For deep prospects in the foreland thrust belt,southern Junggar Basin,NW China,there are uncertainties in factors controlling the structural deformation,distribution of paleo-structures and detachment layers,and distr...For deep prospects in the foreland thrust belt,southern Junggar Basin,NW China,there are uncertainties in factors controlling the structural deformation,distribution of paleo-structures and detachment layers,and distribution of major hydrocarbon source rocks.Based on the latest 3D seismic,gravity-magnetic,and drilling data,together with the results of previous structural physical simulation and discrete element numerical simulation experiments,the spatial distribution of pre-existing paleo-structures and detachment layers in deep strata of southern Junggar Basin were systematically characterized,the structural deformation characteristics and formation mechanisms were analyzed,the distribution patterns of multiple hydrocarbon source rock suites were clarified,and hydrocarbon accumulation features in key zones were reassessed.The exploration targets in deep lower assemblages with possibility of breakthrough were expected.Key results are obtained in three aspects.First,structural deformation is controlled by two-stage paleo-structures and three detachment layers with distinct lateral variations:the Jurassic layer(moderate thickness,wide distribution),the Cretaceous layer(thickest but weak detachment),and the Paleogene layer(thin but long-distance lateral thrusting).Accordingly,a four-layer composite deformation sequence was identified,and the structural genetic model with paleo-bulge controlling zonation by segments laterally and multiple detachment layers controlling sequence vertically.Second,the Permian source rocks show a distribution pattern with narrow trough(west),multiple sags(central),and broad basin(east),which is depicted by combining high-precision gravity-magnetic data and time-frequency electromagnetic data for the first time,and the Jurassic source rocks feature thicker mudstones in the west and rich coals in the east according to the reassessment.Third,two petroleum systems and a four-layer composite hydrocarbon accumulation model are established depending on the structural deformation strength,trap effectiveness and source-trap configuration.The southern Junggar Basin is divided into three segments with ten zones,and a hierarchical exploration strategy is proposed for deep lower assemblages in this region,that is,focusing on five priority zones,expanding to three potential areas,and challenging two high-risk targets.展开更多
The geological characteristics and enrichment laws of the shale oil in the third submember of the seventh member of Triassic Yanchang Formation(Chang 7_(3)) in the Ordos Basin were analyzed by using the information of...The geological characteristics and enrichment laws of the shale oil in the third submember of the seventh member of Triassic Yanchang Formation(Chang 7_(3)) in the Ordos Basin were analyzed by using the information of core observations, experiments and logging, and then the exploration potential and orientation of the Chang 7_(3) shale oil were discussed. The research findings are obtained in three aspects. First, two types of shale oil, i.e. migratory-retained and retained, are recognized in Chang 7_(3). The former is slightly better than the latter in quality. The migratory-retained shale oil reservoir is featured with the frequent interbedding and overlapping of silty-sandy laminae caused by sandy debris flow and low-density turbidity current and semi-deep-deep lacustrine organic-rich shale laminae. The retained shale oil reservoir is composed of black shale with frequent occurrence of bedding and micro-laminae. Second, high-quality source rocks provide a large quantity of hydrocarbon-rich high-quality fluids with high potential energy. The source-reservoir pressure difference provides power for oil accumulation in thin interbeds of organic-poor sandstones with good seepage conditions and in felsic lamina, tuffaceous lamina and bedding fractures in shales. Hydrocarbon generation-induced fractures, bedding fractures and microfractures provide high-speed pathways for oil micro-migration. Frequent sandstone interlayers and felsic laminae provide a good space for large-scale hydrocarbon accumulation, and also effectively improve the hydrocarbon movability. Third, sand-rich areas around the depression are the main targets for exploring migratory-retained shale oil. Mature deep depression areas are the main targets for exploring retained oil with medium to high maturity. Theoretical research and field application of in-situ conversion in low-mature deep depression areas are the main technical orientations for exploring retained shale oil with low to medium maturity.展开更多
The exploration direction and targets for the large-scale Middle Permian gas reservoirs in the Sichuan Basin are hot spots and challenges in current exploration researches.The exploration successes of large gas field ...The exploration direction and targets for the large-scale Middle Permian gas reservoirs in the Sichuan Basin are hot spots and challenges in current exploration researches.The exploration successes of large gas field of Cambrian Longwangmiao Formation in Gaoshiti-Moxi region,Central Sichuan Basin,indicated that prospective sedimentary facies belt was the basis for the formation of large gas fields.In this paper,based on seismic data,outcrop data and drilling data,the tectonic framework and sedimentary features of the Middle Permian in the SW Sichuan Basin were comprehensively studied.The following conclusions were reached from the perspective of sedimentary facies control:(1)during the Middle Permian,this region was in shallow water gentle slope belts with high energy,where thick reef flat facies were deposited;(2)the basement was uplifted during Middle Permian,resulting in the unconformity weathering crust at the top of Maokou Formation due to erosion;the SW Sichuan Basin was located in the karst slope belt,where epigenic karstification was intense;and(3)reef flat deposits superimposed by karst weathering crust was favorable for the formation of large-scale reef flat karst reservoirs.Based on the combination of the resources conditions and hydrocarbon accumulation conditions in this region,it was pointed out that the Middle Permian has great potential of large-scale reef flat karst gas reservoir due to its advantageous geological conditions;the Middle Permian traps with good hydrocarbon accumulation conditions were developed in the Longmen Mountain front closed structural belt in the SW Sichuan Basin andWestern Sichuan Basin depression slope belt,which are favorable targets for large-scale reef flat karst reservoirs.展开更多
