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2013 Vol. 35, No. 3

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2013, 35(3)
Abstract(725) PDF-CN(558)
Abstract:
Hydrocarbon accumulation characteristics and exploration prospects of stratigraphic unconformity in basin margin of Junggar Basin
Zhang Shanwen
2013, 35(3): 231-237. doi: 10.11781/sysydz201303231
Abstract(1472) PDF-CN(772)
Abstract:
Based on a large number of geological and geophysical data,it was analyzed in this paper the structural characteristics of stratigraphic unconformity styles in basin margin of the Junggar Basin.The hydrocarbon ac-cumulation feature and pattern were concluded,and the exploration prospect in the future was pointed out.Multiphase tectonic movements and frequent facies change in the Junggar Basin led to the wide development of unconformity in basin edge.In the macro style,three types of on lap truncation,leveled truncate and parallel conformity developed.In vertical direction,there were three or two layers,forming many combination forms of permeability.Influenced by unconformity style structure,permeability combination,geologic background in basin margin and source rock generation condition in basin,the accumulation of unconformity reservoir in basin margin has three characteristics.a) Unconformity trap can form stratigraphic trap and other related types.b) Hydrocarbon generates from multiple sources and charges during different phases.Primary and secondary reservoirs co-exist.c) Unconformity itself has a certain ability of conducting,but the scope of transverse conducting is limited and petroleum migrates along "fault-blanket" type migration systems formed by faults,framework sand body and unconformity.Basin edge unconformity reservoirs have great exploration potentials,so relevant research and eva-luation are needed to develop according to the exploration degree in each area.
New understanding of sedimentary facies of Shawan Formation in Chunfeng Oilfield, Junggar Basin
Song Fan, Yang Shaochun, Su Nina, Xiang Kui, Zhao Yongfu
2013, 35(3): 238-242. doi: 10.11781/sysydz201303238
Abstract(1582) PDF-CN(682)
Abstract:
The Chunfeng Oilfield locates in the northeast of the Chepaizi Uplift,the western margin of the Junggar Basin.The sedimentary environment,source direction and sedimentary facies of the Shawan Formation in the study area are still under discussion.Based on core observation,carrying out experiments of light/heavy mineral,grain size and trace element,combining with well logging facies,it has been concluded that,the first member of the Shawan Formation in the study area was deposited in a typical underwater sedimentary environment.Sandbodies migrated to basin center from northwest and southwest.Sedimentary microfacies mainly include subaqueous distributary channel of fan-delta front in the northwest,distributary channel and interdistributary bay of braided delta front which distribute from southwest to northeast,and a few beach-bar sandbodies parallel to coast in the west.
Neotectonic movement feature and its controlling effect on accumulation in western Qaidam Basin
Wu Yanxiong, Xue Jianqin, Feng Yunfa, Zhang Xia, Jiang Yinghai, Huang Jianhong
2013, 35(3): 243-248. doi: 10.11781/sysydz201303243
Abstract(1473) PDF-CN(737)
Abstract:
Since the late Himalayan Movement,neotectonic movements have been active and have played important roles on petroleum accumulation in the western Qaidam Basin.Based on the studies of outcrops,seismic profile geological tectonic interpretations and oil reservoir anatomies,combined with the previous research results,the features of neotectonic movements and their controlling effects on petroleum accumulations were discussed.The neotectonic movements resulted in the present regional unconformities in the Shizigou Formation and the NWW-oriented modern landscapes.During the neotectonic movements,deep faults activated again while new faults came into being,and 4 kinds of structural pattern were formed,including back thrust fault,propagation anticline,longitudinal bend anticline and detachment fold.The neotectonic movements promoted the formation of traps,and had controlling effects on petroleum charging and accumulations.Influenced by the neotectonic movements,the good matching of tectonic trap formation and petroleum charging as well as the weak destruction of fault on tectonic trap are favorable for petroleum accumulation.
