An unconventional, continuous petroleum system consists of an accumulation of hydrocarbons that is found in low-matrix-permeability rocks and contain large amounts of hydrocarbons. Tight-sand gas in the Jurassic and shale gas within the fifth member of Xujiahe Formation (T3x5) are currently regarded as the most prolific emerging unconventional gas plays in China. The conventional and systematical evaluation of T3x5 source rocks was carried out for the first time in the western Sichuan basin (WSD). Hydrocarbon generation and expulsion characteristics (including intensity, efficiency, and amount) of T3x5 source rocks were investigated. Results show that T3x5 source rocks are thick (generally >200 m), have high total organic content (TOC, ranging from 2.5 to 4.5 wt%), and dominated by III-type kerogen. These favorable characteristics result in a great hydrocarbon generating potential under the high thermal evolution history (Ro > 1.2%) of the area. An improved hydrocarbon generation potential methodology was applied to well data from the area to unravel the hydrocarbon generation and expulsion characteristics of T3x5 source rocks in the WSD. Results indicate that the source rocks reached hydrocarbon expulsion threshold at 1.06% Ro and the comprehensive hydrocarbon expulsion efficiency was about 60%. The amount of generation and expulsion from T3x5 source rocks was 3.14 × 1010 and 1.86 × 1010 t, respectively, with a residual amount of 1.28 × 1010 t within the source rocks. Continuous-type tight-sand gas was predicted to develop in the Jurassic in the Chengdu Sag of the WSD because of the good source-reservoir configuration (i.e., the hydrocarbon generation and expulsion center was located in Chengdu Sag), the Jurassic sandstone reservoirs were tight, and the gas expelled from the T3x5 source rocks migrated for very short distances vertically and horizontally. The amount of gas accumulation in the Jurassic reservoirs derived from T3x5 source rocks is up to 9.3 × 108 t. The T3x5 gas shale has good accumulation potential compared with several active US shale-gas plays. Volumetrically, the geological resource of shale gas is up to 1.05 × 1010 t. Small differences between the amounts calculated by volumetric method compared with that by hydrocarbon generation potential methodology may be due to other gas accumulations present within interbedded sands associated with the gas shales. 相似文献
In summer of 2001, 2002 and 2003, ten, six and seventeen satellite-tracked surface drifters with drogues centered at 15 and 4 m were deployed, respectively, in the southern Yellow Sea (YS). 23 drifters of them transmitted useful data of at least 30 days. The wind-driven component of the drift was removed from the original drift velocity of drifters. The wind data used are from NCEP (National Center for Environmental Prediction), USA.Trajectories and drift velocities of the 23 drifters depicted the upper circulation structure in the southern YS. There exists an anti-cyclonic eddy with a mean speed and radius of 0.063 m/s and 50km in the central southern YS, whose center lingered within 35.3-36.0°N / 123.5-124.0°E. Showed by 6 drifters, a basin-scale elliptic cyclonic gyre with a mean speed of 0.114 m/s, long and short radius of 250 and 200 km surrounds the anti-cyclonic eddy. In the southwestern part of the southern YS has obvious frontal eddy activities within about 100 km with a mean speed about 0.076 相似文献
Information regarding antioxidant enzymes in amphioxus remains lacking, and this study was carried out to examine the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX) in different genders and tissues of amphioxus Branchiostoma belcheri tsingtauense. Results show that (1) CuZn-SOD, CAT and GPX activities in the whole amphioxus B. belcheri tsing- tauense were basically at the same levels in male and female amphioxus, whereas both T-SOD and Mn-SOD activities in male amphioxus were significantly higher than that in the female (P<0.05); (2) The testis had significantly higher T-SOD and CuZn-SOD activities than the ovary (P<0.05); (3) CuZn-SOD activity was undetectable in the guts of male and female amphioxus; (4) For both male and female am- phioxus, the activities of CAT and GPX in the gonads including testis and ovary were the lowest (P<0.05) among the tissues examined; (5) The gut and gill had the same level GPX activities while the gut had a higher CAT activity; (6) There was no clear difference in CAT and GPX activities in the corresponding tissues between male and female amphioxus. The study on SOD, CAT and GPX activities in different genders and tissues of the protochordate provides data for future comparison of amphioxus antioxidant enzymes with those of invertebrates and vertebrates. 相似文献
Abundant Fe–Ti oxide inclusions in cumulus olivine (Fo77–81) from the Panzhihua and Hongge intrusions, Emeishan large igneous province, SW China, document the first evidence for early
crystallization of Fe–Ti oxides in ferrobasaltic systems in nature. The intrusions also contain significant stratiform Fe–Ti–V
oxide ores. The oxide inclusions are sub-rounded or irregular, range from ∼5 to 50 μm in diameter, and are dominated by either
titanomagnetite or ilmenite. The fact that the inclusions are either titanomagnetite- or ilmenite-dominant suggests that they
are trapped crystals, instead of immiscible oxide melt, formed during growth of the host olivine. The absence of other silicate
phases in the inclusion-bearing olivine is difficult to reconcile with a possible xenocrystic origin of the oxide inclusions.