The geothermal resources in Fujian Province are mainly hydrothermal resources of medium-low temperature.To better understand the whole process and conditions of heat control in the middle and deep crust,this study foc...The geothermal resources in Fujian Province are mainly hydrothermal resources of medium-low temperature.To better understand the whole process and conditions of heat control in the middle and deep crust,this study focuses on the analysis of heat accumulation model in Hongtang Area of Xiamen,and the main conditions of the model such as faults and sags are explored and interpreted in detail by using gravity and wide-field electromagnetic methods.4 main faults(F33,F2,F12 and HT-F1)and 10 secondary faults(HT-F2,HT-F3,HT-F4,HT-F5,HT-F6,HT-F7,HT-F8,HT-F9,HT-F10 and HT-F11)were inferred,and the distribution range of sags was delineated.The convective geothermal system is composed of four components:Heat source,geothermal reservoir,heat-conductive fault and heat retaining cover,which form a quaternary heat accumulation model.According to the model,the intersection of the main faults F12,HTF1 and F33 can be delineated as the primary target area of geothermal exploration,while the intersection of the secondary faults(F12 and HT-F6;F12 and HT-F2;HT-F9,HT-F10 and F12;F12 and HT-F11;F33 and HT-F3;HT-F8 and HT-F3;HT-F2,HT-F10 and HT-F1)can be delineated as the secondary target area.Borehole DR01,which is located in the primary target area,shows that the water temperature increases from fast to slow in the depth range of 0–500 m,and stays at 36℃below 500 m.The reliability of the heat accumulation model and the target area was tested via geothermal boreholes,which is of great significance to the exploitation and utilization of geothermal resources in Hongtang Area of Xiamen.展开更多
Based on the organic geochemical data and the molecular and stable carbon isotopic compositions of natural gas of the Lower Permian Fengcheng Formation in the western Central Depression of Junggar Basin,combined with ...Based on the organic geochemical data and the molecular and stable carbon isotopic compositions of natural gas of the Lower Permian Fengcheng Formation in the western Central Depression of Junggar Basin,combined with sedimentary environment analysis and hydrocarbon-generating simulation,the gas-generating potential of the Fengcheng source rock is evaluated,the distribution of large-scale effective source kitchen is described,the genetic types of natural gas are clarified,and four types of favorable exploration targets are selected.The results show that:(1)The Fengcheng Formation is a set of oil-prone source rocks,and the retained liquid hydrocarbon is conducive to late cracking into gas,with characteristics of high gas-generating potential and late accumulation;(2)The maximum thickness of Fengcheng source rock reaches 900 m.The source rock has entered the main gas-generating stage in Penyijingxi and Shawan sags,and the area with gas-generating intensity greater than 20×10^(8) m^(3)/km^(2) is approximately 6500 km^(2).(3)Around the western Central Depression,highly mature oil-type gas with light carbon isotope composition was identified to be derived from the Fengcheng source rocks mainly,while the rest was coal-derived gas from the Carboniferous source rock;(4)Four types of favorable exploration targets with exploration potential were developed in the western Central Depression which are structural traps neighboring to the source,stratigraphic traps neighboring to the source,shale-gas type within the source,and structural traps within the source.Great attention should be paid to these targets.展开更多
The giant potash deposit on the Khorat Plateau is one of the most promising targets for exploitation of potassium salts.So far,many researches and geologic survey have been conducted on the giant potash deposits.Hence...The giant potash deposit on the Khorat Plateau is one of the most promising targets for exploitation of potassium salts.So far,many researches and geologic survey have been conducted on the giant potash deposits.Hence,it is necessary to make an overall review on the potash deposits.The potash deposit on the Khorat Plateau was formed during the Middle to Late Cretaceous,during which seawater was enriched in Ca2+and depleted in SO42-compared with those of modern seawater.In addition to seawater,continental water and hydrothermal fluids could have affected the evaporite basins.The seawater was probably derived from Tethys ocean,and the brine should have evaporated to some extent before entering into the basin systems based on the evidence of absence of carbonates and unproportionate sulphate compared with chloride salts.The paleo-climate during Middle to Late Cretaceous was characterized as high temperature and extremely arid environment,which is favourable for deposition of potassium-magnesium saline minerals.The major saline minerals are of anhydrite,halite,carnallite,sylvite and,tachyhydrite,with trace amounts of borates.The resources of the potash deposit on the Khorat Plateau could be approximately as much as 400×109 t of carnallite and 7×109 t of sylvite.The evaporite sequences have been deformed and altered by postdepositinal processes,including tectonic movements and chemical alteration.Salt domes were formed in the postdepositional processes.Based on the analyses of geophysical surveys and drilling projects,high-quality sylvinite ores are commonly found at the flanks of those salt domes due to incongruent dissolution of carnallite.The furure potential prospecting areas for the highquality sylvinite ores would be on the edges of the Khorat Plateau.展开更多
To comprehensively utilize the valuable geological map,exploration profile,borehole,and geochemical logging data and the knowledge on the formation of the Jinshan Ag-Au deposit for forecasting the exploration targets ...To comprehensively utilize the valuable geological map,exploration profile,borehole,and geochemical logging data and the knowledge on the formation of the Jinshan Ag-Au deposit for forecasting the exploration targets of concealed ore bodies,three-dimensional Mineral Prospectivity Modeling(MPM)of the deposit has been conducted using the weights-of-evidence(WofE)method.Conditional independence between evidence layers was tested,and the outline results using the prediction-volume(P-V)and Student's t-statistic methods for delineating favorable mineralization areas from continuous posterior probability map were critically compared.Four exploration targets delineated ultimately by the Student's t-statistic method for the discovery of minable ore bodies in each of the target areas were discussed in detail.The main conclusions include:(1)three-dimensional modeling of a deposit using multi-source reconnaissance data is useful for MPM in interpreting their relationships with known ore bodies;(2)WofE modeling can be used as a straightforward tool for integrating deposit model and reconnaissance data in MPM;(3)the Student's t-statistic method is more applicable in binarizing the continuous prospectivity map for exploration targeting than the PV approach;and(4)two target areas within high potential to find undiscovered ore bodies were diagnosed to guide future near-mine exploration activities of the Jinshan deposit.展开更多