Petroleum dynamic accumulation process and its implications in Kelasu structural belt, Kuqa Depression, Tarim Basin
Ma Yujie, Zhuo Qingong, Yang Xianzhang, Fang Shihu, Tang Yangang, Guo Xiaowen, Wang Yuan, Jiang Lin
2013, 35(3): 249-254. doi: 10.11781/sysydz201303249
Abstract(1316) PDF-CN(738)
Abstract:
The thermal evolution and dynamic accumulation process of hydrocarbon in the Kelasu structural belt were analyzed using various maturity parameters,microscopic observation of rock,reservoir bitumen testing,and particle fluorescence analysis techniques.Studies suggested that the crude oils in the study area are mature and high-mature.Mature oil charged during the early stage while high-mature and over-mature oils charged during the late stage.The subsalt ancient reservoirs formed in the early stage were destructed by faults during the late Neogene,and were partially forced by high-mature and over-mature oils into shallow anticlinal traps.As the plasticity of gypsum caprock enhanced,faults through salts disappeared,and high-mature and over-mature oils accumulated again in subsalt traps.The Bozi segment of the Kelasu structural belt has great exploration potential,and the shallow anticlinal reservoirs should be paid attention to.Therefore,the determination of petroleum maturity and the dynamic accumulation process are important for identifying oil and gas composition and exploration in petroliferous basins.
Features and controlling factors of differential structural deformation of Kalashayi Fault in Bachu Uplift, Tarim Basin
Zhang Yuhang, Tang Liangjie, Yun Lu, Xie Daqing, Qiu Haijun, Jiang Huashan
2013, 35(3): 255-262. doi: 10.11781/sysydz201303255
Abstract(1361) PDF-CN(677)
Abstract:
Based on latest seismic interpretation data,the features of differential deformation of the Kalashayi Fault in the central Bachu Uplift were analyzed by means of fault-related fold theory and balanced section technique.The Kalashayi Fault is an active fault of multiple stages in the Bachu Uplift.It has suffered several stages of deformation,such as the early Caledonian,the episode Ⅰ of the middle Caledonian,the late Hercynian and the early Himalayan.On the plane,two faults of different scales converge like scissors from SW to NE.In profile,the Kalashayi Fault is composed of ramp-flat blind thrust fault which slips in Cambrian and high-angle basement-involved thrust fault.Gypsum-salt rocks control the multi-level deformation features of the Kalashayi Fault.The difference of pre-structure in basement leads to the segmental deformation features.Regional stress field transition results in the poly-phase deformation features.
Accumulation conditions of shale gas in Sujiatun Sub-depression, Lishu Fault Depression, Songliao Basin
Zhou Zhuoming, Shen Zhongmin, Zhang Xi, Song Zhenxiang
2013, 35(3): 263-268. doi: 10.11781/sysydz201303263
Abstract(1436) PDF-CN(887)
Abstract:
The geologic features of the Sujiatun Sub-depression in the Lishu Fault Depression indicated that during the heyday of fault depression development,a large set of mudstone interbedded with sandstone generated stably in the first member of the Yingcheng Formation.This set of shale is characterized by rich organic content,various organic types and is mature and high-mature for gas generation.The average porosity is 3.52% and a mass of fractures can be observed,providing room for free gas accumulation.In addition,the content of brittle minerals is relatively higher,with an average value of 41.1%.The content of quartz ranges from 15.1% to 23.4%.The shale is easy to crack.Field works have shown that the highest gas content in the shale may amount to 3.09 m3/t.The abnormity in total hydrocarbon measuring also predicts the existence of shale gas,indicating for good potential.
