A Numerical Simulation Study of Temperature and Pressure Effects on the Breakthrough Pressure of CO2 in Unsaturated Low-permeability Rock Core

Gas breakthrough pressure is a key parameter to evaluate the sealing capacity of caprock, and it also plays important roles in safety and capacity of CO2 geological storage. Based on the published experimental results, we present numerical simulations on CO2 breakthrough pressure in unsaturated low-permeability rock under 9 multiple P-T conditions (which can keep CO2 in gaseous, liquid and supercritical states) and thus, a numerical method which can be used to accurately predict CO2 breakthrough pressure on rock-core scale is proposed. The simulation results show that CO2 breakthrough pressure and breakthrough time are exponential correlated with P-T conditions. Meanwhile, pressure has stronger effects on experimental results than that of temperature. Moreover, we performed sensitivity studies on the pore distribution index λ (0.6, 0.7, 0.8, and 0.9) in van Genuchten-Muale model. Results show that with the increase of λ, CO2 breakthrough pressure and breakthrough time both show decreasing trends. In other words, the larger the value of λ is, the better the permeability of the caprock is, and the worse the CO2 sealing capacity is. The numerical method established in this study can provide an important reference for the prediction of gas breakthrough pressure on rock-core scale and for related numerical studies.     

On the Morphological Complexity of the Graptolite Tubaria in the Darriwilian(Middle Ordovician)

正1 Introduction As one of the major zooplanktonic organisms in the Ordovician and Silurian marine ecosystems,graptolites played a unique role in the GOBE (Great Ordovician Biodiversification Event) and underwent a considerable variation of diversities both in lifestyle and in speciation through the Ordovician (Sadler et al.,2011;Cooper et al.,2014).Graptolites are among the early     

Estimation of Land Surface Temperature over the Tibetan Plateau Using AVHRR and MODIS Data

Estimation of large-scale land surface temperature from satellite images is of great importance for the study of climate change. This is especially true for the most challenging areas, such as the Tibetan Plateau (TP). In this paper, two split window algorithms (SWAs), one for the NOAA’s Advanced Very High Resolu-tion Radiometer (AVHRR), and the other for the Moderate Resolution Imaging Spectroradiometer (MODIS), were applied to retrieve land surface temperature (LST) over the TP simultaneously. AVHRR and M...     

用水热平衡法估算水资源量

一、引言在估算一个流域或一个地区的水资源时,主要应用流域还原法进行计算。还原法虽有较成熟的计算方法,并且有一定精度,但还原法的工作量很大,所涉及的诸如灌溉回归水量、水库蒸发、渗漏损失水量等基本资料获取困难。另外在一些无实测水文资料的地区和河流,用还原法估算水资源就更为困难。相比而言,水热平衡法的工作量较还原法显著减小,所需之气象资料获取较为容易,在基本资料齐     

Stable Isotope and Element Geochemistry of Saline Springs in Evaporite-bearing Mengla Basin,South Yunnan,China

正1 Introduction Mengla Basin is a sub-basin in southern evaporitebearing Lanping-Simao Basin.There are many salt springs in the basin.In 2012,11 spring samples were collected for analyses of chemistry and boron,hydrogen and oxygen     

Geochemistry Characteristics of Granodiorite Porphyry in the Degongniuchang Copper Deposit, Muli, Sichuan Province, China

<正>1 Introduction 1The Sanjiang region in SE Tibet Plateau and NW Yunnan is known to have formed by amalgamation of Gongwanaderived continental blocks and arc terranes as a result of oceanic subduction followed by continental     

Behavior of REE Fractionation during Weathering of Dolomite Regolith Profile in Southwest China