In 2023,the China National Petroleum Corporation(CNPC)has successfully drilled a 10000-m ultra-deep well-TK-1 in the Tarim Basin,NW China.This pioneering project has achieved dual breakthroughs in ten-thousand-meter u...In 2023,the China National Petroleum Corporation(CNPC)has successfully drilled a 10000-m ultra-deep well-TK-1 in the Tarim Basin,NW China.This pioneering project has achieved dual breakthroughs in ten-thousand-meter ultra-deep earth science research and hydrocarbon exploration while driving technological advancements in ultra-deep well drilling engineering.The successful completion of TK-1 has yielded transformative geological discoveries.For the first time in exploration history,comprehensive data including cores,well logs,fluids,temperature and pressure were obtained from 10000-meter depths.These findings conclusively demonstrate the existence of effective source rocks,carbonate reservoirs,and producible conventional hydrocarbons at such extreme depths-fundamentally challenging established petroleum geology paradigms.The results not only confirm the enormous hydrocarbon potential of ultra-deep formations in the Tarim Basin but also identify the most promising exploration targets.From an engineering perspective,the project has established four groundbreaking technological systems:safe drilling in complex pressure systems of ultra-deep wells,optimized and fast drilling in complex and difficult-to-drill formations of ultra-deep wells,wellbore quality control under harsh conditions in ultra-deep wells,and data acquisition in ultra-deep,ultra-high-temperature complex formations.Additionally,ten key tools for ultra-deep well drilling and completion engineering were developed,enabling the successful completion of Asia’s first and the world’s second-deepest vertical well.This achievement has significantly advanced the understanding of geological conditions at depths exceeding 10000 m and positioned China as one of the few countries with core technologies for ultra-deep well drilling.展开更多
Based on the situation and progress of marine oil/gas exploration in the Sichuan Basin,SW China,the whole petroleum system is divided for marine carbonate rocks of the basin according to the combinations of hydrocarbo...Based on the situation and progress of marine oil/gas exploration in the Sichuan Basin,SW China,the whole petroleum system is divided for marine carbonate rocks of the basin according to the combinations of hydrocarbon accumulation elements,especially the source rock.The hydrocarbon accumulation characteristics of each whole petroleum system are analyzed,the patterns of integrated conventional and unconventional hydrocarbon accumulation are summarized,and the favorable exploration targets are proposed.Under the control of multiple extensional-convergent tectonic cycles,the marine carbonate rocks of the Sichuan Basin contain three sets of regional source rocks and three sets of regional cap rocks,and can be divided into the Cambrian,Silurian and Permian whole petroleum systems.These whole petroleum systems present mainly independent hydrocarbon accumulation,containing natural gas of affinity individually.Locally,large fault zones run through multiple whole petroleum systems,forming a fault-controlled complex whole petroleum system.The hydrocarbon accumulation sequence of continental shelf facies shale gas accumulation,marginal platform facies-controlled gas reservoirs,and intra-platform fault-and facies-controlled gas reservoirs is common in the whole petroleum system,with a stereoscopic accumulation and orderly distribution pattern.High-quality source rock is fundamental to the formation of large gas fields,and natural gas in a whole petroleum system is generally enriched near and within the source rocks.The development and maintenance of large-scale reservoirs are essential for natural gas enrichment,multiple sources,oil and gas transformation,and dynamic adjustment are the characteristics of marine petroleum accumulation,and good preservation conditions are critical to natural gas accumulation.Large-scale marginal-platform reef-bank facies zones,deep shale gas,and large-scale lithological complexes related to source-connected faults are future marine hydrocarbon exploration targets in the Sichuan Basin.展开更多
Sequence stratigraphy can be used to predict the oil and gas reservoir bodies and to choose the oil targets. Fan delta and sublacustrine fan systems are developed in the HGZ Area, which is located in front of the Altu...Sequence stratigraphy can be used to predict the oil and gas reservoir bodies and to choose the oil targets. Fan delta and sublacustrine fan systems are developed in the HGZ Area, which is located in front of the Altun Mountain in the west of the Qaidam Basin. On the basis of seismic and well drilling data, the deposits in the area were studied by using sequence stratigraphy and reservoir prediction techniques. Various reservoir prediction techniques used under the constraint of high resolution sequence framework could help to improve the precision of reservoir prediction and to recognize the pinch out line of sand layers, the distribution of isolated sandstone bodies and the types of oil pools. The study of sequence stratigraphy makes reservoir prediction more effective by dividing different scales of sequences and distinguishing the system tracts and parasequence sets, and indicates the internal relationship between oil/gas and sedimentary bodies in different system tracts with evolution in time and space.展开更多
The purpose of this study was to examine the sedimentary facies characteristics of lower Cambrian Niutitang Formation(∈1n)in South China,to reveal the mechanism of organic matter enrichment,and to guide exploration o...The purpose of this study was to examine the sedimentary facies characteristics of lower Cambrian Niutitang Formation(∈1n)in South China,to reveal the mechanism of organic matter enrichment,and to guide exploration of shale gas.Macro investigation and experimental analyses were used to assess the lithology in detail,total organic matter mass fraction w(TOC),mineral composition,and trace element characteristics of∈1n.The influencing factors of organic matter enrichment were discussed extensively,and a sedimentary facies mode was suggested.In the early stage of∈1n,the locations of Well E’yangye 1,Well Ciye 1,Well Changye 1,and Well Anye 1 respectively develop,platform inner sag,outer shelf,Jiangnan slope belt,and South China detention basin.In the late stage of∈1n,the sedimentary facies evolve with decreasing sea level.The study area presents a complete three-step basin in the Early Cambrian.In the early stage of∈1n,the first step is the Yangtze carbonate platform,the second step is the outer shelf and slope,and the third step is the deep-water basin.From the Yangtze carbonate platform to the deep-water basin,w(TOC)and the mass fraction of quartz gradually increase,the mass fraction of carbonate mineral decreases,and the mass fraction of clay mineral is higher in the second step.The sea level fluctuation results in a higher w(TOC)vertically in the lower∈1n shale,and the paleogeographic(provenance)conditions lead to better horizontal development of organic matter in the outer shelf,slope and detention basin.Trace elements are abundant in the lower∈1n,and w(TOC)is correlated positively with many trace elements.In the outer shelf,slope,and adjacent areas,hydrothermal activity and upwelling current bring nutrient-rich material and promote organic matter enrichment under a strong reducing condition.Deep-shelf,slope and deep-water basin are the best facies for the formation and preservation of organic matter,especially deep-water basin facies.It remains necessary to strengthen the exploration of shale gas in the deep-water basin of∈1n in central Hunan,China.展开更多
