The molecular compositions and stable carbon and hydrogen isotopic compositions of natural gas from the Xinchang gas field in the Sichuan Basin were investigated to determine the genetic types. The natural gas is main...The molecular compositions and stable carbon and hydrogen isotopic compositions of natural gas from the Xinchang gas field in the Sichuan Basin were investigated to determine the genetic types. The natural gas is mainly composed of methane （88.99%-98.01%）, and the dryness coefficient varies between 0.908 and 0.997. The gas generally displays positive alkane carbon and hydrogen isotopic series. The geochemical characteristics and gas-source correlation indicate that the gases stored in the 5th member of the Upper Triassic Xujiahe Formation are coal-type gases which are derived from source rocks in the stratum itself. The gases reservoired in the 4th member of the Xujiahe Formation and Jurassic strata in the Xinchang gas field are also coal-type gases that are derived from source rocks in the 3rd and 4th members of the Xujiahe Formation. The gases reservoired in the 2nd member of the Upper Triassic Xujiahe Formation are mainly coal-type gases with small amounts of oil-type gas that is derived from source rocks in the stratum itself. This is accompanied by a small amount of contribution brought by source rocks in the Upper Triassic Ma＇antang and Xiaotangzi formations. The gases reservoired in the 4th member of the Middle Triassic Leikoupo Formation are oil-type gases and are believed to be derived from the secondary cracking of oil which is most likely to be generated from the Upper Permian source rocks.展开更多
Different genetic types of meter-scale cyclic sequences in stratigraphic records result from episodic accumulation of strata related to Milankovitch cycles. The distinctive fabric natures of facies succession result f...Different genetic types of meter-scale cyclic sequences in stratigraphic records result from episodic accumulation of strata related to Milankovitch cycles. The distinctive fabric natures of facies succession result from the sedimentation governed by different sediment sources and sedimentary dynamic conditions in different paleogeographical backgrounds, corresponding to high-frequency sea-level changes. Naturally, this is the fundamental criterion for the classification of genetic types of meter-scale cyclic sequences. The widespread development in stratigraphic records and the regular vertical stacking patterns in long-term sequences, the evolution characters of earth history and the genetic types reflected by specific fabric natures of facies successions in different paleogeographical settings, all that show meter-scale cyclic sequences are not only the elementary working units in stratigraphy and sedimentology, but also the replenishment and extension of parasequence of sequence stratigraphy. Two genetic kinds of facies succession for meter-scale cyclic sequence in neritic-facies strata of carbonate and clastic rocks, are normal grading succession mainly formed by tidal sedimentation and inverse grading succession chiefly made by wave sedimentation, and both of them constitute generally shallowing upward succession, the thickness of which ranges from several tens of centimeters to several meters. The classification of genetic types of meter-scale cyclic sequence could be made in terms of the fabric natures of facies succession, and carbonate meter-scale cyclic sequences could be divided into four types: L-M type, deep-water asymmetrical type, subtidal type and peritidal type. Clastic meter-scale cyclic sequences could be grouped into two types: tidal-dynamic type and wave-dynamic type. The boundaries of meter-scale cyclic sequences are marked by instantaneous punctuated surface formed by non-deposition resulting from high-frequency level changes, which include instantaneous exposed punctuated surface, drowned punctuated surface as well as their relative surface. The development of instantaneous punctuated surface used as the boundary of meter-scale cyclic sequence brings about the limitations of Walter's Law on the explanation of facies distribution in time and space, and reaffirm the importance of Sander's Rule on analysis of stratigraphic records. These non-continuous surface could be traced for long distance and some could be correlative within same basin range. The study of meter-scale cyclic sequences and their regularly vertical stacking patterns in long-term sequences indicate that the research into cyclicity of stratigraphic records is a useful way to get more regularity from stratigraphic records that are frequently complex as well as non-integrated.展开更多
CO2 gas is a nonhydrocarbon gas, with a high economic value and a broad prospect for application. In the Huanghua Depression, there exist many genetic types of CO2 gases, i.e. organic CO2, thermal metamorphic CO2 and ...CO2 gas is a nonhydrocarbon gas, with a high economic value and a broad prospect for application. In the Huanghua Depression, there exist many genetic types of CO2 gases, i.e. organic CO2, thermal metamorphic CO2 and crust-mantle mixed CO2. The distribution of different types of CO2 gases is controlled by different factors. Organic CO2 that occurs mainly around the oil-generating center is associated with hydrocarbon gases as a secondary product and commonly far away from large faults. Thermal metamorphic CO2 occurs mainly in areas where carbonate strata are developed and igneous activity is strong, and tends to accumulate near large faults. CO2 of such an origin is higher in concentration than organic CO2, but lower than crust-mantle mixed CO2. Crust-mantle mixed CO2 occurs mainly along large faults. Its distribution is limited, but its purity is the highest.展开更多
Natural gases were widely distributed in the Jiyang Depression with complicated component composition, and it is difficult to identify their genesis. Based on investigation of gas composition, carbon isotope ratios, l...Natural gases were widely distributed in the Jiyang Depression with complicated component composition, and it is difficult to identify their genesis. Based on investigation of gas composition, carbon isotope ratios, light hydrocarbon properties, as well as geological analysis, natural gases in the Jiyang Depression are classified into two types, one is organic gas and the other is abiogenic gas. Abiogenic gas is mainly magmatogenic or mantlederived CO2. Organic gases are further divided into coaltype gas, oil-type gas, and biogas according to their kero- gen types and formation mechanisms. The oil-type gases are divided into mature oil-type gas （oil-associated gas） and highly mature oil-type gas. The highly mature oil-type gases can be subdivided into oil-cracking gas and kerogen thermal degradation gas. Identification factors for each kind of hydrocarbon gas were summarized. Based on genesis analysis results, the genetic types of gases buried in different depths were discussed. Results showed that shallow gases （〈1,500 m） are mainly mature oil-type gases, biogas, or secondary gases. Secondary gases are rich in methane because of chromatographic separation during migration and secondary biodegradation. Secondary biodegradation leads to richness of heavy carbon isotope ratios in methane and propane. Genesis of middle depth gases （1,500-3,500 m） is dominated by mature oil-type gases.Deep gases （3,500-5,500 m） are mainly kerogen thermal degradation gas, oil-cracking gas, and coal-type gas.展开更多
