石油实验地质

LATE HYDROCARBON ACCUMULATION MECHANISM AND DYNAMICS OFFSHORE THE NORTHERN SOUTH CHINA SEA

Liu Baoming, Niu Binhua, Sun Chunyan, Xia Bin, Li Xuxuan, Jin Qinghuan

2007, 29(5): 441-445. doi: 10.11781/sysydz200705441

Abstract(811) PDF-CN(369)

Abstract:
Exploration technologies and methods for late hydrocarbon accumulations offshore the northern South China Sea have been summarized in this paper.The late hydrocarbon accumulations are characterized by seismic anomalies such as bottom caves,gas chimneys,"obscure seismic area" and "bright points".Based on geochemical features,three types of accumulations can be identified:biogas in shallow layer,mature-highly mature gas and thermal gas with high CO₂ content.According to neotectonism,late dynamics of petroleum systems related to thrust fault,normal fault as well as diapire-structure and strike-fault have been analyzed.The late movements of faults and the fast thermal subsidence have promoted hydrocarbon migration and redistribution with series of petroleum accumulation distributed along Yingdong ramp and Dongfang-Ledong area in the Yinggehai Basin,No.2 fault zone in the Qiongdongnan Basin and edge ramps of depressions in the Pearl River Mouth Basin.It contributes to the exploration of hydrocarbon and hydrate offshore the northern South China Sea.

TECTONIC EVOLUTION AND PROTOTYPES ANALYSIS FROM NEOPROTEROZOIC TO EARLY PALEOZOIC IN SOUTH CHINA

Zhou Xiaojin, Yang Fan

2007, 29(5): 446-451. doi: 10.11781/sysydz200705446

Abstract(1146) PDF-CN(428)

Abstract:
At the end Mesoproterozoic,Jinning movement takes place.Collisional orogenic belts generate around the edge of Yangtze block in South China.Huaxia block and Sichuan-Yunnan-Tibet block collide with Yangtze block and form South China ancient continent,founding basement for basin generation from Neoproterozoic to early Paleozoic.From Neoproterozoic to early Paleozoic,South China experiences series of tectonic evolution as "block rift,divergence and convergence",and forms different basin prototypes with different evolution histories around and in Yangtze block.At the southern and northern edge of Yangtze block,basin prototype evolution process is from rift,passive continent margin depression to foreland basin.In Yangtze block,carbonate platform deposited under block divergeoce and extension background develops to intraplatform depression basin formed uoder block convergence and compression background.After Caledonian movement,South China continent has been newly accreted and unified and the basic tectonic pattern has been formed.

HYDROCARBON ACCUMULATION PATTERN AND TYPE IN THE SOUTHERN JUNGGAR FORELAND BASIN

Li Bin, Song Yan, Meng Zifang, Xia Bin

2007, 29(5): 452-456. doi: 10.11781/sysydz200705452

Abstract(849) PDF-CN(259)

Abstract:
There are 4 sets of petroleum systems in the southern Junggar Foreland Basin:Middle Permian,Middle-Lower Jurassic,Lower Cretaceous and Anjihaihe Formation of Lower Tertiary,defined by source rock evolution and reservoir forming period.Regional tectonic evolution characteristics,tectonic types and reservoir features indicate that,main reservoir types in this region include compaction-wrench anticline and anticline-lithologic ones,and fault-screened anticlinal ones take the second position.Based on studies of tectonic characteristics,reservoir forming condition and main controlling factors,accumulation patterns of 3 accumulation zones are set up:accumulations in the west are characterized by thrust rupture belt and unconformities with one-way injection;accumulations in the center are characterized by fault-screened hydrocarbon accumulation with multi-direction injection;and accumulations in the east are characterized by thrust anticline and fault-screened hydrocarbon accumulation with one-way injection.

