Based on the practice of oil and gas exploration in the Huizhou Sag of the Pearl River Mouth Basin,the geochemical indexes of source rocks were measured,the reservoir development morphology was restored,the rocks and ...Based on the practice of oil and gas exploration in the Huizhou Sag of the Pearl River Mouth Basin,the geochemical indexes of source rocks were measured,the reservoir development morphology was restored,the rocks and minerals were characterized microscopically,the measured trap sealing indexes were compared,the biomarker compounds of crude oil were extracted,the genesis of condensate gas was identified,and the reservoir-forming conditions were examined.On this basis,the Paleogene Enping Formation in the Huizhou 26 subsag was systematically analyzed for the potential of oil and gas resources,the development characteristics of large-scale high-quality conglomerate reservoirs,the trapping effectiveness of faults,the hydrocarbon migration and accumulation model,and the formation conditions and exploration targets of large-and medium-sized glutenite-rich oil and gas fields.The research results were obtained in four aspects.First,the Paleogene Wenchang Formation in the Huizhou 26 subsag develops extensive and thick high-quality source rocks of semi-deep to deep lacustrine subfacies,which have typical hydrocarbon expulsion characteristics of"great oil generation in the early stage and huge gas expulsion in the late stage",providing a sufficient material basis for hydrocarbon accumulation in the Enping Formation.Second,under the joint control of the steep slope zone and transition zone of the fault within the sag,the large-scale near-source glutenite reservoirs are highly heterogeneous,with the development scale dominated hierarchically by three factors(favorable facies zone,particle component,and microfracture).The(subaqueous)distributary channels near the fault system,with equal grains,a low mud content(<5%),and a high content of feldspar composition,are conducive to the development of sweet spot reservoirs.Third,the strike-slip pressurization trap covered by stable lake flooding mudstone is a necessary condition for oil and gas preservation,and the NE and nearly EW faults obliquely to the principal stress have the best control on traps.Fourth,the spatiotemporal configuration of high-quality source rocks,fault transport/sealing,and glutenite reservoirs controls the degree of hydrocarbon enrichment.From top to bottom,three hydrocarbon accumulation units,i.e.low-fill zone,transition zone,and high-fill zone,are recognized.The main area of the channel in the nearly pressurized source-connecting fault zone is favorable for large-scale hydrocarbon enrichment.The research results suggest a new direction for the exploration of large-scale glutenite-rich reservoirs in the Enping Formation of the Pearl River Mouth Basin,and present a major breakthrough in oil and gas exploration.展开更多
Based on the analysis of light hydrocarbon compositions of natural gas and regional comparison in combination with the chemical components and carbon isotopic compositions of methane,the indication of geochemical char...Based on the analysis of light hydrocarbon compositions of natural gas and regional comparison in combination with the chemical components and carbon isotopic compositions of methane,the indication of geochemical characteristics of light hydrocarbons on the migration features,dissolution and escape of natural gas from the Dongsheng gas field in the Ordos Basin is revealed,and the effect of migration on specific light hydrocarbon indexes is further discussed.The study indicates that,natural gas from the Lower Shihezi Formation(Pix)in the Dongsheng gas field displays higher iso-C5-7contents than n-C5-7contents,and the C6-7light hydrocarbons are composed of paraffins with extremely low aromatic contents(<0.4%),whereas the C7light hydrocarbons are dominated by methylcyclohexane,suggesting the characteristics of coal-derived gas with the influence by secondary alterations such as dissolution.The natural gas from the Dongsheng gas field has experienced free-phase migration from south to north and different degrees of dissolution after charging,and the gas in the Shiguhao area to the north of the Borjianghaizi fault has experienced apparent diffusion loss after accumulation.Long-distance migration in free phase results in the decrease of the relative contents of the methylcyclohexane in C7 light hydrocarbons and the toluene/n-heptane ratio,as well as the increase of the n-heptane/methylcyclohexane ratio and heptane values.The dissolution causes the increase of isoheptane values of the light hydrocarbons,whereas the diffusion loss of natural gas in the Shiguhao area results in the increase of n-C5-7contents compared to the iso-C5-7contents.展开更多
Exploration and development of large gas fields is an important way for a country to rapidly develop its natural gas industry.From 1991 to 2020,China discovered 68 new large gas fields,boosting its annual gas output t...Exploration and development of large gas fields is an important way for a country to rapidly develop its natural gas industry.From 1991 to 2020,China discovered 68 new large gas fields,boosting its annual gas output to 1925×108m3in 2020,making it the fourth largest gas-producing country in the world.Based on 1696 molecular components and carbon isotopic composition data of alkane gas in 70 large gas fields in China,the characteristics of carbon isotopic composition of alkane gas in large gas fields in China were obtained.The lightest and average values ofδ^(13)C_(1),δ13C2,δ13C3andδ13C4become heavier with increasing carbon number,while the heaviest values ofδ^(13)C_(1),δ13C2,δ13C3andδ13C4become lighter with increasing carbon number.Theδ^(13)C_(1)values of large gas fields in China range from-71.2‰to-11.4‰(specifically,from-71.2‰to-56.4‰for bacterial gas,from-54.4‰to-21.6‰for oil-related gas,from-49.3‰to-18.9‰for coal-derived gas,and from-35.6‰to-11.4‰for abiogenic gas).Based on these data,theδ^(13)C_(1)chart of large gas fields in China was plotted.Moreover,theδ^(13)C_(1)values of natural gas in China range from-107.1‰to-8.9‰,specifically,from-1071%o to-55.1‰for bacterial gas,from-54.4‰to-21.6‰for oil-related gas,from-49.3‰to-13.3‰for coal-derived gas,and from-36.2‰to-8.9‰for abiogenic gas.Based on these data,theδ^(13)C_(1)chart of natural gas in China was plotted.展开更多
The Zhongjiang gas field is a typical large gas field in terrigenous strata of the Western Sichuan Depression.It remains debatable which member of the Upper Triassic Xujiahe Formation served as the source rocks and ho...The Zhongjiang gas field is a typical large gas field in terrigenous strata of the Western Sichuan Depression.It remains debatable which member of the Upper Triassic Xujiahe Formation served as the source rocks and how significant the member contributed to the gas accumulations in the Zhongjiang gas field.In this study,we analyzed the essential characteristics of the Lower Jurassic source rocks and the geochemical features of light hydrocarbons in natural gas from the 2nd(T3χ^(2))and 4th members(T3χ^(4))of the Upper Triassic Xujiahe Formation(T3χ),as well as the Middle Jurassic Shaximiao(J2s)and Qianfoya(J2q)formations.Based on this,we explored the sources of the natural gas in the Zhongjiang gas field and determined the natural gas migration patterns and their effects on the properties of light hydrocarbons in the natural gas.The results indicate that the Lower Jurassic lacustrine source rocks of the Zhongjiang gas field contain humic organic matter,with vitrinite reflectance(R_(0))values ranging from 0.86%to 0.98%.Samples meeting the criterion for effective source rocks[total organic carbon(TOC)content≥0.75%]exhibited an average TOC content of merely 1.02%,suggesting significantly lower hydrocarbon generation potential than source rocks in the underlying T3x,which show higher thermal maturity and TOC contents.For natural gas samples from T3χ^(2),T3χ^(4),J2s,and J2q reservoirs,their C_(5-7)iso-alkane content was significantly higher than their n-alkane content,and their methylcyclohexane(MCH)index ranged from 59.0%to 77.3%,indicating the predominance of methylcyclohexane in C_(7)light hydrocarbons.As indicated by the origin identification and gas-source correlation based on the geochemical features of light hydrocarbons,the natural gas in the Zhongjiang gas field is typical coal-derived gas.The gas from the primary pay zone of the Shaximiao Formation,with significantly high K_(1),(P_(2)+N_(2))/C_(7),and P_(3)/C_(7)values,predominantly originated from the 5th member of the T3x and migrated in the free phase,with a small amount possibly sourced from the Lower Jurassic source rocks.The dissolution and adsorption during gas migration led to a decrease in the aromatic content in C_(6-7)light hydrocarbons and an increase in the isoheptane values.Therefore,their effects must be considered when determining the gas origin and thermal maturity based on the aromatic content in C_(6-7) light hydrocarbons and iso-heptane values.展开更多