Objective:To characterize the semen of three genetic types of boars(local,improved and Large White)reared in Benin.Methods:Semen of local,improved and Large White boars reared in Benin were collected using the gloved ...Objective:To characterize the semen of three genetic types of boars(local,improved and Large White)reared in Benin.Methods:Semen of local,improved and Large White boars reared in Benin were collected using the gloved hand method and analyzed to determine volume,pH,concentration,mobility,motility,and morphology.The effect of the genetic type of boar on semen characteristics was aslo studied.Results:Duration of ejaculation and semen volume of Large White boar were significantly higher than those of local and improved boars(P<0.05).The semen of improved boars had a higher motility score than that of Large White and local boars(P<0.001).The semen of local boars was more concentrated in the spermatozoa than that of improved and Large White boars(P<0.05).The proportion of spermatozoa of improved boars with normal morphology(93.6%)was significantly higher than that of local(82.2%)and Large White boars(81.6%)(P<0.001).The proportion of spermatozoa with folded tails in the semen of Large White boars(9.2%)was significantly higher than that observed in improved(1.8%)and local(5.0%)boars(P<0.001).The proportion of spermatozoa with proximal cytoplasmic droplets in semen of improved boars(2.7%)was significantly lower than that in Large White(6.8%)and local(9.7%)boars(P<0.001).The local(1.5%)and Large White boars(1.1%)showed more spermatozoa with distal cytoplasmic droplets in their semen compared to the improved boars(0.4%).Conclusions:The semen characteristics of pigs reared in Benin vary from one genetic type to another.Each genetic type has a strong point.The Large White boar produces larger semen,the local boar produces more concentrated semen and the improved boar produces spermatozoa that are morphologically better.The semen of these three genetic types can be used in artificial insemination but the improved boar's semen is more recommended.展开更多
Great volumes of shallow-buried （〈2,000 m） natural gases which are mainly composed of biogases and low-mature gases have been found in the Mesozoic-Cenozoic sedimentary basins in China. Many shallow gas reservoirs ...Great volumes of shallow-buried （〈2,000 m） natural gases which are mainly composed of biogases and low-mature gases have been found in the Mesozoic-Cenozoic sedimentary basins in China. Many shallow gas reservoirs in China are characterized by coexistence of biogas and low-mature gas, so identifying the genetic types of shallow gases is important for exploration and development in sedimentary basins. In this paper, we study the gas geochemistry characteristics and distribution in different basins, and classify the shallow gas into two genetic types, biogas and low-mature gas. The biogases are subdivided further into two subtypes by their sources, the source rock-derived biogas and hydrocarbon-derived biogas. Based on the burial history of the source rocks, the source rock-derived biogases are divided into primary and secondary biogas. The former is generated from the source rocks in the primary burial stage, and the latter is from uplifted source rocks or those in a secondary burial stage. In addition, the identifying parameters of each type of shallow gas are given. Based on the analysis above, the distributions of each type of shallow gas are studied. The primary biogases generated from source rocks are mostly distributed in Quaternary basins or modem deltas. Most of them migrate in watersoluble or diffused mode, and their migration distance is short. Reservoir and caprock assemblages play an important role in primary biogas accumulation. The secondary biogases are distributed in a basin with secondary burial history. The oil-degraded biogases are distributed near heavy oil pools. The low-mature gases are widely distributed in shallow-buried reservoirs in the Meso-Cenozoic basins.展开更多
A systematic geological and geochemical study was conducted for the granitoids of different periods in the western Kunlun orogenic belt. The study indicates that the granitoids belong to tholeiitic, calc-alkaline, hig...A systematic geological and geochemical study was conducted for the granitoids of different periods in the western Kunlun orogenic belt. The study indicates that the granitoids belong to tholeiitic, calc-alkaline, high-K calc-alkaline, alkaline and shoshonitic series, and that there are 5 genetic types, i.e., I-, S-, M-, A- and SH-type, of which SH-type is first put forward in this paper, which corresponds to shoshonitic granitoids.展开更多
As a typical Palaeozoic island arc system, the eastern Tianshan area, Xinjiang, is different from eastern China but similar to the Meso-Cenozoic island arc metallogenic provinces along the coast of the Pacific Ocean i...As a typical Palaeozoic island arc system, the eastern Tianshan area, Xinjiang, is different from eastern China but similar to the Meso-Cenozoic island arc metallogenic provinces along the coast of the Pacific Ocean in metallogenic environment, geology and geochemistry. Three types of gold deposits, ductile shear zone-hosted gold deposits (Kanggur'), magmatic hydrothermal gold deposits (Jinwozi) and volcanic- or subvolcanic-hosted gold deposits (Xitan and Mazhuangshan), have been identified in this area. Regionally, gold deposits are structurally controlled by the Kanggur Tag ductile shear zone, Shaquanzi fault, Hongliuhe fault and Yamansu fault. Generally, gold mineralization occurs in the transition zones from volcanic rocks to sedimentary rocks. The horizon bearing well-developed jasper is an important indicator for gold mineralization. Each of the three types of gold deposits has its distinctive metallogenic background and geological-geochemical characteristics.展开更多
The origin and genetic types of natural gas in the Sichuan Basin are still disputed.To classify the origin and genetic types in different areas,the paper analyzes the carbon isotopic composition of gases and geologic ...The origin and genetic types of natural gas in the Sichuan Basin are still disputed.To classify the origin and genetic types in different areas,the paper analyzes the carbon isotopic composition of gases and geologic features in the Sichuan Basin.The results showed that the gas sourced from terrestrial layers is typically characterized by terrestrial origin and was mainly accumulated nearby to form reservoir.The carbon isotopic composition of gas showed a normal combination sequence distribution,suggesting that natural gas in continental strata is not affected by secondary alteration or that this deformation is very weak.The gas source is singular,and only gas from the southern and northern Sichuan Basin shows the characteristic of mixed sources.However,marine gas presents the characteristics of an oil-formed gas.The carbon isotopic composition of natural gas in the western and central part of the basin mostly distributes in a normal combination sequence,and few of them showed an inversion,indicating that the gas perhaps had not experienced secondary alteration.The carbon isotopic composition of marine-origin gas in the southern,northern and eastern Sichuan Basin displays a completely different distribution pattern,which is probably caused by different mixing ratio of gas with multi-source and multi-period.展开更多
