The petroleum generation potential and effective oil window of humic coals related to coal composition and age

A worldwide data set of more than 500 humic coals from the major coal-forming geological periods has been used to analyse the evolution in the remaining (Hydrogen Index, HI) and total (Quality Index, QI) generation potentials with increasing thermal maturity and the ‘effective oil window’ (‘oil expulsion window’). All samples describe HI and QI bands that are broad at low maturities and that gradually narrow with increasing maturity. The oil generation potential is completely exhausted at a vitrinite reflectance of 2.0–2.2%R_o or T_max of 500–510 °C. The initial large variation in the generation potential is related to the original depositional conditions, particularly the degree of marine influence and the formation of hydrogen-enriched vitrinite, as suggested by increased sulphur and hydrogen contents. During initial thermal maturation the HI increases to a maximum value, HI_max. Similarly, QI increases to a maximum value, QI_max. This increase in HI and QI is related to the formation of an additional generation potential in the coal structure. The decline in QI with further maturation is indicating onset of initial oil expulsion, which precedes efficient expulsion. Liquid petroleum generation from humic coals is thus a complex, three-phase process: (i) onset of petroleum generation, (ii) petroleum build-up in the coal, and (iii) initial oil expulsion followed by efficient oil expulsion (corresponding to the effective oil window). Efficient oil expulsion is indicated by a decline in the Bitumen Index (BI) when plotted against vitrinite reflectance or T_max. This means that in humic coals the vitrinite reflectance or T_max values at which onset of petroleum generation occurs cannot be used to establish the start of the effective oil window. The start of the effective oil window occurs within the vitrinite reflectance range 0.85–1.05%R_o or T_max range 440–455 °C and the oil window extends to 1.5–2.0%R_o or 470–510 °C. For general use, an effective oil window is proposed to occur from 0.85 to 1.7%R_o or from 440 to 490 °C. Specific ranges for HI_max and the effective oil window can be defined for Cenozoic, Jurassic, Permian, and Carboniferous coals. Cenozoic coals reach the highest HI_max values (220–370 mg HC/g TOC), and for the most oil-prone Cenozoic coals the effective oil window may possibly range from 0.65 to 2.0%R_o or 430 to 510 °C. In contrast, the most oil-prone Jurassic, Permian and Carboniferous coals reach the expulsion threshold at a vitrinite reflectance of 0.85–0.9%R_o or T_max of 440–445 °C.     

Carbonates calibrated against oceanographic parameters along a latitudinal transect in the Gulf of California, Mexico

Trophic resources are an important control governing carbonate production. Though this importance has long been recognized, no calibration exists to quantitatively compare biogenic assemblages within trophic resource fields. This study presents a field calibration of carbonate producers in a range of settings against high‐resolution in situ measurements of nutrients, temperature and salinity. With its latitudinal extent from 30° to 23° N, the Gulf of California, Mexico, spans the warm‐temperate realm and encompasses nutrient regimes from oligo‐mesotrophic in the south to eutrophic in the north. Accordingly, from south to north carbonates are characterized by: (i) coral‐dominated shallow carbonate factories (5–20 m water depth) with average sea‐surface temperatures of 25 °C (min. 18 °C, max. 31 °C), average salinities of 35·06‰ and average chlorophyll a levels, which are a proxy for nutrients, of 0·25 mg Chl a m^?3 (max. 0·48, min. 0·1). (ii) Red algal‐dominated subtidal to inner‐shelf carbonate formation (10–25 m) in the central Gulf of California exhibiting average temperatures of 23 °C (min. 18 °C, max. 30 °C), average salinities of 35·25‰, and average Chl a levels of 0·71 Chl a m^?3 (max. 5·62, min. 0). (iii) Molluskan bryozoan‐rich inner to outer shelf factories in the northern Gulf of California (20–50 m) with average sea surface temperatures of only 20 °C (min. 13 °C, max 29 °C), average salinities of 35·01‰, and average contents of 2·2 mg Chl a m^?3 (max. 8·38, min. 0). By calibrating sedimentological data with in situ measured oceanographic information in different environments, the response of carbonate producers to environmental parameters was established and extrapolated to carbonates on a global scale. The results demonstrate the importance of recognizing and quantifying trophic resources as a dominant control determining the biogenic composition and facies character of both modern and fossil carbonates.     

Hydrology and hydrogeology of Sakaryabaşı Karstic springs, Çifteler, Turkey

The Sakarya River is one of the largest rivers in Turkey and is fed mainly from Sakaryabaşı springs. The Sakaryabaşı springs are located in the Central Anatolia and issue from confined/semi-confined karst having a thermal component and therefore, having quite different hydrogeological characteristics as compared to the Taurus Karst region, a typical example of the Mediterranean type of karst. The karstic carbonate rocks that form the groundwater reservoir are overlain by a thick semi-pervious overburden of mainly clastics of Neogene age. Tectonics is the major factor controlling the occurrence of the karst springs in the area where topography is rather flat. This study aimed at explaining the occurrence and movement of the karst groundwater within the system by use of hydrogeological, chemical, and isotopic tools. Isotopic composition of the waters revealed that all waters in the region are of meteoric origin and the thermal component is due to deep circulation. The catchment area of the hydrogeological system extends to the south and groundwater movement is towards the outlets, which are in a depression along a major fault. The movement of the groundwater, based on analysis of remotely sensed images, is controlled mainly by structural elements.     

