The surface geochemical exploration of oil and gas in the Gangbatong-Ya’anxiang and the Dongqiao-Nam Co of the Qinghai-Tibet region

Due to the complexity of geological background and the adverseness of natural geographical environment in the Qinghai-Tibet Plateau, it is very difficult to carry out petroleum geological study in this region. The Qinghai-Tibet Plateau is the only blank space of petroleum exploration on a large scale. The authors carried out the surface geochemical exploration of oil and gas in the Gangbatong-Ya’anxiang and Dongqiao-Nam Co of the Qinghai-Tibet region. Based on the data of actual detection and experiments in the studied area, the characteristics of concentration and profile distribution of the main geochemical exploration indicators (total adsorbed hydrocarbon, altered carbonate, thermal released mercury, etc.) were discussed. The origin of hydrocarbon was also discussed. Moreover, the oil and gas potential of different sections in the Qiangtang Basin and the Biru Basin were evaluated, which could provide references for the exploration and prediction of oil and gas in this region. The concentrations of total adsorbed hydrocarbons in the Ya’anxiang of Suoxian County-Zadong of Baqing County and the Jiecha-Dangxiong of Anduo County in the Qinghai-Tibet region are high, averaging 312.64 μL·kg^?1 and 164.36 μL·kg^?1. Their altered carbonate concentrations are relatively low, averaging 0.11% and 0.56%. Their concentrations of thermal released mercury are relatively high, averaging 13.09×10^?9 and 1.94×10^?9. Geochemical exploration results in fact reflect hydrocarbon information in the underground, which are mainly petroleum associated gas and over-matured cracking gas. The Jiecha-Charenluma and the Xiamaya’ertong-Suoba sections in the Qiangtang Basin are the most favorable ones for oil and gas and the Ekou-Zadong section is relatively favorable one, while the Nam Co and the Zigetangcuo-Dongqiao sections in the Biru Basin are the favorable ones for oil and gas, and the Jiang Co-Nading Co and the Ya’anxiang-Ya’ertong sections are relatively favorable ones.     

Use of brGDGTs in surface geochemical exploration for petroleum —A case study of oil and gas fields in the Jiyang depression

Branched glycerol dialkyl glycerol tetraethers(brGDGTs),likely produced by bacteria in soil and peat,are widely distributed,easily detected,newly adopted biomarker compounds.In this study,brGDGTs were used to explore the relationship between the absolute abundance of brGDGTs and the distribution of oil and gas fields in the Duoshiqiao area of the Jiyang depression.The results showed that the concentrations at the Xiakou fault and in the oil and gas fields were obviously higher than those in the contrast areas.The clear relationship among the concentration of brGDGTs,the distribution of oil and gas fields,and the acidolysis hydrocarbon(ethane)indicates that the concentration effectively responds to hydrocarbon seeps from the oil and gas field below.brGDGTs may become some of the most important indicators in surface geochemical prospecting for oil and gas.     

Characteristics of China’s oil and gas pool formation in latest geological history

1 Introduction China’s continent is a mountain-building zone made up of numerous micro-continental blocks and mini- continental blocks[1,2]. The continent has been sub- jected to the processes and evolution of three continual geodynamic systems of Paleo-Asia Ocean, Pa- leo-Tethys Ocean and Pacific Ocean[3]. The structural framework of China’s continent had been gradually finalized in the Neogene-Quaternary period owing to the India-Eurasia collision and its continuous com- pression[3], …     

The role of urbanization in the flooding and surface water chemistry of Puerto Rico’s mangroves

ABSTRACT

In this study, water level models are constructed to characterize mangrove flooding across urban gradients in Puerto Rico. The most urban sites exhibited 95% longer hydroperiods, 23% lower flood frequencies, and 110% lower depths than the least urban sites. Rainfall importance was explained more by geomorphology and tidal connectivity than by urbanization, but there was evidence for changes in tidal amplitudes along the urban gradient. Relationships between surface water chemical metrics and land cover contradicted previous studies by suggesting lower nutrients and biochemical oxygen demand with increasing urbanization. However, much of this changed with the exclusion of potential outlier sites, as well as under different statistical comparisons. These results reinforce the understanding that the most important drivers of urban mangrove hydrology and water quality in Puerto Rico are likely geomorphology and tidal connectivity, with some influence from surrounding land cover. Results should be considered alongside the reported errors stemming from digital elevation and rainfall response models.     