Uranium(U)can be enriched in U-polymetallic deposits of various genetic types,with different ore-metal associations including U and many other critical metals.The major U-polymetallic deposits in the world are divided...Uranium(U)can be enriched in U-polymetallic deposits of various genetic types,with different ore-metal associations including U and many other critical metals.The major U-polymetallic deposits in the world are divided into nine genetic types,i.e.,hydrothermal iron oxide-copper-gold-U type(herein,referred to as IOCG),quartz-pebble conglomerate type,unconformity-related type,alkaline rock-and carbonatite type,metamorphite type,volcanic-and granite-related type,carbonaceous-siliceous-pelitic type(herein,referred to as CSP),phosphate type,and co-basin coexistence type(including U-rich coaland sandstone types).Among them,the first six are the main genetic types,and the last three are collectively referred to as the“Black rock-series type”,all belonging to the unconventional U resource type.Although these U-polymetallic deposits of different genetic types occur in different or specific tectonic settings,they generally exhibit complex metallogenic processes and special ore-forming mechanisms.Besides the involvement of the important geological and biological events occurring during the evolution of the Earth,other various factors differentially acting on U-polymetal mineralization processes are the direct causes controlling the presence of U-polymetals as symbiotic and/or concomitant products,and thereby result in different ore-metal associations in the U-polymetallic deposits of different genetic types.These factors include the differentiation in source regions of U polymetals or lithologies of ore-forming parent rocks,the physicochemical properties of ore-bearing hydrothermal fluids/melts,the geochemical behaviors of different ore-forming elements in the same magmatic-hydrothermal mineral systems,the similarities and differences in complex type and their stability or activity,as well as the mixing of fluids/melts with different redox states,and interaction between oxidizing fluids/melts and reducing substances such as organic matters or fluids/melts-rock interaction.The authors finally point out that there are potential to find U-polymetallic deposits such as the hydrothermal IOCG-,the quartz-pebble conglomerate-,the unconformity-related-,the metamorphite-,and the alkaline rock-and carbonatite types in China.展开更多
The Jiyang Depression is an important oil and gas production zone in the Bohai Bay Basin.Through a systematic investigation of the gas components and stable carbon isotopes,the genetic types of natural gas found in th...The Jiyang Depression is an important oil and gas production zone in the Bohai Bay Basin.Through a systematic investigation of the gas components and stable carbon isotopes,the genetic types of natural gas found in the Jiyang Depression were determined,that is,biogas,oilassociated gas,coal-derived gas,high-mature oil-related gas,and mantle-derived carbon dioxide(CO_(2)).From the results,natural gas in the Jiyang Depression can be divided into four groups.Group I,which is distributed in the northwest area,is the only typical oil-associated gas.Group II,distributed in the northeast area,is dominated by oil-associated gas,and involves biogas,coal-derived gas,and high-mature oil-related gas.Group Ⅲ,distributed in the southeast area,has all genetic types of gas that are dominated by oil-associated gas and have mantle-derived CO_(2).Group IV,distributed in the southwest area,is dominated by biogas and involves coal-derived gas and oil-associated gas.The differences in each group illustrate the lateral distribution of the natural gas types is characterized by the eastern and southern areas being more complex than the western and northern areas,the vertical distribution of gas reservoirs has no obvious evolutionary law.The main controlling factor analysis of the spatiotemporal changes of the gas reservoirs revealed that the synergy of geochemical characteristics,thermal evolution of the Shahejie Formation and Carboniferous-Permian source rocks,and sealing properties of various faults are jointly responsible for determining the gas reservoir spatiotemporal changes.展开更多
Despite its significant exploration potential,the origin of natural gas in the tectonically complex southwestern Tarim Basin remains controversial due to multiple potential source rocks.This study identifies the genet...Despite its significant exploration potential,the origin of natural gas in the tectonically complex southwestern Tarim Basin remains controversial due to multiple potential source rocks.This study identifies the genetic types and sources of natural gas by integrating gas molecular and isotopic compositions with the geochemical characteristics of potential source rocks.The results indicate that the Kekeya gas field mainly contains coal-derived gas sourced from the Permian Pusige Formation,whereas the Akemomu field and the QT-1 well contain highly overmature gas from the Permian Qipan Formation with some mantle-derived He and inorganic CO_(2).Furthermore,the oil-associated gas in the FS-8 well originates from Permian sapropelic source rocks,while the KS-6 well contains a mixed,oil-associated gas predominantly sourced from the Jurassic Yangye Formation.These findings reveal a complex gas accumulation scenario with multiple genetic types and sources in the southwestern Tarim Basin,providing critical insights for future exploration.展开更多
Type 1 diabetes(T1D)is an autoimmune disease that usually strikes early in life,but can affect individuals at almost any age.It is caused by autoreactive T cells that destroy insulin-producing beta cells in the pancre...Type 1 diabetes(T1D)is an autoimmune disease that usually strikes early in life,but can affect individuals at almost any age.It is caused by autoreactive T cells that destroy insulin-producing beta cells in the pancreas.Epidemiological studies estimate a prevalence of 1 in 300 children in the United States with an increasing incidence of 2%-5%annually worldwide.The daily responsibility,clinical management,and vigilance required to maintain blood sugar levels within normal range and avoid acute complications(hypoglycemic episodes and diabetic ketoacidosis)and long term micro-and macro-vascular complications significantly affects quality of life and public health care costs.Given the expansive impact of T1D,research work has accelerated and T1D has been intensively investigated with the focus to better understand,manage and cure this condition.Many advances have been made in the past decades in this regard,but key questions remain as to why certain people develop T1D,but not others,with the glaring example of discordant disease incidence among monozygotic twins.In this review,we discuss the field’s current understanding of its pathophysiology and the role of genetics and environment on the development of T1D.We examine the potential implications of these findings with an emphasis on T1D inheritance patterns,twin studies,and disease prevention.Through a better understanding of this process,interventions can be developed to prevent or halt it at early stages.展开更多
Charcot-Marie-Tooth （CMT） disease is the most common hereditary neuropathy, with a population prevalence of 1 in 2500. CMT disease type 1A （CMT1A）, accounting for ~70% of CMT1 cases and ~ 50% of all CMT cases, is ...Charcot-Marie-Tooth （CMT） disease is the most common hereditary neuropathy, with a population prevalence of 1 in 2500. CMT disease type 1A （CMT1A）, accounting for ~70% of CMT1 cases and ~ 50% of all CMT cases, is transmitted in an autosomal dominant manner. CMT1A maps to chromo- some 17pl 1.2 and is caused, in the majority of cases, by a 1.4- Mb tandem duplication that includes the peripheral myelin protein22 （PMP22） gene （Li et al., 2013）. The disease usually presents in the first 20 years of age, causing difficulty in walking or running, distal symmetrical muscle weakness and wasting, and sensory loss （van Paassen et al., 2014）.展开更多
The highest-level interference essence against virus and turnour genetic engineering medicine is a new type created in the 1980s. Compared with chemical medicines, the interference essence has a special effect in the ...The highest-level interference essence against virus and turnour genetic engineering medicine is a new type created in the 1980s. Compared with chemical medicines, the interference essence has a special effect in the treatment of viruses and tumours. The human a, type genetic engineering interference essense is prepared by the Institute of Viruses of the Chinese Academy of Preventive Medical Sciences, the Shanghai Vaccine展开更多
