Search

The mechanisms governing pore development, particularly of organic pores, in marine–continental transitional shales remain poorly constrained. This study investigated the primary controls on pore evolution within transitional shales of the Benxi Formation using low-pressure gas adsorption, field emission scanning electron microscopy, bulk mineralogy and maceral analyses, and other techniques. Total organic carbon (TOC) contents exhibit positive correlations with shale microporosity and negative correlations with macroporosity. On the basis of S/TOC ratios and sedimentological evidence, the Benxi shales accumulated across a range of marine, brackish, and freshwater depositional environments. In general, more negative δ13Ckerogenvalues correlate with higher S/TOC, consistent with a marine source for the most 13C-depleted kerogens. Kerogens with δ13C of < –25‰ reflect a marine origin, while those with δ13C of > –25‰ indicate varying salinity conditions. Both organic matter composition and pore development within type III kerogens proved highly sensitive to paleosalinity. Specifically, marine-sourced organic matter possesses substantially lower microporosity but higher meso- and macroporosities compared to material deposited in freshwater settings. Accordingly, thermally mature marine-influenced Benxi shales likely retain greater shale gas potential versus non-marine equivalents.

The Ordovician system of the Ordos Basin is rich in oil and gas resources, but the tectonic evolution of Ordovician strata and controls on natural gas generation and accumulation are poorly understood. In this study, we integrate field observations, seismic and drill core interpretation, and geochemical data analysis [total organic carbon (TOC) and vitrinite reflectance (Ro)] to address this issue. Results show a clear depositional axis, with thick (>2500 m) Ordovician sediments in the southern half of the basin, and thinner strata in the central and northern parts. Rovalues range from 2.04% to 3.45%, and 55 of 73 samples have TOC > 0.23 wt%. Our novel findings made as below: (i) Ordovician strata have high contents of organic matter and that thermal evolution reached the dry gas stage, favorable for natural gas generation. (ii) Ordovician strata have recorded multiple tectonic events and experienced erosion that resulted in the formation of a karst type residuum in the central and northeastern parts of the basin. (iii) An Early Cretaceous tectono-thermal event controlled the generation and accumulation of natural gas, and this was the peak period of gas generation of Ordovician strata. (iv) Natural gas accumulation and adjustment occurred during the Cretaceous and Cenozoic, respectively. The Ordos Basin has experienced strong deformation and denudation since the Late Cretaceous. Collectively, the deformation was more intense in the south and weaker in the north, preventing hydrocarbon preservation in the southern part of the basin. These findings provide new insights to guide oil and gas exploration of the Ordos Basin.

In this work, we analyzed the biochemical changes and cultivation feasibility of microalgae Desmodesmussp. mutated by atmospheric and room temperature plasma (ARTP) technology in mixed wastewater. The mutant strain AT151 was cultivated in different types of pretreated wastewaters for suitable pretreatment, resulting in the highest biomass content of > 354 mg/L, with a > 52% increase in lipid production in the filtered wastewater, and the difference between 0.22-μm and 0.45-um filtration was not significant (P > 0.05). The fatty acids of AT151 indicated a majority of C16and C18at > 86%, and the monounsaturated fatty acid content exceeded 18%, which was beneficial for high-quality biodiesel. Nutrient removal was found to be visible in wastewater by cultivating mutant microalgae AT151. The removal rates of total nitrogen (TN), total phosphorus (TP), and total organic carbon (TOC) for AT151 cultivated in wastewater were more than 87%, 94% and 47%, respectively. Furthermore, the relationship between the microalgae and bacteria was studied, showing significant differences in bacterial community (P < 0.05). The obvious phenomenon consisted of dominant bacteria changes, where Brevundimonas balnearisand Synechocystissp. served as stable strains during cultivation, forming a symbiotic relationship with mutant microalgae AT151. The dominant bacteria showed obvious metabolism according to functional KEGG prediction, mainly affecting the factors of amino acids, carbohydrates, and growth factor metabolism. Therefore, enhancing microalgae biomass and lipid production through wastewater cultivation holds both scientific significance and practical feasibility.