Hydrogeochemical characteristics of Yingcheng Formation in Changling Fault Depression and its petroleum geologic significance
Han Zhiyan, Lu Jianlin, Wang Baohua, Zhang Yanxia
2013, 35(3): 269-273. doi: 10.11781/sysydz201303269
Abstract(827) PDF-CN(464)
Abstract:
The conventional chemical composition and trace element characteristics of oilfield water from main exploratory wells of the Yingcheng Formation in Yaoyingtai-Chaganhua area in the Changling Fault Depression were analyzed.The NaHCO3 type water accounts for 80% of water samples.The CaCl2 type water mainly distri-butes around wells YS1 and YS2.ρ(HCO3-),total salinity (TDS),and desulfurization coefficient (rSO42-×100/rCI-)are well consistent with each other.High TDS area corresponds to low desulfurization coefficient,indicating for good sealing capacity and slow water exchange,which are favorable for petroleum accumulation and pre-servation.The high content of K is a sign for good permeability reservoir.The high content of Ba reflects a strong reducing environment and may be more favorable for natural gas preservation.In brief,combined with tectonic activity,the hydrogeochemical characteristics of formation water can be used to effectively judge the conditions for petroleum accumulation and preservation.
Tectonic feature and evolution mechanism of central anticline belt of Dongying Sag, Bohai Bay Basin
Lu Shenqiang, Chen Guanjun, Wu Kongyou, Feng Deyong
2013, 35(3): 274-279. doi: 10.11781/sysydz201303274
Abstract(1386) PDF-CN(538)
Abstract:
The present of plastic substances such as evaporate beds in the 4th member (Es4) of the Shahejie Formation and the over-pressured mudstone layers in the 3rd member (Es3) of the Shahejie Formation in the Dongying Sag provides the necessary material foundation for the application of Cantilever theory in this area.Since the late Es4 period,the loading state in the east of the Dongying Sag as well as its deformation resembled a plastically-founded cantilever which was based on the underlying cream salt layer,fixed on the southern Guangrao Uplift and free on the northern Chennan Fault.With its own gravity and the growing load of overburden sediments,the amplitude of sinking in the free end was gradually increasing,making the basin look like a dustpan.During the sinking,plastic substances kept flowing and aggregating,forcing the overburden layer to arch and finally forming the central anticline belt.Then the cantilever split into two parts which performed individually and continued to drive the evolution of the Dongying Sag.
Reservoir characteristics of Shahejie Formation in Qingdong Sag, Jiyang Depression
Jing Yali
2013, 35(3): 280-284. doi: 10.11781/sysydz201303280
Abstract(1448) PDF-CN(611)
Abstract:
The exploration degree of the Qingdong Sag of the Jiyang Depression is very low,so it is necessary to carry out studies of basic geological conditions such as sedimentary reservoir.The Shahejie Formation is the main oil-bearing sequence in the Qingdong Sag.Based on core,thin section and physical property analyses,the reservoir characteristics in the study area have been systematically researched.Pores in the Shahejie Formation are mainly primary intergranular,intergranular dissolved and intragranular dissolved ones.The 4th member of the Shahejie Formation is from the early diagenesis stage B to the late diagenetic stage A,and has strong heterogeneity.The 3rd member of the Shahejie Formation is during the early diagenesis stage B,and has high porosity and high permeability.Sedimentary microfacies and diagenesis are the main influencing factors for reservoir property in the study area.Corrosion happens when organic acid generates as organic matter expulsing,which improving reservoir property.Cementation and compaction make the reservoir porosity and permeability become worse.
Sub-sag sorting and petroleum distribution in Beibuwan Basin
Zhao Zhigang, Wu Jingfu, Li Chunrong
2013, 35(3): 285-290. doi: 10.11781/sysydz201303285
Abstract(1366) PDF-CN(868)
Abstract:
The Beibuwan Basin is a typical rift basin.It is divided into 15 sub-sags of 3 types (presenile,inhe-rited and late-formed).These 15 sub-sags are evaluated as 4 grades.The inherited sub-sags are most favorable for source rock generation and distribution.The discovered reservoirs are mainly located around petroliferous sub-sags which are controlled by the inherited sub-sags.Faults control the type and vertical distribution of reservoirs which are mainly sealed by faults and distribute along main faults.A complex hydrocarbon accumulation model,which is superimposed vertically and distributed along faults horizontally,is developed along inherited long-term active faults.In the presenile sub-sags,petroleum mainly accumulates in the 3rd member of the Liushagang Formation and is sealed by antithetic faults.