BACKGROUND Dystrophic epidermolysis bullosa is characterized by fragile ulcerations of the skin caused by mutations in specific genes.However,genetic typing of this con-dition is rare.CASE SUMMARY An 11-year-old femal...BACKGROUND Dystrophic epidermolysis bullosa is characterized by fragile ulcerations of the skin caused by mutations in specific genes.However,genetic typing of this con-dition is rare.CASE SUMMARY An 11-year-old female suffered from recurrent fever,visible ulcerations of the entire skin,and severe malnutrition.Genetic testing revealed a frameshift mu-tation in the coding region 4047 of the 35th intron region of COL7A1,and she was diagnosed as malnutrition-type epidermolysis bullosa.Drug therapy(immu-noglobulin,fresh frozen plasma),topical therapy(silver ion dressing),fever redu-ction,cough relief,and promotion of gastrointestinal peristalsis are mainly used for respiratory and gastrointestinal complications.The patient’s condition impro-ved after treatment.CONCLUSION Dystrophic epidermolysis bullosa caused by a new framework shift mutation in COL7A1 should be taken seriously.展开更多
The northern Xinjiang region is one of the most significant iron metallogenic provinces in China.Iron deposits are found mainly within three regions:the Altay,western Tianshan,and eastern Tianshan orogenic belts.Previ...The northern Xinjiang region is one of the most significant iron metallogenic provinces in China.Iron deposits are found mainly within three regions:the Altay,western Tianshan,and eastern Tianshan orogenic belts.Previous studies have elaborated on the genesis of Fe deposits in the Altay orogenic belt and western Tianshan.However,the geological characteristics and mineralization history of iron deposits in the eastern Tianshan are still poorly understood.In this paper I describe the geological characteristics of iron deposits in the eastern Tianshan,and discuss their genetic types as well as metallogenic-tectonic settings,Iron deposits are preferentially distributed in central and southern parts of the eastern Tianshan.The known iron deposits in the eastern Tianshan show characteristics of magmatic Fe-Ti-V(e.g.,Weiya and Niumaoquan),sedimentary-metamorphic type(e.g.,Tianhu),and iron skarn(e.g.,Hongyuntan).In addition to the abovementioned iron deposits,many iron deposits in the eastern Tianshan are hosted in submarine volcanic rocks with well-developed skarn mineral assemblages.Their geological characteristics and magnetite compositions suggest that they may belong to distal skarns.SIMS zircon U-Pb analyses suggest that the Fe-Ti oxide ores from Niumaoquan and Weiya deposits were formed at 307.7±1.3 Ma and 242.7±1.9 Ma,respectively.Combined with available isotopic age data,the timing of Fe mineralization in the eastern Tianshan can be divided into four broad intervals:Early Ordovician-Early Silurian(476-438 Ma),Carboniferous(335-303 Ma),Early Permian(295-282 Ma),and Triassic(ca.243 Ma).Each of these episodes corresponds to a period of subduction,post-collision,and intraplate tectonics during the Paleozoic and Mesozoic time.展开更多
In order to distinguish the source and migration direction of natural gas by geochemical characteristics of butane,the components and carbon isotopes of natural gas from major hydrocarbonbearing basins in China were a...In order to distinguish the source and migration direction of natural gas by geochemical characteristics of butane,the components and carbon isotopes of natural gas from major hydrocarbonbearing basins in China were analyzed.The results showed that：（1） Oil-type gas has i-C 4 /n-C 4 0.8,δ 13 C butane -28‰,δ 13 C i-butane -27‰,δ 13 C n-butane -28.5‰,whereas coal-type gas has i-C 4 /n-C 4 0.8,δ 13 C butane -25.5‰,δ 13 C i-butane -24‰,δ 13 C n-butane -26‰.（2） When δ 13 C i-butane-δ 13 C n-butane is greater than 0,the maturity of oil-type gas is generally more than 2.4% and that of coal-type gas is greater than 1.4%,whereas when the difference is less than 0,the maturity of oil-type gas is generally less than 1.1% and that of coal-type gas is less than 0.8%.（3） When natural gas migrates through dense cap rocks,the value of i-C 4 /n-C 4 increases,whereas when it migrates laterally along a reservoir,the value of i-C 4 /n-C 4 decreases.（4） Sapropelic transition zone gas with composition and carbon isotopic signatures similar to those of oil-type gas in the low thermal evolution stage is found to have a relatively high butane content.（5） The values of i-C 4 /n-C 4 and δ 13 C n-butane δ 13 C i-butane of gas which has suffered biological degradation are significantly higher than those obtained from thermogenic and bio-thermocatalytic transition zone gas.Thus,natural gas of different genetic types can be recognized through component analysis and carbon isotopic signatures of butane,the natural gas maturity can be estimated from the difference in carbon isotopic content between isobutane and n-butane,and the migration direction of natural gas can be determined from i-C 4 /n-C 4 ratios and transport conditions,which can also be used to thermogenic and bio-thermocatalytic transition zone gas.展开更多
It is significant to distinguish the dynamic systems of petroleum accumulation （DSPA） for the understanding of petroleum accumulation and distribution. According to the formation pressure framework, genetic types of...It is significant to distinguish the dynamic systems of petroleum accumulation （DSPA） for the understanding of petroleum accumulation and distribution. According to the formation pressure framework, genetic types of petroleum and characteristics of conduit systems, three dynamic systems of petroleum accumulation were identified in the vertical profile in the Nanpu depression, Bohai Bay basin. The deeper DSPA （including formations Es3 to Es2） is a sealed system with high-overpressure and high-mature self-sourced oil. Most of the crude oil in the system accumulated in the periods of late Oligocene （23.5 Ma） and late Pliocene （2.4 Ma）. The middle DSPA （including formations Es~ to Edl） is an overpressured half-sealed system with mature or lower-mature self-sourced oil. The accumulation of oil in the system also occurred in the late Oligocene （23.5 Ma） and late Pliocene （2.4 Ma）. The shallower DSPA （including formations Ed2 to Q） is a hydrostatic system with lower-mature aliensourced oil from the middle system. Oil within this system accumulated only in the late Pliocene period. The oil in the shallower system migrated vertically along the faults from the formerly accumulated oil in the middle system by lateral migration along the sandbodies, whereas petroleum accumulation in the deeper system was mainly derived from the system itself by lateral migration along the sandbodies and rarely migrated out of the system. In this case, it seems that the deeper system is a more potential exploration prospect in addition to the other two proved favorable systems.展开更多
Coalbed methane （CBM） is an important type of unconventional gas. Commercial development of CBM in America has been very successful since the 1980s. The CBM industry in Australia and Canada has developed rapidly dur...Coalbed methane （CBM） is an important type of unconventional gas. Commercial development of CBM in America has been very successful since the 1980s. The CBM industry in Australia and Canada has developed rapidly during the last decade. Commercial development of CBM in China started in the 1990s, and has made great progress. The geological theory of CBM in China has achieved great advancement in genesis, occurrence and accumulation. On the aspect of CBM genesis, five CBM genetic types （primary biogenic gas, secondary biogenic gas, thermal degradation gas, pyrolysis gas and mixed gas） are identified by studying the geochemical characteristics of CBM, and a tracing indicator system is established. The discovery of secondary biogenic gas in medium-high rank coal reservoirs has widened the potential of CBM resources. On the aspect of CBM occurrence, the gas adsorption regulation under combined action of temperature and pressure is revealed by conducting adsorption experiments of different coal ranks under varying temperature and pressure conditions. Besides, by applying the adsorption potential theory in CBM research, the adsorption model under combined action of temperature and pressure is established. The new model can predict CBM resources accurately, and overcome the limitation of the traditional Langmuir model which uses just a single factor to describe the adsorption characteristics of deep buried coal. On the aspect of CBM accumulation, it is proposed that there are three evolutionary stages during CBM accumulation, including gas generation and adsorption, unsaturated gas adsorption, gas desorption-diffusion and preservation. Controlled by tectonic evolution, hydrodynamics and sealing conditions, CBM tends to be regionally enriched in synclines. Advances in geological theory of CBM in China can not only improve understanding of natural gas, but also provide new ideas for further exploration of CBM.展开更多