INVERSION STRUCTRURE AND ITS IMPLICATION TO HYDROCARBON ACCUMULATION IN WEIXI EXPLORATION REGION OF THE BEIBUWAN BASIN

Zhao Yongqiang

2007, 29(5): 457-461. doi: 10.11781/sysydz200705457

Abstract(994) PDF-CN(363)

Abstract:
It was indicated that there were two different inversion structures formed in two period based on analysis of seismic profiles in Weixi exploration region of the Beibuwan Basin.The first inversion structure was developed during the end of the Oligocene and the second during the end of the Miocene.These two periods of inversion structures can be divided into two types which were fault type and fold type.Formation of these inversion structures was resulted from the directional and qualitative adjustment of regional stress.On the one hand these inversion structures formed favourable traps,and on the other hand these inversion structures caused the early faults reactivation and made for oil migration.In addition,the formation periods of these inversion structures were matchable with the peak stages of hydrocarbon generation and expulsion.These inversion structures are preferred targets for finding giant-medium size of oil-gas fields.

THE FRAMEWORK OF SEQUENCE STRATIGRAPHY IN THE SHIWU FAULT DEPRESSION OF THE SONGLIAO BASIN

Chen Xinjun, Xu Xuhui, Zhu Jianhui, Wang Guoshou, Ji Youliang

2007, 29(5): 462-465. doi: 10.11781/sysydz200705462

Abstract(759) PDF-CN(309)

Abstract:
The Shiwu Fault Depression is the one with faults in the west and overlap in the east in the Songliao Basin.Based on synthetic study of core,drilling and logging data,three super sequences and six third-order sequences were identified and several types of sedimentary facies were recognized in the depre-ssion.Among these sedimentary facies,alluvial fan and fan delta were deposited in the step slope in the west of the depression,braided river delta and turbidity fans in the ramp of the southeast,and half-deep and deep lake in the middle sag.It was indicated that the Shiwu Fault Depression underwent three times of lake transgression.The evolution of the sequences can be summarized as early formation stage,continuously developing stage and well developed stage.

PETROLEUM MIGRATION AND POOL-FORMING MODELS OF THE SOUTHWEST MARGIN OF JIANGHAN BASIN

Liu Qiong, He Sheng

2007, 29(5): 466-471. doi: 10.11781/sysydz200705166

Abstract(738) PDF-CN(223)

Abstract:
The results of oil and source rock correlation and fluid potential in the southwest margin of Jianghan Basin show that,the oils in the north primarily come from the high maturity source rock in the Meiguiqiao-Niutougang Sag,and the oils in the south primarily come from the local low maturity source rock,and the oils in the medium are mixed.The distance of petroleum migration in this region is short.The distribution and accumulation of petroleum are controlled by some factors such as faults and the type of entrapment.The reservoir beds in uplifted wall being connected with the source beds in throw wall by fault was the key factor of forming the new-sourced and old-reservoired.The fault seals better in the upside than in the underlayer,fault-seal controlled the distribution of the better reservoirs.There are two important petroleum trap called fault-nose and fault-block,fault-nose locates in throw wall and fault-block locates in uplifted wall.According to the diversities of accumulation and reservoir,the petroleum pools are sorted out three different models which known as self-sourced and self-reservoired,new-sourced and old-reservoired and old-sourced and new-reservoired.

STUDY OF FACIES AND POTENTIAL COUPLING EFFECT IN OIL AND GAS POOL FORMATION——A CASE STUDY IN THE JIYANG DEPRESSION, THE BOHAI BAY BASIN

Wang Yongshi

2007, 29(5): 472-476. doi: 10.11781/sysydz200705472

Abstract(829) PDF-CN(311)

Abstract:
Exploration practices in the Jiyang Depression of the Bohai Bay Basin have indicated that,under the same dynamic condition of oil and gas pool forming,resistivity(breakthrough pressure) of entrance and exit interface is different,so fluid enters reservoir and pore respectively.It is caused by reservoir property(facies),fluid dynamics(potential) and their coupling effect.Mechanism of the effect is discussed and pool-controlling model is set up.Critical terms for reservoir to hold oil and gas are pointed out.As reservoir getting shallow and far away from source bed,buoyancy and residual entry pressures of source rock reduce,oil-water interface tension increases,and critical permeability and porosity for reservoir to hold hydrocarbon gradually increase.Thereby,critical qualification forecast model of pool forming is set up to enrich exploration theory and method in continental fault basins.