Petroleum geologic features and accumulation rules of Cte D’Ivoire Basin, West Africa
Cheng Jian, Duan Tiejun, Ni Chunhua, Yuan Dongfeng
2013, 35(3): 291-295. doi: 10.11781/sysydz201303293
Abstract(1617) PDF-CN(841)
Abstract:
The CÖte D'Ivoire Basin is an east-west oriented and elongated basin located in the north of the Gulf of Guinea,the West Africa.The basin is characterized by both transcontinental margin and passive continental margin.The tectonic evolution is divided into 3 phases: pre-rift phase before Aptian,rift phase from Aptian to the early Cinemania,and syn-rift phase ever since Cinemania.Different sedimentary systems form during different phases.The discovered hydrocarbon reservoirs mainly locate in the east-west oriented positive structures in the south of the Jacqueville trough.There are 2 accumulation patterns: rift stratigraphic one and passive continental margin stratigraphic one.Traps are of structural,structural-unconformity and stratigraphic types.
Main controlling factors of hydrocarbon accumulation in Mesopotamia Basin
Zhou Changqian, Zhang Qingchun, Yang Peiguang, Duan Haigang
2013, 35(3): 296-301. doi: 10.11781/sysydz201303296
Abstract(1435) PDF-CN(876)
Abstract:
The Mesopotamia Basin is one of the most prolific petroliferous basins in the world.The most important productive layer is Cretaceous.Based on the comprehensive analyses of structure,sedimentary,drilling and testing,the paper summarizes the controlling factors of hydrocarbon accumulation.They are high-quality source rocks,good reservoir-seal assemblages,huge structural traps,migration pathways and so on.There are two kinds of accumulation models in the Mesopotamia Basin.In the center and south of the basin,petroleum gene-rates in the lower formation and is reserved in the upper formation.Carrier beds are the main pathways for oil-and-gas migrations in the parallel direction.The characteristics of petroleum are controlled by source rocks.In the north,oil and gas migrate from the Jurassic and the Lower Cretaceous source rocks to the Upper Cretaceous reservoirs along strike slip faults.The differential hydrocarbon accumulations lead to light oil in the lower formation and heavy oil in the upper formation.
Compound specific carbon isotope composition of light hydrocarbons in crude oils from the north of the Northern Tarim Uplift
Li Hongbo
2013, 35(3): 302-306. doi: 10.11781/sysydz201303302
Abstract(1400) PDF-CN(549)
Abstract:
Compound specific carbon isotope compositions of different fractions and different original crude oils were analyzed to investigate light hydrocarbon characteristics of crude oils in the north of the Northern Tarim Uplift.Compound specific carbon isotope divergences of cyclopentane compounds in different crude oils were the least,which indicated that cyclopentanes had poor diagnosis in light hydrocarbons.A significant law can be found by compound specific carbon isotope compositions of optimized light hydrocarbons.Compound specific carbon isotope of light hydrocarbons in coal-formed oils from the Luntai Oilfield was the highest,ranging from -21‰ to -19‰.Lacustrine oils from the Dalaoba Oilfield took the second place,ranging from -25‰ to -21‰.Marine oils in the Yakela Oilfield were the lowest,ranging from -31.5‰ to -28‰.Compound specific carbon isotope composition of light hydrocarbons in crude oils which derived from Cambrian-Lower Ordovician in well YN2 was unique.It is suggested that compound specific carbon isotope composition of light hydrocarbons can be a diagnosis index for group crude oil,especially for gas-condensate and light oils.