Geophysical methods applied to fault characterization and earthquake potential assessment in the Lower Tagus Valley, Portugal

The study region is located in the Lower Tagus Valley, central Portugal, and includes a large portion of the densely populated area of Lisbon. It is characterized by a moderate seismicity with a diffuse pattern, with historical earthquakes causing many casualties, serious damage and economic losses. Occurrence of earthquakes in the area indicates the presence of seismogenic structures at depth that are deficiently known due to a thick Cenozoic sedimentary cover. The hidden character of many of the faults in the Lower Tagus Valley requires the use of indirect methodologies for their study. This paper focuses on the application of high-resolution seismic reflection method for the detection of near-surface faulting on two major tectonic structures that are hidden under the recent alluvial cover of the Tagus Valley, and that have been recognized on deep oil-industry seismic reflection profiles and/or inferred from the surface geology. These are a WNW–ESE-trending fault zone located within the Lower Tagus Cenozoic basin, across the Tagus River estuary (Porto Alto fault), and a NNE–SSW-trending reverse fault zone that borders the Cenozoic Basin at the W (Vila Franca de Xira–Lisbon fault). Vertical electrical soundings were also acquired over the seismic profiles and the refraction interpretation of the reflection data was carried out. According to the interpretation of the collected data, a complex fault pattern disrupts the near surface (first 400 m) at Porto Alto, affecting the Upper Neogene and (at least for one fault) the Quaternary, with a normal offset component. The consistency with the previous oil-industry profiles interpretation supports the location and geometry of this fault zone. Concerning the second structure, two major faults were detected north of Vila Franca de Xira, supporting the extension of the Vila Franca de Xira–Lisbon fault zone northwards. One of these faults presents a reverse geometry apparently displacing Holocene alluvium. Vertical offsets of the Holocene sediments detected in the studied geophysical data of Porto Alto and Vila Franca de Xira–Lisbon faults imply minimum slip rates of 0.15–0.30 mm/year, three times larger than previously inferred for active faults in the Lower Tagus Valley and maximum estimates of average return periods of 2000–5000 years for M 6.5–7 co-seismic ruptures.     

新疆和田河水资源利用与绿色走廊生态建设研究

水是和田河绿色走廊形成与演变最重要的因素。虽然和田河径流量年际变化比较平稳．但年内径流量洪枯季节差异十分悬殊，人工调配水资源的难度较大。随着人类开发利用水资源规模扩大．水资源时空分布格局发生变化，中上游人工绿洲面积扩大，下游绿色走廊植被衰竭，土地荒漠化日趋严重，走廊生态环境持续恶化。文章分析了和田河水资源变化对下游绿色走廊兴衰的影响过程，提出了合理利用水资源、保护绿色走廊生态环境的对策建议。     

基于芬兰经验的我国森林资源型城市的发展研究--以伊春市为例

资源型城市的可持续发展问题一直是学术界的研究热点,但对于森林资源型城市的研究却不多见。本文概括介绍了芬兰的资源和经济发展情况,系统分析了芬兰这样一个以森林起家的经济发达国家的成功经验;并以伊春为例提出了森林资源型城市经济转型和可持续发展可资借鉴的对策和建议。     

四川盆地地下卤水资源优势及综合开发前景

四川盆地地下卤水自震旦系至白垩系各层系皆有分布。卤水具有分布广泛、资源丰富、品质优异、高承压及气卤同产等优势特点,是四川得天独厚的液态矿产资源。卤水中含有K+、Br-I、-、B3+、Li+、Sr2+、Rb+等多种有用组分,皆为国家紧缺和紧俏物质,其含量多数可达工业开采品位,为优质化工原料水,经济价值极高,综合开发利用前景广阔。     

Compressibility and swelling characteristics of Al-Khobar Palygorskite, eastern Saudi Arabia

Expansive soils are found in different locations in eastern Saudi Arabia. The area is arid with high temperatures, highly variable humidity and an excessive rate of evaporation compared to the low precipitation. This resulted in the formation of water sensitive soils. In the present investigation, line valve buildings for a sweet water feeder (1118 mm in diameter) were constructed on a highly expansive material consisting mainly of brown palygorskite and gray palygorskite with thin sheets of gypsum and limestone. Block samples from both palygorskites were brought to the laboratory and cores as well as remolded samples were obtained from the blocks. The two palygorskites were found to be highly plastic and have a very high swelling potential. The liquid limit (LL) and plastic limit (PL) values for the brown palygorskite are 261% and 140%, respectively. The gray palygorskite has a LL of a 285% and a PL of 123%. The oedometer free swell tests for the two palygorskites produced an expansion ranging between 31.8% and 42.5% for the remolded samples. However, the expansion for cores ranges between 8.3% and 19.3%. The constant volume pressure tests produced a stress in excess of 4240 kPa. The swell potential reached a steady state after four days while the swelling pressure reached a steady state in about 3 h. The paper addresses the geology of the area, the characterization of the geomaterial including mineralogical composition using X-ray diffraction and SEM techniques and the swelling characteristics of the material.     

Impact of Flood Disasters on Taiwan in the Last Quarter Century

The increasing natural disasters, especially floods during the last quarter century, are raising the economic losses in Taiwan. The most severe hazard in Taiwan is flooding induced by typhoons and storms in summer and autumn. By comparing the rivers around the world, the ones in Taiwan have the steepest slopes, the largest discharge per unit drainage area, and the shortest time of concentrations. Rapid urbanization without proper land uses managements usually worsen the flood problems. Consequently, flood hazards mitigation has become the most essential task for Taiwan to deal with. Although the government keeps improving flood defense structures, the flood damage grows continuously. In this article, possible flood mitigation strategies are identified for coping with complex environmental and social decisions with flood risk involved.