RESEARCH OF LOWER PALAEOZOIC CAP FORMATION IN THE NORTHWEST OF GUIZHOU PROVINCE

Wang Jinyi, Fu Xiaoyue, Pan Wenlei, He Ziai

2007, 29(5): 477-481. doi: 10.11781/sysydz200705477

Abstract(707) PDF-CN(338)

Abstract:
Similar to the Sichuan Basin,the northwest region of Guizhou Province is of stiff and stable basement.Only middle and lower petroleum systems have been preserved in the northwest of Guizhou.In the middle of Guizhou,only lower petroleum system is accessible.As to cap formation of lower system,gypsiferous rock of Loushanguan Formation as well as mudstone of Jindingshan and Niutitang Formations play important roles.They are the keys for exploration potential preservation and serve as overall seal.Though multi-stages of tectonic movements take place during the late stage,gypsiferous rock of Loushanguan Formation is still preserved and seals the lower system.Mudstone cap formation also has strong seal ability with breakthrough pressure over 15.97 MPa and belongs to type I cap formation.Pressure seal may exist in the northwest of Guizhou because that,though the Middle Guizhou Uplift up rises greatly during the late stage,Cambrian seal system is not yet destroyed and can work as effective seal.The most favorable place for accumulation is the Dafang-Jinsha tectonic belt and its northern and southern slopes.

THE STUDY OF MAIN CONTROL FACTORS OF GAS ACCUMULATION IN THE YINGJISU SAG OF TARIM BASIN

Shi Baohong, Zhang Yan, Zhao Jingzhou, Wang Qinghua

2007, 29(5): 482-485. doi: 10.11781/sysydz200705482

Abstract(769) PDF-CN(313)

Abstract:
Through the studying of the structure background,source rocks,reservoirs and seals and preservation in the Yingjisu Sag in the east of Tarim Basin,the geologic conditions and main control factors of the accumulation are discussed.There are favorable conditions for accumulation in the Yingjisu Sag.Because of the evolvement characteristics of source rocks,the traps in Mesozoic groups accumulate mainly gas.It is the particular history of tectonic evolution and characteristics of accumulation that determine faults from Palaeozoic to Mesozoic are the crucial control of Mesozoic groups accumulation.Meanwhile,effective caprocks and paleouplifts are also the main controls.

GEOCHEMICAL CHARACTERISTICS OF THE HYDROCARBONS IN DONGYING FORMATION RESERVOIR OF WENLIU AREA, THE DONGPU SAG OF THE BOHAI BAY BASIN

Chen yicai, Luo Xiaoping, Zhao Junxing, Shen Zhongming, Chang Zhengheng, Hu Yujie

2007, 29(5): 486-489. doi: 10.11781/sysydz200705486

Abstract(805) PDF-CN(301)

Abstract:
The hydrocarbons in Dongying Formation reservoir in Wenliu area,the Dongpu Sag of the Bohai Bay Basin,have undergone various degrees of biodegradation as the results of being relatively shallowly buried.The comparison analyses of the gas chromatography data and the chromatography-mass spectrometry data of the free hydrocarbons in the pores,the adsorbed hydrocarbons on the mineral grain surfaces and the wrapped hydrocarbons in the organic mineral inclusions show that,in the same oil sand sample from the unbiodegrated sections,the above 3 states of hydrocarbons have similar component characteristics with only some indicators being different.The similarities are reflected by the high contents of gammacerane(the gammacerane/C₃₀ hopane ratio is about 0.28 to 0.81) and the relatively low Pr/Ph ratio(about 0.21 to 0.51),indicating that the parent materials are mainly from aquatic orga-nism,which were formed in a kind of saline-lacustrine deposition environment under a strong reduction condition.The differences are reflected by the relatively low carbon number of the highest chromatographic peaks of free saturated hydrocarbons(between C₂₂ to C₂₄),and the unique values of the sterane maturity indicator C_{29 aaa}20S/(20S+20R) of the inclusion hydrocarbons(0.25 to 0.35).Whereas in the sections being biodegrated,the distribution of the normal alkanes in the inclusions are generally intact,while the normal alkanes in free hydrocarbons and adsorbed hydrocarbons are almost disappeared,indicating that the hydrocarbons in the reservoir are the results of different phases of recharge.

