Petroleum was generated from sedimentary rocks. The world＇s oldest oil source rock so far was found in Proterozoic rocks. Since then, 73% to 81% of the earth＇s surface has been covered with sedimentary rocks. Howeve...Petroleum was generated from sedimentary rocks. The world＇s oldest oil source rock so far was found in Proterozoic rocks. Since then, 73% to 81% of the earth＇s surface has been covered with sedimentary rocks. However, only quite a limited area is rich in oil and gas. It is found that source rocks have controlled oil and gas distribution, and they are mainly formed in two systems： （1） river-lake systems and （2） river-gulf systems. Phytoplankton is an important source of kerogen, the blooming of which is strongly dependent on nutrients. Rivers are the major nutrient provider for basins. Rivers around lakes and an undercompensation （where the sedimentation rate is less than the rate of basin subsidence） environment provide favorable conditions for phytoplankton blooming in lakes. Gulfs are usually located at the estuary of big rivers, characterized by restricted current circulation and exchange with the open sea, which benefit maintaining the nutrient density, phytoplankton levels and organic matter preservation. The river-gulf system is the most favorable place for marine source rock development. Most of the world famous marine petroleum-rich provinces are developed from river-gulf systems in geological history, such as the Persian Gulf Basin, Siberian Basin, Caspian Basin, North Sea, Sirte Basin, Nigerian Basin, Kwanza Basin, Gulf of Mexico, Maracaibo Basin and the Eastern Venezuelan Basin.展开更多
High quality marine source rock （HQMSR） is the key prerequisite for medium to large hydrocarbon accumulations. However, the forming mechanism remains unclear. On the basis of the in-vestigation for the geodynamic se...High quality marine source rock （HQMSR） is the key prerequisite for medium to large hydrocarbon accumulations. However, the forming mechanism remains unclear. On the basis of the in-vestigation for the geodynamic setting of the Middle-Upper Yangtze during the Early Cambrian in dif-ferent spatial scales and the analysis of trace elements, the main controlling factors of the development of high quality marine source rock are discussed, with specific consideration of the burial rate of the organic matter. The formation of high quality marine source rocks is suggested to be the result of a co-ordinated development and the interaction between geological environments and organism evolution during the major geological transition periods. We perceived that the burial rate of organic matter was influenced by the primary productivity and its burial conditions. The abundance of autogenetic molyb-denum gained directly by the chemical speciation analysis of rocks could be used as a proxy for the burial organic matter. The burial rate of autogenetic molybdenum and the sedimentary organics in modern marine environments could be used to estimate the sedimentary organics in ancient environ-ments effectively.展开更多
This study evaluated the hydrocarbon-bearing potential of Upper Jurassic marine source rocks in the Qiangtang （羌塘） Basin through a comprehensive organic geochemical analysis of the samples from a large number of o...This study evaluated the hydrocarbon-bearing potential of Upper Jurassic marine source rocks in the Qiangtang （羌塘） Basin through a comprehensive organic geochemical analysis of the samples from a large number of outcrops in different structural units to predict the location of favorable hydro- carbon kitchens, based on the evaluation standards of Mesozoic marine source rocks in the Qiangtang Ba- sin. Rocks＇ depositional environment, thickness and organic geochemistry feature were analyzed in this study. The principal controlling factors of the occurrences of favorable source rocks were analyzed. Upper Jurassic Suowa （索瓦） Formation source rocks are mainly platform limestone in the Dongcuo （洞错）-Hulu （葫芦） Lake deep sag and Tupocuo （吐坡错）-Baitan （白滩） Lake deep sag. Lithologically, the Suowa Fro- mation is made up of a suite of marls in intra-platform sags, micrites and black shales, which were all de- posited in the closed, deep and static water depositional environment. Marl could form hydrocarbon-rich source rocks and its organic matter type is mainly II type in mature to highly-mature stage, the limestone forms a medium-level source rock. In addition, the favorable source kitchen of limestone is larger than that of mudstone. This study provides an important reference for the evaluation of Jurassic marine source rocks and for prediction of petroleum resources in the Qiangtang Basin.展开更多
Based on the results of conventional geochemistry analysis including thin sections and SEM observations, different shapes of bacterial fossils, with size ranging from dozens of nanometers to several microns, were disc...Based on the results of conventional geochemistry analysis including thin sections and SEM observations, different shapes of bacterial fossils, with size ranging from dozens of nanometers to several microns, were discovered in the low-mature marine source rocks and coal seams in South China, of which the Permian source rocks were dominated by the bacterial fossils derived from symbiotic sulphur bacteria with gypsum, and the Chengkou section in the Cambrian strata were occupied by abundant nanoscale bacterial fossils with rod and bar shapes. In contrast, a large quantity of possible bacterial fossils found in the high-mature Permian, Silurian, and Cambrian source rocks using SEM need to be further explored. Despite this,this study has indicated that bacterial fossils were prevalent in the source rocks, such as mudstone, siliceous rock and gypsum-bearing coal seams in South China, which has been ignored before. It also suggests that the bacterial fossils may play an important role in the formation and accumulation of shale gas in the geological history.展开更多
Drilling wells reveal that the organic matter abundance of Miocene marine source rocks in shallow water area of the Qiongdongnan Basin is relatively low with poor hydrocarbon generation poten- tial. However, in some d...Drilling wells reveal that the organic matter abundance of Miocene marine source rocks in shallow water area of the Qiongdongnan Basin is relatively low with poor hydrocarbon generation poten- tial. However, in some drilling wells of deep water area close to the central depression belt, Miocene marine source rocks with better organic matter abundance and hydrocarbon generation have been found, which have achieved better source rock standard based on the analysis of geochemical charac- teristics. Although there are no exploratory wells in deep water area of the research region, through the comparative analysis of geochemical data of several typical exploratory wells respectively from shallow water area in the basin, central depression belt margin in deep-water area of the basin and Site 1148 of deep sea drilling in the South China Sea Basin, it reveals that the tendency of the quality of source rocks becomes positive gradually from delta to bathyal environment, which then becomes negative as in deep oceanic environment. Owing to the lack of terrestrial organic matter input, the important controlling factors of Miocene marine source rocks in the Qiongdongnan Basin are ocean productivity and preservation conditions of organic matter. The element geochemistry data indicate that the tendency of the paleoproductivity and the preservation conditions of organic matter become positive as water depth increase from shallow area to bathyal area close to central depression belt. So it is speculated that there must exist high quality source rocks in the central depression area where the preservation conditions of organic matter are much better. Besides, in theory, in oxygen-poor zone of oceanic environment at the water depth 400–1 000 m, the preservation conditions of organic matter are well thus forming high-quality marine source rocks. The result- ing speculation, it is reasonable to consider that there are high hydrocarbon generation potential source rocks in bathyal environment of the Qiongdongnan Basin, especially at the water depth 400– 1 000 m.展开更多
Offshore carbon dioxide(CO_(2)) storage is an effective method for reducing greenhouse gas emissions. However, when using traditional seismic wave methods to monitor the migration of sequestration CO_(2) plumes, the c...Offshore carbon dioxide(CO_(2)) storage is an effective method for reducing greenhouse gas emissions. However, when using traditional seismic wave methods to monitor the migration of sequestration CO_(2) plumes, the characteristics of wave velocity changes tend to become insignificant beyond a certain limit. In contrast, the controllable source electromagnetic method(CSEM) remains highly sensitive to resistivity changes. By simulating different CO_(2) plume migration conditions, we established the relevant models and calculated the corresponding electric field response characteristic curves, allowing us to analyze the CSEM's ability to monitor CO_(2) plumes. We considered potential scenarios for the migration and diffusion of offshore CO_(2) storage, including various burial depths, vertical extension diffusion, lateral extension diffusion,multiple combinations of lateral intervals, and electric field components. We also obtained differences in resistivity inversion imaging obtained by CSEM to evaluate its feasibility in monitoring and to analyze all the electric field(Ex, Ey, and Ez) response characteristics. CSEM has great potential in monitoring CO_(2) plume migration in offshore saltwater reservoirs due to its high sensitivity and accuracy. Furthermore, changes in electromagnetic field response reflect the transport status of CO_(2) plumes, providing an important basis for monitoring and evaluating CO_(2)transport behavior during storage processes.展开更多