Craton basins are the main sites where marine carbonate oil and gas reservoirs develop in China.However,the previous studies scarcely focused on the controlling effects of tectonic differentiation on the formation of ...Craton basins are the main sites where marine carbonate oil and gas reservoirs develop in China.However,the previous studies scarcely focused on the controlling effects of tectonic differentiation on the formation of large oil and gas fields in the ancient craton basins.In such circumstances,it is difficult to evaluate and select the favorable zones for exploring carbonate oil and gas.In this paper,based on the research results of the SinianeTriassic prototype basin and lithofacies paleogeography of the Sichuan Basin,the tectonic differentiation pattern of craton basins and its controls on the accumulation elements and the distribution of hydrocarbons were analyzed with reference to the concept that structures control the sedimentation and distribution of oil and gas.The study reveals the results in three aspects.First,the intra-cratonic graben controls the high-quality source rocks and the hydrocarbon generation center,which forms good source-reservoir assemblage with the highquality reservoir in the platform margin at the flank,showing excellent near-source accumulation conditions.Second,the three types of paleo-uplifts(i.e.differential denudation,syn-sedimentary,and folding)and the deep-large faults developed in the craton are favorable for the formation and distribution of large-scale carbonate reservoirs.Third,the superimposed areas with tectonic differentiation in multiple periods and multiple types are favorable for forming large oil and gas fields.It is concluded that the marine carbonate rocks show a huge oil and gas exploration potential in the Sichuan Basin.Attention should be paid to the new exploration targets of natural gas,such as the Sinian Dengying Fm.in the platform margin at the east flank of DeyangeAnyue graben,the Lower Cambrian Longwangmiao Fm.on the slope of paleo-uplift in central Sichuan Basin,and the Middle Permian Maokou Fm.in centralewest Sichuan Basin,where oil and gas accumulation conditions are favorable.展开更多
The hydrocarbon accumulation modes and differences in the Tethyan realm serve as a hot research topic in the petroleum geology community at home and abroad.Both the Persian Gulf Basin in the Middle East and the Sichua...The hydrocarbon accumulation modes and differences in the Tethyan realm serve as a hot research topic in the petroleum geology community at home and abroad.Both the Persian Gulf Basin in the Middle East and the Sichuan Basin in China,situated on the southern and northern sides of the Tethyan realm,respectively,record the whole geological process of the opening and closure of the Prototethys,the Paleotethys,and the Neotethys sequentially,exhibiting anomalous hydrocarbon enrichment.Based on the analysis of the plate tectonic evolution in the Tethyan realm,this study dissects the structures and hydrocarbon accumulation conditions of both basins.Followed by a systematic comparative analysis of the factors controlling hydrocarbon enrichment in the process of plate breakup and convergence in the Tethyan realm,this study proposes petroleum exploration targets in the realm.The results are as follows:(1)Since the Meso-Neoproterozoic,the Persian Gulf Basin and the Sichuan Basin have undergone similar tectonic evolution in the early stage but different in the late stage.Under the influence of the formation and evolution of the Prototethys,Paleotethys,and Neotethys oceans,both basins experienced multi-stage development and modification,forming two major extension-convergence cycles.Consequently,both basins are characterized by the vertical orderly superimposition of various basin prototypes in the order of rift-intracratonic basin(passive continental margin)-foreland.(2)The fact that the Tethyan realm was long located at medium-low latitudes and the local anoxic environment formed in the process of plate breakup and convergence played a vital role in the formation of extensive source rocks.The source rocks are predominantly distributed in underfilled rifts and deep depressions that were connected to the ocean in the unidirectional continental breakup process;basin-slopes and intra-shelf basins on passive continental margins;basinal lows within intracratonic basins,and underfilled foredeeps in foreland basins.The favorable areas for the formation of carbonate reservoirs include platform margins,submarine highs and paleo-uplifts within platforms,and fault zones.The evaporite cap rocks,intimately associated with the basin evolutionary stages and global dry-hot events,are critical for large-scale hydrocarbon preservation.(3)Under the influence of Tethyan evolution,the Persian Gulf Basin and the Sichuan Basin share similar primary factors controlling hydrocarbon enrichment.The moderate tectono-sedimentary differentiation and structural modification in the process of prototype basin superimposition,as well as the spatio-temporal matching of elements critical for hydrocarbon accumulation,are beneficial for the development of large oil and gas fields.The macroscopic hydrocarbon distribution is dictated by source rock-cap rock assemblages,while the local hydrocarbon distribution is governed by trap-reservoir assemblages.The critical factors determining the differential hydrocarbon enrichment in the Persian Gulf Basin and the Sichuan Basin include plate size and position,basement stability,eustatic movement,paleoclimate,and tectonic transformation.Besides,different tectonic modification intensities are closely related to the type,enrichment degree,and distribution of hydrocarbon reservoirs.展开更多
Identifying geochemical anomalies related to ore deposition processes facilitates the practice of vectoring toward undiscovered mineral deposit sites.In districtscale exploration studies,analysis of dispersion pattern...Identifying geochemical anomalies related to ore deposition processes facilitates the practice of vectoring toward undiscovered mineral deposit sites.In districtscale exploration studies,analysis of dispersion patterns of ore-forming elements results in more-reliable targets.Therefore,deriving significant geochemical footprints and mapping the ensuing geochemical anomalies are of important issues that lead exploration geologists toward anomaly sources,e.g.,mineralization.This paper aims to examine the effectiveness of local relative enrichment index and singularity mapping technique,as two methods of local neighborhood statistics,in the delineation of anomalous areas for further exploration.A data set of element contents obtained from stream sediment samples in Baft area,Iran,therefore was applied to illustrate the procedure proposed.The close relationship between anomalous patterns recognized and known Cu-occurrences demonstrated that the procedures proposed can efficiently model complex dispersion patterns of geochemical anomalies in the study area.The results showed that singularity mapping method is a better technique,compared to local relative enrichment index,to delineate targets for follow-up exploration in the area.We made this comparison because,as pointed out by exploration geochemists,dispersion patterns of geochemical indicators in stream sediments vary in different areas even for the same deposit type.The variety in the dispersion patterns is due to the operation of post-mineralization subsystems,which are affected by local factors such as landscape of the areas under study.Therefore,the effectiveness of the methods should be evaluated in every area for every targeted deposit.展开更多