In the Jiaoshiba block of the Fuling shale gas field,the employed reserves and recovery factor by primary well pattern are low,no obvious barrier is found in the development layer series,and layered development is dif...In the Jiaoshiba block of the Fuling shale gas field,the employed reserves and recovery factor by primary well pattern are low,no obvious barrier is found in the development layer series,and layered development is difficult.Based on the understanding of the main factors controlling shale gas enrichment and high production,the theory and technology of shale gas three-dimensional development,such as fine description and modeling of shale gas reservoir,optimization of three-dimensional development strategy,highly efficient drilling with dense well pattern,precision fracturing and real-time control,are discussed.Three-dimensional development refers to the application of optimal and fast drilling and volume fracturing technologies,depending upon the sedimentary characteristics,reservoir characteristics and sweet spot distribution of shale gas,to form"artificial gas reservoir"in a multidimensional space,so as to maximize the employed reserves,recovery factor and yield rate of shale gas development.In the research on shale gas three-dimensional development,the geological+engineering sweet spot description is fundamental,the collaborative optimization of natural fractures and artificial fractures is critical,and the improvement of speed and efficiency in drilling and fracturing engineering is the guarantee.Through the implementation of three-dimensional development,the overall recovery factor in the Jiaoshiba block has increased from 12.6%to 23.3%,providing an important support for the continuous and stable production of the Fuling shale gas field.展开更多
This study focused on the quantitative analysis of the petrophysical parameters in characterizing the reservoir properties of the Srikail gas field using multi-scale wireline logs.Petrophysical parameters(shale volume...This study focused on the quantitative analysis of the petrophysical parameters in characterizing the reservoir properties of the Srikail gas field using multi-scale wireline logs.Petrophysical parameters(shale volume,porosity,water saturation and hydrocarbon saturation)were estimated from the combination of gamma ray log,resistivity log,density log and neutron log for three hydrocarbon(gas)-bearing zones at well#3.At the first time,log records at 0.1 m and 0.2 m intervals were read for this study.Result showed the average shale volume is 21.07%,53.67%and 51.71%for zone-1,zone-2 and zone-3,respectively.For these zones,the estimated average porosity was 35.89%,29.83%and 28.76%,respectively.The average water saturation of 31.54%,16.83%and 23.39%and average hydrocarbon saturation of 68.46%,83.17%and 76.61%were calculated for zone-1,zone-2 and zone-3,respectively.Thus zone-2 is regarded the most productive zone of well#3.It was found that the values of some parameters(porosity,hydrocarbon saturation and permeability)are higher than the existing results.Therefore,this study confirmed that the log reading at minute/close interval provides better quantitive values of the reservoir’s petrophysical properties.It is expected that this result will contribute to the national gas field development program in future.展开更多
In order to determine the genesis and the factors that control the low-porosity and low- permeability sandstone reservoirs in the eastern Sulige Gas Field in the Ordos Basin, systematic studies on the sedimentary faci...In order to determine the genesis and the factors that control the low-porosity and low- permeability sandstone reservoirs in the eastern Sulige Gas Field in the Ordos Basin, systematic studies on the sedimentary facies and diagenesis were conducted by means of analysis of cores, thin sections, fluid inclusions, X-ray diffraction, cathode luminescence and scanning electron microscope. It was found that the sand bodies of the major gas reservoirs in the Shan1 section (P1S1) and the He8 section (P2H8) were formed during the Permian as sedimentary facies such as braided-channel bars, braided-river channels and point bars of a meandering river. Four types of diagenetic facies developed subsequently: in order from the best to the poorest properties these are type A (weak compaction, early calcite cement-chlorite film facies), type B (moderate compaction, quartz overgrowth-feldspar corrosion-kaolinite filling facies), type C (strong compaction, late calcite cement-quartz corrosion facies) and type D (matrix filling and strong compaction facies). This diagenesis is undoubtedly the main reason for the poor reservoir properties of sandstone reservoirs, but the sedimentary facies are the underlying factors that greatly affect the diagenesis and thus the reservoir performance. Favorable diagenetic facies developed mainly in relatively small lithofacies such as braided-river channels, channel bars and point bars. The vertical distribution of the physical properties and the diagenetic facies of the reservoirs are related to the stratigraphic succession. Most of the sandstones between mudstones and thin beds of sandstone are unfavorable diagenetic facies. Analyses indicate that siliceous cementation can hardly be stopped by hydrocarbon filling. Authigenic chlorite could hardly protect the primary porosity. It not only occupies pore space, but also blocks pathways through sandstone reservoirs, so that it has significant influence on the permeability. Authigenic chlorite cannot be used as a marker for a specific sedimentary facies because it can be formed in different sedimentary facies, but it indicates high hydrodynamic conditions and presence of favorable reservoirs.展开更多
Comparisons have been made among lithology, diagenesis, and reservoir characteristics of gas-bearing and non-gas-bearing ones in the Sulige gas field of the Ordos Basin based on the laboratory analysis of thin section...Comparisons have been made among lithology, diagenesis, and reservoir characteristics of gas-bearing and non-gas-bearing ones in the Sulige gas field of the Ordos Basin based on the laboratory analysis of thin sections, scanning electron microscope, and liquid inclusion of the reservoirs. The reservoirs of the Sulige gas field are now in the middle stage of diagenesis and have undergone compaction, cementation and dissolution. The secondary pore of the reservoir originated from the dissolution of the feldspar and tuff because of the organic acid action from the source rocks during the diagenetic middle stage. Gas-bearing reservoirs are common in soluble pore diagenetic facies of coarse detritus quartzose sandstone, whereas non-gas-bearing ones are common in tense compaction diagenetic facies of mud-bearing medium-fine detritus quartzose sandstone and residual intergranular pore diagenetic facies of mud-bearing medium-coarse detritus quartzose sandstone. The secondary pore is developed in gas-bearing reservoirs of the Sulige gas-field as the medium-coarse grain reservoirs formed in a powerful sedimentary environment and experienced strong dissolution. However, the sediments of fine grain size form the non-gas-bearing reservoirs because of less residual primary pore and secondary pore.展开更多
The molecular compositions and stable carbon and hydrogen isotopic compositions of natural gas from the Xinchang gas field in the Sichuan Basin were investigated to determine the genetic types. The natural gas is main...The molecular compositions and stable carbon and hydrogen isotopic compositions of natural gas from the Xinchang gas field in the Sichuan Basin were investigated to determine the genetic types. The natural gas is mainly composed of methane (88.99%-98.01%), and the dryness coefficient varies between 0.908 and 0.997. The gas generally displays positive alkane carbon and hydrogen isotopic series. The geochemical characteristics and gas-source correlation indicate that the gases stored in the 5th member of the Upper Triassic Xujiahe Formation are coal-type gases which are derived from source rocks in the stratum itself. The gases reservoired in the 4th member of the Xujiahe Formation and Jurassic strata in the Xinchang gas field are also coal-type gases that are derived from source rocks in the 3rd and 4th members of the Xujiahe Formation. The gases reservoired in the 2nd member of the Upper Triassic Xujiahe Formation are mainly coal-type gases with small amounts of oil-type gas that is derived from source rocks in the stratum itself. This is accompanied by a small amount of contribution brought by source rocks in the Upper Triassic Ma'antang and Xiaotangzi formations. The gases reservoired in the 4th member of the Middle Triassic Leikoupo Formation are oil-type gases and are believed to be derived from the secondary cracking of oil which is most likely to be generated from the Upper Permian source rocks.展开更多
