石油实验地质

2011, 33(1)

Abstract(309) PDF-CN(31)

Abstract:

Yanshan Movement and its influence on petroleum preservation in middle-upper Yangtze region

He Zhiliang, Wang Xinwei, Li Shuangjian, Wo Yujing, Zhou Yan

2011, 33(1): 1-11. doi: 10.11781/sysydz201101001

Abstract(3270) PDF-CN(1059)

Abstract:
Based on systemic researches on unconformity,tectonic dating and deformation of Jurassic and Cretaceous in different locations of the middle-upper Yangtze region,the Yanshan Movement was divided into 4 stages:the end of Middle Jurassic(Ⅰ),the end of Late Jurassic to the beginning of Early Cretaceous(Ⅱ),the end of Early Cretaceous(Ⅲ)and the Late Cretaceous(Ⅳ),among which the stage Ⅱ was the main deformation stage.The Yanshan Movement was significant for tectonic transformations in the middle-upper Yangtze region.Tectonic movements during the early stages(Ⅰ and Ⅱ)were characterized by multi-direction compression and thrusting,while those of the late stages(Ⅲ and Ⅳ)held the structural features of 'western compressing vs.eastern extending' with differences in basin-mountain relationship,deformation pattern and geodynamic mechanism.Meanwhile,the stage Ⅱ had controlling effects on hydrocarbon preservation in the study area.It caused differences in uplifting-subsiding and marine facies hydrocarbon preservation,and further influenced exploration potential in diffe-rent structural belts.For example,the Sichuan Basin which continued subsiding was favorable for hydrocarbon preservation,and had experienced 3 accumulation stages:early reservoir,conversion from oil to gas,and late adjustment.The fold-thrust belt on the upper Yangtze margin which continued uplifting and eroding was unfavorable for hydrocarbon preservation,and had experienced 2 accumulation stages:early reservoir as well as late reconstruction and destruction.The middle Yangtze region developed to depositional system of tectonic rift within mainland after the stage Ⅱ.Its hydrocarbon preservation conditions lay in the sealing capacity of re-type continental caps and the accumulation was limited by the-effectiveness of secondary hydrocarbon generation.The upper and lower combinations in the Sichuan Basin are the most potential exploration targets.On the margin of Central Guizhou Uplift and in the western Hunan and Hubei region to the east of Qiyueshan Fault,the lower combination below the Cambrian gypsum layers may have some exploration prospects.In the southern depression of the Jianghan Basin,conditions for secondary hydrocarbon generation,late accumulation and preservation may be good under continental covers.

Key tectonic changes, deformation styles and hydrocarbon preservations in Middle-Upper Yangtze region

Tang Liangjie, Cui Min

2011, 33(1): 12-16. doi: 10.11781/sysydz201101012

Abstract(3171) PDF-CN(728)

Abstract:
Controlled by different geodynamic backgrounds and tectonic stress fields,the Middle-Upper Yangtze region had experienced stages of tectonic movements,resulting in styles of faults,folds and unconformities.There were 4 key tectonic movements including the Guangxi,the Indosinian,the Yan-shanian and the Himalayan.During the Guangxi Movement,large-scale NE-trending tectonic deformations were formed in the study area.The changes from marine to continent took place in the Indosinian Movement.Large terrestrial facies sedimentary was well developed during the Yanshanian period.The study area was extruded from 3 directions during the Himalayan period.The 4 key tectonic movements played important roles in development and preservation of mudstone cap formations.The Guangxi Movement made a large destruction of the Silurian mudstones which were important cap formations in the Middle-Upper Yangtze region.The Middle-Lower Triassic mudstones suffered extensive erosion during the Indosinian Movement.Tectonic movements during the middle Yanshanian period strongly destroyed the regional cap formations of the early Yanshanian period except for those in the Sichuan Basin.Due to the Himalayan Movement,the Middle-Upper Mesozoic and the Cenozoic mudstone cap formations in the uplift were completely destroyed,only preserved in some regional depressions.Besides the mudstone cap formations,tectonic deformation styles of the key tectonic movements also controlled-hydrocarbon preservation in the study area.Chevron anticlines and relieved synclines were well developed in the east of Sichuan.Detachments in the west of Hunan and Hubei(mainly composed of the Silurian and the Lower Cambrian mudstones)were deeper than those in the east of Sichuan.The Xuefeng Uplift thrusted from SE to NW,resulting in large amounts of high-angle breakthroughs in the northwestern periphery.Meanwhile,in the west of Hunan and Hubei,low-angle thrusts matched with the Lower Cambrian and the Silurian cap formations,providing good conditions for hydrocarbon preservation.