The Tarim Basin is the only petroliferous basin enriched with marine oil and gas in China.It is presently also the deepest basin for petroleum exploration and development in the world.There are two main sets of marine...The Tarim Basin is the only petroliferous basin enriched with marine oil and gas in China.It is presently also the deepest basin for petroleum exploration and development in the world.There are two main sets of marine Source Rocks(SRs)in the Tarim Basin,namely the high over-mature Cambrian-Lower Ordovician(∈-O_(1))and the moderately mature Middle-Upper Ordovician(O_(2-3)).The characteristic biomarkers of SRs and oils indicate that the main origin of the marine petroleum is a mixed source of∈-O_(1) and O_(2-3) SRs.With increasing burial,the hydrocarbon contribution of the∈-O_(1) SRs gradually increases.Accompanied by the superposition of multi-stage hydrocarbon-generation of the SRs and various secondary alteration processes,the emergence and abnormal enrichment of terpenoids,thiophene and trimethylaryl isoprenoid in deep reservoirs indicate a complex genesis of various deep oils and gases.Through the analysis of the biofacies and sedimentary environments of the∈-O_(1) and O_(2-3) SRs,it is shown that the lower Paleozoic high-quality SRs in the Tarim Basin were mainly deposited in a passive continental margin and the gentle slope of the platform,deep-water shelf and slope facies,which has exhibited a good response to the local tectonic-sedimentary environment.The slope of the paleo-uplift is the mutual area for the development of carbonate reservoirs and the deposition of marine SRs,which would be favorable for the accumulation of petroleum.Due to the characteristics of low ground temperature,the latest rapid and deep burial does not cause massive oil-cracking in the paleo-uplift and slope area.Therefore,it is speculated that the marine reservoirs in the slope of the Tabei Uplift are likely to be a favorable area for deep petroleum exploration,while the oilcracking gas would be a potential reserve around the west margin of the Manjiaer Depression.Hydrocarbons were generated from various unit SRs,mainly migrating along the lateral unconformities or reservoirs and the vertical faults.They eventually brought up three major types of exploration fields:middle and lower Cambrian salt-related assemblages,dolomite inner reservoirs and Middle and Lower Ordovician oil-bearing karst,which would become the most favorable target of marine ultra-deep exploration in the Tarim Basin.展开更多
Marine aerosols over the East China Seas are heavily polluted by continental sources. During the Chinese Comprehensive Ocean Experiment in November 2012, size and mass spectra of individual atmospheric particles in th...Marine aerosols over the East China Seas are heavily polluted by continental sources. During the Chinese Comprehensive Ocean Experiment in November 2012, size and mass spectra of individual atmospheric particles in the size range from 0.2 to 2.0 μm were measured on board by a single particle aerosol mass spectrometer （SPAMS）. The average hourly particle number （PN） was around 4560 ＋ 3240 in the South Yellow Sea （SYS）, 2900 ± 3970 in the North Yellow Sea （NYS）, and 1700 ± 2220 in the Bohai Sea （BS）. PN in NYS and BS varied greatly over 3 orders of magnitude, while that in SYS varied shghtly. The size distributions were fitted with two log-normal modes. Accumulation mode dominated in NYS and BS, especially during episodic periods. Coarse mode particles played an important role in SYS. Particles were dassifled using an adaptive resonance theory based neural network algorithm （ART-2a）. Six particle types were identified with secondary-containing, aged sea-salt, soot-like, biomass burning, fresh sea-salt, and lead-containing particles accounting for 32%, 21%, 18%, 16%, 4%, and 3% of total PN, respectively. Aerosols in BS were relatively enriched in particles from anthropogenic sources compared to SYS, probably due to emissions from more developed upwind regions and indicating stronger influence of continental outflow on marine environment. Variation of source types depended mainly on origins of transported air masses. This study examined rapid changes in PN, size distribution and source types of fine particles in marine atmospheres. It also demonstrated the effectiveness of hi,h-time-resolution source apportionment by ART-2a.展开更多
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 mat...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.展开更多
A complete Permian section in Guangyuan （广元）, Northeast Sichuan （四川）, has been investigated, to explore the variation in organic matter richness and its main controlling factors. The research results of the de...A complete Permian section in Guangyuan （广元）, Northeast Sichuan （四川）, has been investigated, to explore the variation in organic matter richness and its main controlling factors. The research results of the detailed lithological description and organic/inorganic geochemical analysis of about 325 samples indicate that a high content of total organic carbon （TOC） occurs in calcareous mudstones and laminated marls or thin-bedded limestones. In carbonate rocks, the TOC content is negatively related to the thickness of the massive beds; the thinner the bed is, the higher the TOC content is. Marine organic matter is enriched in the outer shelf and relatively shallow basin floor environments with the maximum TOC contents of 5.07% and 14.6%, respectively. The main factors that affect the quantity and quality of marine organic matter include primary productivity, depositional processes, and redox conditions during deposition and the early diagenesis stage. Three intervals of marine good quality source rocks are identified in this section; they are lower Chihsia Formation, topmost Maokou （茅口） Formation, and the middle segment of the Dalong （大隆） Formation. They are formed in anoxic environments, in association with high primary productivity. Among these, high productivity in the lower Chihsia interval may originate from an upwelling flow area, whereas, in the rest of the intervals, it is inferred to be related to hot fluid activity due to volcanic eruption. The results of this study suggest that good quality marine source rocks in the Permian strata offer significant hydrocarbon potential.展开更多
Based on drilling cores, well logging and seismic data, source rocks and reservoirs are evaluated;and the natural gas genesis is identified through the analysis of natural gas isotopes, components and fluid inclusions...Based on drilling cores, well logging and seismic data, source rocks and reservoirs are evaluated;and the natural gas genesis is identified through the analysis of natural gas isotopes, components and fluid inclusions, to study the gas accumulation conditions of the gypsum salt rock related strata of the Ordovician lower assemblage in Ordos Basin.(1) The natural gas from Ordovician lower assemblage is high thermal evolution dry gas from marine source rock, characterized by relatively light δ^(13)C value of methane and heavy δ^(13)C value of ethane. The natural gas is identified as gas cracking from crude oil according to component analysis. Thermochemical sulfate reduction(TSR) reaction has happened between the hydrocarbon fluid and sulfate as sulfur crystals are found in the cores, hydrogen sulfide is found in the natural gas, and hydrocarbon and hydrogen sulfide fluid inclusions are widespread in secondary minerals.(2) Around the gypsum-salt lows, argillaceous rocks are extensive in the Ordovician lower assemblage, reaching a cumulative thickness of 20–80 m. The effective source rocks include argillaceous rock rich in organic laminae, algal clump and algal dolomite. Analysis shows that the source rocks have a dominant TOC of 0.1%–0.5%, 0.31% on average and 3.24% at maximum. The source rocks have an average TOC of 0.58% after recovered through organic acid salt method, indicating the source rocks have high hydrocarbon supply potential.(3) In the sedimentary period, the palaeo-uplift controlled the distribution of reservoirs. The inherited secondary palaeo-uplift in Wushenqi–Jingbian east of the central palaeo-uplift and the low uplift formed by thick salt rocks near Shenmu–Zizhou area controlled the distribution of penecontemporaneous grain shoal dolomite reservoirs. The salinization sedimentary environment of gypsum salt rock can promote the development of reservoir. There are three types of dolomite reservoirs, the one with intercrystalline pore, with dissolution pore, and with fracture;intercrystalline and dissolution pores are main reservoir spaces.(4) There are two types of cap rocks, namely tight carbonate rock and gypsum-salt rock, constituting two types of source-reservoir-cap assemblages respectively. The general accumulation model is characterized by marine source rock supplying hydrocarbon, beach facies limy dolomite reservoir, small fractures acting as migration pathways, and structural-lithologic traps as accumulation zones.(5) The third and fourth members of Majiagou Formation are major target layers in the lower assemblage. The Wushengqi–Jingbian secondary paleo-uplift area and Shenmu–Zizhou low uplift are dolomite and limestone transition zone, there develops tight limestone to the east of the uplift zone, which is conducive to the formation of gas reservoir sealed by lithology in the updip. Two risk exploration wells drilled recently have encouraging results, indicating that the two uplift zones are important prospects.展开更多