基金Supported by the Science and Technology Special Project of CNPC(2023YQX10111)Key Research and Development Special Project of Xinjiang Uygur Autonomous Region(2024B01015-3)。
文摘For deep prospects in the foreland thrust belt,southern Junggar Basin,NW China,there are uncertainties in factors controlling the structural deformation,distribution of paleo-structures and detachment layers,and distribution of major hydrocarbon source rocks.Based on the latest 3D seismic,gravity-magnetic,and drilling data,together with the results of previous structural physical simulation and discrete element numerical simulation experiments,the spatial distribution of pre-existing paleo-structures and detachment layers in deep strata of southern Junggar Basin were systematically characterized,the structural deformation characteristics and formation mechanisms were analyzed,the distribution patterns of multiple hydrocarbon source rock suites were clarified,and hydrocarbon accumulation features in key zones were reassessed.The exploration targets in deep lower assemblages with possibility of breakthrough were expected.Key results are obtained in three aspects.First,structural deformation is controlled by two-stage paleo-structures and three detachment layers with distinct lateral variations:the Jurassic layer(moderate thickness,wide distribution),the Cretaceous layer(thickest but weak detachment),and the Paleogene layer(thin but long-distance lateral thrusting).Accordingly,a four-layer composite deformation sequence was identified,and the structural genetic model with paleo-bulge controlling zonation by segments laterally and multiple detachment layers controlling sequence vertically.Second,the Permian source rocks show a distribution pattern with narrow trough(west),multiple sags(central),and broad basin(east),which is depicted by combining high-precision gravity-magnetic data and time-frequency electromagnetic data for the first time,and the Jurassic source rocks feature thicker mudstones in the west and rich coals in the east according to the reassessment.Third,two petroleum systems and a four-layer composite hydrocarbon accumulation model are established depending on the structural deformation strength,trap effectiveness and source-trap configuration.The southern Junggar Basin is divided into three segments with ten zones,and a hierarchical exploration strategy is proposed for deep lower assemblages in this region,that is,focusing on five priority zones,expanding to three potential areas,and challenging two high-risk targets.
基金Supported by the CNPC Science and Technology Project (2021DJ1806)the National Key Basic Research and Development Program (973 Program),China (2014CB239003)。
文摘The geological characteristics and enrichment laws of the shale oil in the third submember of the seventh member of Triassic Yanchang Formation(Chang 7_(3)) in the Ordos Basin were analyzed by using the information of core observations, experiments and logging, and then the exploration potential and orientation of the Chang 7_(3) shale oil were discussed. The research findings are obtained in three aspects. First, two types of shale oil, i.e. migratory-retained and retained, are recognized in Chang 7_(3). The former is slightly better than the latter in quality. The migratory-retained shale oil reservoir is featured with the frequent interbedding and overlapping of silty-sandy laminae caused by sandy debris flow and low-density turbidity current and semi-deep-deep lacustrine organic-rich shale laminae. The retained shale oil reservoir is composed of black shale with frequent occurrence of bedding and micro-laminae. Second, high-quality source rocks provide a large quantity of hydrocarbon-rich high-quality fluids with high potential energy. The source-reservoir pressure difference provides power for oil accumulation in thin interbeds of organic-poor sandstones with good seepage conditions and in felsic lamina, tuffaceous lamina and bedding fractures in shales. Hydrocarbon generation-induced fractures, bedding fractures and microfractures provide high-speed pathways for oil micro-migration. Frequent sandstone interlayers and felsic laminae provide a good space for large-scale hydrocarbon accumulation, and also effectively improve the hydrocarbon movability. Third, sand-rich areas around the depression are the main targets for exploring migratory-retained shale oil. Mature deep depression areas are the main targets for exploring retained oil with medium to high maturity. Theoretical research and field application of in-situ conversion in low-mature deep depression areas are the main technical orientations for exploring retained shale oil with low to medium maturity.
文摘The exploration direction and targets for the large-scale Middle Permian gas reservoirs in the Sichuan Basin are hot spots and challenges in current exploration researches.The exploration successes of large gas field of Cambrian Longwangmiao Formation in Gaoshiti-Moxi region,Central Sichuan Basin,indicated that prospective sedimentary facies belt was the basis for the formation of large gas fields.In this paper,based on seismic data,outcrop data and drilling data,the tectonic framework and sedimentary features of the Middle Permian in the SW Sichuan Basin were comprehensively studied.The following conclusions were reached from the perspective of sedimentary facies control:(1)during the Middle Permian,this region was in shallow water gentle slope belts with high energy,where thick reef flat facies were deposited;(2)the basement was uplifted during Middle Permian,resulting in the unconformity weathering crust at the top of Maokou Formation due to erosion;the SW Sichuan Basin was located in the karst slope belt,where epigenic karstification was intense;and(3)reef flat deposits superimposed by karst weathering crust was favorable for the formation of large-scale reef flat karst reservoirs.Based on the combination of the resources conditions and hydrocarbon accumulation conditions in this region,it was pointed out that the Middle Permian has great potential of large-scale reef flat karst gas reservoir due to its advantageous geological conditions;the Middle Permian traps with good hydrocarbon accumulation conditions were developed in the Longmen Mountain front closed structural belt in the SW Sichuan Basin andWestern Sichuan Basin depression slope belt,which are favorable targets for large-scale reef flat karst reservoirs.