With the continuous deepening of natural gas exploration, the quality of discovered resources gets worse and exploration targets are getting more and more complicated, so it is necessary to develop and improve natural gas geological theories continuously in order to tap and discover more natural gas resources. Therefore, geological theories on the formation of large gas fields were studied during the 12th Five-Year Plan period and the following progresses were mainly achieved. (1) Gas generation modes were established of oil cracking and highly evolved coal-measure source rocks in different geologic conditions. (2) A model was set up for evaluating quantitatively the hydrocarbon expulsion and detainment of various source rocks with different abundance. (3) Natural gas genesis identification chart was built up with multiple parameters and indexes. (4) Two carbonate rock sedimentation patterns and two tight sandstone sedimentation patterns were established. (5) A new method was developed for evaluating caprock–reservoir displacement pressure difference of immediate caprocks. (6) The hydrocarbon accumulation pattern of large gas fields was established and their main controlling factors and distribution laws were summarized. Then, the natural gas exploration theories were deepened in the following five fields and their application achievements are remarkable. First, the hydrocarbon-accumulation geological theory used for large ancient carbonate gas fields was innovatively understood to promote the discovery and confirmation of the Anyue supergiant gas field in the Sichuan Basin. Second, the hydrocarbon-accumulation geological theory suitable for large tight sandstone gas fields was developed to guide the exploration of tight sandstone gas in the Ordos and Songliao basins. Third, the hydrocarbon-accumulation theory of platform margin reefs was deepened to expand the exploration of platform margin reef gas in the Sichuan Basin. Fourth, the hydrocarbon accumulation mechanism and enrichment theory of large condensate gas reservoirs were deepened to guide the exploration of large condensate gas reservoirs in the Tarim Basin. And fifth, the exploration theory of volcanic gas reservoirs with hydrocarbon-generation fault troughs as basic units was completed to realize the strategic replacement of volcanic gas reservoir exploration.

Schizophrenia (SCZ) is a complex neuropsychiatric disorder with high heritability. Abnormal gene methylation was found to play a key role in the development of SCZ, suggesting that histone deacetylases (HDACs) may increase the expression of several key genes in the brain. However, recent studies evaluating the association between SCZ and genetic polymorphisms in histone deacetylase 3 (encoded by HDAC3) have shown conflicting results. In this study, we designed a two‐stage case‐control study to investigate the association of the HDAC3with SCZ. Fourteen tag single nucleotide polymorphisms (SNPs) entirely covering the region of HDAC3were analyzed in the testing group of 1,421 patients and 2,823 healthy controls, and the SNP rs14251 was found to be significant (and rs2530223 to be nominally significant). The significant result of rs14251 was successfully replicated in the validation group consisting of 896 cases and 1,815 healthy controls (P= 0.009276, OR = 1.219), and also confirmed by haplotype based analyses (rs976552‐rs14251, global P < 0.001). To sum up, our results provide additional evidence that HDAC3confers the increasing risk of SCZ susceptibility in Han Chinese individuals, suggesting this gene as a potential genetic modifier for SCZ development. © 2016 Wiley Periodicals, Inc.

PetroChina Changqing Oilfield Company (hereinafter referred to as Changqing Oilfield) built the largest oil and gas production base of China in the Ordos Basin in 2013, achieving the yearly natural gas production of 375 × 108 m3in 2015. For the further sustainable and stable production and quality and benefit improvement, such great achievements made in the 12th Five-Year Plan were first summarized, and the relevant favorable conditions for natural gas development were also analyzed as follows: abundant natural gas resources; increasingly mature E&P technologies; continuously improved delicacy management; and a surging demand for natural gas. Then, challenges to natural gas development were also discussed, including obvious deterioration of natural gas resources; diminished capacity of stable production of produced gasfields; increasing number of low-yield wells; and prominent supply–demand contradiction in present natural gas market. Finally, its prospect in the 13th Five-Year Plan was studied: to carry out natural gas exploration with focus on Upper Paleozoic tight gas, Lower Paleozoic carbonate rocks, and new areas and new domains, so as to achieve rapid growth of natural gas reserves and orderly replacement in exploration domains; to make rational development planning with focus on the stable production of mature gasfields; and to enhance tight gas recovery and strengthen capacity building in new areas, so as to achieve a steady rise of annual gas production in the giant gas province. It is expected that by the end of 13th Five-Year Plan period, Changqing Oilfield will achieve its annual gas production of up to 400 × 108 m3.

During the progressive exploration of the Jingbian Gas Field in the Ordos Basin, multiple gas-bearing regions have been discovered in the dolomite reservoirs in the Middle Ordovician assemblages of Lower Paleozoic in Jingxi area, but these gas-bearing regions and intervals are significantly different in terms of gas enrichment degrees. So far, however, the reasons for the difference have not been figured out. In this paper, the origin and source of natural gas in the Middle Ordovician assemblages in Jingxi area was investigated on the basis of geochemical data (e.g. natural gas composition and carbon isotope), and then the main factors controlling the gas accumulation were analyzed. It is shown that the natural gas in the Middle Ordovician assemblages in the Middle Ordovician assemblages in Jingxi area is similar to that in the Upper Ordovician assemblages and Upper Paleozoic reservoir in terms of genesis and sources, and they are mainly the Upper Paleozoic coaliferous gas with some oil-derived gas. Under the influence of hydrocarbon generation center of coal source rocks and the source–rock–reservoir contact relationship, the proportion of coaliferous gas increases areally from the north to the south and vertically from Ma55sub-member of the Lower Ordovician Majiagou Fm. It is concluded that the natural gas enrichment degree is controlled by the gas charging capacity at the hydrocarbon-supplying windows. Second, the vertical migration and distribution of natural gas is dominated by the differences of Ma55−Ma510transport pathways. And third, the lateral migration direction of natural gas and the range of gas accumulation are controlled by the superimposition relationship between structures and reservoirs.