The gas sources in the eastern Cote d’Ivoire Basin(Tano Basin)are seldom reported and remain controversial due to multiple sets of potential source rocks and poorly documented geochemical characteristics of natural g...The gas sources in the eastern Cote d’Ivoire Basin(Tano Basin)are seldom reported and remain controversial due to multiple sets of potential source rocks and poorly documented geochemical characteristics of natural gases.The marine source rock potential from the Upper Albian to Turonian as well as the molecular composition and the stable carbon isotope composition of natural gases in the eastern Cote d’Ivoire Basin were studied in detail to investigate the origins of natural gases.The total organic carbon(TOC),hydrogen index(HI),and generation potential(S_(1)+S_(2))of source rocks indicate that both sapropelic source rocks and humic source rocks developed during the late Albian,whereas sapropelic source rocks developed during the Cenomanian and the Turonian.The normal order ofδ^(13)CH_(4)<δ^(13)C_(2)H6<δ^(13)C_(3)H_(8)(δ^(13)C_(1)<δ^(13)C_(2)<δ^(13)C_(3)),the relationship between C_(2)/C_(3)molar ratio andδ^(13)C_(2)-δ^(13)C_(3),and the plot ofδ^(13)C_(1)versus C_(1)/(C_(2)+C_(3))collectively show that the natural gases are thermogenic due to the primary cracking of kerogen,including the typical oil-associated gases from Well D-1,the mixed oil-associated gases and coal-derived gases from Well G-1 and Well L-1.Based on the plot ofδ^(13)C_(1)versusδ^(13)C_(2)and the established relationship betweenδ^(13)C_(1)and equivalent vitrinite reflectance(Ro),we proposed that the natural gases are in a mature stage(Ro generally varies from 1.0%to 1.3%).Combined with results of basin modelling and oil-to-source correlation,the transitional to marine source rocks during the late Albian were thought to have made a great contribution to the natural gases.Our study will make a better understanding on petroleum system in the eastern Cote d’Ivoire Basin.展开更多
Coal-type source rocks include both coal and terrigenous marine source rocks.By studying the distribution of secondary depressions,uplifts,as well as the characteristics of peat formation and accumulation in the north...Coal-type source rocks include both coal and terrigenous marine source rocks.By studying the distribution of secondary depressions,uplifts,as well as the characteristics of peat formation and accumulation in the northern marginal sea basin of the South China Sea,and combining them with coal formation characteristics observed in other basins,five genetic theories on the relationship between peat accumulation and dispersed organic matter accumulation are proposed.The northern marginal sea basin of the South China Sea is characterized by“disadvantageous coals formation and favorable terrigenous marine source rocks formation.”This paper provides a distribution map of coal seams and terrigenous marine source rocks in the Qiongdongnan Basin and determines their distribution patterns.Research shows that the migration of sedimentary facies in the basins and inner depressions led to the formation and migration of the peat accumulation centers.In addition,the vertical migration of the peat accumulation centers led to planar migration,which is actually a type of coupling relationship.Previous research results have revealed that the formation of coal-type source rock is multi-phased.The marginal sea basin is composed of several fault-depression basins,with each basin developing a second order of depression and uplift.There is no unified basin center or depositional center to be found.As a result,the concentration centers of coal-forming materials also vary greatly.Based on the distribution characteristics of coal-type source rocks in different basins within the marginal sea basins of the South China Sea,the research results have practical significance and provide guidance for exploring coal-type oil and gas reservoirs in this area.展开更多
Oligocene(fan)delta-associated coal measures and marine source rocks are the main gas-generating source rocks in the Qiongdongnan Basin,and(fan)delta sand bodies are the dominant types of reservoirs.By comprehensively...Oligocene(fan)delta-associated coal measures and marine source rocks are the main gas-generating source rocks in the Qiongdongnan Basin,and(fan)delta sand bodies are the dominant types of reservoirs.By comprehensively utilizing a large amount of 2D and 3D seismic data and new drilling data,the distribution of(fan)deltas and three types of Oligocene fault fan systems were systematically identified;these are thought to have had joint control over the development of hydrocarbon source rocks and reservoirs.The three types of Oligocene fault fan coupling relationships in the Qiongdongnan Basin were found to be fault bend,fault gully,and fault tip.The fault bend type of(fan)delta developed at the bend of the fault and was distributed in the downthrown block of Fault Nos.5 and 2.The fault tip type developed where the fault died out toward the source direction and was distributed near the eastewest faults on the north and south sides of Baodao and Changchang Sags.The fault gully type developed along the fault trend in the downthrown block and was mainly distributed in areas including the northern part of Ya'nan Sag and the Fault No.3 downthrown block.The fault bend(fan)delta is surrounded by a relatively closed bay environment,and the terrigenously dominated marine source rocks in the still water bay environment were developed with a high hydrocarbon generation index and high hydrocarbon generation potential.Fault tip and fault gully types of(fan)delta plain facies have a wide distribution of plain subfacies,which is conducive to the development of coal-measure source rocks that have excellent gas potential.During sedimentation of the fault gully and the fault tip delta,the terrain was relatively flat,with sand bodies strongly reworked by hydrodynamic force;the reservoir quality of the sand bodies in the underwater distributary channel and estuary dam are good,and the sand bodies have wide distribution.The sand bodies of the fault bend type of(fan)delta were deposited rapidly near the source kitchen,and the degree of sorting and rounding was poor,which resulted in the poor physical properties of the plain subfacies.In the southern and northern step-fault zones of Baodao Sag in the eastern part of this basin,the fault bend,fault tip,and fault trench(fan)deltas were inherited and further developed,and the source-reservoir configuration conditions were favorable.Exploration deployment was carried out in the Baodao 21 area in the northern step-fault zone and the Yongle 10 area in the southern step-fault zone,where new discoveries in natural gas exploration have been realized.In the eastern part of this basin,the fault bend,fault tip,and fault gully(fan)deltas in the southern and northern fault step zones of Baodao Sag were successively developed,which were beneficial for favorable sourceereservoir configuration conditions.The natural gas exploration successes in the Baodao-21 area in the northern fault step zone and the Yongle-10 area in the southern fault step zone are beneficial for new discoveries in natural gas exploration in the Qiongdongnan Basin.展开更多