The genesis of a reservoir is a result of the combined action of deposition, diagenesis, tectonic reworking, and interaction of rock and fluid and the evolutionary environment. We discuss the genetic and evolution mec...The genesis of a reservoir is a result of the combined action of deposition, diagenesis, tectonic reworking, and interaction of rock and fluid and the evolutionary environment. We discuss the genetic and evolution mechanism of a low-permeability reservoir bed of the Xujiahe Formation in the western Sichuan Depression on the basis of the study of diagenesis, diagenetic reservoir facies and the diagenetic evolution sequence. The research indicated that this reservoir bed can be divided into five types of diagenetic reservoir facies, namely strong dissolution, chlorite-lined intergranular pores, compaction and pressure solution, carbonate cementation and secondary quartz increase. There are, however, just two diagenetic reservoir facies which provide low-permeability reservoir beds, namely strong dissolution and chlorite-lined intergranular pores. We also analyzed their diagenetic evolution sequences and the origin of the low-permeability reservoir bed. Besides, it was also indicated that the composition and structure of sandstones, types of sedimentary microfacies, diagenesis history as well as the tectonic reworking in later periods are the main factors controlling the formation of the low-permeability reservoir bed. The above- mentioned factors establish the foundation for the forecasting the distribution of high quality reservoir beds.展开更多
Detailed geochemistry studies were conducted to investigate the origin of solid bitumens and hydrocarbon gases in the giant Puguang gas field. Two types of solid bitumens were recognized: low sulfur content, low refl...Detailed geochemistry studies were conducted to investigate the origin of solid bitumens and hydrocarbon gases in the giant Puguang gas field. Two types of solid bitumens were recognized: low sulfur content, low reflectance (LSLR) solid bitumens in sandstone reservoirs in the Xujiahe Formation and high sulfur content, high reflectance (HSHR) solid bitumens in the carbonate reservoirs in the Lower Triassic Feixianguan and Upper Permian Changxing formations. Solid bitumens in the Upper Triassic Xujiahe Formation correlate well with extracts from the Upper Triassic to Jurassic nonmarine source rocks in isotopic composition of the saturated and aromatic fractions and biomarker distribution. Solid bitumens in the Feixianguan and Changxing formations are distinctly different from extracts from the Cambrian and Silurian rocks but display reasonable correlation with extracts from the Upper Permian source rocks both in isotopic composition of the saturated and aromatic fractions and in biomarker distribution, suggesting that the Permian especially the Upper Permian Longtan Formation was the main source of solid bitumens in the carbonate reservoirs in the Feixianguan and Changxing formations in the Puguang gas field. Chemical and isotopic composition of natural gases indicates that the majority of hydrocarbon gases originated from sapropelic organic matter and was the products of thermal cracking of accumulated oils. This study indicates that source rock dominated by sapropelic organic matter existed in the Upper Permian and had made major contribution to the giant Puguang gas field, which has important implication for petroleum exploration in marine sequences in South China.展开更多
In a very gentle platform-margin paleogeographic environment, platform-margin reef flat facies carbonate reservoir rocks were developed in the Changxing Formation of Yuanba field. Later weak structural evolution and d...In a very gentle platform-margin paleogeographic environment, platform-margin reef flat facies carbonate reservoir rocks were developed in the Changxing Formation of Yuanba field. Later weak structural evolution and diagenetic evolution caused the Changxing Formation to form lithologic traps, with good reservoirs such as dissolved bioclastic dolostone and dissolved pore dolostone. The Changxing Formation gas reservoir is a pseudo-layered porous lithologic gas reservoir under pressure depletion drive, with high H2S and moderate CO2 contents. This paper predictes that the conducting system for the Changxing Formation gas reservoir is possibly composed of the pores and microfractures in the Changxing Formation reservoir, the top erosional surface of the Changxing Formation, as well as the micropores and microfractures in the underlying formations. The Changxing Formation reservoir has experienced 3 hydrocarbon charging stages. This paper suggests that diffusion is the major formation mechanism for this gas reservoir. In the Middle and Late Yanshanian, the Yuanba area entered the major gas charging stage. The gas migrated mainly through diffusion and with the assistance of seepage flow in small faults and microfractures from the source rocks and the other oil-bearing strata to the Changxing Formation carbonate reservoir rocks, forming lithologic gas pools. In the Himalayan Epoch, the lithologic traps were uplifted as a whole without strong modification or overlapping, and were favorable for gas preservation.展开更多
The static flux chamber method was applied to study natural emissions of methane to the atmosphere in the Luntai fault region of Yakela Condensed Oil/Gas Field in the Tarim Basin, Xinjiang Municipality, northwestern C...The static flux chamber method was applied to study natural emissions of methane to the atmosphere in the Luntai fault region of Yakela Condensed Oil/Gas Field in the Tarim Basin, Xinjiang Municipality, northwestern China. Using an online method, which couples together a gas chromatography/high-temperature conversion/isotope ratio mass spectrometry (GC/C/MS), 13^C/12^C ratios of methane in flux chambers were measured and showed that methane gases are liable to migrate from deep oil/gas reservoirs to the surface through fault regions and that a part of the migrated methane, which remains unoxidized can be emitted into the atmosphere. Methane emission rates were found to be highest in the mornings, lowest in the afternoons and then increase gradually in the evenings. Methane emission rates varied dramatically in different locations in the fault region. The highest methane emission rate was 10.96 mg/m^2·d, the lowest 4.38 mg/m^2, and the average 7.55 mg/ m^2·d. The 13^C/12^C ratios of the methane in the flux chambers became heavier as the enclosed methane concentrations increased gradually, which reveals that methane released from the fault region might come from thermogenic methane of the deep condensed oil/gas reservoir.展开更多
Multi-layer sandstone reservoirs occur globally and are currently in international production. The 3D characteristics of these reservoirs are too complicated to be accurately delineated by general structural-facies-re...Multi-layer sandstone reservoirs occur globally and are currently in international production. The 3D characteristics of these reservoirs are too complicated to be accurately delineated by general structural-facies-reservoir modelling. In view of the special geological features, such as the vertical architecture of sandstone and mudstone interbeds, the lateral stable sedimentation and the strong heterogeneity of reservoir poroperm and fluid distribution, we developed a new three-stage and six-phase procedure for 3D characterization of multi-layer sandstone reservoirs. The procedure comprises two-phase structural modelling, two-phase facies modelling and modelling of two types of reservoir properties. Using this procedure, we established models of the formation structure, sand body structure and microfacies, reservoir facies and properties including porosity, permeability and gas saturation and provided a 3D fine-scale, systematic characterization of the Sebei multi-layer sandstone gas field, China. This new procedure, validated by the Sebei gas field, can be applied to characterize similar multi-layer sandstone reservoirs.展开更多
The Callovian-Oxfordian carbonate reservoirs are the most important hydrocarbon reservoir in the Samandepe gas field,Amu Darya basin,Turkmenistan.Based on the analysis of Fe,Mn and Sr trace elements,and carbon,oxygen ...The Callovian-Oxfordian carbonate reservoirs are the most important hydrocarbon reservoir in the Samandepe gas field,Amu Darya basin,Turkmenistan.Based on the analysis of Fe,Mn and Sr trace elements,and carbon,oxygen and strontium isotopes,the genesis and evolutionary characteristics of the carbonate reservoirs were studied,and the conclusions were follows:1) Sustained transgressive-regressive cycles played an important role during Callovian-Oxfordian.The reservoir of reef-bank facies was well developed in the period of transgression,while the regional dense cap rocks developed in the period of regression;2) The 87 Sr/86 Sr ratio measured from rudist shells yields an age of 157.2 Ma according to the global strontium isotope curve;3) As diagenetic intensity increased,δ 13 C changed little,and δ 18 O showed strong negative deviation but was still limited to the range of Late Jurassic seawater.High Fe and Sr contents,and low Mn content,and the evolutionary trend of δ 13 C and δ 18 O all indicate that diagenesis occurred in a relatively confined environment,where the fluids were relatively reducing and contained hot brine.The stage of diagenesis reached is mesodiagenesis,which is very favorable for preservation of primary pores in carbonates;4) Strong dissolution of reef limestones,burial dolomitization and hydrothermal calcite precipitation were all the results of the interaction between the 87 Sr-rich diagenetic fluid and rocks;5) The analysis results of isotopes,fluid inclusions and vitrinite reflectance show that the diagenetic fluid was compaction-released water that originated from the deep,coal-bearing clastic strata.展开更多