Natural gas resources is abundant in the Ordos Basin, where six gas fields with more than 100 billion cubic meters of gas reserves have been successively developed and proved, including Jingbian, Yulin, Zizhou, Wushenqi, Sulige and Shenmu. This study aims to summarize the fruitful results and functional practices achieved in the huge gas province exploration, which will be regarded as guidance and reference for the further exploration and development in this basin. Based on the past five decades' successful exploration practices made by PetroChina Changqing Oilfield Company, we first comb the presentation of geological theories at different historical stages as well as the breakthrough in the course. Then, we analyze a complete set of adaptive techniques obtained from the long-time technological research and conclude historical experiences and effective measures in terms of broadening exploration ideas, such as the fluvial delta reservoir-forming theory, giant tight gas reservoir-forming theory, the idea of sediment source system in the southern basin, etc., and innovating technical and management mechanism, such as all-digit seismic prediction, fine logging evaluation for gas formations, stimulation of tight sand reservoirs, flat project and benchmarking management, and so on.

By the end of 2014, the giant Shenmu Gas Field had been found in the Ordos Basin with an explored gas-bearing area of 4069 km2and the proved geological gas reserves of 333.4 billion m3. This paper aims to review the exploration history of this field and discusses its reservoir-forming mechanism and geological characteristics, which may guide the further discovery and exploration of such similar gas fields in this basin and other basins. The following research findings were concluded. (1) There are typical tight sand gas reservoirs in this field primarily with the pay zones of the Upper Paleozoic Taiyuan Fm, and secondly with those of the Shanxi and Shihezi Fms. (2) Gas types are dominated by coal gas with an average methane content of 88% and no H2S content. (3) The gas reservoirs were buried 1700–2800 m deep underneath with multiple pressure systems and an average pressure coefficient of 0.87. (4) The reservoir strata are composed of fluvial delta facies sandstones with an average porosity of 7.8% and permeability of 0.63 mD, having high pressure sensibility and a strong water-locking effect because the pore throat radius are mostly less than 1 μm. (5) There are different dynamics at various stages in the gas reservoir-forming process. The abnormal well-developed strata pressure was the main reservoir-forming force at the Early Cretaceous setting stage while the fluid expansibility became the main gas-migrating force at the uplift and denudation stage after the Early Cretaceous period. (6) Gas reservoirs with ultra-low water saturation are mainly controlled by many factors such as changes of high temperature and high pressure fields in the Late Jurassic and Early Cretaceous periods, the charging of dry gas at the highly-mature stage, and the gas escape and dissipation at the post-reservoir-forming periods. (7) Natural gas migrated and accumulated vertically in a shortcutting path to form gas reservoirs. At such areas near the source rocks, large-scale gas reservoirs were easily found with plenty of gas sources and high gas saturation; but at those far from the source rocks, relatively small-scale and mostly secondary gas reservoirs were discovered.

The article offers an analysis of the parent rock properties and tectonic setting to provide a theoretical basis for future oil and gas exploration in the Yanchi area in China. Topics covered include the sedimentary source direction and the condition of mixed sources in Member 8 of the Shihezi formation and Member 1 of Shanxi formation, a variety of source analysis methods used for exploration, and the sandstone mineral composition of 429 samples from 65 wells in the formation.

Sequencing of the human genome and new microarray technology make it possible to assess all genes on a single chip or array. Recent studies show different patterns of gene expression related to different tissues and diseases, and these patterns of gene expression are beginning to be used for diagnosis and treatment decisions in various types of lymphoid and solid malignancies. Because of obvious problems obtaining brain tissue, progress in genomics of neurological diseases has been slow. To address this, we demonstrated that different types of acute injury in rodent brain produced different patterns of gene expression in peripheral blood. These animal studies have now been extended to human studies. Two groups have shown that there are specific genomic profiles in the blood of patients after ischemic stroke that are highly sensitive and specific for predicting stroke. Other recent studies demonstrate specific genomic profiles in the blood of patients with Down syndrome, neurofibromatosis, tuberous sclerosis, Huntington disease, multiple sclerosis, Tourette syndrome, and others. In addition, data demonstrate specific profiles of gene expression in the blood related to different drugs, toxins, and infections. Although all of these studies are still preliminary basic scientific endeavors, they suggest that this approach will have clinical applications to neurological diseases in humans.Arch Neurol. 2006;63:1529-1536--