Structure and Significance of S-wave Velocity and Poisson’s Ratio in the Crust beneath the Eastern Side of the Qinghai-Tibet Plateau

The receiver functions of body waves of distant earthquakes obtained for the regions beneath 41 digital stations (Lhasa and GANZ in Tibet, Mandalay and Rangoon in Myanmar, SHIO in India, CHTO in Thailand, and station network in Sichuan and Yunnan) were used to invert for S-wave structure in the crust and upper mantle in Sichuan, Yunnan, and their surrounding areas. Meanwhile the distribution characteristics of the Poisson’s ration and the crustal thickness in Sichuan and Yunnan areas were also obtained. Results indicate that the depth of Moho beneath the eastern side of Qinghai-Tibetan plateau varies strikingly. It is obvious that the greatest changes in crustal thickness occur in a north-south direction. The crustal thickness decreases from north to south, being as thick as 70 km in eastern Tibet, the northern portion of our area of interest, and less than 30 km in Chaing Mai and Rangoon, the southern portion of our area. There are, however, exceptions regarding the trend. The thickness exhibits an east-west variation trend in the area from Ma’erkong-Kongding in Sichuan to Lijiang in Yunnan. In general the Jinpingshan-Longmenshan fault and Anninghe fault can be taken as the boundaries of this exception area. The thickness in Kongding in the west is 68 km, while it is only 39 km in Yongchuan in the east. Moreover the Poisson’s ratio values in the blocks of central Sichuan and Sichuan-Yunnan Diamond are high, and a low velocity layer in the crust of this area can be obviously detected. The distribution characteristics of the high Poisson’s ratio and the low velocity of the crust in this block correspond to the tectonic structure, being in contrast with the surrounding areas. Combining with the distribution features of the modern tectonic stress field, it is deduced that the Sichuan-Yunnan area is probably the channel through which the materials of the lithosphere flow eastward.     

The heterogeneous characteristics of crust-mantle structures and the seismic activities in the northwest Beijing region

Introduction Zhangjiakou-Bohai seismic zone is a major active seismic zone that passes through the north-ern part of North China. Zhangjiakou-Beijing area, the northwest part of North China, is located at the intersection position of Yanshan, Taihangshan uplift, and Shanxi down-faulted zone, and the geological structures in this area are extremely complicated. Many researchers in the geoscience circle always pay close attention to this region because Yanqing-Huailai region is located in th…     

Migration of sources of small earthquakes in the Garm region and variations in velocity of the Earth’s rotation

The spatial-temporal variations in localization of the sources of earthquakes with H ≥ 14 km are reviewed for the Garm region. The uneven distribution of such earthquakes is related to the block structure: their amount is higher in the weakened zones rather than in blocks. Three weakened zones are characterized by higher activity of deepened seismicity, which varies in time and increases before the earthquakes with K ≥ 12.5. The temporal variations in distribution of earthquake sources with depth allow a suggestion of the relation of the velocity of the Earth’s rotation and activity of deepened seismicity.     

The application of the high-frequency electromagnetic sounding method in the exploration of underground thermal water

High-frequency electromagnetic sounding is an electromagnetic exploration method using the natural high-frequency electromagnetic field as a field source. It has higher resolution and greater depth penetration than the direct current method and is especially fit for geothermal energy exploration and low- and mid-level groundwater detection. We introduce a successful application of high-frequency electromagnetic sounding for evaluating geothermal water resources. The high frequency electromagnetic system （MT-USA with a frequency range from 10 KHz to 1 Hz） is first applied to sample field data from China. A remote reference station is used to assure sampled data quality. We then perform 2D inversion image processing with the electrical method data. The results basically indicate the spatial distribution of underground geothermal water and provide favorable clues to finding the sources of the subsurface geothermal water in this area.     

The application of seismic-geological integrated interpretation in the eastern depression of the Liaohe oil field

It is very important to comprehensively interpret areal seismic data with geological data in a research area. For the structural interpretations in the middle depression of the eastern basin of Liaohe oilfield, we first analyze and study geological phenomena on outcrop pictures collected in the field and establish geological outcrop models. Second, we make fault and structural interpretations based on the structural characteristics of the outcrop pictures. Third, we analyze the migration, accumulation, and formation of oil and gas using characteristics of seismic profiles. By geologic and geophysical comprehensive interpretation, it is inferred that, in the research area, the dominant factor controlling oil and gas accumulation is strike-slip faults. Structural modes and the relationship of the oil and gas in the Huangshatuo and Oulituozi oil fields are also analyzed and investigated.     

The abnormal mantle and deep tectonic process in the southern region of North China Plain

ＴｈｅａｂｎｏｒｍａｌｍａｎｔｌｅａｎｄｄｅｅｐｔｅｃｔｏｎｉｃｐｒｏｃｅｓｓｉｎｔｈｅｓｏｕｔｈｅｒｎｒｅｇｉｏｎｏｆＮｏｒｔｈＣｈｉｎａＰｌａｉｎＳｈｉ－ＹｕＧＡＯ（高世玉），Ｈｏｎｇ－ＸｉａｎｇＨＵ（胡鸿翔）ａｎｄＳｈａｎＤＩＮＧ（丁山）（Ｉｎ...     

The surface spherical harmonics and the development of tidal generating potential

ＴｈｅｓｕｒｆａｃｅｓｐｈｅｒｉｃａｌｈａｒｍｏｎｉｃｓａｎｄｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｔｉｄａｌｇｅｎｅｒａｔｉｎｇｐｏｔｅｎｔｉａｌＱＩＮ－ＷＥＮＸＩ（郗钦文）ＣｅｎｔｅｒｆｏｒＡｎａｌｙｓｉｓａｎｄＰｒｅｄｉｃｔｉｏｎ,ＣｈｉｎａＳｅｉｓ...     