CHARACTERISTICS AND ORIGINS OF THE CRUDE OIL IN OULITUOZI AREA OF THE EAST SAG, THE LIAOHE BASIN

Zhou Luyang, Liu Huaishan, Jiang Jianqun, Jing Xiangchun

2007, 29(5): 490-494. doi: 10.11781/sysydz200705490

Abstract(1290) PDF-CN(278)

Abstract:
Oil-oil meticulous correlation research shows that there exist both immature and mature oils in Oulituozi area of the Liaohe Basin,and the maturity level of these oils is generally lower than those in the other areas of the East Sag.The lower maturity level of the oils in Oulituozi area is reveald by the following aspects:the ratio of saturated to aromatic hydrocarbons is low(3.0),the values of the maturity parameters of biomarkers and the stable carbon isotope values of saturated hydrocarbons and aromatics(-26.00‰～-27.50‰ and -25.00‰～-26.50‰ respectively) are also lower respectively than those in the other areas of the East Sag.The characteristics of the isotope contours of various individual hydrocarbons also indicates that the maturity of the oil in Oulituozi area is low.The results of oil-source correlation research suggest that the crude oil in Oulituozi area comes from the dark mudstone layers of the middle and lower parts of the 3rd member of Shahejie Formation,and the results of biomarker research show that the thermal evolution degree of the source rocks in Oulituozi area is apparently lower than those in the other areas of the East Sag,which causes the low maturity of the crude oil in the area.

OIL TYPE AND GENESIS ANALYSIS OF CRUDE OIL IN THE DAWANGBEI SUBSAG OF THE CHEZHEN SAG, THE BOHAI BAY BASIN

Ren Yongjun, Qiu Longwei, Liu Kuiyuan

2007, 29(5): 495-499. doi: 10.11781/sysydz200705495

Abstract(626) PDF-CN(270)

Abstract:
Crude oil from the Dawangbei Subsag of the Chezhen Sag of the Bohai Bay Basin can be divided into 2 types,i.e.the medium-low density,low viscosity,low sulfur content oil,and the medium-high density,medium-high viscosity,high sulfur content oil,through study of physical properties,sulfur content and oil group-type.Carbon isotopes and biomarkers are used to study the genesis and accumulation of oil,and the result shows that type Ⅰ origins from fresh-weak salt water,medium-deep water genesis mature source rock of the 3rd segment of Shahejie Formation,which is well preserved and has not experienced distinct secondary change.Type Ⅱ is mixed origin oil of at least 2 origins and is preserved under different conditions.Low maturity and high sulfur content oil from the 4th segment of Shahejie Formation of salt lacustrine-salt water lacustrine environment provides the 1st origin.After accumulation,oil has experienced biodegradation since it is buried low.Then oil from mature source rock of the 3rd segment of Shahejie Formation mixes in.Low-mature oil from the 1st segment of Shahejie Formation also contributes to type Ⅱ.Hence composition and distribution of oil type Ⅱ are complicated.

STUDY OF CHARGE HISTORY IN THE JURONG SAG, JIANGSU REGION

Gong Se, Peng Ping'an, Liu Dongying

2007, 29(5): 500-505. doi: 10.11781/sysydz200705500

Abstract(683) PDF-CN(342)

Abstract:
Regarding exploration of marine Palaeozoic and Mesozoic strata in South of China,the Jurong Sag in the Jiangsu region belongs to the area where was explored in the early stage.Oil and gas show were discovered in many levels in the Jurong Sag.Organic inclusions hosted in calcite vein in reservoir rock from Well Rong2 in the Jurong Sag were divided into different groups according to fluorescence color.Off-line crushing was used to analyze the hydrocarbon released by organic inclusions hosted in calcite vein from reservoir rock in Well Rong2 and Rong3.Through comparing organic inclusion oils with light oil in reservoir,source of hydrocarbon and charge history in the Jurong Sag were discussed combining burial history in Jurong Sag.The results show that multiple charging episodes took place in Well Rong2 and Rong3;Fluid inclusion oils represent the earlier charge while different n-alkanes distribution in different groups fluid inclusions in Well Rong2 shows that hydrocarbons charged in the earlier stage underwent biodegradation;Hydrocarbons charged in the earlier charging episode were derived from Permian source rock,however present light oils in Triassic reservoir rock charged in the later charging episode were derived from Permian and part Triassic source rocks due to its quick subsiding during the Late Cretaceous.