Since the discovery of the Tahe oilfield, it has been controversial on whether the main source rock is in the Cambrian or Middle-Upper Ordovician strata. In this paper, it is assumed that the crude oil from the Wells ...Since the discovery of the Tahe oilfield, it has been controversial on whether the main source rock is in the Cambrian or Middle-Upper Ordovician strata. In this paper, it is assumed that the crude oil from the Wells YM 2 and TD 2 was derived from the Middle-Upper Ordovician and Cambrian source rocks, respectively. We analyzed the biomarkers of the crude oil, asphalt-adsorbed hydrocarbon and saturated hydrocarbon in bitumen inclusions from the Lunnan and Hade areas in the North Uplift of the Tarim Basin. Results show that the ratios of tricyclic terpane C2~/C23 in the crude oil, asphalt-adsorbed hydrocarbon and saturated hydrocarbon in bitumen inclusions are less than 1.0, indicating that they might be from Upper Ordovician source rocks; the ratios of C28/（C27＋C28＋C29） steranes in the saturated hydrocarbon from reservoir bitumen and bitumen inclusions are higher than 25, suggesting that they might come from the Cambrian source rocks, however, the ratios of C28/（C27＋C28＋C29） steranes in oil from the North Uplift are less than 25, suggesting that they might be sourced from the Upper Ordovician source rocks. These findings demonstrate that the sources of crude oil in the Tarim Basin are complicated. The chemical composition and carbon isotopes of Ordovician reservoired oil in the Tarim Basin indicated that the crude oil in the North Uplift （including the Tahe oilfield） and Tazhong Depression was within mixture areas of crude oil from the Wells YM 2 and TD 2 as the end members of the Cambrian and Middle-Upper Ordovician sourced oils, respectively. This observation suggests that the crude oil in the Ordovician strata is a mixture of oils from the Cambrian and Ordovician source rocks, with increasing contribution from the Cambrian source rocks from the southern slope of the North Uplift to northern slope of the Central Uplift of the Tarim Basin. Considering the lithology and sedimentary facies data, the spatial distribution of the Cambrian, Middle-Lower Ordovician and Upper Ordovician source rocks was reconstructed on the basis of seismic reflection characteristics, and high-quality source rocks were revealed to be mainly located in the slope belt of the basin and were longitudinally developed over the maximum flooding surface during the progressive-regressive cycle. Affected by the transformation of the tectonic framework in the basin, the overlays of source rocks in different regions are different and the distribution of oil and gas was determined by the initial basin sedimentary structure and later reformation process. The northern slope of the Central Uplift-Shuntuo-Gucheng areas would be a recent important target for oil and gas exploration, since they have been near the slope area for a long time.展开更多
Objective:To investigate antibiotics and heavy metals resistance profile of Aeromonas species isolated from Kuala Gula and Kuala Sepetang,Perak.Methods:Isolated Aeromonas species were subjected to 12 antibiotics:penic...Objective:To investigate antibiotics and heavy metals resistance profile of Aeromonas species isolated from Kuala Gula and Kuala Sepetang,Perak.Methods:Isolated Aeromonas species were subjected to 12 antibiotics:penicillin G 10 units,tetracycline 30μg,novobiocin 5μg,nitrofurantoin 100μg,ampicillin 10μg,chloramphenicol 10μg,fluconazole 25μg,gentamicin 10μg,streptomycin 10μg and 25μg,kanamycin 30μg,and vancomycin 30μg and 5 heavy metals:MnSO_(4).H_(2)O,Cr(NO_(3)).9H2O,CuSO_(4),Pb(NO_(3))_(2),HgCl_(2).Results:Results from this study revealed that isolates from the two sources-displayed varied resistance.Isolates from Kuala Sepetang showed 91%,66%,61%,and 52%resistance to vancomycin,Novobiocin,streptomycin and gentamycin while Kuala Gula isolates showed 76%,93%,28%and 14%respectively.High rate of resistance was shown to be against lead(Pb),Chromium(Cr),copper(Cu)and Manganese(Mn)with minimum inhibitory concentration ranging from 2560μg/mL to>5120μg/mL.Low resistance to mercury was observed among isolates from Kuala Gula.Conclusions:This study showed that there was widespread of both heavy metals and antibiotics resistance among Aeromonas isolates from the two marine sources with isolates from Kuala Sepetang showing more resistance thereby posing danger to both aquatic animals and human health.展开更多
Blue mussel meat(Mytilus edulis)is an alternative and sustainable protein source for functional food proteins such as myofibrillar proteins.However,the impact of the purification process for obtaining myofibrillar pro...Blue mussel meat(Mytilus edulis)is an alternative and sustainable protein source for functional food proteins such as myofibrillar proteins.However,the impact of the purification process for obtaining myofibrillar proteins on the yield and physicochemical properties is unknown.This study investigated the effect of various washing solvents(distilled water,phosphate buffer,and NaCl solution(0.1 M vs.0.6 M))on protein yield,composition,solubility,and protein structure of the myofibrillar fractions.The results indicated a significant protein loss during the prewashing step with distilled water.Subsequent washing with phosphate buffer and low salt content(0.1 M NaCl)yielded higher myofibrillar protein from the mussel meat along the extraction process in comparison with 0.6 M NaCl as evidenced by size exclusion-high-performance liquid chromatography.FTIR spectroscopy detected conformational changes with more β-sheet structure in proteins extracted by high salt concentration compared to low salt.The findings of this study indicate to consider a prewashing step with distilled water followed by washing with phosphate buffer and 0.1 M NaCl to obtain myofibrillar protein powders with light color(yield of 56% corresponds to 0.18 g protein/per 15 g dry mussel meat)and preserved native protein folding.Alternatively,the prewashing step can be skipped to increase the yield of extraction to 64%(0.96 g protein/per 15 g dry mussel meat)and thus preserving more of the proteins,but the color of powder is darker.展开更多
Natural gases discovered up to now in Lishui Sag,the East China Sea Basin,differ greatly in gaseous compositions,of which hydrocarbon gases amount to 2%―94%while non-hydrocarbon gases are dominated by CO2.Their hydro...Natural gases discovered up to now in Lishui Sag,the East China Sea Basin,differ greatly in gaseous compositions,of which hydrocarbon gases amount to 2%―94%while non-hydrocarbon gases are dominated by CO2.Their hydrocarbon gases,without exception,contain less than 90%of methane and over 10%of C2+heavier hydrocarbons,indicating a wet gas.Carbon isotopic analyses on these hydrocarbon gases showed thatδ13C 1,δ13C 2 andδ13C 3 are basically lighter than-44‰,-29‰and-26‰,respectively.The difference in carbon isotopic values between methane and ethane is great,suggesting a biogenic oil-type gas produced by the mixed organic matter at peak generation.δ13C CO2 values of nonhydrocarbon gases are all heavier than-10‰,indicating a typical abiogenic gas.The simulation experiment on hydrocarbon generation of organic matter in a closed gold-tube system showed that the proportion of methane in natural gases produced by terrigenous organic matter in the Lingfeng Formation marine deposit is obviously higher than that in natural gases derived from the aquatic and terrigenous mixed organic matter in the Yueguifeng Formation lacustrine deposit,consequently the proportion of heavier hydrocarbons of the former is remarkably lower than that of the latter.Moreover,δ13C 1 values of natural gases produced by terrigenous organic matter in the Lingfeng Formation marine deposit are about 5‰heavier than those of natural gases derived from the aquatic and terrigenous mixed organic matter in the Yueguifeng Formation lacustrine deposit whileδ13C 2 andδ13C 3 values of the former are over 9‰heavier than those of the latter.Currently the LS36-1 oil-gas pool is the only commercial oil-gas reservoir in Lishui Sag,where carbon isotopic compositions of various hydrocarbon components differ greatly from those of natural gases produced by the Lingfeng Formation organic matter but are very similar to those of natural gases derived from the Yueguifeng Formation organic matter,therefore,natural gases in the LS36-1 oil-gas pool are mainly derived from the Yueguifeng Formation lacustrine source rock rather than the Lingfeng Formation marine or Mingyuefeng Formation coal-measures source rocks.展开更多
文摘Petroleum was generated from sedimentary rocks. The world＇s oldest oil source rock so far was found in Proterozoic rocks. Since then, 73% to 81% of the earth＇s surface has been covered with sedimentary rocks. However, only quite a limited area is rich in oil and gas. It is found that source rocks have controlled oil and gas distribution, and they are mainly formed in two systems： （1） river-lake systems and （2） river-gulf systems. Phytoplankton is an important source of kerogen, the blooming of which is strongly dependent on nutrients. Rivers are the major nutrient provider for basins. Rivers around lakes and an undercompensation （where the sedimentation rate is less than the rate of basin subsidence） environment provide favorable conditions for phytoplankton blooming in lakes. Gulfs are usually located at the estuary of big rivers, characterized by restricted current circulation and exchange with the open sea, which benefit maintaining the nutrient density, phytoplankton levels and organic matter preservation. The river-gulf system is the most favorable place for marine source rock development. Most of the world famous marine petroleum-rich provinces are developed from river-gulf systems in geological history, such as the Persian Gulf Basin, Siberian Basin, Caspian Basin, North Sea, Sirte Basin, Nigerian Basin, Kwanza Basin, Gulf of Mexico, Maracaibo Basin and the Eastern Venezuelan Basin.