基金supported by the National Natural Science Foundation of China (Grants Nos. 41902242)the Geological Survey Projects Foundation of the Institute of Hydrogeology and Environmental Geology (Grants Nos. DD20190303, DD20221773)。
文摘The geothermal resources in Fujian Province are mainly hydrothermal resources of medium-low temperature.To better understand the whole process and conditions of heat control in the middle and deep crust,this study focuses on the analysis of heat accumulation model in Hongtang Area of Xiamen,and the main conditions of the model such as faults and sags are explored and interpreted in detail by using gravity and wide-field electromagnetic methods.4 main faults(F33,F2,F12 and HT-F1)and 10 secondary faults(HT-F2,HT-F3,HT-F4,HT-F5,HT-F6,HT-F7,HT-F8,HT-F9,HT-F10 and HT-F11)were inferred,and the distribution range of sags was delineated.The convective geothermal system is composed of four components:Heat source,geothermal reservoir,heat-conductive fault and heat retaining cover,which form a quaternary heat accumulation model.According to the model,the intersection of the main faults F12,HTF1 and F33 can be delineated as the primary target area of geothermal exploration,while the intersection of the secondary faults(F12 and HT-F6;F12 and HT-F2;HT-F9,HT-F10 and F12;F12 and HT-F11;F33 and HT-F3;HT-F8 and HT-F3;HT-F2,HT-F10 and HT-F1)can be delineated as the secondary target area.Borehole DR01,which is located in the primary target area,shows that the water temperature increases from fast to slow in the depth range of 0–500 m,and stays at 36℃below 500 m.The reliability of the heat accumulation model and the target area was tested via geothermal boreholes,which is of great significance to the exploitation and utilization of geothermal resources in Hongtang Area of Xiamen.
基金Supported by the National Natural Science Foundation of China(41802177,42272188)PetroChina Basic Technology Research and Development Project(2021DJ0206,2022DJ0507)Research Fund of PetroChina Basic Scientific Research and Strategic Reserve Technology(2020D-5008-04).
文摘Based on the organic geochemical data and the molecular and stable carbon isotopic compositions of natural gas of the Lower Permian Fengcheng Formation in the western Central Depression of Junggar Basin,combined with sedimentary environment analysis and hydrocarbon-generating simulation,the gas-generating potential of the Fengcheng source rock is evaluated,the distribution of large-scale effective source kitchen is described,the genetic types of natural gas are clarified,and four types of favorable exploration targets are selected.The results show that:(1)The Fengcheng Formation is a set of oil-prone source rocks,and the retained liquid hydrocarbon is conducive to late cracking into gas,with characteristics of high gas-generating potential and late accumulation;(2)The maximum thickness of Fengcheng source rock reaches 900 m.The source rock has entered the main gas-generating stage in Penyijingxi and Shawan sags,and the area with gas-generating intensity greater than 20×10^(8) m^(3)/km^(2) is approximately 6500 km^(2).(3)Around the western Central Depression,highly mature oil-type gas with light carbon isotope composition was identified to be derived from the Fengcheng source rocks mainly,while the rest was coal-derived gas from the Carboniferous source rock;(4)Four types of favorable exploration targets with exploration potential were developed in the western Central Depression which are structural traps neighboring to the source,stratigraphic traps neighboring to the source,shale-gas type within the source,and structural traps within the source.Great attention should be paid to these targets.
基金This study is finished through the cooperation project between China Geological Survey and Department of Mineral Resources(Thailand)supported by the National Key Project for Basic Research of China(2011CB403007)+2 种基金the National Natural Science Foundation of China(41572067,91855104,41802111)the Geological Survey Project(DD20190437)"Mineral potential exploration and assessment for potash"by the Government of Thailand.
文摘The giant potash deposit on the Khorat Plateau is one of the most promising targets for exploitation of potassium salts.So far,many researches and geologic survey have been conducted on the giant potash deposits.Hence,it is necessary to make an overall review on the potash deposits.The potash deposit on the Khorat Plateau was formed during the Middle to Late Cretaceous,during which seawater was enriched in Ca2+and depleted in SO42-compared with those of modern seawater.In addition to seawater,continental water and hydrothermal fluids could have affected the evaporite basins.The seawater was probably derived from Tethys ocean,and the brine should have evaporated to some extent before entering into the basin systems based on the evidence of absence of carbonates and unproportionate sulphate compared with chloride salts.The paleo-climate during Middle to Late Cretaceous was characterized as high temperature and extremely arid environment,which is favourable for deposition of potassium-magnesium saline minerals.The major saline minerals are of anhydrite,halite,carnallite,sylvite and,tachyhydrite,with trace amounts of borates.The resources of the potash deposit on the Khorat Plateau could be approximately as much as 400×109 t of carnallite and 7×109 t of sylvite.The evaporite sequences have been deformed and altered by postdepositinal processes,including tectonic movements and chemical alteration.Salt domes were formed in the postdepositional processes.Based on the analyses of geophysical surveys and drilling projects,high-quality sylvinite ores are commonly found at the flanks of those salt domes due to incongruent dissolution of carnallite.The furure potential prospecting areas for the highquality sylvinite ores would be on the edges of the Khorat Plateau.
基金financially supported by the Ministry of Science and Technology of China(Nos.2022YFF0801201,2021YFC2900300)the National Natural Science Foundation of China(Nos.41872245,U1911202)the Guangdong Basic and Applied Basic Research Foundation(No.2020A1515010666)。
文摘To comprehensively utilize the valuable geological map,exploration profile,borehole,and geochemical logging data and the knowledge on the formation of the Jinshan Ag-Au deposit for forecasting the exploration targets of concealed ore bodies,three-dimensional Mineral Prospectivity Modeling(MPM)of the deposit has been conducted using the weights-of-evidence(WofE)method.Conditional independence between evidence layers was tested,and the outline results using the prediction-volume(P-V)and Student's t-statistic methods for delineating favorable mineralization areas from continuous posterior probability map were critically compared.Four exploration targets delineated ultimately by the Student's t-statistic method for the discovery of minable ore bodies in each of the target areas were discussed in detail.The main conclusions include:(1)three-dimensional modeling of a deposit using multi-source reconnaissance data is useful for MPM in interpreting their relationships with known ore bodies;(2)WofE modeling can be used as a straightforward tool for integrating deposit model and reconnaissance data in MPM;(3)the Student's t-statistic method is more applicable in binarizing the continuous prospectivity map for exploration targeting than the PV approach;and(4)two target areas within high potential to find undiscovered ore bodies were diagnosed to guide future near-mine exploration activities of the Jinshan deposit.