Fluid characteristics and hydrocarbon preservation conditions in marine facies strata of middle-upper Yangtze region

Liu Guangxiang, Wo Yujin, Pan Wenlei, Zhang Changjiang

2011, 33(1): 17-21. doi: 10.11781/sysydz201101017

Abstract(3406) PDF-CN(746)

Abstract:
Based on studies of formation water chemical characteristics,H,O and S isotopes in formation water,natural gas composition,C isotope in alkane,H isotope in methane and light hydrocarbon composition in the middle-upper Yangtze region,combined with petroleum shows and productions,the research area was divided into 5 blocks according to fluid characteristics:the middle and western Sichuan Basin(Ⅰ),the northern,eastern and southern Sichuan Basin(Ⅱ),the southern Jianghan Basin(Ⅲ),the depression in the southeast of Guizhou Province(Ⅳ),as well as the west of Hunan and Hubei Pro-vinces,the middle of Guizhou Province,and the northern Jianghan Basin(Ⅴ).Preservation conditions decrease from I to V.

Distinguishing indicators and prospect significance of Cambrian dissolved gypseous breccias in southern Sichuan Basin

Peng Yongmin, Gao Bo, Zhang Rongqiang, Zhang Dianwei, Sun Dongsheng, Wo Yujin, Zhou Yan, Wang Xinwei, Li Shuanjian

2011, 33(1): 22-27. doi: 10.11781/sysydz201101022

Abstract(3541) PDF-CN(812)

Abstract:
Dissolved gypseous breccias were discovered with gypseous rocks in the Cambrian surface outcrops in Huocaoping region of Leibo County and Heima region of Ganluo County in the southern Sichuan Basin.According to profile analyses of the Cambrian,several dissolved gypseous breccias were found in Zhuazhuayan(13 layers,over 30 m thick),Changping(4 layers,17.5 m thick),Fandian(4 layers,over 20 m thick)and Sanhuichang(4 layers,35 m thick).The dissolved gypseous breccias were divided into 2 types,including amaranth gypsum-bearing breccia mudstones and lark gypsum-dissolved breccia dolostones,with locally well preserved lamellar and flaser deposit structures.The breccias were gene-rally 3 cm long and 2 cm wide.The compositions were micrite dolostones and the cements included clays and calcites.Initial rocks of the dissolved gypseous breccias were rhythmically banding dolomitic gypseous rocks,which could be compared with the Middle and Lower Cambrian gypseous rocks(10 lay-ers,26.9 m)from Well Dingshan 1.It is predicted that,from the southeast to the center of the basin,there exist thick gypseous rocks of lagoon facies.

Control on cap rock seal capacity by sequence style in middle-upper Yangtze region

Zhou Yan, Peng Yongmin, Li Shuangjian

2011, 33(1): 28-33. doi: 10.11781/sysydz201101028

Abstract(2649) PDF-CN(673)

Abstract:
The marine strata in the middle-upper Yangtze region can be divided into 3 types:T,H and TH.Different sequence style has different effect on accumulation.Cap rock deposition and evolution are mainly controlled by the H style.As to muddy cap formations,the cap rocks in the 2nd grade transgre-ssion system tracts(TST)of the H style are good in quality.For gypsum cap formations,the cap rocks in good quality mainly locate in the 2nd grade high-stand system tracts(HST)of the H style,which has experienced fast transgression and slow regression.Meanwhile,the mudstones in the 3rd grade TST of the H style are also favorable for petroleum sealing.On the profile of Qifeng tunnel,Luoyixi Town,Guzhang City,Hunan Province,from HST to TST,breakthrough pressure and calcareousness content increase,while specific surface area and sandy content decrease.It illustrates that the seal capacity of muddy cap rocks in transgression system tracts is better than that in high-stand system tracts.

Primary discussion on relationship between hydrocarbon preservation and tectonic movement—a case study in upper Yangtze region

Wang Xinwei, Wo Yujin, Zhou Yan, Zhang Rongqiang, Li Shuangjian, Yuan Yusong

2011, 33(1): 34-42. doi: 10.11781/sysydz201101034

Abstract(2953) PDF-CN(1074)

Abstract:
The previous studies of the relationship between tectonic movement and hydrocarbon preservation mainly focused on the destructive functions of tectonic movement rather than the constructive functions.Taking the upper Yangtze region as an example,it was discussed in this paper the influence of tectonic movement on hydrocarbon preservation from both destructive and constructive aspects.The dynamic transformation from one function to another was also studied.In space distribution,from oroge-nic belts to detachment belts,hydrocarbon preservation conditions were improved.As to detachment belts,preservation conditions of the infrastructures were better than those of the superstructures.In the regions which had experienced stages of tectonic movements,the main faults forming traps might change from filling faults to escaping faults,and vice versa.