A static flux chamber method was applied to study natural emissions of methane into the atmosphere in the Yakela condensed oil/gas field in Talimu Basin, Xinjiang, China. Using an online method, which couples a gas ch...A static flux chamber method was applied to study natural emissions of methane into the atmosphere in the Yakela condensed oil/gas field in Talimu Basin, Xinjiang, China. Using an online method, which couples a gas chromatography/high-temperature conversion/isotope ratio mass spectrometry (GC/C/MS) together, the 13C/12C ratios of methane in the flux chambers were measured. The results demonstrated that methane gases were liable to migrate from deep oil/gas reservoir to the surface through microseepage and p...展开更多
In this review on the exploration and development process of the Shunbei ultra-deep carbonate oil and gas field in the Tarim Basin, the progress of exploration and development technologies during the National 13th Fiv...In this review on the exploration and development process of the Shunbei ultra-deep carbonate oil and gas field in the Tarim Basin, the progress of exploration and development technologies during the National 13th Five-Year Plan of China has been summarized systematically, giving important guidance for the exploration and development of ultra-deep marine carbonate reservoirs in China and abroad. Through analyzing the primary geological factors of “hydrocarbon generation-reservoir formation-hydrocarbon accumulation” of ancient and superposed basin comprehensively and dynamically, we point out that because the Lower Cambrian Yuertusi Formation high-quality source rocks have been located in a low-temperature environment for a long time, they were capable of generating hydrocarbon continuously in late stage, providing ideal geological conditions for massive liquid hydrocarbon accumulation in ultra-deep layers. In addition, strike-slip faults developed in tectonically stable areas have strong control on reservoir formation and hydrocarbon accumulation in this region. With these understandings, the exploration focus shifted from the two paleo-uplifts located in the north and the south to the Shuntuoguole lower uplift located in between and achieved major hydrocarbon discoveries. Through continuing improvement of seismic exploration technologies for ultra-deep carbonates in desert, integrated technologies including seismic acquisition in ultra-deep carbonates,seismic imaging of strike-slip faults and the associated cavity-fracture systems, detailed structural interpretation of strike-slip faults, characterization and quantitative description of fault-controlled cavities and fractures, description of fault-controlled traps and target optimization have been established. Geology-engineering integration including well trajectory optimization,high efficiency drilling, completion and reservoir reformation technologies has provided important support for exploration and development of the Shunbei oil and gas field.展开更多
Solid bitumens were found throughout the carbonate reservoirs in the Puguang gas field, the largest gas field so far found in marine carbonates in China, confirming that the Puguang gas field evolved from a paleo-oil ...Solid bitumens were found throughout the carbonate reservoirs in the Puguang gas field, the largest gas field so far found in marine carbonates in China, confirming that the Puguang gas field evolved from a paleo-oil reservoir. The fluid conduit system at the time of intensive oil accumulation in the field was reconstructed, and petroleum migration pathways were modeled using a 3-D model and traced by geochemical parameters. The forward modeling and inversion tracing coincided with each other and both indicated that oils accumulated in the Puguang-Dongyuezhai structure originated from a generative kitchen to the northwest of the Puguang gas field. The deposition of organic-rich Upper Permian source rocks dominated by sapropelic organic matter in the Northeast Sichuan Basin, the development of fluid conduit system that was vertically near-source rock and laterally near-generative kitchen, and the focusing of oils originated from a large area of the generative kitchen, were the three requirements for the formation of the giant paleo-oil reservoir from which the giant Puguang gas field evolved. The Puguang gas field had experienced a three-stage evolution. The post-accumulation processes, especially the organic-inorganic interaction in the hydrocarbon-water-rock system, had not only profoundly altered the composition and characteristics of the petroleum fluids, but also obviously changed the physicochemical conditions in the reservoir and resulted in complicated precipitation and solution of carbonate minerals.展开更多
The effect of HCO3^- concentration on CO2 corrosion was investigated by polarization measurement of potentiodynamic scans and weight-loss method, Under the conditions of high pressure and high temperature, the corrosi...The effect of HCO3^- concentration on CO2 corrosion was investigated by polarization measurement of potentiodynamic scans and weight-loss method, Under the conditions of high pressure and high temperature, the corrosion rate of steel X65 decreased with the increase of HCO3^- concentration, while pH of solution increased. SEM, EDS, and XRD results of the corrosion scales indir cated that the typical FeCO3 crystallite was found at low HCO3^- concentration but Ca(Fe,Mg)(CO3)2 was found at high HCO3^- con- centration. Ca^2+ and Mg^2+ are precipitated preferential to Fe^2+ at high pH value. Potentiodynamic polarization curves showed that the cathodic current density decreases with the increase of HCO3^- concentration at low HCO3^- concentration. When the HCO3^- concentration reaches 0.126 mol/L, increasing HCO3^- concentration promotes cathodic reactions. Anodic behavior is an active process at low HCO3^- concentration and the anodic current density decreases with the increase of HCO3^- concentration. An evident active-passive behavior is exhibited in anodic process at 0.126 mol/L HCO3^-.展开更多
There are rich oil and gas resources in marine carbonate strata worldwide.Although most of the oil and gas reserves discovered so far are mainly distributed in Mesozoic,Cenozoic,and upper Paleozoic strata,oil and gas ...There are rich oil and gas resources in marine carbonate strata worldwide.Although most of the oil and gas reserves discovered so far are mainly distributed in Mesozoic,Cenozoic,and upper Paleozoic strata,oil and gas exploration in the Proterozoic–Lower Paleozoic(PLP)strata—the oldest marine strata—has been very limited.To more clearly understand the oil and gas formation conditions and distributions in the PLP marine carbonate strata,we analyzed and characterized the petroleum geological conditions,oil and gas reservoir types,and their distributions in thirteen giant oil and gas fields worldwide.This study reveals the main factors controlling their formation and distribution.Our analyses show that the source rocks for these giant oil and gas fields are mainly shale with a great abundance of type I–II organic matter and a high thermal evolution extent.The reservoirs are mainly gas reservoirs,and the reservoir rocks are dominated by dolomite.The reservoir types are mainly karst and reef–shoal bodies with well-developed dissolved pores and cavities,intercrystalline pores,and fractures.These reservoirs arehighly heterogeneous.The burial depth of the reservoirs is highly variable and somewhat negatively correlated to the porosity.The cap rocks are mainly thick evaporites and shales,with the thickness of the cap rocks positively correlated to the oil and gas reserves.The development of high-quality evaporite cap rock is highly favorable for oil and gas preservation.We identified four hydrocarbon generation models,and that the major source rocks have undergone a long period of burial and thermal evolution and are characterized by early and long periods of hydrocarbon generation.These giant oil and gas fields have diverse types of reservoirs and are mainly distributed in paleo-uplifts,slope zones,and platform margin reef-shoal bodies.The main factors that control their formation and distribution were identified,enabling the prediction of new favorable areas for oil and gas exploration.展开更多
基金Supported by the CNOOC Major Technology Project During the 14th FIVE-YEAR PLAN PERIOD(KJGG2022-0403)CNOOC Major Technology Project(KJZH-2021-0003-00).
