塔中Ⅰ号坡折带礁滩复合体大型凝析气田成藏机制

利用油气碳同位素、生物标志化合物等地球化学分析手段,明确了满加尔凹陷及塔中深层寒武系-下奥陶统烃源岩、古油藏裂解气是形成塔中Ⅰ号坡折带大型凝析气田的主要烃源;利用包裹体、储集层地球化学分析技术,结合烃源岩演化史、构造发展史以及储集层演化史对成藏期次及油气运移聚集进行研究,指出塔中Ⅰ号断裂及晚期深大走滑断裂、塔中古隆起形成过程中的多期不整合是礁滩复合体油气成藏的主要油气输导体系;晚加里东运动期是油气聚集期,晚海西运动期是古油藏油气调整期,喜马拉雅运动期是古油藏裂解气对早期油藏气侵的多期充注期;礁滩复合体强非均质性和输导体系的差异是导致流体分布复杂的主要因素;指出了塔中Ⅰ号坡折带外带富气、内带富油分布的油气分布规律,丰富了塔里木盆地海相碳酸盐岩油气成藏理论。

Removal of Pyrene from Contaminated Soils by White Clover

Phytoremediation has been used as an emerging technology for remediation of soil contamination with polycyclic aromatic hydrocarbons(PAHs),ubiquitous persistent environmental pollutants derived from natural and anthropogenic processes,in the last decade.In this study,a pot experiment was conducted to investigate the potential of phytoremediation of pyrene from spiked soils planted with white clover(Trifolium repens)in the greenhouse with a series of pyrene concentrations ranging from 4.22 to 365.38 mg kg-1.The results showed that growth of white clover on pyrenecontaminated soils was not affected.The removal of pyrene from the spiked soils planted with white clover was obviously higher than that from the unplanted soils.At the end of the experiment(60 d),the average removal ratio of pyrene in the spiked soils with white clover was 77%,which was 31%and 57%higher than those of the controls with or without micobes, respectively.Both roots and shoots of white clover took up pyrene from the spiked soils and pyrene uptake increased with the soil pyrene concentration.However,the plant-enhanced dissipation of soil pyrene may be the result of plant-promoted microbial degradation and direct uptake and accumulation of pyrene by white clover were only a small part of the pyrene dissipation.Bioconcentration factors of pyrene(BCFs,ratio of pyrene,on a dry weight basis,in the plant to that in the soil)tended to decrease with increase in the residual soil pyrene concentration.Therefore,removal of pyrene in the contaminated soils was feasible using white clove.

Distribution and sources of polycyclic aromatic hydrocarbons in main aquacultural areas in Guangdong, China

The environmental quality status of Daya Bay （22.56-22.77°N, 114.51-114.73°E）, a main aquaculture area in Guangdong of China, was investigated using 16 polycyclic aromatic hydrocarbon （PAH） sediment samples of the bay. The total concentrations of 16 PAHs varied from 115 to 1 134 ng/g dry weight. The PAH composition pattern in sediments suggest dominance of 4-ring PAHs in Sites 2 and 4, and the ratio of certain related PAHs indicated important pyrolytic and petrogemc sources. The results enhance the understanding of current contamination levels and make a better assessment of likely impacts of organic contamination on ecosystems and the sustainability of local aquaculture in the area especially after the establishment of the Nuclear Power Station by the bay.

Discovery and prediction of high natural gamma sandstones in Chang 73 Submember of Triassic Yanchang Formation in Ordos Basin, China