基金financially supported by the National Natural Science Foundation of China (grants No.41625009, 41302118 and U1663201)the National Key Foundational Research and Development Project (Grant No:2016YFB0600804)the National Science & Technology Special Project (grant No.2016ZX05002-006)
文摘The molecular compositions and stable carbon and hydrogen isotopic compositions of natural gas from the Xinchang gas field in the Sichuan Basin were investigated to determine the genetic types. The natural gas is mainly composed of methane （88.99%-98.01%）, and the dryness coefficient varies between 0.908 and 0.997. The gas generally displays positive alkane carbon and hydrogen isotopic series. The geochemical characteristics and gas-source correlation indicate that the gases stored in the 5th member of the Upper Triassic Xujiahe Formation are coal-type gases which are derived from source rocks in the stratum itself. The gases reservoired in the 4th member of the Xujiahe Formation and Jurassic strata in the Xinchang gas field are also coal-type gases that are derived from source rocks in the 3rd and 4th members of the Xujiahe Formation. The gases reservoired in the 2nd member of the Upper Triassic Xujiahe Formation are mainly coal-type gases with small amounts of oil-type gas that is derived from source rocks in the stratum itself. This is accompanied by a small amount of contribution brought by source rocks in the Upper Triassic Ma＇antang and Xiaotangzi formations. The gases reservoired in the 4th member of the Middle Triassic Leikoupo Formation are oil-type gases and are believed to be derived from the secondary cracking of oil which is most likely to be generated from the Upper Permian source rocks.
基金ThestudyisjointlysupportedbyNationalNaturalScienceFoundationofChina (No .4980 2 0 1 2 )andMinistryofSciencesandTechnology (SSER
文摘Different genetic types of meter-scale cyclic sequences in stratigraphic records result from episodic accumulation of strata related to Milankovitch cycles. The distinctive fabric natures of facies succession result from the sedimentation governed by different sediment sources and sedimentary dynamic conditions in different paleogeographical backgrounds, corresponding to high-frequency sea-level changes. Naturally, this is the fundamental criterion for the classification of genetic types of meter-scale cyclic sequences. The widespread development in stratigraphic records and the regular vertical stacking patterns in long-term sequences, the evolution characters of earth history and the genetic types reflected by specific fabric natures of facies successions in different paleogeographical settings, all that show meter-scale cyclic sequences are not only the elementary working units in stratigraphy and sedimentology, but also the replenishment and extension of parasequence of sequence stratigraphy. Two genetic kinds of facies succession for meter-scale cyclic sequence in neritic-facies strata of carbonate and clastic rocks, are normal grading succession mainly formed by tidal sedimentation and inverse grading succession chiefly made by wave sedimentation, and both of them constitute generally shallowing upward succession, the thickness of which ranges from several tens of centimeters to several meters. The classification of genetic types of meter-scale cyclic sequence could be made in terms of the fabric natures of facies succession, and carbonate meter-scale cyclic sequences could be divided into four types: L-M type, deep-water asymmetrical type, subtidal type and peritidal type. Clastic meter-scale cyclic sequences could be grouped into two types: tidal-dynamic type and wave-dynamic type. The boundaries of meter-scale cyclic sequences are marked by instantaneous punctuated surface formed by non-deposition resulting from high-frequency level changes, which include instantaneous exposed punctuated surface, drowned punctuated surface as well as their relative surface. The development of instantaneous punctuated surface used as the boundary of meter-scale cyclic sequence brings about the limitations of Walter's Law on the explanation of facies distribution in time and space, and reaffirm the importance of Sander's Rule on analysis of stratigraphic records. These non-continuous surface could be traced for long distance and some could be correlative within same basin range. The study of meter-scale cyclic sequences and their regularly vertical stacking patterns in long-term sequences indicate that the research into cyclicity of stratigraphic records is a useful way to get more regularity from stratigraphic records that are frequently complex as well as non-integrated.
文摘CO2 gas is a nonhydrocarbon gas, with a high economic value and a broad prospect for application. In the Huanghua Depression, there exist many genetic types of CO2 gases, i.e. organic CO2, thermal metamorphic CO2 and crust-mantle mixed CO2. The distribution of different types of CO2 gases is controlled by different factors. Organic CO2 that occurs mainly around the oil-generating center is associated with hydrocarbon gases as a secondary product and commonly far away from large faults. Thermal metamorphic CO2 occurs mainly in areas where carbonate strata are developed and igneous activity is strong, and tends to accumulate near large faults. CO2 of such an origin is higher in concentration than organic CO2, but lower than crust-mantle mixed CO2. Crust-mantle mixed CO2 occurs mainly along large faults. Its distribution is limited, but its purity is the highest.
文摘Natural gases were widely distributed in the Jiyang Depression with complicated component composition, and it is difficult to identify their genesis. Based on investigation of gas composition, carbon isotope ratios, light hydrocarbon properties, as well as geological analysis, natural gases in the Jiyang Depression are classified into two types, one is organic gas and the other is abiogenic gas. Abiogenic gas is mainly magmatogenic or mantlederived CO2. Organic gases are further divided into coaltype gas, oil-type gas, and biogas according to their kero- gen types and formation mechanisms. The oil-type gases are divided into mature oil-type gas （oil-associated gas） and highly mature oil-type gas. The highly mature oil-type gases can be subdivided into oil-cracking gas and kerogen thermal degradation gas. Identification factors for each kind of hydrocarbon gas were summarized. Based on genesis analysis results, the genetic types of gases buried in different depths were discussed. Results showed that shallow gases （〈1,500 m） are mainly mature oil-type gases, biogas, or secondary gases. Secondary gases are rich in methane because of chromatographic separation during migration and secondary biodegradation. Secondary biodegradation leads to richness of heavy carbon isotope ratios in methane and propane. Genesis of middle depth gases （1,500-3,500 m） is dominated by mature oil-type gases.Deep gases （3,500-5,500 m） are mainly kerogen thermal degradation gas, oil-cracking gas, and coal-type gas.
基金supported by the“Académie de Recherche et d’Enseignement Supérieur(ARES)de la Commission de la Coopération au Développement(CUD)”of Belgium for its support to the realization of this work through Research and Development Project(PRD)titled“Professionalisation of swine value chain actors in the Ouémé and Plateau regions,Benin.”