Characteristics of carbon and oxygen isotopes of carbonate rocks in South Yellow Sea Basin and their implication
Zheng Yangdi, Cai Jingong
2013, 35(3): 307-313. doi: 10.11781/sysydz201303307
Abstract(1402) PDF-CN(634)
Abstract:
Based on the analyses of carbon and oxygen isotope composition and palynofacies of carbonate source rocks (P1q-T1q) from the South Yellow Sea Basin,the formation and controlling factors of effective source rocks of marine facies were studied.The correlation between δ13C and δ18O indicated that the carbon and oxygen carbon isotope compositions were similar to those in original ocean.The δ13CPDB values in P1q were heavier than those in T1q,indicating for higher biological productivity,which was favorable for source rock generation.Based on mean value,the δ13CPDB values of P1q were divided into 3 evolution stages corresponding to the changes of palynofacies,indicating that the formation of source rocks varied among different layers.The δ13CPDB values in P1q from well WX5-ST1 were 3.83‰ in average,obviously heavier than those from well CZ24-1-1 (-1.34‰ in average).It corresponded to the high content of amorphous organic matter,and proved the differences of source rock formation among different regions in the same layer.The comparison of carbon and oxygen isotopes and palynofacies showed that the effective matching of biological productivity and preservation condition was favorable for source rock formation.
Experimental study on reformation of volcanic clastic rocks by alkaline formation water
Guo Xinxin, Liu Li, Qu Xiyu, Meng Qi'an, Song Tushun, Yu Miao
2013, 35(3): 314-319. doi: 10.11781/sysydz201303314
Abstract(1265) PDF-CN(632)
Abstract:
The hydrothermal experiments of volcanic clastic rocks chosen from the Nanbeier Sag of the Tamtsag Basin and formation water were researched under different temperatures in a closed container.The results show that quartz can be dissolved by alkaline formation water and the dissolution intensity will be enhanced with the increasing of temperature;on the contrary,the dissolution degree of feldspar and calcite is very low.Meanwhile,by scanning electronic microscope (SEM),phillipsite is found on the surface of rhyolitic tuff sample (at the temperature of 100,120,140 and 160℃) and sedimentary tuff sample (at the temperature of 120 and 180℃);calcite is found on the surface of sedimentary tuff at 100℃.Considering the good preservation of quartz and strong dissolution of feldspar and carbonate,it is proved that the formation water contributes few to the secondary poro-sity of the Nanbeier Sag of the Tamtsag Basin.
Genesis features of crude oil in Ordovician, Yubei area, Tarim Basin
Lu Qinghua, Shao Zhibing, Jia Cunshan, Yue Yong, Liu Shaojie
2013, 35(3): 320-324. doi: 10.11781/sysydz201303320
Abstract(1550) PDF-CN(684)
Abstract:
The Ordovician oil in Yubei area has middle density,low freezing point and high waxy content.The distribution of normal alkane is complete while the baseline of saturated hydrocarbon chromatogram shows various degrees of excursion.It shows upside-down phenomenon that the δ13C value of nonhydrocarbon and asphaltene is smaller than that of saturated and aromatic hydrocarbon.All of these indicate that the reservoir underwent no less than two periods of oil charging.The early charging oil experienced strong biodegradation and mixed with the later higher mature charging oil.Geochemical properties are mainly attributed to the late charging oil with weak phytane predominance (Pr/Ph≤1.0),abundance of gammacerne (G/C30-hopanes 0.14-0.24),and higher C35-hopane/ C34-hopane value (>1.0) characteristics,showing reduction-strong reduction sedimentary environment.The predominance of n-heptane (46.47%-48.57%),and C23-tricyclic terpane and higher tricyclic terpane/hopane indicate that the original source materials of later oil are homonemeaes.High heptane value and tetramethylnaphthalene index suggest that the oil is in high mature stage and probably generated from the Cambrian source rock.