THE SUBTLE RESERVOIR FORMING MODELING IN THE LIAOZHONG SAG, THE LIAODONG BAY BASIN

Jiang Shu, Cai Dongsheng, Zhu Guanghui, Tong Zhigang, He Qing, ZhuXiaomin

2007, 29(5): 506-511. doi: 10.11781/sysydz200705511

Abstract(803) PDF-CN(358)

Abstract:
The research results of high precision sequence stratigraphy in the Liaozhong Sag of the Liaodong Bay Basin are used to build up detailed sedimentary sections that can exhibit the subtle sandbodies,and Temis2D software of IFP is employed to model the subtle reservoirs forming process for the first time.The results indicate that the modeling outcome is consistent with the drilling activities,which shows the subtle reservoir modeling is feasible.The modeling results reveal:the subtle lens reservoirs in Shahejie Fm in the Liaodong Sag of the Liaodong Bay Basin were formed by primary migration while the stratigraphic reservoirs were formed by secondary migration;the forming time of the subtle reservoirs in Shahejie Fm is relatively earlier than that in Dongying Fm;subtle reservoirs in Shahejie Fm were mainly formed at the final stage of Dongying and early stage of Guantao,but the forming time of some subtle reservoirs far away from the hydrocarbon kitchen were delayed due to the long distance migration.The subtle reservoirs in Dongying Fm were formed by the conduits of fault pathways and secondary migration,some were formed by the conduits of micro-crack or primary migration with the result of overpressure surpassing the seal pressure.The subtle reservoirs within Dongying Fm were formed later than those within Shahejie Fm,most were formed at the time of about 12 Ma,but some far away from the hydrocarbon kitchen were even formed after 6 Ma.Moreover,the forming of subtle reservoirs in this basin is related to the pathway system,lateral seal and top seal,the oil and gas would leak under the conditions of the open conduit and poor seal characteristics.

RESEARCH ON THE QUANTITATIVE ANALYSIS METHOD OF C₆-C₁₅ LIGHT HYDROCARBON IN SOURCE ROCK SAMPLES

Jiang Qigui, Zhang Caiming, Zhang Meizhen, Zhang Qu

2007, 29(5): 512-515. doi: 10.11781/sysydz200705512

Abstract(847) PDF-CN(289)

Abstract:
Supported by the low boiling-point solvent extraction technique and the gas chromatography technique of Programmed Temperature Vaporization(PTV) cut-out and back-flow,a quantitative research has been made on the C₆-C₁₅ light hydrocarbon compounds in the source rock samples by means of an internal standard method.It is found that the light components before C₇ lose more than other hydrocarbon components in the sample pre-processing process due to the volatility differences.So 1-hexenes was chosen as an internal standard reference to assure the quantitative analysis of C₆ to C₇,and 1-nonene was chosen as an internal standard reference to assure the quantitative analysis of C₇ to C₁₅(including C₇).The results show high recovery(>85%) and good reproducibility(with RE<10%),indicating that this quantitative analysis method is stable and reliable.With this kind of analysis,not only the quantitative data of C₆-C₁₅ light hydrocarbons can be provided,the light hydrocarbon fingerprint parameters can also be offered.So it can bring rich geochemical information and has certain application values in the fields of oil and gas exploration and energy resource evaluation.

GC-MS ANALYSIS OF MATURE CONDENSATE OIL AND ITS APPLICATION IN PETROLEUM GEOLOGY

Zhang Yunxian, Shen Zhongmin, Wang Ying, Liu Haiyan

2007, 29(5): 516-521. doi: 10.11781/sysydz200705516

Abstract(790) PDF-CN(275)