文摘Based on the practice of oil and gas exploration in the Huizhou Sag of the Pearl River Mouth Basin,the geochemical indexes of source rocks were measured,the reservoir development morphology was restored,the rocks and minerals were characterized microscopically,the measured trap sealing indexes were compared,the biomarker compounds of crude oil were extracted,the genesis of condensate gas was identified,and the reservoir-forming conditions were examined.On this basis,the Paleogene Enping Formation in the Huizhou 26 subsag was systematically analyzed for the potential of oil and gas resources,the development characteristics of large-scale high-quality conglomerate reservoirs,the trapping effectiveness of faults,the hydrocarbon migration and accumulation model,and the formation conditions and exploration targets of large-and medium-sized glutenite-rich oil and gas fields.The research results were obtained in four aspects.First,the Paleogene Wenchang Formation in the Huizhou 26 subsag develops extensive and thick high-quality source rocks of semi-deep to deep lacustrine subfacies,which have typical hydrocarbon expulsion characteristics of"great oil generation in the early stage and huge gas expulsion in the late stage",providing a sufficient material basis for hydrocarbon accumulation in the Enping Formation.Second,under the joint control of the steep slope zone and transition zone of the fault within the sag,the large-scale near-source glutenite reservoirs are highly heterogeneous,with the development scale dominated hierarchically by three factors(favorable facies zone,particle component,and microfracture).The(subaqueous)distributary channels near the fault system,with equal grains,a low mud content(<5%),and a high content of feldspar composition,are conducive to the development of sweet spot reservoirs.Third,the strike-slip pressurization trap covered by stable lake flooding mudstone is a necessary condition for oil and gas preservation,and the NE and nearly EW faults obliquely to the principal stress have the best control on traps.Fourth,the spatiotemporal configuration of high-quality source rocks,fault transport/sealing,and glutenite reservoirs controls the degree of hydrocarbon enrichment.From top to bottom,three hydrocarbon accumulation units,i.e.low-fill zone,transition zone,and high-fill zone,are recognized.The main area of the channel in the nearly pressurized source-connecting fault zone is favorable for large-scale hydrocarbon enrichment.The research results suggest a new direction for the exploration of large-scale glutenite-rich reservoirs in the Enping Formation of the Pearl River Mouth Basin,and present a major breakthrough in oil and gas exploration.
基金Supported by the National Natural Science Foundation of China(42172149,U2244209)Sinopec Science and Technology Research Project(P23230,P22132)。
文摘Based on the analysis of light hydrocarbon compositions of natural gas and regional comparison in combination with the chemical components and carbon isotopic compositions of methane,the indication of geochemical characteristics of light hydrocarbons on the migration features,dissolution and escape of natural gas from the Dongsheng gas field in the Ordos Basin is revealed,and the effect of migration on specific light hydrocarbon indexes is further discussed.The study indicates that,natural gas from the Lower Shihezi Formation(Pix)in the Dongsheng gas field displays higher iso-C5-7contents than n-C5-7contents,and the C6-7light hydrocarbons are composed of paraffins with extremely low aromatic contents(<0.4%),whereas the C7light hydrocarbons are dominated by methylcyclohexane,suggesting the characteristics of coal-derived gas with the influence by secondary alterations such as dissolution.The natural gas from the Dongsheng gas field has experienced free-phase migration from south to north and different degrees of dissolution after charging,and the gas in the Shiguhao area to the north of the Borjianghaizi fault has experienced apparent diffusion loss after accumulation.Long-distance migration in free phase results in the decrease of the relative contents of the methylcyclohexane in C7 light hydrocarbons and the toluene/n-heptane ratio,as well as the increase of the n-heptane/methylcyclohexane ratio and heptane values.The dissolution causes the increase of isoheptane values of the light hydrocarbons,whereas the diffusion loss of natural gas in the Shiguhao area results in the increase of n-C5-7contents compared to the iso-C5-7contents.
基金Supported by the National Natural Science Foundation of China(41472120)General Project of National Natural Science Foundation of China(42272188)+1 种基金Special Fund of PetroChina and New Energy Branch(2023YQX10101)Petrochemical Joint Fund of Fund Committee(U20B6001)。
文摘Exploration and development of large gas fields is an important way for a country to rapidly develop its natural gas industry.From 1991 to 2020,China discovered 68 new large gas fields,boosting its annual gas output to 1925×108m3in 2020,making it the fourth largest gas-producing country in the world.Based on 1696 molecular components and carbon isotopic composition data of alkane gas in 70 large gas fields in China,the characteristics of carbon isotopic composition of alkane gas in large gas fields in China were obtained.The lightest and average values ofδ^(13)C_(1),δ13C2,δ13C3andδ13C4become heavier with increasing carbon number,while the heaviest values ofδ^(13)C_(1),δ13C2,δ13C3andδ13C4become lighter with increasing carbon number.Theδ^(13)C_(1)values of large gas fields in China range from-71.2‰to-11.4‰(specifically,from-71.2‰to-56.4‰for bacterial gas,from-54.4‰to-21.6‰for oil-related gas,from-49.3‰to-18.9‰for coal-derived gas,and from-35.6‰to-11.4‰for abiogenic gas).Based on these data,theδ^(13)C_(1)chart of large gas fields in China was plotted.Moreover,theδ^(13)C_(1)values of natural gas in China range from-107.1‰to-8.9‰,specifically,from-1071%o to-55.1‰for bacterial gas,from-54.4‰to-21.6‰for oil-related gas,from-49.3‰to-13.3‰for coal-derived gas,and from-36.2‰to-8.9‰for abiogenic gas.Based on these data,theδ^(13)C_(1)chart of natural gas in China was plotted.
基金funded by the National Natural Science Foundation of China(No.42172149,No.U2244209)the SINOPEC Science and Technology Project(No.P22132,No.P21077-1).
文摘The Zhongjiang gas field is a typical large gas field in terrigenous strata of the Western Sichuan Depression.It remains debatable which member of the Upper Triassic Xujiahe Formation served as the source rocks and how significant the member contributed to the gas accumulations in the Zhongjiang gas field.In this study,we analyzed the essential characteristics of the Lower Jurassic source rocks and the geochemical features of light hydrocarbons in natural gas from the 2nd(T3χ^(2))and 4th members(T3χ^(4))of the Upper Triassic Xujiahe Formation(T3χ),as well as the Middle Jurassic Shaximiao(J2s)and Qianfoya(J2q)formations.Based on this,we explored the sources of the natural gas in the Zhongjiang gas field and determined the natural gas migration patterns and their effects on the properties of light hydrocarbons in the natural gas.The results indicate that the Lower Jurassic lacustrine source rocks of the Zhongjiang gas field contain humic organic matter,with vitrinite reflectance(R_(0))values ranging from 0.86%to 0.98%.Samples meeting the criterion for effective source rocks[total organic carbon(TOC)content≥0.75%]exhibited an average TOC content of merely 1.02%,suggesting significantly lower hydrocarbon generation potential than source rocks in the underlying T3x,which show higher thermal maturity and TOC contents.For natural gas samples from T3χ^(2),T3χ^(4),J2s,and J2q reservoirs,their C_(5-7)iso-alkane content was significantly higher than their n-alkane content,and their methylcyclohexane(MCH)index ranged from 59.0%to 77.3%,indicating the predominance of methylcyclohexane in C_(7)light hydrocarbons.As indicated by the origin identification and gas-source correlation based on the geochemical features of light hydrocarbons,the natural gas in the Zhongjiang gas field is typical coal-derived gas.The gas from the primary pay zone of the Shaximiao Formation,with significantly high K_(1),(P_(2)+N_(2))/C_(7),and P_(3)/C_(7)values,predominantly originated from the 5th member of the T3x and migrated in the free phase,with a small amount possibly sourced from the Lower Jurassic source rocks.The dissolution and adsorption during gas migration led to a decrease in the aromatic content in C_(6-7)light hydrocarbons and an increase in the isoheptane values.Therefore,their effects must be considered when determining the gas origin and thermal maturity based on the aromatic content in C_(6-7) light hydrocarbons and iso-heptane values.
