矿富F热液的出溶;但总体上,富F岩浆—热液体系具有成矿专属性的原因之一仍在于:F首先通过对熔体物理化学性质的影响间接支配着高场强亲氟元素如W、Sn、Nb、Ta、REE、U等的热液成矿效应。     

云南昭通铅锌矿pH-logfo_2和pH-loga相图对铅锌共生分异的制约

云南昭通大型铅锌矿是滇东北矿集区乃至川滇黔铅锌成矿域铅锌矿床的典型代表。矿床具有明显的矿物组合分带性的特点,区别于典型的MVT型铅锌矿床。根据矿物组合特征构建、计算、绘制了该矿床的p H-logfo2、p Hloga相图,剖析了铅锌矿共生分异的形成机理。研究表明p H、氧逸度、组分浓度的协同作用造成了铅、锌的共生分异,对矿物组合分带起控制作用,且温度下降、氧逸度升高和p H升高有利于金属硫化物的沉淀,成功解释了昭通铅锌矿床独具特色的矿物分带地质特征。     

拉萨地块松多榴辉岩的变质演化过程:NCKMnFMASHTO体系中的相平衡关系

拉萨地块松多榴辉岩主要矿物组合为石榴子石、绿辉石、角闪石、多硅白云母、绿帘石、金红石。石榴子石环带不明显,核部成分均一,从核部到边部,镁铝榴石和钙铝榴石含量降低,可能分别记录了榴辉岩峰期及退变质过程信息。绿辉石显示微弱的成分环带,硬玉含量从核部到边部略有升高,部分绿辉石边部发育韭闪石退变质边,反映了在减压过程中外来流体进入体系的过程。多硅白云母具有高的Si含量(3.5~3.6),其中石榴石包体中的多硅白云母相对基质中的白云母有更高的Si值。本文利用Thermocalc变质相平衡模拟软件,结合详细岩相学观察,在NCKMn FMASHTO体系下,模拟松多含多硅白云母榴辉岩的变质演化过程。其中,榴辉岩峰期矿物组合为g+o+law+phn+ru,石榴石核部最大镁铝榴石值和石榴子石包体中多硅白云母最大Si值确定的榴辉岩峰期温压条件约为620℃,32×105Pa,榴辉岩经历了近等温降压的退变质过程。相平衡模拟结果表明拉萨地块松多榴辉岩经历了超高压变质作用过程,并经历了相对快速的折返过程到中部地壳层次。