These oxide inclusions are thus interpreted to be cumulus minerals crystallized together and trapped in olivine from the same
parental magma. In addition to Fe–Ti oxides, some inclusions contain amphibole + biotite ± fluorapatite that might have formed
by reaction of trapped hydrous liquid with the host olivine. Numerical modeling of high-Ti Emeishan basalts using the MELTS
program successfully simulates early crystallization of olivine (∼Fo81) and Fe–Ti spinel in the presence of a moderate amount of H2O (∼1.5 wt%) under pressure and fO2 conditions generally pertinent to the Panzhihua and Hongge intrusions. The modal mineralogy of the oxide inclusions is in
good agreement with the bulk compositions of the ore, as inferred from whole-rock data, in a given intrusion. This is consistent
with the interpretation that the stratiform oxide ores in the intrusions formed by accumulation of Fe–Ti oxide crystals that
appeared on the liquidus with olivine and clinopyroxene. 相似文献
GPS Solutions - Under high dynamic conditions, a robust tracking loop is essential for accuracy positioning with the global position system. In previous studies, the extended Kalman filter... 相似文献
Seven emissions trading scheme (ETS) pilots have been established in China. They have introduced some unique methods to set emissions caps and allocate allowances, different from textbook models and their counterparts in the EU, California, and many other regions. This article provides a detailed introduction to the methods for cap setting and allowance allocation adopted by the pilots, and presents detailed comparisons of these methods. In terms of cap setting, the pilots adopt flexible caps that can be adjusted where necessary, which primarily depends on the outcomes of the bottom-up approach, namely aggregating the allowances allocated to participants. As for allowance allocation, the pilots not only adopt such methods as grandfathering and benchmarking, which are also widely applied in other existing schemes, but also some special methods that require ex post adjustment, such as those based on enterprises’ historical emissions intensity (including both physical quantity and added-value intensity) and current production/output. The factors influencing the design are further analysed, including the impacts of theory and experience from foreign systems, concerns about economic development, traditions regarding intensity targets and policy, constraints from data availability and preparation time, tight regulation of the electricity and heat generation sector, and concerns regarding price stability. The practice of pilots presents an improvement opportunity and a challenge for China to further balance the theoretical and practical requirements in ETS design in establishing its national system.
Policy relevance
China is piloting emissions trading in seven regions, as part of efforts to try to rely more on market-based instruments to achieve GHG emissions control targets. All seven pilots have been confronted with special issues in the design process when compared with existing foreign schemes. This article analyses in depth the special issues related to cap setting and allowance allocation and the approaches adopted to address these issues. Flexible cap setting through a bottom-up approach and different types of allocation methods with or without ex post adjustment are adopted in the pilots. The flexible and innovative approaches the pilots have developed could provide useful experience for designing the nationwide ETS in China and promoting emissions trading policy in other parts of the world. 相似文献
Niutuozhen geothermal field is located in the Jizhong graben, belonging to the northern part of Bohai Bay Basin in North China. Chemical and isotopic analyses were carried out on 14 samples of the geothermal fluids discharged from Neogene Minghuazhen (Nm), Guantao (Ng), and Jixianian Wumishan (Jxw) formations. The δ2H and δ18O in water, δ13C in CH4, δ13C in CO2, and 3He/4He ratio in the gases were analyzed in combination with chemical analyses on the fluids in the Niutuozhen geothermal field. The chemical and isotopic compositions indicate a meteoric origin of the thermal waters. The reservoir temperatures estimated by chemical geothermometry are in the range between 60 and 108 °C. The results show that the gases are made up mainly by N2 (18.20–97.42 vol%), CH4 (0.02–60.95 vol%), and CO2 (0.17–25.14 vol%), with relatively high He composition (up to 0.52 vol%). The chemical and isotopic compositions of the gas samples suggest the meteoric origin of N2, predominant crustal origins of CH4, CO2, and He. The mantle-derived He contributions are calculated to be from 5 to 8% based on a crust–mantle binary mixing model. The deep temperatures in the Jxw reservoir were evaluated based on gas isotope geothermometry to be in the range from 141 to 165 °C. The mantle-derived heat fraction in the surface heat flow is estimated to be in the range of 48–51% based on 3He/4He ratios. 相似文献