基金Supported by the Sinopec Science and Technology Project(P22183).
文摘In the Jiaoshiba block of the Fuling shale gas field,the employed reserves and recovery factor by primary well pattern are low,no obvious barrier is found in the development layer series,and layered development is difficult.Based on the understanding of the main factors controlling shale gas enrichment and high production,the theory and technology of shale gas three-dimensional development,such as fine description and modeling of shale gas reservoir,optimization of three-dimensional development strategy,highly efficient drilling with dense well pattern,precision fracturing and real-time control,are discussed.Three-dimensional development refers to the application of optimal and fast drilling and volume fracturing technologies,depending upon the sedimentary characteristics,reservoir characteristics and sweet spot distribution of shale gas,to form"artificial gas reservoir"in a multidimensional space,so as to maximize the employed reserves,recovery factor and yield rate of shale gas development.In the research on shale gas three-dimensional development,the geological+engineering sweet spot description is fundamental,the collaborative optimization of natural fractures and artificial fractures is critical,and the improvement of speed and efficiency in drilling and fracturing engineering is the guarantee.Through the implementation of three-dimensional development,the overall recovery factor in the Jiaoshiba block has increased from 12.6%to 23.3%,providing an important support for the continuous and stable production of the Fuling shale gas field.
基金the K.C. Wong Education Foundation (GJTD-2019-04)the Chinese Academy of Sciences as President ’s International Fellowship Initiative (PIFI) for a Postdoctoral fellow to M. Moklesur Rahman (2019PE0025).
文摘This study focused on the quantitative analysis of the petrophysical parameters in characterizing the reservoir properties of the Srikail gas field using multi-scale wireline logs.Petrophysical parameters(shale volume,porosity,water saturation and hydrocarbon saturation)were estimated from the combination of gamma ray log,resistivity log,density log and neutron log for three hydrocarbon(gas)-bearing zones at well#3.At the first time,log records at 0.1 m and 0.2 m intervals were read for this study.Result showed the average shale volume is 21.07%,53.67%and 51.71%for zone-1,zone-2 and zone-3,respectively.For these zones,the estimated average porosity was 35.89%,29.83%and 28.76%,respectively.The average water saturation of 31.54%,16.83%and 23.39%and average hydrocarbon saturation of 68.46%,83.17%and 76.61%were calculated for zone-1,zone-2 and zone-3,respectively.Thus zone-2 is regarded the most productive zone of well#3.It was found that the values of some parameters(porosity,hydrocarbon saturation and permeability)are higher than the existing results.Therefore,this study confirmed that the log reading at minute/close interval provides better quantitive values of the reservoir’s petrophysical properties.It is expected that this result will contribute to the national gas field development program in future.
基金supported by the major national special projects for technology:Enrichment Regularity and Distribution Prediction for Hydrocarbon of Key Clastic Rocks in Central and Western Regions (Approval No.: 2011ZX05002-006)National Natural Science Foundation of China (Approval No.: 41372135 and 41402120)Research and Innovation Team Plan Fund of Shandong University of Science and Technology (Approval No.: 2010KYTD103)
文摘In order to determine the genesis and the factors that control the low-porosity and low- permeability sandstone reservoirs in the eastern Sulige Gas Field in the Ordos Basin, systematic studies on the sedimentary facies and diagenesis were conducted by means of analysis of cores, thin sections, fluid inclusions, X-ray diffraction, cathode luminescence and scanning electron microscope. It was found that the sand bodies of the major gas reservoirs in the Shan1 section (P1S1) and the He8 section (P2H8) were formed during the Permian as sedimentary facies such as braided-channel bars, braided-river channels and point bars of a meandering river. Four types of diagenetic facies developed subsequently: in order from the best to the poorest properties these are type A (weak compaction, early calcite cement-chlorite film facies), type B (moderate compaction, quartz overgrowth-feldspar corrosion-kaolinite filling facies), type C (strong compaction, late calcite cement-quartz corrosion facies) and type D (matrix filling and strong compaction facies). This diagenesis is undoubtedly the main reason for the poor reservoir properties of sandstone reservoirs, but the sedimentary facies are the underlying factors that greatly affect the diagenesis and thus the reservoir performance. Favorable diagenetic facies developed mainly in relatively small lithofacies such as braided-river channels, channel bars and point bars. The vertical distribution of the physical properties and the diagenetic facies of the reservoirs are related to the stratigraphic succession. Most of the sandstones between mudstones and thin beds of sandstone are unfavorable diagenetic facies. Analyses indicate that siliceous cementation can hardly be stopped by hydrocarbon filling. Authigenic chlorite could hardly protect the primary porosity. It not only occupies pore space, but also blocks pathways through sandstone reservoirs, so that it has significant influence on the permeability. Authigenic chlorite cannot be used as a marker for a specific sedimentary facies because it can be formed in different sedimentary facies, but it indicates high hydrodynamic conditions and presence of favorable reservoirs.
基金financed by the National Key Basic Program (National 973 project,2001CB209100,2006CB202306)
文摘Comparisons have been made among lithology, diagenesis, and reservoir characteristics of gas-bearing and non-gas-bearing ones in the Sulige gas field of the Ordos Basin based on the laboratory analysis of thin sections, scanning electron microscope, and liquid inclusion of the reservoirs. The reservoirs of the Sulige gas field are now in the middle stage of diagenesis and have undergone compaction, cementation and dissolution. The secondary pore of the reservoir originated from the dissolution of the feldspar and tuff because of the organic acid action from the source rocks during the diagenetic middle stage. Gas-bearing reservoirs are common in soluble pore diagenetic facies of coarse detritus quartzose sandstone, whereas non-gas-bearing ones are common in tense compaction diagenetic facies of mud-bearing medium-fine detritus quartzose sandstone and residual intergranular pore diagenetic facies of mud-bearing medium-coarse detritus quartzose sandstone. The secondary pore is developed in gas-bearing reservoirs of the Sulige gas-field as the medium-coarse grain reservoirs formed in a powerful sedimentary environment and experienced strong dissolution. However, the sediments of fine grain size form the non-gas-bearing reservoirs because of less residual primary pore and secondary pore.