Abstract:
GC-MS analysis has become an applied technique in seeking oil-and gas-layers.With its great contributions to oil and gas discoveries,this technique has played an important role in petroleum exploration.11 condensate oil samples from Wen 23 gasfield,Baimiao gas pool and Qiaokou area in Pu-yang Sag,Bohai Bay Basin as well as Well Zhong-1 in Tarim Basin have been analyzed by GC-MS technique.The qualitative and quantitative analyses of the isomeric alkanes have been made,some new light hydrocarbon geochemical parameters have been determined,and the oil and gas signatures have been identified.The results show that Wen 23 gasfield generally belongs to coal condensate gas reservoir,and its condensate oil is generated during the high to ripen mature stages;the condensate oil in Baimiao gas pool is the product of the mudstone strata during their high mature stage;whereas the condensate oil in Well Zhong-1 inTarim Basin is the product of the marine carbonate strata in their high to ripen mature stages,different distinctively from the condensate oil of Wen 23 gasfield and Baimiao area,Dongpu Sag.

NUMERICAL SIMULATION AND ANALYSIS OF OIL-WATER DISPLACEMENT BEHAVIOR IN ROUGH CAPILLARY CHANNEL

Liu Changchun, Liu Shi, Wang Xueyao

2007, 29(5): 522-526. doi: 10.11781/sysydz200705522

Abstract(704) PDF-CN(311)

Abstract:
The research on oil-water migration and accumulation plays an important role in understanding reservoir forming regularities,as well as guiding oil and gas exploration.As an important influence factor in oil-water migration,surface tension may act as driving force or resistance of oil-water displacement,depending on the geometric shape differences of the migration channels.A numerical simulation of oil-water displacement in the capillary channel has been made by using the surface regular protuberances for simulating the rough elements,using the unsteady Navier-Stokes equation with volume of fluid(VOF) interface tracking method and the continuum surface force(CSF) model for the surface tension.The results show that the shape and size of the rough element have important effect on the shape of oil-water interface and the mass flow rate;and when driven by surface tension,water phase can be wrapped by oil phase around the throat formed by rough elements,whereas oil may flow separately in water phase when driven by the entrance pressure.

DEVELOPMENT OF PETROLEUM POOL-FORMING DYNAMICS SIMULATION AND EVALUATION SYSTEM

He Dawei, Mao Xiaoping, Yang Jiaming, Wu Jingfu, Pan Mingtai

2007, 29(5): 527-530. doi: 10.11781/sysydz200705527

Abstract(717) PDF-CN(248)

Abstract:
Based on the petroleum pool-forming dynamics simulation and evaluation,the more geologic factors have been considered,such as quick basal geologic data modeling,querying and editing for the simulation,the primary migration model,the multi-factor oil and gas accumulation simulation and ray-tracking oil and gas migration method and so on.The geologic models have been made,and transferred farther into mathematic and computer models.Therefore,the system can be acted as 3D visual analytic tool for oil and gas migration and accumulation.The system has been made application for the Lishui Sag,the East China Sea Basin,this simulation result has been approbated for integrated research team of the Lishui Sag,the East China Sea Basin.

EXPERIMENTAL STUDY OF THE DIFFERENCE BETWEEN FLUID ENTRY PRESSURES

Nie Haikuan, Xu Bo, Li Xuechao

2007, 29(5): 531-534. doi: 10.11781/sysydz200705531

Abstract(666) PDF-CN(250)

Abstract:
Micro-migration process of oil/gas-drive-water has been studied with actual core clip and micro-experiment technology.Research shows that entry pressures of both oil-drive-water and gas-drive-water increase obviously according to porosity decrease.The statistical regularity submits to power function variation regularity.However,there is complex changing relationship between porosity and oil/gas-drive-water entry pressure difference,forming 3 fragment curves with different accumulation significance.When porosity is over 10%-12%,the difference between oil/gas-drive-water entry pressures is small and the probabilities of oil and gas reservoir formation are nearly equal.When porosity is between 5% and 10%-12%,the difference is big,indicating that reservoir can seal hydrocarbon.It is the reservoir for not oil but gas.When porosity is less than 5%,the difference is small and the entry pressures of capillary show the same sealing function for oil and gas.Oil and gas pools are both difficult to form.Experimental results have given rational explanation for the difference of accumulation probability between source-contacting gas and source-contacting oil,and for the mechanism problem of tight sand as cap rock,too.

2007 Vol. 29, No. 5

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