文摘In 2023,the China National Petroleum Corporation(CNPC)has successfully drilled a 10000-m ultra-deep well-TK-1 in the Tarim Basin,NW China.This pioneering project has achieved dual breakthroughs in ten-thousand-meter ultra-deep earth science research and hydrocarbon exploration while driving technological advancements in ultra-deep well drilling engineering.The successful completion of TK-1 has yielded transformative geological discoveries.For the first time in exploration history,comprehensive data including cores,well logs,fluids,temperature and pressure were obtained from 10000-meter depths.These findings conclusively demonstrate the existence of effective source rocks,carbonate reservoirs,and producible conventional hydrocarbons at such extreme depths-fundamentally challenging established petroleum geology paradigms.The results not only confirm the enormous hydrocarbon potential of ultra-deep formations in the Tarim Basin but also identify the most promising exploration targets.From an engineering perspective,the project has established four groundbreaking technological systems:safe drilling in complex pressure systems of ultra-deep wells,optimized and fast drilling in complex and difficult-to-drill formations of ultra-deep wells,wellbore quality control under harsh conditions in ultra-deep wells,and data acquisition in ultra-deep,ultra-high-temperature complex formations.Additionally,ten key tools for ultra-deep well drilling and completion engineering were developed,enabling the successful completion of Asia’s first and the world’s second-deepest vertical well.This achievement has significantly advanced the understanding of geological conditions at depths exceeding 10000 m and positioned China as one of the few countries with core technologies for ultra-deep well drilling.
基金Supported by the National Natural Science Foundation of China(42090022)。
文摘Based on the situation and progress of marine oil/gas exploration in the Sichuan Basin,SW China,the whole petroleum system is divided for marine carbonate rocks of the basin according to the combinations of hydrocarbon accumulation elements,especially the source rock.The hydrocarbon accumulation characteristics of each whole petroleum system are analyzed,the patterns of integrated conventional and unconventional hydrocarbon accumulation are summarized,and the favorable exploration targets are proposed.Under the control of multiple extensional-convergent tectonic cycles,the marine carbonate rocks of the Sichuan Basin contain three sets of regional source rocks and three sets of regional cap rocks,and can be divided into the Cambrian,Silurian and Permian whole petroleum systems.These whole petroleum systems present mainly independent hydrocarbon accumulation,containing natural gas of affinity individually.Locally,large fault zones run through multiple whole petroleum systems,forming a fault-controlled complex whole petroleum system.The hydrocarbon accumulation sequence of continental shelf facies shale gas accumulation,marginal platform facies-controlled gas reservoirs,and intra-platform fault-and facies-controlled gas reservoirs is common in the whole petroleum system,with a stereoscopic accumulation and orderly distribution pattern.High-quality source rock is fundamental to the formation of large gas fields,and natural gas in a whole petroleum system is generally enriched near and within the source rocks.The development and maintenance of large-scale reservoirs are essential for natural gas enrichment,multiple sources,oil and gas transformation,and dynamic adjustment are the characteristics of marine petroleum accumulation,and good preservation conditions are critical to natural gas accumulation.Large-scale marginal-platform reef-bank facies zones,deep shale gas,and large-scale lithological complexes related to source-connected faults are future marine hydrocarbon exploration targets in the Sichuan Basin.
基金Supported by the Project of "Ktqq-2005-013" from PetroChina, China National Petroleum Corporation(CNPC)
文摘Sequence stratigraphy can be used to predict the oil and gas reservoir bodies and to choose the oil targets. Fan delta and sublacustrine fan systems are developed in the HGZ Area, which is located in front of the Altun Mountain in the west of the Qaidam Basin. On the basis of seismic and well drilling data, the deposits in the area were studied by using sequence stratigraphy and reservoir prediction techniques. Various reservoir prediction techniques used under the constraint of high resolution sequence framework could help to improve the precision of reservoir prediction and to recognize the pinch out line of sand layers, the distribution of isolated sandstone bodies and the types of oil pools. The study of sequence stratigraphy makes reservoir prediction more effective by dividing different scales of sequences and distinguishing the system tracts and parasequence sets, and indicates the internal relationship between oil/gas and sedimentary bodies in different system tracts with evolution in time and space.
基金Project(2017GK2233)supported by the Science and Technology Innovation Program of Hunan Provine,ChinaProject(2017JJ1034)supported by the Natural Science Foundation of Hunan Province,China。
文摘The purpose of this study was to examine the sedimentary facies characteristics of lower Cambrian Niutitang Formation(∈1n)in South China,to reveal the mechanism of organic matter enrichment,and to guide exploration of shale gas.Macro investigation and experimental analyses were used to assess the lithology in detail,total organic matter mass fraction w(TOC),mineral composition,and trace element characteristics of∈1n.The influencing factors of organic matter enrichment were discussed extensively,and a sedimentary facies mode was suggested.In the early stage of∈1n,the locations of Well E’yangye 1,Well Ciye 1,Well Changye 1,and Well Anye 1 respectively develop,platform inner sag,outer shelf,Jiangnan slope belt,and South China detention basin.In the late stage of∈1n,the sedimentary facies evolve with decreasing sea level.The study area presents a complete three-step basin in the Early Cambrian.In the early stage of∈1n,the first step is the Yangtze carbonate platform,the second step is the outer shelf and slope,and the third step is the deep-water basin.From the Yangtze carbonate platform to the deep-water basin,w(TOC)and the mass fraction of quartz gradually increase,the mass fraction of carbonate mineral decreases,and the mass fraction of clay mineral is higher in the second step.The sea level fluctuation results in a higher w(TOC)vertically in the lower∈1n shale,and the paleogeographic(provenance)conditions lead to better horizontal development of organic matter in the outer shelf,slope and detention basin.Trace elements are abundant in the lower∈1n,and w(TOC)is correlated positively with many trace elements.In the outer shelf,slope,and adjacent areas,hydrothermal activity and upwelling current bring nutrient-rich material and promote organic matter enrichment under a strong reducing condition.Deep-shelf,slope and deep-water basin are the best facies for the formation and preservation of organic matter,especially deep-water basin facies.It remains necessary to strengthen the exploration of shale gas in the deep-water basin of∈1n in central Hunan,China.