<正>REE fractionation during the weathering of dolomite has been recognized for decades.A regolith profile on dolomite in southwest Yunnan of China was selected to investigate the behaviors of REE during weathering.The weathering of dolomite is divided into two stages:the pedogenesis stage and soil evolution stage,corresponding to the saprolites and soils respectively in the regolith profile. SiO_2,TiO_2,P_2O_5,Zr,Hf,Nb and Ta were immobile components during the weathering by and large, while Al_2O_3,K_2O and Fe_2O_3 were lost during the soil evolution stage in the physical form(clay minerals probably).REE were fractionated during the whole weathering of dolomite.The field weathering profile and the lab acid-leaching experiments on dolomite indicate that MREE were enriched clearly relative to other REE during the pedogenesis stage in a capillary ascending-adsorption mechanism, but they did not fractionate clearly in the soil evolution stage.REE were lost and accumulated in the weathering front of dolomite during the soil evolution stage in a physical-chemical leaching mechanism.     

Geochronology of the Guyang Granite-Greenstone Terrene and the Implications for Continental Crust Growth

<正>Objective The North China Craton(NCC)is the largest and oldest one among the worldwide cratons.It preserves important imprints of the Earth's early history,including crust formation,stabilization and reworking.The Yinshan Block(YB)constitutes the northwestern part of NCC,and contains extensive exposure of Archean rocks(Fig.1).This block has documented intricate Neoarchean tectonothermal events,which can provide constraints on the geodynamic processes responsible for the evolution of     

Indosinian Supergene Karsts in the Qaidam Basin, NW China: Evidence from Paleo-tectonics, Paleoclimates and Paleo-fluids

In the Qaidam basin,Northwest China,karstic fissures and caves are developed in many places of the Lower Carboniferous Chengqianggou Fm.and Huaitoutala Fm.and the Upper Carboniferous Keluke Fm.,in which are found typical karstic marks.Several suites of transgressive carbonate rocks formed during the Late Paleozoic epoch are preserved as reservoir properties in the Qaidam basin,with paleokarst-related cave-fractured diagenetic structures,which provided the basis for cavefractured development.Carbonate and clastic samples covering or infilling caves and fractures in Carboniferous strata were collected in the eastern Qaidam basin to focus on petrological and geochemical analyses of karst and infilling materials.Based on this study of the Caledonian diagenetic sequence,and bitumen-infilled inclusion temperature and burial history,there existed a continuous atmospheric freshwater leaching process,which played a critical role in the construction of the Carboniferous supergene paleokarsts.Investigation and survey of the tectonic setting,plate paleolatitude and river development intensity also proves that there was abundant rainfall during the Indosinian period,after which the strata undergo a shallow burial process.Because Indosinian period is earlier than the key timing of hydrocarbon-generation of the Carboniferous source rocks,this kind of karst reservoir has potential significance for oil-gas resources in this area.     

Rapid Identification and Emergency Investigation of Surface Ruptures and Geohazards Induced by the M_s 7.1 Yushu Earthquake

<正>The rapid identification based on InSAR technology was proved to be effective in our emergency investigation of surface ruptures and geohazards induced by the Yushu earthquake.The earthquake-generating fault of the Yushu earthquake is the Yushu section of the Garze-Yushu faults zone.It strikes NWW-NW,23 km long near the Yushu County seat,dominated by left-lateral strike slip,and appearing as a surface rupture zone.The macroscopic epicenter is positioned at Guo-yang-yan -song-duo of Gyegu Town(33°03'11N,96°51'26E),where the co-seismic horizontal offset measured is 1.75 m.Geohazards induced by the Yushu earthquake are mainly rockfalls,landslides,debris flows, and unstable slopes.They are controlled by the earthquake-generating fault and are mostly distributed along it.There are several geohazard chains having been established,such as earthquake,canal damage,soil liquefying,landslide-debris flow,earthquake,soil liquefying,roadbed deformation,etc.In order to prevent seismic hazards,generally,where there is a visible surface rupture induced by the Yushu earthquake,reconstruction should be at least beyond 20 m,on each side,from it.Sufficient attention should also be given to potential geohazards or geohazard chains induced by the earthquake.