The large scale development of high natural gamma sandstones has been discovered in the Chang 73 Submember of the Triassic Yanchang Formation in the Ordos Basin, China. High natural gamma sandstones consist of terrigenous detrital rocks with particle sizes ranging from silt to sand. They represent turbidite deposits characterized by high gamma ray values that are more than 180 American Petroleum Institute (API) units on a natural gamma ray log profile. For a long time, very high natural gamma sandstones had been identified as high-quality source rocks, such as oil shales, from conventional well log profiles, such as natural gamma ray well logs. Therefore, predicting the distribution of high natural gamma sandstones was studied. The sedimentary, lithological, and well log characteristics, as well as the genesis of the high radioactivity of high natural gamma sandstones were analyzed in the Chang 73 Submember. Thorium (Th), uranium (U) and other radioactive elements were found, carried by deep hydrothermal activity, and probably resulted in the formation of a relatively high radioactive zone in the cross-section, where high natural gamma sandstones usually develop in large quantities. This caused many turbidite sand bodies, which should have a continuous distribution in the cross-section, to appear to have a discontinuous distribution, when using conventional well log profiles, such as natural gamma ray well logs. From the above mentioned apparent discontinuous distribution of turbidite sand bodies in the cross-section, a continuous distribution can be predicted. It is obvious that the prediction of areas of continuous turbidite sand bodies in the cross-section usually corresponds with areas where high natural gamma sandstones are developed in large quantities. Exploration and development practice demonstrated that the developed method is fast and effective in predicting high natural gamma sandstones in the Chang 73 Submember.

Spatial Distribution and Sources Identification of Polycyclic Aromatic Hydrocarbons in Wolong Lake, Northeast China

The aquatic ecosystem maybe significantly affected by polycyclic aromatic hydrocarbons(PAHs) released from fresh water sediments. In order to protect biodiversity, the spatial distribution and sources of PAHs in the sediment of Wolong Lake in Northeast China were studied. A total of 17 surface sediment samples were collected and 12 PAHs were analyzed. The results were as follows. The concentration of total PAHs(TPAHs) ranged between 1412.9 μg/kg and 3948.3 μg/kg(dry weight). Indeno [1, 2, 3-c, d] pyrene was the dominant contaminant which accounted for 87%–98% of TPAHs. Diagnostic ratios of PAHs and principal component analysis showed that biomass combustion and vehicle emissions were likely to be the dominant sources of PAHs in the sediment. PAHs can be considered safe in the context of environmental and human health protection, based on the overall toxicity. Individual PAHs were positively correlated with total organic carbons. These results will be helpful to control PAHs and protect the aquatic ecosystem in the lake.

Presence of carboxylate salts in marine carbonate strata of the Ordos Basin and their impact on hydrocarbon generation evaluation of low TOC, high maturity source rocks

The total organic carbon （TOC） in the marine source rock of the Ordos Basin mostly ranges from 0.2% to 0.5%. The industrial standard commonly states that the TOC value has to be no less than 0.5% （0.4% for high mature or over-mature source rock） to form large petroleum reservoirs. However, gas source correlation indicates that the natural gas in the Jingbian gas field does receive contribution from marine source rocks. In order to determine the effect of Carboxylate salts （or called as organic acid salts） on TOC in highly mature source rocks with low TOC value, we sampled the Ordovician marine source rock and the Permian transitional facies source rock in one drilled well in the southern Ordos Basin and performed infrared and GC-MS analysis. It is found that both kerogen-derived organic acids and carboxylate salt-conversed organic acids exist in both marine and transitional facies source rocks. The carboxylate salt-conversed organic acids mainly come from the complete acidification of carboxylate salts, which confirms the presence of carboxylate salts in the marine source rocks. Although the C16：o peak is the main peak for the organic acids both before and after acidification, the carboxylate salt-conversed organic acids have much less relative abundance ahead of C^6：o compared with that of the kerogen-based and free organic acids. This observation suggests that the kerogen-based and free organic acids mainly decarboxylate to form lower carboxylic acids, whereas the carboxylate salt-conversed organic acids mainly break down into paraffins. By using calcium hexadecanoate as the reference to quantify the kerogen-derived and carboxylate salt-conversed organic acids, the high TOC （〉2.0%） marine source rocks have low carboxylate salt content and the low TOC （0.2%-0.5%） marine source rocks contain high content of carboxylate salt. Therefore, for the marine source rocks with 0.2%-0.5% TOC, the carboxylate salts may be a potential gas source at high maturity stage.