基金financially supported by the National Natural Science Foundation of China (grants No.41625009, 41302118 and U1663201)the National Key Foundational Research and Development Project (Grant No:2016YFB0600804)the National Science & Technology Special Project (grant No.2016ZX05002-006)
文摘The molecular compositions and stable carbon and hydrogen isotopic compositions of natural gas from the Xinchang gas field in the Sichuan Basin were investigated to determine the genetic types. The natural gas is mainly composed of methane (88.99%-98.01%), and the dryness coefficient varies between 0.908 and 0.997. The gas generally displays positive alkane carbon and hydrogen isotopic series. The geochemical characteristics and gas-source correlation indicate that the gases stored in the 5th member of the Upper Triassic Xujiahe Formation are coal-type gases which are derived from source rocks in the stratum itself. The gases reservoired in the 4th member of the Xujiahe Formation and Jurassic strata in the Xinchang gas field are also coal-type gases that are derived from source rocks in the 3rd and 4th members of the Xujiahe Formation. The gases reservoired in the 2nd member of the Upper Triassic Xujiahe Formation are mainly coal-type gases with small amounts of oil-type gas that is derived from source rocks in the stratum itself. This is accompanied by a small amount of contribution brought by source rocks in the Upper Triassic Ma'antang and Xiaotangzi formations. The gases reservoired in the 4th member of the Middle Triassic Leikoupo Formation are oil-type gases and are believed to be derived from the secondary cracking of oil which is most likely to be generated from the Upper Permian source rocks.
文摘The genesis of a reservoir is a result of the combined action of deposition, diagenesis, tectonic reworking, and interaction of rock and fluid and the evolutionary environment. We discuss the genetic and evolution mechanism of a low-permeability reservoir bed of the Xujiahe Formation in the western Sichuan Depression on the basis of the study of diagenesis, diagenetic reservoir facies and the diagenetic evolution sequence. The research indicated that this reservoir bed can be divided into five types of diagenetic reservoir facies, namely strong dissolution, chlorite-lined intergranular pores, compaction and pressure solution, carbonate cementation and secondary quartz increase. There are, however, just two diagenetic reservoir facies which provide low-permeability reservoir beds, namely strong dissolution and chlorite-lined intergranular pores. We also analyzed their diagenetic evolution sequences and the origin of the low-permeability reservoir bed. Besides, it was also indicated that the composition and structure of sandstones, types of sedimentary microfacies, diagenesis history as well as the tectonic reworking in later periods are the main factors controlling the formation of the low-permeability reservoir bed. The above- mentioned factors establish the foundation for the forecasting the distribution of high quality reservoir beds.
文摘Detailed geochemistry studies were conducted to investigate the origin of solid bitumens and hydrocarbon gases in the giant Puguang gas field. Two types of solid bitumens were recognized: low sulfur content, low reflectance (LSLR) solid bitumens in sandstone reservoirs in the Xujiahe Formation and high sulfur content, high reflectance (HSHR) solid bitumens in the carbonate reservoirs in the Lower Triassic Feixianguan and Upper Permian Changxing formations. Solid bitumens in the Upper Triassic Xujiahe Formation correlate well with extracts from the Upper Triassic to Jurassic nonmarine source rocks in isotopic composition of the saturated and aromatic fractions and biomarker distribution. Solid bitumens in the Feixianguan and Changxing formations are distinctly different from extracts from the Cambrian and Silurian rocks but display reasonable correlation with extracts from the Upper Permian source rocks both in isotopic composition of the saturated and aromatic fractions and in biomarker distribution, suggesting that the Permian especially the Upper Permian Longtan Formation was the main source of solid bitumens in the carbonate reservoirs in the Feixianguan and Changxing formations in the Puguang gas field. Chemical and isotopic composition of natural gases indicates that the majority of hydrocarbon gases originated from sapropelic organic matter and was the products of thermal cracking of accumulated oils. This study indicates that source rock dominated by sapropelic organic matter existed in the Upper Permian and had made major contribution to the giant Puguang gas field, which has important implication for petroleum exploration in marine sequences in South China.
基金supported by the National Major Fundamental Research and Development project(No. 2005CB422100)the project of Southern Exploration Division Company,SINOPEC
文摘In a very gentle platform-margin paleogeographic environment, platform-margin reef flat facies carbonate reservoir rocks were developed in the Changxing Formation of Yuanba field. Later weak structural evolution and diagenetic evolution caused the Changxing Formation to form lithologic traps, with good reservoirs such as dissolved bioclastic dolostone and dissolved pore dolostone. The Changxing Formation gas reservoir is a pseudo-layered porous lithologic gas reservoir under pressure depletion drive, with high H2S and moderate CO2 contents. This paper predictes that the conducting system for the Changxing Formation gas reservoir is possibly composed of the pores and microfractures in the Changxing Formation reservoir, the top erosional surface of the Changxing Formation, as well as the micropores and microfractures in the underlying formations. The Changxing Formation reservoir has experienced 3 hydrocarbon charging stages. This paper suggests that diffusion is the major formation mechanism for this gas reservoir. In the Middle and Late Yanshanian, the Yuanba area entered the major gas charging stage. The gas migrated mainly through diffusion and with the assistance of seepage flow in small faults and microfractures from the source rocks and the other oil-bearing strata to the Changxing Formation carbonate reservoir rocks, forming lithologic gas pools. In the Himalayan Epoch, the lithologic traps were uplifted as a whole without strong modification or overlapping, and were favorable for gas preservation.
基金This study was supported by the Natural Science Foundation of China (grant No. 40273034)the Science Foundation of Hongzhou Danzi University.
文摘The static flux chamber method was applied to study natural emissions of methane to the atmosphere in the Luntai fault region of Yakela Condensed Oil/Gas Field in the Tarim Basin, Xinjiang Municipality, northwestern China. Using an online method, which couples together a gas chromatography/high-temperature conversion/isotope ratio mass spectrometry (GC/C/MS), 13^C/12^C ratios of methane in flux chambers were measured and showed that methane gases are liable to migrate from deep oil/gas reservoirs to the surface through fault regions and that a part of the migrated methane, which remains unoxidized can be emitted into the atmosphere. Methane emission rates were found to be highest in the mornings, lowest in the afternoons and then increase gradually in the evenings. Methane emission rates varied dramatically in different locations in the fault region. The highest methane emission rate was 10.96 mg/m^2·d, the lowest 4.38 mg/m^2, and the average 7.55 mg/ m^2·d. The 13^C/12^C ratios of the methane in the flux chambers became heavier as the enclosed methane concentrations increased gradually, which reveals that methane released from the fault region might come from thermogenic methane of the deep condensed oil/gas reservoir.
基金granted by the National Basic Research Program of China(grant no.2014CB239205)National Science and Technology Major Project of China (grant no.20011ZX05030-005-003)
文摘Multi-layer sandstone reservoirs occur globally and are currently in international production. The 3D characteristics of these reservoirs are too complicated to be accurately delineated by general structural-facies-reservoir modelling. In view of the special geological features, such as the vertical architecture of sandstone and mudstone interbeds, the lateral stable sedimentation and the strong heterogeneity of reservoir poroperm and fluid distribution, we developed a new three-stage and six-phase procedure for 3D characterization of multi-layer sandstone reservoirs. The procedure comprises two-phase structural modelling, two-phase facies modelling and modelling of two types of reservoir properties. Using this procedure, we established models of the formation structure, sand body structure and microfacies, reservoir facies and properties including porosity, permeability and gas saturation and provided a 3D fine-scale, systematic characterization of the Sebei multi-layer sandstone gas field, China. This new procedure, validated by the Sebei gas field, can be applied to characterize similar multi-layer sandstone reservoirs.