基金supported by the National Natural Science Foundation of China (No. 40839910)State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of Geology and Palaeontology, CAS) (No. 113101)
文摘High quality marine source rock （HQMSR） is the key prerequisite for medium to large hydrocarbon accumulations. However, the forming mechanism remains unclear. On the basis of the in-vestigation for the geodynamic setting of the Middle-Upper Yangtze during the Early Cambrian in dif-ferent spatial scales and the analysis of trace elements, the main controlling factors of the development of high quality marine source rock are discussed, with specific consideration of the burial rate of the organic matter. The formation of high quality marine source rocks is suggested to be the result of a co-ordinated development and the interaction between geological environments and organism evolution during the major geological transition periods. We perceived that the burial rate of organic matter was influenced by the primary productivity and its burial conditions. The abundance of autogenetic molyb-denum gained directly by the chemical speciation analysis of rocks could be used as a proxy for the burial organic matter. The burial rate of autogenetic molybdenum and the sedimentary organics in modern marine environments could be used to estimate the sedimentary organics in ancient environ-ments effectively.
基金supported by the National Natural Science Foundation of China(Nos.41372139,41072098,41002027)the National Major Projects of China(Nos.2011ZX05018-001-002,2011ZX05009-002-205)
文摘This study evaluated the hydrocarbon-bearing potential of Upper Jurassic marine source rocks in the Qiangtang （羌塘） Basin through a comprehensive organic geochemical analysis of the samples from a large number of outcrops in different structural units to predict the location of favorable hydro- carbon kitchens, based on the evaluation standards of Mesozoic marine source rocks in the Qiangtang Ba- sin. Rocks＇ depositional environment, thickness and organic geochemistry feature were analyzed in this study. The principal controlling factors of the occurrences of favorable source rocks were analyzed. Upper Jurassic Suowa （索瓦） Formation source rocks are mainly platform limestone in the Dongcuo （洞错）-Hulu （葫芦） Lake deep sag and Tupocuo （吐坡错）-Baitan （白滩） Lake deep sag. Lithologically, the Suowa Fro- mation is made up of a suite of marls in intra-platform sags, micrites and black shales, which were all de- posited in the closed, deep and static water depositional environment. Marl could form hydrocarbon-rich source rocks and its organic matter type is mainly II type in mature to highly-mature stage, the limestone forms a medium-level source rock. In addition, the favorable source kitchen of limestone is larger than that of mudstone. This study provides an important reference for the evaluation of Jurassic marine source rocks and for prediction of petroleum resources in the Qiangtang Basin.
基金supported by Petrochemical Fund (B) for "Research on the effect of gas containing indigenous organic matter in the Paleozoic shale" (No. U1663202)
文摘Based on the results of conventional geochemistry analysis including thin sections and SEM observations, different shapes of bacterial fossils, with size ranging from dozens of nanometers to several microns, were discovered in the low-mature marine source rocks and coal seams in South China, of which the Permian source rocks were dominated by the bacterial fossils derived from symbiotic sulphur bacteria with gypsum, and the Chengkou section in the Cambrian strata were occupied by abundant nanoscale bacterial fossils with rod and bar shapes. In contrast, a large quantity of possible bacterial fossils found in the high-mature Permian, Silurian, and Cambrian source rocks using SEM need to be further explored. Despite this,this study has indicated that bacterial fossils were prevalent in the source rocks, such as mudstone, siliceous rock and gypsum-bearing coal seams in South China, which has been ignored before. It also suggests that the bacterial fossils may play an important role in the formation and accumulation of shale gas in the geological history.
基金The Major State Basic Research Development Program (973 Program) under contract No. 2009CB219402
文摘Drilling wells reveal that the organic matter abundance of Miocene marine source rocks in shallow water area of the Qiongdongnan Basin is relatively low with poor hydrocarbon generation poten- tial. However, in some drilling wells of deep water area close to the central depression belt, Miocene marine source rocks with better organic matter abundance and hydrocarbon generation have been found, which have achieved better source rock standard based on the analysis of geochemical charac- teristics. Although there are no exploratory wells in deep water area of the research region, through the comparative analysis of geochemical data of several typical exploratory wells respectively from shallow water area in the basin, central depression belt margin in deep-water area of the basin and Site 1148 of deep sea drilling in the South China Sea Basin, it reveals that the tendency of the quality of source rocks becomes positive gradually from delta to bathyal environment, which then becomes negative as in deep oceanic environment. Owing to the lack of terrestrial organic matter input, the important controlling factors of Miocene marine source rocks in the Qiongdongnan Basin are ocean productivity and preservation conditions of organic matter. The element geochemistry data indicate that the tendency of the paleoproductivity and the preservation conditions of organic matter become positive as water depth increase from shallow area to bathyal area close to central depression belt. So it is speculated that there must exist high quality source rocks in the central depression area where the preservation conditions of organic matter are much better. Besides, in theory, in oxygen-poor zone of oceanic environment at the water depth 400–1 000 m, the preservation conditions of organic matter are well thus forming high-quality marine source rocks. The result- ing speculation, it is reasonable to consider that there are high hydrocarbon generation potential source rocks in bathyal environment of the Qiongdongnan Basin, especially at the water depth 400– 1 000 m.
基金Supported by Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory (2019BT02H594)Sanya Technology Innovation Special Project (2022KJCX08)。
文摘Offshore carbon dioxide(CO_(2)) storage is an effective method for reducing greenhouse gas emissions. However, when using traditional seismic wave methods to monitor the migration of sequestration CO_(2) plumes, the characteristics of wave velocity changes tend to become insignificant beyond a certain limit. In contrast, the controllable source electromagnetic method(CSEM) remains highly sensitive to resistivity changes. By simulating different CO_(2) plume migration conditions, we established the relevant models and calculated the corresponding electric field response characteristic curves, allowing us to analyze the CSEM's ability to monitor CO_(2) plumes. We considered potential scenarios for the migration and diffusion of offshore CO_(2) storage, including various burial depths, vertical extension diffusion, lateral extension diffusion,multiple combinations of lateral intervals, and electric field components. We also obtained differences in resistivity inversion imaging obtained by CSEM to evaluate its feasibility in monitoring and to analyze all the electric field(Ex, Ey, and Ez) response characteristics. CSEM has great potential in monitoring CO_(2) plume migration in offshore saltwater reservoirs due to its high sensitivity and accuracy. Furthermore, changes in electromagnetic field response reflect the transport status of CO_(2) plumes, providing an important basis for monitoring and evaluating CO_(2)transport behavior during storage processes.