文摘Objective:To characterize the semen of three genetic types of boars(local,improved and Large White)reared in Benin.Methods:Semen of local,improved and Large White boars reared in Benin were collected using the gloved hand method and analyzed to determine volume,pH,concentration,mobility,motility,and morphology.The effect of the genetic type of boar on semen characteristics was aslo studied.Results:Duration of ejaculation and semen volume of Large White boar were significantly higher than those of local and improved boars(P<0.05).The semen of improved boars had a higher motility score than that of Large White and local boars(P<0.001).The semen of local boars was more concentrated in the spermatozoa than that of improved and Large White boars(P<0.05).The proportion of spermatozoa of improved boars with normal morphology(93.6%)was significantly higher than that of local(82.2%)and Large White boars(81.6%)(P<0.001).The proportion of spermatozoa with folded tails in the semen of Large White boars(9.2%)was significantly higher than that observed in improved(1.8%)and local(5.0%)boars(P<0.001).The proportion of spermatozoa with proximal cytoplasmic droplets in semen of improved boars(2.7%)was significantly lower than that in Large White(6.8%)and local(9.7%)boars(P<0.001).The local(1.5%)and Large White boars(1.1%)showed more spermatozoa with distal cytoplasmic droplets in their semen compared to the improved boars(0.4%).Conclusions:The semen characteristics of pigs reared in Benin vary from one genetic type to another.Each genetic type has a strong point.The Large White boar produces larger semen,the local boar produces more concentrated semen and the improved boar produces spermatozoa that are morphologically better.The semen of these three genetic types can be used in artificial insemination but the improved boar's semen is more recommended.
文摘Great volumes of shallow-buried （〈2,000 m） natural gases which are mainly composed of biogases and low-mature gases have been found in the Mesozoic-Cenozoic sedimentary basins in China. Many shallow gas reservoirs in China are characterized by coexistence of biogas and low-mature gas, so identifying the genetic types of shallow gases is important for exploration and development in sedimentary basins. In this paper, we study the gas geochemistry characteristics and distribution in different basins, and classify the shallow gas into two genetic types, biogas and low-mature gas. The biogases are subdivided further into two subtypes by their sources, the source rock-derived biogas and hydrocarbon-derived biogas. Based on the burial history of the source rocks, the source rock-derived biogases are divided into primary and secondary biogas. The former is generated from the source rocks in the primary burial stage, and the latter is from uplifted source rocks or those in a secondary burial stage. In addition, the identifying parameters of each type of shallow gas are given. Based on the analysis above, the distributions of each type of shallow gas are studied. The primary biogases generated from source rocks are mostly distributed in Quaternary basins or modem deltas. Most of them migrate in watersoluble or diffused mode, and their migration distance is short. Reservoir and caprock assemblages play an important role in primary biogas accumulation. The secondary biogases are distributed in a basin with secondary burial history. The oil-degraded biogases are distributed near heavy oil pools. The low-mature gases are widely distributed in shallow-buried reservoirs in the Meso-Cenozoic basins.
基金supported by the Key Project(No.9502010)of the former Chinese Ministry of Geology and Mineral Resources.
文摘A systematic geological and geochemical study was conducted for the granitoids of different periods in the western Kunlun orogenic belt. The study indicates that the granitoids belong to tholeiitic, calc-alkaline, high-K calc-alkaline, alkaline and shoshonitic series, and that there are 5 genetic types, i.e., I-, S-, M-, A- and SH-type, of which SH-type is first put forward in this paper, which corresponds to shoshonitic granitoids.
文摘As a typical Palaeozoic island arc system, the eastern Tianshan area, Xinjiang, is different from eastern China but similar to the Meso-Cenozoic island arc metallogenic provinces along the coast of the Pacific Ocean in metallogenic environment, geology and geochemistry. Three types of gold deposits, ductile shear zone-hosted gold deposits (Kanggur'), magmatic hydrothermal gold deposits (Jinwozi) and volcanic- or subvolcanic-hosted gold deposits (Xitan and Mazhuangshan), have been identified in this area. Regionally, gold deposits are structurally controlled by the Kanggur Tag ductile shear zone, Shaquanzi fault, Hongliuhe fault and Yamansu fault. Generally, gold mineralization occurs in the transition zones from volcanic rocks to sedimentary rocks. The horizon bearing well-developed jasper is an important indicator for gold mineralization. Each of the three types of gold deposits has its distinctive metallogenic background and geological-geochemical characteristics.
基金supported by the National Key Research and Development Plan Program(Grant No. 2016YFC0601005)
文摘The origin and genetic types of natural gas in the Sichuan Basin are still disputed.To classify the origin and genetic types in different areas,the paper analyzes the carbon isotopic composition of gases and geologic features in the Sichuan Basin.The results showed that the gas sourced from terrestrial layers is typically characterized by terrestrial origin and was mainly accumulated nearby to form reservoir.The carbon isotopic composition of gas showed a normal combination sequence distribution,suggesting that natural gas in continental strata is not affected by secondary alteration or that this deformation is very weak.The gas source is singular,and only gas from the southern and northern Sichuan Basin shows the characteristic of mixed sources.However,marine gas presents the characteristics of an oil-formed gas.The carbon isotopic composition of natural gas in the western and central part of the basin mostly distributes in a normal combination sequence,and few of them showed an inversion,indicating that the gas perhaps had not experienced secondary alteration.The carbon isotopic composition of marine-origin gas in the southern,northern and eastern Sichuan Basin displays a completely different distribution pattern,which is probably caused by different mixing ratio of gas with multi-source and multi-period.
基金supported by the National Natural Science Foundation of China(Grant Nos.41930428&U2344205)the Joint Innovation Fund Project of China Uranium Corporation Limited and the State Key Laboratory of Nuclear Resources and Environment,East China University of Science and Technology(Grant No.2022NRE-LH-04)。
文摘Uranium(U)can be enriched in U-polymetallic deposits of various genetic types,with different ore-metal associations including U and many other critical metals.The major U-polymetallic deposits in the world are divided into nine genetic types,i.e.,hydrothermal iron oxide-copper-gold-U type(herein,referred to as IOCG),quartz-pebble conglomerate type,unconformity-related type,alkaline rock-and carbonatite type,metamorphite type,volcanic-and granite-related type,carbonaceous-siliceous-pelitic type(herein,referred to as CSP),phosphate type,and co-basin coexistence type(including U-rich coaland sandstone types).Among them,the first six are the main genetic types,and the last three are collectively referred to as the“Black rock-series type”,all belonging to the unconventional U resource type.Although these U-polymetallic deposits of different genetic types occur in different or specific tectonic settings,they generally exhibit complex metallogenic processes and special ore-forming mechanisms.Besides the involvement of the important geological and biological events occurring during the evolution of the Earth,other various factors differentially acting on U-polymetal mineralization processes are the direct causes controlling the presence of U-polymetals as symbiotic and/or concomitant products,and thereby result in different ore-metal associations in the U-polymetallic deposits of different genetic types.These factors include the differentiation in source regions of U polymetals or lithologies of ore-forming parent rocks,the physicochemical properties of ore-bearing hydrothermal fluids/melts,the geochemical behaviors of different ore-forming elements in the same magmatic-hydrothermal mineral systems,the similarities and differences in complex type and their stability or activity,as well as the mixing of fluids/melts with different redox states,and interaction between oxidizing fluids/melts and reducing substances such as organic matters or fluids/melts-rock interaction.The authors finally point out that there are potential to find U-polymetallic deposits such as the hydrothermal IOCG-,the quartz-pebble conglomerate-,the unconformity-related-,the metamorphite-,and the alkaline rock-and carbonatite types in China.