The correlation between the characteristics of seismic wave propagation in Western Caucasus and the geological–tectonic features of the region

The relationship between the characteristics of seismic waves in the Western Caucasus and the geological-tectonic structure of the region is studied for identifying the specificity of seismic propagation in the mountainous regions with a complicated geological structure and forecasting the characteristics of the propagation from the geological and tectonic data. The interpretation is presented for the estimates of the Q-factor of the medium (Q(f) ~ 55f^0.9 in the region of Sochi and Q(f) ~ 90f^0.7 in the region of Anapa), seismic wave enhancement in the upper crustal layers (A(f) ~ 1), and peak ground acceleration residuals, which were previously determined from the records of the local earthquakes and show the distributions of local variations in the parameters of seismic wave radiation and propagation. The obtained characteristics are interpreted in the context of the up-to-date information about the tectonic, geological, and deep structure of the epicentral zones in the Western Caucasus and neighboring territory of the Black Sea. The discrepancies revealed in the low-frequency behavior of the Q-factor in the vicinities of Sochi and Anapa is accounted for by the spatial scale and character of tectonic dislocations of the rocks in these regions. The local variations in the parameters of seismic radiation and propagation are probably related to the geological features of the region such as the fault structures, including the thrusts, shatter zones, oblique seismic boundaries, variations in the thickness and consolidation of the sedimentary cover, as well as the peculiarities in the structure and material composition of the basement.     

Fluorine in surface and subsoil waters in the Middle Klyaz’ma Basin

Data on fluorine concentration in water in the Middle Klyaz’ma Basin during summer low-water period have been obtained. Fluorine background concentration has been determined in streams (Klyaz’ma R., small rivers, and creeks), water bodies (drainage ditches, lakes), and subsoil waters. Anthropogenic fluorine hydrochemical anomalies have been determined and localized with respect to urbanized industrial areas. An assumption has been made and experimentally substantiated, according to which fluorine concentration in subsoil water is governed by the processes of its distribution between water and host rocks. It has been established that the interaction of soils with snowmelt water and alluvial deposits with river water in neutral and acid media is accompanied by fluorine removal from solution, while in a weakly alkaline medium, fluorine passes from solid phase into solution. The effect of dissolved organic matter on the process of fluorine leaching from rock minerals also depends, primarily, on the equilibrium pH value: in weakly alkaline media, the presence of organic acids contributes to fluorine mobilization, while in weakly acid media, it reduces mobilization rate.     

Excitation of small-scale convection in the continental lithosphere by disturbances in the topography of the Earth’s surface

After the buildup of a steady convective motion in a layer, the topography of its surface is determined only by the displacements of the material particles lying on its surface.     

Changes in surface water chemistry of the Chul’man River and its tributaries in coal mining regions

The physicochemical properties and chemistry of surface water of rivers in South-Yakutia Fuel and Production Complex were examined in the summer-autumn dry period. Changes in the properties and chemistry of the Chul’man River and its tributaries were analyzed to assess the effect of coal mining industry on the character and degree of technogenic pollution of surface water in the examined northern region.     

Spatial and temporal variation of gravity field in the capital region

Ｓｐａｔｉａｌａｎｄｔｅｍｐｏｒａｌｖａｒｉａｔｉｏｎｏｆ　ｇｒａｖｉｔｙ　ｆｉｅｌｄｉｎｔｈｅｃａｐｉｔａｌｒｅｇｉｏｎＣｈａｎｇ－ＣａｉＨＵＡ；（华昌才）ＹｏｎｇＧＵＯ；（果勇）Ｄｕａｎ－ＦａＬＩＵ；（刘瑞法）ＧａｎｇＸＩＡＯ；（肖钢），Ｊ．Ｔ．...     

Comparison and analysis of the stress field in the source region of Tangshan and Lancang earthquake sequences

ＣｏｍｐａｒｉｓｏｎａｎｄａｎａｌｙｓｉｓｏｆｔｈｅｓｔｒｅｓｓｆｉｅｌｄｉｎｔｈｅｓｏｕｒｃｅｒｅｇｉｏｎｏｆＴａｎｇｓｈａｎａｎｄＬａｎｃａｎｇｅａｒｔｈｑｕａｋｅｓｅｑｕｅｎｃｅｓＧｕｉ－ＬｉｎｇＤＩＡＯ；（刁桂苓）Ｌｉ－ＭｉｎＹＵ；（于利民）...     

Estimation of the temperature in the Earth’s interior from surface measurements of the electromagnetic field

The possibility of contactless remote estimation of the temperature in the Earth’s interior from surface magnetotelluric (MT) measurements is examined. The neuronet analysis of MT and temperature measurements in the Bishkek geodynamic research area (the Northern Tien Shan) showed that a contactless electromagnetic geothermometer can in principle be realized. An optimal method including MT measurements and treatment of available thermograms is developed. The method minimizes uncertainties of the remote temperature estimation. The use of six to eight thermograms for calibration of electromagnetic data is shown to provide a 12% relative error of prediction, and a priori geological information available for the region under study can reduce this error. Areas of practical application of a contactless electromagnetic geothermometer are outlined.