Geochemical characteristics of aromatic hydrocarbons of coal-bearing gas source rocks from Upper Triassic Xujiahe Formation in Sichuan Basin
Cai Jie, Zhang Min
2013, 35(3): 325-330. doi: 10.11781/sysydz201303325
Abstract(1334) PDF-CN(693)
Abstract:
Thirty three coal-bearing gas source rock samples from the Upper Triassic Xujiahe Formation in the Sichuan Basin were analyzed by GC-MS.The results show that the concentration of cadalene,retene,1,2,5-tri-methylnaphthalene and 1,2,5,6-tetramethylnaphthalene derived from terrigenous higher plant organic matter of the coal-bearing gas source rocks are extremely lower than those of the typical coal-bearing source rocks.The relative contents of dibenzothiophenes and fluorenes are higher while the relative content of dibenzofurans is lower compared to the high content of dibenzofurans in typical coal-bearing source rocks.The particular distribution may be explained by transgression effect and high maturity.
Calculating methods and assessment of stretching factor：A case study of Northern Jiangsu Basin
Bao Hanyong, Guo Zhanfeng, Zhang Luolei, Huang Yaping
2013, 35(3): 331-338. doi: 10.11781/sysydz201303331
Abstract(1623) PDF-CN(714)
Abstract:
Basin stretching factor is a key parameter of extensional basin study and it was normally calculated from definition,balanced cross-section and tectonic-thermal modeling.The principles of traditional methods were briefly introduced in this paper,and the stretching factor of extension rifting in the Northern Jiangsu Basin after the late Cretaceous was also calculated.Basin stretching factor can be acquired by definition based on crust thickness,and it can be easily compared in different regions.For multi-phases stretch basin,it is hard to determine the stretching factor in different phases.The balanced cross-section method can reconstruct the basin stretching factor of multi-phases stretch,but the real equilibrium is actually hard to reach while the tectonic-thermal subsidence of the lower crust is not taken into consideration,thus other methods are needed for better comparison.The tectonic-thermal modeling method considers tectonic-thermal subsidence,and can also read curst thickness in any period.As a result,the tectonic-thermal modeling method is regarded as the more precise and convenient approach to calculate basin stretching factor.
Experimental evaluation of crushability of shale reservoirs in Luojia area, Shengli Oilfield
Guo Haixuan, Guo Tiankui
2013, 35(3): 339-346. doi: 10.11781/sysydz201303339
Abstract(1416) PDF-CN(829)
Abstract:
At present,there is no unified method for crushability evaluation on shale reservoirs at home and abroad.Based on rock mechanics and physical parameter tests in laboratory as well as brittleness index calculations,a systematic evaluation method of laboratory experiment has been proposed.Compared to sandstones and carbonate rocks,the tensile strength,uniaxial compressive strength,shear strength and fracture toughness of shales are lower.Along sedimentary bedding plane,the shear strength of shales is very small and the internal cohesion of vertical bedding is greater than that of parallel bedding.The cementation of sedimentary layer (natural fracture) is very fragile,easily happening shear failure.Under the action of induced stress,the greater the angle between parallel natural fracture and main hydraulic fracture,the easier the fracture initiates.When the included angle between herringbone grooving and sedimentary layer is less than 45°,it is easy to propagate along bedding plane for fractures,but when more than 45°,it can cross the bedding plane.In the end,this shale reservoir is considered to have the conditions of crushability.
Micro-column convenient chromatography for separation of aromatic hydrocarbon compound and GC/IRMS analysis
Chen Zulin, Zhang Min, Liu Haiyu
2013, 35(3): 347-350. doi: 10.11781/sysydz201303347
Abstract(1361) PDF-CN(654)
Abstract:
An easy and economic method to separate alkylated napthalenes and alkylated phenanthrenes from aromatic hydrocarbons was introduced in this paper.The GC-MS tests showed that this method could provide a complete and enriched separation of alkylated napthalenes and alkylated phenanthrenes from crude oils and sedimentary samples,solving the problem that several methyls were difficult to determine accurately by GC-MS tests because of heavy co-elution and laying the foundation for free carbon isotope tests.As an application,this method can be used for aromatic hydrocarbons of monomer hydrocarbon carbon isotope analysis of pre treatment.

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