基金supported by the National Natural Science Foundation of China(Grant Nos.42072172 and 41772120)the Shandong Province Natural Science Fund for Distinguished Young Scholars(No.JQ201311)the Graduate Scientific and Technological Innovation Project Financially Supported by Shandong University of Science and Technology(No.SDKDYC190313).
文摘The Jiyang Depression is an important oil and gas production zone in the Bohai Bay Basin.Through a systematic investigation of the gas components and stable carbon isotopes,the genetic types of natural gas found in the Jiyang Depression were determined,that is,biogas,oilassociated gas,coal-derived gas,high-mature oil-related gas,and mantle-derived carbon dioxide(CO_(2)).From the results,natural gas in the Jiyang Depression can be divided into four groups.Group I,which is distributed in the northwest area,is the only typical oil-associated gas.Group II,distributed in the northeast area,is dominated by oil-associated gas,and involves biogas,coal-derived gas,and high-mature oil-related gas.Group Ⅲ,distributed in the southeast area,has all genetic types of gas that are dominated by oil-associated gas and have mantle-derived CO_(2).Group IV,distributed in the southwest area,is dominated by biogas and involves coal-derived gas and oil-associated gas.The differences in each group illustrate the lateral distribution of the natural gas types is characterized by the eastern and southern areas being more complex than the western and northern areas,the vertical distribution of gas reservoirs has no obvious evolutionary law.The main controlling factor analysis of the spatiotemporal changes of the gas reservoirs revealed that the synergy of geochemical characteristics,thermal evolution of the Shahejie Formation and Carboniferous-Permian source rocks,and sealing properties of various faults are jointly responsible for determining the gas reservoir spatiotemporal changes.
基金supported by the National Natural Science Foundation of China(Grant No.41903013)university—enterprise cooperation projects(041021090118)the Hubei Key Laboratory of Petroleum Geochemistry and Environment at Yangtze University(Grant No.HKLPGE-202308).
文摘Despite its significant exploration potential,the origin of natural gas in the tectonically complex southwestern Tarim Basin remains controversial due to multiple potential source rocks.This study identifies the genetic types and sources of natural gas by integrating gas molecular and isotopic compositions with the geochemical characteristics of potential source rocks.The results indicate that the Kekeya gas field mainly contains coal-derived gas sourced from the Permian Pusige Formation,whereas the Akemomu field and the QT-1 well contain highly overmature gas from the Permian Qipan Formation with some mantle-derived He and inorganic CO_(2).Furthermore,the oil-associated gas in the FS-8 well originates from Permian sapropelic source rocks,while the KS-6 well contains a mixed,oil-associated gas predominantly sourced from the Jurassic Yangye Formation.These findings reveal a complex gas accumulation scenario with multiple genetic types and sources in the southwestern Tarim Basin,providing critical insights for future exploration.
文摘Type 1 diabetes(T1D)is an autoimmune disease that usually strikes early in life,but can affect individuals at almost any age.It is caused by autoreactive T cells that destroy insulin-producing beta cells in the pancreas.Epidemiological studies estimate a prevalence of 1 in 300 children in the United States with an increasing incidence of 2%-5%annually worldwide.The daily responsibility,clinical management,and vigilance required to maintain blood sugar levels within normal range and avoid acute complications(hypoglycemic episodes and diabetic ketoacidosis)and long term micro-and macro-vascular complications significantly affects quality of life and public health care costs.Given the expansive impact of T1D,research work has accelerated and T1D has been intensively investigated with the focus to better understand,manage and cure this condition.Many advances have been made in the past decades in this regard,but key questions remain as to why certain people develop T1D,but not others,with the glaring example of discordant disease incidence among monozygotic twins.In this review,we discuss the field’s current understanding of its pathophysiology and the role of genetics and environment on the development of T1D.We examine the potential implications of these findings with an emphasis on T1D inheritance patterns,twin studies,and disease prevention.Through a better understanding of this process,interventions can be developed to prevent or halt it at early stages.
文摘Charcot-Marie-Tooth （CMT） disease is the most common hereditary neuropathy, with a population prevalence of 1 in 2500. CMT disease type 1A （CMT1A）, accounting for ~70% of CMT1 cases and ~ 50% of all CMT cases, is transmitted in an autosomal dominant manner. CMT1A maps to chromo- some 17pl 1.2 and is caused, in the majority of cases, by a 1.4- Mb tandem duplication that includes the peripheral myelin protein22 （PMP22） gene （Li et al., 2013）. The disease usually presents in the first 20 years of age, causing difficulty in walking or running, distal symmetrical muscle weakness and wasting, and sensory loss （van Paassen et al., 2014）.
文摘The highest-level interference essence against virus and turnour genetic engineering medicine is a new type created in the 1980s. Compared with chemical medicines, the interference essence has a special effect in the treatment of viruses and tumours. The human a, type genetic engineering interference essense is prepared by the Institute of Viruses of the Chinese Academy of Preventive Medical Sciences, the Shanghai Vaccine
文摘BACKGROUND Dystrophic epidermolysis bullosa is characterized by fragile ulcerations of the skin caused by mutations in specific genes.However,genetic typing of this con-dition is rare.CASE SUMMARY An 11-year-old female suffered from recurrent fever,visible ulcerations of the entire skin,and severe malnutrition.Genetic testing revealed a frameshift mu-tation in the coding region 4047 of the 35th intron region of COL7A1,and she was diagnosed as malnutrition-type epidermolysis bullosa.Drug therapy(immu-noglobulin,fresh frozen plasma),topical therapy(silver ion dressing),fever redu-ction,cough relief,and promotion of gastrointestinal peristalsis are mainly used for respiratory and gastrointestinal complications.The patient’s condition impro-ved after treatment.CONCLUSION Dystrophic epidermolysis bullosa caused by a new framework shift mutation in COL7A1 should be taken seriously.
基金This research was jointly supported by the National Key R&D Program of China(Nos.2018YFC0603801 and 2018YFC0604004)National Natural Science Foundation of China(Nos.41903042 and 41530206)+1 种基金China Postdoctoral Science Foundation(Nos.2016LH0003 and 2017M610984)open fund of the Key Lab of Mineralogy and Metallogeny,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences(No.KLMM20170202).