基金funded by the National Key Research and Development Program of China(2017YFC0603101)the Strategic Priority Research Program of the Chinese Academy of Sciences‘Development of Deep Source Rocks and Evolution Mechanism of Hydrocarbon Generation’(XDA14010000)。
文摘The Tarim Basin is the only petroliferous basin enriched with marine oil and gas in China.It is presently also the deepest basin for petroleum exploration and development in the world.There are two main sets of marine Source Rocks(SRs)in the Tarim Basin,namely the high over-mature Cambrian-Lower Ordovician(∈-O_(1))and the moderately mature Middle-Upper Ordovician(O_(2-3)).The characteristic biomarkers of SRs and oils indicate that the main origin of the marine petroleum is a mixed source of∈-O_(1) and O_(2-3) SRs.With increasing burial,the hydrocarbon contribution of the∈-O_(1) SRs gradually increases.Accompanied by the superposition of multi-stage hydrocarbon-generation of the SRs and various secondary alteration processes,the emergence and abnormal enrichment of terpenoids,thiophene and trimethylaryl isoprenoid in deep reservoirs indicate a complex genesis of various deep oils and gases.Through the analysis of the biofacies and sedimentary environments of the∈-O_(1) and O_(2-3) SRs,it is shown that the lower Paleozoic high-quality SRs in the Tarim Basin were mainly deposited in a passive continental margin and the gentle slope of the platform,deep-water shelf and slope facies,which has exhibited a good response to the local tectonic-sedimentary environment.The slope of the paleo-uplift is the mutual area for the development of carbonate reservoirs and the deposition of marine SRs,which would be favorable for the accumulation of petroleum.Due to the characteristics of low ground temperature,the latest rapid and deep burial does not cause massive oil-cracking in the paleo-uplift and slope area.Therefore,it is speculated that the marine reservoirs in the slope of the Tabei Uplift are likely to be a favorable area for deep petroleum exploration,while the oilcracking gas would be a potential reserve around the west margin of the Manjiaer Depression.Hydrocarbons were generated from various unit SRs,mainly migrating along the lateral unconformities or reservoirs and the vertical faults.They eventually brought up three major types of exploration fields:middle and lower Cambrian salt-related assemblages,dolomite inner reservoirs and Middle and Lower Ordovician oil-bearing karst,which would become the most favorable target of marine ultra-deep exploration in the Tarim Basin.
基金supported by the National Natural Science Foundation of China (Nos. 41121004, 21190050)the National Basic Research Program of China (No. 2014CB953701)
文摘Marine aerosols over the East China Seas are heavily polluted by continental sources. During the Chinese Comprehensive Ocean Experiment in November 2012, size and mass spectra of individual atmospheric particles in the size range from 0.2 to 2.0 μm were measured on board by a single particle aerosol mass spectrometer （SPAMS）. The average hourly particle number （PN） was around 4560 ＋ 3240 in the South Yellow Sea （SYS）, 2900 ± 3970 in the North Yellow Sea （NYS）, and 1700 ± 2220 in the Bohai Sea （BS）. PN in NYS and BS varied greatly over 3 orders of magnitude, while that in SYS varied shghtly. The size distributions were fitted with two log-normal modes. Accumulation mode dominated in NYS and BS, especially during episodic periods. Coarse mode particles played an important role in SYS. Particles were dassifled using an adaptive resonance theory based neural network algorithm （ART-2a）. Six particle types were identified with secondary-containing, aged sea-salt, soot-like, biomass burning, fresh sea-salt, and lead-containing particles accounting for 32%, 21%, 18%, 16%, 4%, and 3% of total PN, respectively. Aerosols in BS were relatively enriched in particles from anthropogenic sources compared to SYS, probably due to emissions from more developed upwind regions and indicating stronger influence of continental outflow on marine environment. Variation of source types depended mainly on origins of transported air masses. This study examined rapid changes in PN, size distribution and source types of fine particles in marine atmospheres. It also demonstrated the effectiveness of hi,h-time-resolution source apportionment by ART-2a.
基金supported by National Natural Science Foundation of China(Grant Nos.41173035&41322016)National Key Foundational Research and Development Project(Grant No.2012CB214800)the National Science & Technology Special Project(Grant No.2011ZX05005-004-004)
文摘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.
基金supported by the SINOPEC project (G0800-06-ZS-319)
文摘A complete Permian section in Guangyuan （广元）, Northeast Sichuan （四川）, has been investigated, to explore the variation in organic matter richness and its main controlling factors. The research results of the detailed lithological description and organic/inorganic geochemical analysis of about 325 samples indicate that a high content of total organic carbon （TOC） occurs in calcareous mudstones and laminated marls or thin-bedded limestones. In carbonate rocks, the TOC content is negatively related to the thickness of the massive beds; the thinner the bed is, the higher the TOC content is. Marine organic matter is enriched in the outer shelf and relatively shallow basin floor environments with the maximum TOC contents of 5.07% and 14.6%, respectively. The main factors that affect the quantity and quality of marine organic matter include primary productivity, depositional processes, and redox conditions during deposition and the early diagenesis stage. Three intervals of marine good quality source rocks are identified in this section; they are lower Chihsia Formation, topmost Maokou （茅口） Formation, and the middle segment of the Dalong （大隆） Formation. They are formed in anoxic environments, in association with high primary productivity. Among these, high productivity in the lower Chihsia interval may originate from an upwelling flow area, whereas, in the rest of the intervals, it is inferred to be related to hot fluid activity due to volcanic eruption. The results of this study suggest that good quality marine source rocks in the Permian strata offer significant hydrocarbon potential.
基金Supported by the National Key R&D Program of China(2017YFC0603106)National Petroleum Science and Technology Major Project(2016ZX05004-006)Science and Technology Project of PetroChina Exploration and Production Company(kt20180401)。
文摘Based on drilling cores, well logging and seismic data, source rocks and reservoirs are evaluated;and the natural gas genesis is identified through the analysis of natural gas isotopes, components and fluid inclusions, to study the gas accumulation conditions of the gypsum salt rock related strata of the Ordovician lower assemblage in Ordos Basin.(1) The natural gas from Ordovician lower assemblage is high thermal evolution dry gas from marine source rock, characterized by relatively light δ^(13)C value of methane and heavy δ^(13)C value of ethane. The natural gas is identified as gas cracking from crude oil according to component analysis. Thermochemical sulfate reduction(TSR) reaction has happened between the hydrocarbon fluid and sulfate as sulfur crystals are found in the cores, hydrogen sulfide is found in the natural gas, and hydrocarbon and hydrogen sulfide fluid inclusions are widespread in secondary minerals.(2) Around the gypsum-salt lows, argillaceous rocks are extensive in the Ordovician lower assemblage, reaching a cumulative thickness of 20–80 m. The effective source rocks include argillaceous rock rich in organic laminae, algal clump and algal dolomite. Analysis shows that the source rocks have a dominant TOC of 0.1%–0.5%, 0.31% on average and 3.24% at maximum. The source rocks have an average TOC of 0.58% after recovered through organic acid salt method, indicating the source rocks have high hydrocarbon supply potential.(3) In the sedimentary period, the palaeo-uplift controlled the distribution of reservoirs. The inherited secondary palaeo-uplift in Wushenqi–Jingbian east of the central palaeo-uplift and the low uplift formed by thick salt rocks near Shenmu–Zizhou area controlled the distribution of penecontemporaneous grain shoal dolomite reservoirs. The salinization sedimentary environment of gypsum salt rock can promote the development of reservoir. There are three types of dolomite reservoirs, the one with intercrystalline pore, with dissolution pore, and with fracture;intercrystalline and dissolution pores are main reservoir spaces.(4) There are two types of cap rocks, namely tight carbonate rock and gypsum-salt rock, constituting two types of source-reservoir-cap assemblages respectively. The general accumulation model is characterized by marine source rock supplying hydrocarbon, beach facies limy dolomite reservoir, small fractures acting as migration pathways, and structural-lithologic traps as accumulation zones.(5) The third and fourth members of Majiagou Formation are major target layers in the lower assemblage. The Wushengqi–Jingbian secondary paleo-uplift area and Shenmu–Zizhou low uplift are dolomite and limestone transition zone, there develops tight limestone to the east of the uplift zone, which is conducive to the formation of gas reservoir sealed by lithology in the updip. Two risk exploration wells drilled recently have encouraging results, indicating that the two uplift zones are important prospects.