文摘Craton basins are the main sites where marine carbonate oil and gas reservoirs develop in China.However,the previous studies scarcely focused on the controlling effects of tectonic differentiation on the formation of large oil and gas fields in the ancient craton basins.In such circumstances,it is difficult to evaluate and select the favorable zones for exploring carbonate oil and gas.In this paper,based on the research results of the SinianeTriassic prototype basin and lithofacies paleogeography of the Sichuan Basin,the tectonic differentiation pattern of craton basins and its controls on the accumulation elements and the distribution of hydrocarbons were analyzed with reference to the concept that structures control the sedimentation and distribution of oil and gas.The study reveals the results in three aspects.First,the intra-cratonic graben controls the high-quality source rocks and the hydrocarbon generation center,which forms good source-reservoir assemblage with the highquality reservoir in the platform margin at the flank,showing excellent near-source accumulation conditions.Second,the three types of paleo-uplifts(i.e.differential denudation,syn-sedimentary,and folding)and the deep-large faults developed in the craton are favorable for the formation and distribution of large-scale carbonate reservoirs.Third,the superimposed areas with tectonic differentiation in multiple periods and multiple types are favorable for forming large oil and gas fields.It is concluded that the marine carbonate rocks show a huge oil and gas exploration potential in the Sichuan Basin.Attention should be paid to the new exploration targets of natural gas,such as the Sinian Dengying Fm.in the platform margin at the east flank of DeyangeAnyue graben,the Lower Cambrian Longwangmiao Fm.on the slope of paleo-uplift in central Sichuan Basin,and the Middle Permian Maokou Fm.in centralewest Sichuan Basin,where oil and gas accumulation conditions are favorable.
基金supported by the National Natural Science Foundation of China (Grant Nos.92255302,U19B6003 and 42002137)。
文摘The hydrocarbon accumulation modes and differences in the Tethyan realm serve as a hot research topic in the petroleum geology community at home and abroad.Both the Persian Gulf Basin in the Middle East and the Sichuan Basin in China,situated on the southern and northern sides of the Tethyan realm,respectively,record the whole geological process of the opening and closure of the Prototethys,the Paleotethys,and the Neotethys sequentially,exhibiting anomalous hydrocarbon enrichment.Based on the analysis of the plate tectonic evolution in the Tethyan realm,this study dissects the structures and hydrocarbon accumulation conditions of both basins.Followed by a systematic comparative analysis of the factors controlling hydrocarbon enrichment in the process of plate breakup and convergence in the Tethyan realm,this study proposes petroleum exploration targets in the realm.The results are as follows:(1)Since the Meso-Neoproterozoic,the Persian Gulf Basin and the Sichuan Basin have undergone similar tectonic evolution in the early stage but different in the late stage.Under the influence of the formation and evolution of the Prototethys,Paleotethys,and Neotethys oceans,both basins experienced multi-stage development and modification,forming two major extension-convergence cycles.Consequently,both basins are characterized by the vertical orderly superimposition of various basin prototypes in the order of rift-intracratonic basin(passive continental margin)-foreland.(2)The fact that the Tethyan realm was long located at medium-low latitudes and the local anoxic environment formed in the process of plate breakup and convergence played a vital role in the formation of extensive source rocks.The source rocks are predominantly distributed in underfilled rifts and deep depressions that were connected to the ocean in the unidirectional continental breakup process;basin-slopes and intra-shelf basins on passive continental margins;basinal lows within intracratonic basins,and underfilled foredeeps in foreland basins.The favorable areas for the formation of carbonate reservoirs include platform margins,submarine highs and paleo-uplifts within platforms,and fault zones.The evaporite cap rocks,intimately associated with the basin evolutionary stages and global dry-hot events,are critical for large-scale hydrocarbon preservation.(3)Under the influence of Tethyan evolution,the Persian Gulf Basin and the Sichuan Basin share similar primary factors controlling hydrocarbon enrichment.The moderate tectono-sedimentary differentiation and structural modification in the process of prototype basin superimposition,as well as the spatio-temporal matching of elements critical for hydrocarbon accumulation,are beneficial for the development of large oil and gas fields.The macroscopic hydrocarbon distribution is dictated by source rock-cap rock assemblages,while the local hydrocarbon distribution is governed by trap-reservoir assemblages.The critical factors determining the differential hydrocarbon enrichment in the Persian Gulf Basin and the Sichuan Basin include plate size and position,basement stability,eustatic movement,paleoclimate,and tectonic transformation.Besides,different tectonic modification intensities are closely related to the type,enrichment degree,and distribution of hydrocarbon reservoirs.
文摘Identifying geochemical anomalies related to ore deposition processes facilitates the practice of vectoring toward undiscovered mineral deposit sites.In districtscale exploration studies,analysis of dispersion patterns of ore-forming elements results in more-reliable targets.Therefore,deriving significant geochemical footprints and mapping the ensuing geochemical anomalies are of important issues that lead exploration geologists toward anomaly sources,e.g.,mineralization.This paper aims to examine the effectiveness of local relative enrichment index and singularity mapping technique,as two methods of local neighborhood statistics,in the delineation of anomalous areas for further exploration.A data set of element contents obtained from stream sediment samples in Baft area,Iran,therefore was applied to illustrate the procedure proposed.The close relationship between anomalous patterns recognized and known Cu-occurrences demonstrated that the procedures proposed can efficiently model complex dispersion patterns of geochemical anomalies in the study area.The results showed that singularity mapping method is a better technique,compared to local relative enrichment index,to delineate targets for follow-up exploration in the area.We made this comparison because,as pointed out by exploration geochemists,dispersion patterns of geochemical indicators in stream sediments vary in different areas even for the same deposit type.The variety in the dispersion patterns is due to the operation of post-mineralization subsystems,which are affected by local factors such as landscape of the areas under study.Therefore,the effectiveness of the methods should be evaluated in every area for every targeted deposit.