文摘The Callovian-Oxfordian carbonate reservoirs are the most important hydrocarbon reservoir in the Samandepe gas field,Amu Darya basin,Turkmenistan.Based on the analysis of Fe,Mn and Sr trace elements,and carbon,oxygen and strontium isotopes,the genesis and evolutionary characteristics of the carbonate reservoirs were studied,and the conclusions were follows:1) Sustained transgressive-regressive cycles played an important role during Callovian-Oxfordian.The reservoir of reef-bank facies was well developed in the period of transgression,while the regional dense cap rocks developed in the period of regression;2) The 87 Sr/86 Sr ratio measured from rudist shells yields an age of 157.2 Ma according to the global strontium isotope curve;3) As diagenetic intensity increased,δ 13 C changed little,and δ 18 O showed strong negative deviation but was still limited to the range of Late Jurassic seawater.High Fe and Sr contents,and low Mn content,and the evolutionary trend of δ 13 C and δ 18 O all indicate that diagenesis occurred in a relatively confined environment,where the fluids were relatively reducing and contained hot brine.The stage of diagenesis reached is mesodiagenesis,which is very favorable for preservation of primary pores in carbonates;4) Strong dissolution of reef limestones,burial dolomitization and hydrothermal calcite precipitation were all the results of the interaction between the 87 Sr-rich diagenetic fluid and rocks;5) The analysis results of isotopes,fluid inclusions and vitrinite reflectance show that the diagenetic fluid was compaction-released water that originated from the deep,coal-bearing clastic strata.
基金the National Natural Sci-ence Foundation of China (No. 40273034)the Science Foundation of Hangzhou Dianzi University
文摘A static flux chamber method was applied to study natural emissions of methane into the atmosphere in the Yakela condensed oil/gas field in Talimu Basin, Xinjiang, China. Using an online method, which couples a gas chromatography/high-temperature conversion/isotope ratio mass spectrometry (GC/C/MS) together, the 13C/12C ratios of methane in the flux chambers were measured. The results demonstrated that methane gases were liable to migrate from deep oil/gas reservoir to the surface through microseepage and p...
基金Supported by the National Natural Science Foundation of China Enterprise Innovation and Development Joint Fund Project(U19B6003)。
文摘In this review on the exploration and development process of the Shunbei ultra-deep carbonate oil and gas field in the Tarim Basin, the progress of exploration and development technologies during the National 13th Five-Year Plan of China has been summarized systematically, giving important guidance for the exploration and development of ultra-deep marine carbonate reservoirs in China and abroad. Through analyzing the primary geological factors of “hydrocarbon generation-reservoir formation-hydrocarbon accumulation” of ancient and superposed basin comprehensively and dynamically, we point out that because the Lower Cambrian Yuertusi Formation high-quality source rocks have been located in a low-temperature environment for a long time, they were capable of generating hydrocarbon continuously in late stage, providing ideal geological conditions for massive liquid hydrocarbon accumulation in ultra-deep layers. In addition, strike-slip faults developed in tectonically stable areas have strong control on reservoir formation and hydrocarbon accumulation in this region. With these understandings, the exploration focus shifted from the two paleo-uplifts located in the north and the south to the Shuntuoguole lower uplift located in between and achieved major hydrocarbon discoveries. Through continuing improvement of seismic exploration technologies for ultra-deep carbonates in desert, integrated technologies including seismic acquisition in ultra-deep carbonates,seismic imaging of strike-slip faults and the associated cavity-fracture systems, detailed structural interpretation of strike-slip faults, characterization and quantitative description of fault-controlled cavities and fractures, description of fault-controlled traps and target optimization have been established. Geology-engineering integration including well trajectory optimization,high efficiency drilling, completion and reservoir reformation technologies has provided important support for exploration and development of the Shunbei oil and gas field.
基金supported by the"973"Project (2005CB422105)the Program for Changjiang Scholars and Innovative Research Team at the University (PCSIRT IRT0658).
文摘Solid bitumens were found throughout the carbonate reservoirs in the Puguang gas field, the largest gas field so far found in marine carbonates in China, confirming that the Puguang gas field evolved from a paleo-oil reservoir. The fluid conduit system at the time of intensive oil accumulation in the field was reconstructed, and petroleum migration pathways were modeled using a 3-D model and traced by geochemical parameters. The forward modeling and inversion tracing coincided with each other and both indicated that oils accumulated in the Puguang-Dongyuezhai structure originated from a generative kitchen to the northwest of the Puguang gas field. The deposition of organic-rich Upper Permian source rocks dominated by sapropelic organic matter in the Northeast Sichuan Basin, the development of fluid conduit system that was vertically near-source rock and laterally near-generative kitchen, and the focusing of oils originated from a large area of the generative kitchen, were the three requirements for the formation of the giant paleo-oil reservoir from which the giant Puguang gas field evolved. The Puguang gas field had experienced a three-stage evolution. The post-accumulation processes, especially the organic-inorganic interaction in the hydrocarbon-water-rock system, had not only profoundly altered the composition and characteristics of the petroleum fluids, but also obviously changed the physicochemical conditions in the reservoir and resulted in complicated precipitation and solution of carbonate minerals.
基金financially supported by the National Natural Science Foundation of China Key Program (No.50231020)the National Key Basic Research and Development Plan Program (No. G1999065004)
文摘The effect of HCO3^- concentration on CO2 corrosion was investigated by polarization measurement of potentiodynamic scans and weight-loss method, Under the conditions of high pressure and high temperature, the corrosion rate of steel X65 decreased with the increase of HCO3^- concentration, while pH of solution increased. SEM, EDS, and XRD results of the corrosion scales indir cated that the typical FeCO3 crystallite was found at low HCO3^- concentration but Ca(Fe,Mg)(CO3)2 was found at high HCO3^- con- centration. Ca^2+ and Mg^2+ are precipitated preferential to Fe^2+ at high pH value. Potentiodynamic polarization curves showed that the cathodic current density decreases with the increase of HCO3^- concentration at low HCO3^- concentration. When the HCO3^- concentration reaches 0.126 mol/L, increasing HCO3^- concentration promotes cathodic reactions. Anodic behavior is an active process at low HCO3^- concentration and the anodic current density decreases with the increase of HCO3^- concentration. An evident active-passive behavior is exhibited in anodic process at 0.126 mol/L HCO3^-.
基金sponsored by the National Key Basic Research Program of China (973 Program, 2012CB214806)the National Natural Science Foundation of China (No. 41372144)
文摘There are rich oil and gas resources in marine carbonate strata worldwide.Although most of the oil and gas reserves discovered so far are mainly distributed in Mesozoic,Cenozoic,and upper Paleozoic strata,oil and gas exploration in the Proterozoic–Lower Paleozoic(PLP)strata—the oldest marine strata—has been very limited.To more clearly understand the oil and gas formation conditions and distributions in the PLP marine carbonate strata,we analyzed and characterized the petroleum geological conditions,oil and gas reservoir types,and their distributions in thirteen giant oil and gas fields worldwide.This study reveals the main factors controlling their formation and distribution.Our analyses show that the source rocks for these giant oil and gas fields are mainly shale with a great abundance of type I–II organic matter and a high thermal evolution extent.The reservoirs are mainly gas reservoirs,and the reservoir rocks are dominated by dolomite.The reservoir types are mainly karst and reef–shoal bodies with well-developed dissolved pores and cavities,intercrystalline pores,and fractures.These reservoirs arehighly heterogeneous.The burial depth of the reservoirs is highly variable and somewhat negatively correlated to the porosity.The cap rocks are mainly thick evaporites and shales,with the thickness of the cap rocks positively correlated to the oil and gas reserves.The development of high-quality evaporite cap rock is highly favorable for oil and gas preservation.We identified four hydrocarbon generation models,and that the major source rocks have undergone a long period of burial and thermal evolution and are characterized by early and long periods of hydrocarbon generation.These giant oil and gas fields have diverse types of reservoirs and are mainly distributed in paleo-uplifts,slope zones,and platform margin reef-shoal bodies.The main factors that control their formation and distribution were identified,enabling the prediction of new favorable areas for oil and gas exploration.