基金The Major Science and Technology Project of CNOOC under contract No.KJGG2022-0902the National Natural Science Foundation of China under contract Nos 42202184 and 42272177.
文摘The gas sources in the eastern Cote d’Ivoire Basin(Tano Basin)are seldom reported and remain controversial due to multiple sets of potential source rocks and poorly documented geochemical characteristics of natural gases.The marine source rock potential from the Upper Albian to Turonian as well as the molecular composition and the stable carbon isotope composition of natural gases in the eastern Cote d’Ivoire Basin were studied in detail to investigate the origins of natural gases.The total organic carbon(TOC),hydrogen index(HI),and generation potential(S_(1)+S_(2))of source rocks indicate that both sapropelic source rocks and humic source rocks developed during the late Albian,whereas sapropelic source rocks developed during the Cenomanian and the Turonian.The normal order ofδ^(13)CH_(4)<δ^(13)C_(2)H6<δ^(13)C_(3)H_(8)(δ^(13)C_(1)<δ^(13)C_(2)<δ^(13)C_(3)),the relationship between C_(2)/C_(3)molar ratio andδ^(13)C_(2)-δ^(13)C_(3),and the plot ofδ^(13)C_(1)versus C_(1)/(C_(2)+C_(3))collectively show that the natural gases are thermogenic due to the primary cracking of kerogen,including the typical oil-associated gases from Well D-1,the mixed oil-associated gases and coal-derived gases from Well G-1 and Well L-1.Based on the plot ofδ^(13)C_(1)versusδ^(13)C_(2)and the established relationship betweenδ^(13)C_(1)and equivalent vitrinite reflectance(Ro),we proposed that the natural gases are in a mature stage(Ro generally varies from 1.0%to 1.3%).Combined with results of basin modelling and oil-to-source correlation,the transitional to marine source rocks during the late Albian were thought to have made a great contribution to the natural gases.Our study will make a better understanding on petroleum system in the eastern Cote d’Ivoire Basin.
基金The National Natural Science Foundation of China under contract Nos 42072188,42272205 and 41872172。
文摘Coal-type source rocks include both coal and terrigenous marine source rocks.By studying the distribution of secondary depressions,uplifts,as well as the characteristics of peat formation and accumulation in the northern marginal sea basin of the South China Sea,and combining them with coal formation characteristics observed in other basins,five genetic theories on the relationship between peat accumulation and dispersed organic matter accumulation are proposed.The northern marginal sea basin of the South China Sea is characterized by“disadvantageous coals formation and favorable terrigenous marine source rocks formation.”This paper provides a distribution map of coal seams and terrigenous marine source rocks in the Qiongdongnan Basin and determines their distribution patterns.Research shows that the migration of sedimentary facies in the basins and inner depressions led to the formation and migration of the peat accumulation centers.In addition,the vertical migration of the peat accumulation centers led to planar migration,which is actually a type of coupling relationship.Previous research results have revealed that the formation of coal-type source rock is multi-phased.The marginal sea basin is composed of several fault-depression basins,with each basin developing a second order of depression and uplift.There is no unified basin center or depositional center to be found.As a result,the concentration centers of coal-forming materials also vary greatly.Based on the distribution characteristics of coal-type source rocks in different basins within the marginal sea basins of the South China Sea,the research results have practical significance and provide guidance for exploring coal-type oil and gas reservoirs in this area.
基金funded by the National Natural Science Foundation of China under contract number 91528303the National Science and Technology Major Project under contract numbers 2016ZX05026,2011ZX05025,and 2008ZX05025+1 种基金the National Basic Research Program(973 Program)of China under contract number 2009CB219400the Science and Technology Project of China National Offshore Oil Corporation under contract number KJGG2022-0101.
文摘Oligocene(fan)delta-associated coal measures and marine source rocks are the main gas-generating source rocks in the Qiongdongnan Basin,and(fan)delta sand bodies are the dominant types of reservoirs.By comprehensively utilizing a large amount of 2D and 3D seismic data and new drilling data,the distribution of(fan)deltas and three types of Oligocene fault fan systems were systematically identified;these are thought to have had joint control over the development of hydrocarbon source rocks and reservoirs.The three types of Oligocene fault fan coupling relationships in the Qiongdongnan Basin were found to be fault bend,fault gully,and fault tip.The fault bend type of(fan)delta developed at the bend of the fault and was distributed in the downthrown block of Fault Nos.5 and 2.The fault tip type developed where the fault died out toward the source direction and was distributed near the eastewest faults on the north and south sides of Baodao and Changchang Sags.The fault gully type developed along the fault trend in the downthrown block and was mainly distributed in areas including the northern part of Ya'nan Sag and the Fault No.3 downthrown block.The fault bend(fan)delta is surrounded by a relatively closed bay environment,and the terrigenously dominated marine source rocks in the still water bay environment were developed with a high hydrocarbon generation index and high hydrocarbon generation potential.Fault tip and fault gully types of(fan)delta plain facies have a wide distribution of plain subfacies,which is conducive to the development of coal-measure source rocks that have excellent gas potential.During sedimentation of the fault gully and the fault tip delta,the terrain was relatively flat,with sand bodies strongly reworked by hydrodynamic force;the reservoir quality of the sand bodies in the underwater distributary channel and estuary dam are good,and the sand bodies have wide distribution.The sand bodies of the fault bend type of(fan)delta were deposited rapidly near the source kitchen,and the degree of sorting and rounding was poor,which resulted in the poor physical properties of the plain subfacies.In the southern and northern step-fault zones of Baodao Sag in the eastern part of this basin,the fault bend,fault tip,and fault trench(fan)deltas were inherited and further developed,and the source-reservoir configuration conditions were favorable.Exploration deployment was carried out in the Baodao 21 area in the northern step-fault zone and the Yongle 10 area in the southern step-fault zone,where new discoveries in natural gas exploration have been realized.In the eastern part of this basin,the fault bend,fault tip,and fault gully(fan)deltas in the southern and northern fault step zones of Baodao Sag were successively developed,which were beneficial for favorable sourceereservoir configuration conditions.The natural gas exploration successes in the Baodao-21 area in the northern fault step zone and the Yongle-10 area in the southern fault step zone are beneficial for new discoveries in natural gas exploration in the Qiongdongnan Basin.