文摘The northern Xinjiang region is one of the most significant iron metallogenic provinces in China.Iron deposits are found mainly within three regions:the Altay,western Tianshan,and eastern Tianshan orogenic belts.Previous studies have elaborated on the genesis of Fe deposits in the Altay orogenic belt and western Tianshan.However,the geological characteristics and mineralization history of iron deposits in the eastern Tianshan are still poorly understood.In this paper I describe the geological characteristics of iron deposits in the eastern Tianshan,and discuss their genetic types as well as metallogenic-tectonic settings,Iron deposits are preferentially distributed in central and southern parts of the eastern Tianshan.The known iron deposits in the eastern Tianshan show characteristics of magmatic Fe-Ti-V(e.g.,Weiya and Niumaoquan),sedimentary-metamorphic type(e.g.,Tianhu),and iron skarn(e.g.,Hongyuntan).In addition to the abovementioned iron deposits,many iron deposits in the eastern Tianshan are hosted in submarine volcanic rocks with well-developed skarn mineral assemblages.Their geological characteristics and magnetite compositions suggest that they may belong to distal skarns.SIMS zircon U-Pb analyses suggest that the Fe-Ti oxide ores from Niumaoquan and Weiya deposits were formed at 307.7±1.3 Ma and 242.7±1.9 Ma,respectively.Combined with available isotopic age data,the timing of Fe mineralization in the eastern Tianshan can be divided into four broad intervals:Early Ordovician-Early Silurian(476-438 Ma),Carboniferous(335-303 Ma),Early Permian(295-282 Ma),and Triassic(ca.243 Ma).Each of these episodes corresponds to a period of subduction,post-collision,and intraplate tectonics during the Paleozoic and Mesozoic time.
基金supported by NSFC (Grant No. 41202100)the National Science and Technology Major Projects(Grant No. 2008ZX05007-003)
文摘In order to distinguish the source and migration direction of natural gas by geochemical characteristics of butane,the components and carbon isotopes of natural gas from major hydrocarbonbearing basins in China were analyzed.The results showed that：（1） Oil-type gas has i-C 4 /n-C 4 0.8,δ 13 C butane -28‰,δ 13 C i-butane -27‰,δ 13 C n-butane -28.5‰,whereas coal-type gas has i-C 4 /n-C 4 0.8,δ 13 C butane -25.5‰,δ 13 C i-butane -24‰,δ 13 C n-butane -26‰.（2） When δ 13 C i-butane-δ 13 C n-butane is greater than 0,the maturity of oil-type gas is generally more than 2.4% and that of coal-type gas is greater than 1.4%,whereas when the difference is less than 0,the maturity of oil-type gas is generally less than 1.1% and that of coal-type gas is less than 0.8%.（3） When natural gas migrates through dense cap rocks,the value of i-C 4 /n-C 4 increases,whereas when it migrates laterally along a reservoir,the value of i-C 4 /n-C 4 decreases.（4） Sapropelic transition zone gas with composition and carbon isotopic signatures similar to those of oil-type gas in the low thermal evolution stage is found to have a relatively high butane content.（5） The values of i-C 4 /n-C 4 and δ 13 C n-butane δ 13 C i-butane of gas which has suffered biological degradation are significantly higher than those obtained from thermogenic and bio-thermocatalytic transition zone gas.Thus,natural gas of different genetic types can be recognized through component analysis and carbon isotopic signatures of butane,the natural gas maturity can be estimated from the difference in carbon isotopic content between isobutane and n-butane,and the migration direction of natural gas can be determined from i-C 4 /n-C 4 ratios and transport conditions,which can also be used to thermogenic and bio-thermocatalytic transition zone gas.
基金supported by the National Basic Research Program of China(Grant No. 2007CB209503)
文摘It is significant to distinguish the dynamic systems of petroleum accumulation （DSPA） for the understanding of petroleum accumulation and distribution. According to the formation pressure framework, genetic types of petroleum and characteristics of conduit systems, three dynamic systems of petroleum accumulation were identified in the vertical profile in the Nanpu depression, Bohai Bay basin. The deeper DSPA （including formations Es3 to Es2） is a sealed system with high-overpressure and high-mature self-sourced oil. Most of the crude oil in the system accumulated in the periods of late Oligocene （23.5 Ma） and late Pliocene （2.4 Ma）. The middle DSPA （including formations Es~ to Edl） is an overpressured half-sealed system with mature or lower-mature self-sourced oil. The accumulation of oil in the system also occurred in the late Oligocene （23.5 Ma） and late Pliocene （2.4 Ma）. The shallower DSPA （including formations Ed2 to Q） is a hydrostatic system with lower-mature aliensourced oil from the middle system. Oil within this system accumulated only in the late Pliocene period. The oil in the shallower system migrated vertically along the faults from the formerly accumulated oil in the middle system by lateral migration along the sandbodies, whereas petroleum accumulation in the deeper system was mainly derived from the system itself by lateral migration along the sandbodies and rarely migrated out of the system. In this case, it seems that the deeper system is a more potential exploration prospect in addition to the other two proved favorable systems.
基金supported by National Basic Research Program of China (2009CB219600), State Key Laboratory of Petroleum Resource and Prospecting, Key Laboratory of Basin Structure and Hydrocarbon Accumulation of CNPC
文摘Coalbed methane （CBM） is an important type of unconventional gas. Commercial development of CBM in America has been very successful since the 1980s. The CBM industry in Australia and Canada has developed rapidly during the last decade. Commercial development of CBM in China started in the 1990s, and has made great progress. The geological theory of CBM in China has achieved great advancement in genesis, occurrence and accumulation. On the aspect of CBM genesis, five CBM genetic types （primary biogenic gas, secondary biogenic gas, thermal degradation gas, pyrolysis gas and mixed gas） are identified by studying the geochemical characteristics of CBM, and a tracing indicator system is established. The discovery of secondary biogenic gas in medium-high rank coal reservoirs has widened the potential of CBM resources. On the aspect of CBM occurrence, the gas adsorption regulation under combined action of temperature and pressure is revealed by conducting adsorption experiments of different coal ranks under varying temperature and pressure conditions. Besides, by applying the adsorption potential theory in CBM research, the adsorption model under combined action of temperature and pressure is established. The new model can predict CBM resources accurately, and overcome the limitation of the traditional Langmuir model which uses just a single factor to describe the adsorption characteristics of deep buried coal. On the aspect of CBM accumulation, it is proposed that there are three evolutionary stages during CBM accumulation, including gas generation and adsorption, unsaturated gas adsorption, gas desorption-diffusion and preservation. Controlled by tectonic evolution, hydrodynamics and sealing conditions, CBM tends to be regionally enriched in synclines. Advances in geological theory of CBM in China can not only improve understanding of natural gas, but also provide new ideas for further exploration of CBM.