基金supported by the National Natural Science Foundation of China(Grant Nos.41230312,41322016,41625009)the Key Project of China National Program for Fundamental Research and Development(Grant No. 2012CB214800)
文摘Since the discovery of the Tahe oilfield, it has been controversial on whether the main source rock is in the Cambrian or Middle-Upper Ordovician strata. In this paper, it is assumed that the crude oil from the Wells YM 2 and TD 2 was derived from the Middle-Upper Ordovician and Cambrian source rocks, respectively. We analyzed the biomarkers of the crude oil, asphalt-adsorbed hydrocarbon and saturated hydrocarbon in bitumen inclusions from the Lunnan and Hade areas in the North Uplift of the Tarim Basin. Results show that the ratios of tricyclic terpane C2~/C23 in the crude oil, asphalt-adsorbed hydrocarbon and saturated hydrocarbon in bitumen inclusions are less than 1.0, indicating that they might be from Upper Ordovician source rocks; the ratios of C28/（C27＋C28＋C29） steranes in the saturated hydrocarbon from reservoir bitumen and bitumen inclusions are higher than 25, suggesting that they might come from the Cambrian source rocks, however, the ratios of C28/（C27＋C28＋C29） steranes in oil from the North Uplift are less than 25, suggesting that they might be sourced from the Upper Ordovician source rocks. These findings demonstrate that the sources of crude oil in the Tarim Basin are complicated. The chemical composition and carbon isotopes of Ordovician reservoired oil in the Tarim Basin indicated that the crude oil in the North Uplift （including the Tahe oilfield） and Tazhong Depression was within mixture areas of crude oil from the Wells YM 2 and TD 2 as the end members of the Cambrian and Middle-Upper Ordovician sourced oils, respectively. This observation suggests that the crude oil in the Ordovician strata is a mixture of oils from the Cambrian and Ordovician source rocks, with increasing contribution from the Cambrian source rocks from the southern slope of the North Uplift to northern slope of the Central Uplift of the Tarim Basin. Considering the lithology and sedimentary facies data, the spatial distribution of the Cambrian, Middle-Lower Ordovician and Upper Ordovician source rocks was reconstructed on the basis of seismic reflection characteristics, and high-quality source rocks were revealed to be mainly located in the slope belt of the basin and were longitudinally developed over the maximum flooding surface during the progressive-regressive cycle. Affected by the transformation of the tectonic framework in the basin, the overlays of source rocks in different regions are different and the distribution of oil and gas was determined by the initial basin sedimentary structure and later reformation process. The northern slope of the Central Uplift-Shuntuo-Gucheng areas would be a recent important target for oil and gas exploration, since they have been near the slope area for a long time.
基金Supported by National University of Malaysia through UKMGUP-BTK-07-15-198.
文摘Objective:To investigate antibiotics and heavy metals resistance profile of Aeromonas species isolated from Kuala Gula and Kuala Sepetang,Perak.Methods:Isolated Aeromonas species were subjected to 12 antibiotics:penicillin G 10 units,tetracycline 30μg,novobiocin 5μg,nitrofurantoin 100μg,ampicillin 10μg,chloramphenicol 10μg,fluconazole 25μg,gentamicin 10μg,streptomycin 10μg and 25μg,kanamycin 30μg,and vancomycin 30μg and 5 heavy metals:MnSO_(4).H_(2)O,Cr(NO_(3)).9H2O,CuSO_(4),Pb(NO_(3))_(2),HgCl_(2).Results:Results from this study revealed that isolates from the two sources-displayed varied resistance.Isolates from Kuala Sepetang showed 91%,66%,61%,and 52%resistance to vancomycin,Novobiocin,streptomycin and gentamycin while Kuala Gula isolates showed 76%,93%,28%and 14%respectively.High rate of resistance was shown to be against lead(Pb),Chromium(Cr),copper(Cu)and Manganese(Mn)with minimum inhibitory concentration ranging from 2560μg/mL to>5120μg/mL.Low resistance to mercury was observed among isolates from Kuala Gula.Conclusions:This study showed that there was widespread of both heavy metals and antibiotics resistance among Aeromonas isolates from the two marine sources with isolates from Kuala Sepetang showing more resistance thereby posing danger to both aquatic animals and human health.
基金the financial support providedby the BMBF within the project"MyBioFac"(grant no.031B0832A).
文摘Blue mussel meat(Mytilus edulis)is an alternative and sustainable protein source for functional food proteins such as myofibrillar proteins.However,the impact of the purification process for obtaining myofibrillar proteins on the yield and physicochemical properties is unknown.This study investigated the effect of various washing solvents(distilled water,phosphate buffer,and NaCl solution(0.1 M vs.0.6 M))on protein yield,composition,solubility,and protein structure of the myofibrillar fractions.The results indicated a significant protein loss during the prewashing step with distilled water.Subsequent washing with phosphate buffer and low salt content(0.1 M NaCl)yielded higher myofibrillar protein from the mussel meat along the extraction process in comparison with 0.6 M NaCl as evidenced by size exclusion-high-performance liquid chromatography.FTIR spectroscopy detected conformational changes with more β-sheet structure in proteins extracted by high salt concentration compared to low salt.The findings of this study indicate to consider a prewashing step with distilled water followed by washing with phosphate buffer and 0.1 M NaCl to obtain myofibrillar protein powders with light color(yield of 56% corresponds to 0.18 g protein/per 15 g dry mussel meat)and preserved native protein folding.Alternatively,the prewashing step can be skipped to increase the yield of extraction to 64%(0.96 g protein/per 15 g dry mussel meat)and thus preserving more of the proteins,but the color of powder is darker.
基金the Research Project of CNOOC(Grant No.CT/04-EXP-009)
文摘Natural gases discovered up to now in Lishui Sag,the East China Sea Basin,differ greatly in gaseous compositions,of which hydrocarbon gases amount to 2%―94%while non-hydrocarbon gases are dominated by CO2.Their hydrocarbon gases,without exception,contain less than 90%of methane and over 10%of C2+heavier hydrocarbons,indicating a wet gas.Carbon isotopic analyses on these hydrocarbon gases showed thatδ13C 1,δ13C 2 andδ13C 3 are basically lighter than-44‰,-29‰and-26‰,respectively.The difference in carbon isotopic values between methane and ethane is great,suggesting a biogenic oil-type gas produced by the mixed organic matter at peak generation.δ13C CO2 values of nonhydrocarbon gases are all heavier than-10‰,indicating a typical abiogenic gas.The simulation experiment on hydrocarbon generation of organic matter in a closed gold-tube system showed that the proportion of methane in natural gases produced by terrigenous organic matter in the Lingfeng Formation marine deposit is obviously higher than that in natural gases derived from the aquatic and terrigenous mixed organic matter in the Yueguifeng Formation lacustrine deposit,consequently the proportion of heavier hydrocarbons of the former is remarkably lower than that of the latter.Moreover,δ13C 1 values of natural gases produced by terrigenous organic matter in the Lingfeng Formation marine deposit are about 5‰heavier than those of natural gases derived from the aquatic and terrigenous mixed organic matter in the Yueguifeng Formation lacustrine deposit whileδ13C 2 andδ13C 3 values of the former are over 9‰heavier than those of the latter.Currently the LS36-1 oil-gas pool is the only commercial oil-gas reservoir in Lishui Sag,where carbon isotopic compositions of various hydrocarbon components differ greatly from those of natural gases produced by the Lingfeng Formation organic matter but are very similar to those of natural gases derived from the Yueguifeng Formation organic matter,therefore,natural gases in the LS36-1 oil-gas pool are mainly derived from the Yueguifeng Formation lacustrine source rock rather than the Lingfeng Formation marine or Mingyuefeng Formation coal-measures source rocks.