Destruction types and temporal—spatial distribution of marine hydrocarbon reservoirs in South China

Li Shuangjian, Gao Bo, Wo Yujin, Zhou Yan, Yuan Yusong

2011, 33(1): 43-49. doi: 10.11781/sysydz201101043

Abstract(2847) PDF-CN(803)

Abstract:
According to statistics of destroyed hydrocarbon reservoir,natural asphalt,oil and gas seepage and evidence,with studies of basic geological factors which influenced hydrocarbon accumulation and destruction,it was summarized in this paper the destruction types and the distribution of marine hydrocarbon reservoirs in South China.The destruction of hydrocarbon reservoirs was divided into 6 types:fault-rupturing,reservoir-uplifting,cracking for deep subsidence,magmatic process,fold-alternating and fluid-washing,among which the former 4 types were common.The main factors for hydrocarbon reservoir destructions in the study area were erosions or invalidations of cap rocks caused by tectonic activities.At the end of the Caledonian Movement,the lower reservoirs were destroyed in large scale for the first time.Since the Yanshan Movement,fierce tectonic compressions had taken place around the Yangtze block,resulting in destructions for marine hydrocarbon reservoirs in South China except for the Sichuan Basin.Magmatic processes in the middle-lower Yangtze,the Jiangnan-Xuefeng Uplift as well as Yunnan,Guizhou and Guangxi Provinces during the Yanshan Movement caused reservoir destructions in the region.

Hydrocarbon preservation and exploration in Bachu Uplift of Tarim Basin

Gu Yi, Shao Zhibing, Zhao Ming, He Guangyu

2011, 33(1): 50-55. doi: 10.11781/sysydz201101050

Abstract(5233) PDF-CN(726)

Abstract:
The Bachu Uplift of the Tarim Basin had experienced several tectonic movements during the middle Caledonian(the end of the Late Ordovician),the early Hercynian(the end of the Middle Devonian),the late Hercynian(the Late Permian),the Indosinian-Yanshanian and the Himalayan,among which the middle Himalayan was the most important stage for uplift formation.Different stages of tectonic movements had great effects on hydrocarbon preservation conditions.The Middle Cambrian gypsum-salt rocks,the Middle-Lower Carboniferous mudstones and the Lower Permian Kupukuziman Formation mudstones were good regional cap rocks in the region.Based on integrated analyses of seal properties and hydrocarbon preserving conditions,it was pointed out that there were 2 locations with better conditions for hydrocarbon preservation in the uplift:the southern margin and the east part.Vertically,horizons under the Middle-Lower Cambrian salts were favorable for preservation.Therefore,the southern margin and the east part of the Bachu Uplift as well as the Middle-Lower Cambrian subsalt reservoirs are the favorable targets for future petroleum exploration.

Diagenetic environments of calcite veins hosted in marine carbonate rocks in middle Yangtze region of South China

Wang Furong, He Sheng, Yang Xingye

2011, 33(1): 56-60. doi: 10.11781/sysydz201101056

Abstract(2842) PDF-CN(960)

Abstract:
Analyses of thin slices,cathodoluminescence and carbon—oxygen isotope of calcite veins hosted in marine carbonate rocks distributed around Jingshan County in the middle Yangtze region of South China indicated that,two crystal forms including radial calcite and isometric texture calcite could be identified in calcite veins in the Triassic and the cathodoluminescence intensity was different.The Permian and Ordovician fractures were mainly filled with isometric texture calcite veins and the cathodoluminescence intensity was similar with that of the surrounding rocks.The δ¹³C_PDB value of calcite veins ranged from -6.76‰ to 4.01‰ and the δ¹⁸O_PDB value ranged from -17.95‰ to -5.67‰,indicating the marine phreatic environment and the mixing phreatic environment for calcite veins deposition.Calcite veins in the Triassic were sedimentary origin,and part of calcite veins in the Permian and the Ordovician suffered latter diagenetic fluid dissolution.Fluid generated from organic-matter maturation effected the formation of calcite veins in the Permian to some degree.

Geochemical characteristics and origin of reservoir bitumen in Wangcun paleo-reservoir, western Hunan Province

Gao Bo, Zhou Yan, Liu Quanyou, Peng Yongmin, Li Shuangjian, Wang Xinwei

2011, 33(1): 61-65. doi: 10.11781/sysydz201101061

Abstract(3091) PDF-CN(643)

Abstract:
It was analyzed in this paper the geochemical characteristics and the origin of reservoir bitumen in Wangcun paleo-reservoir in the western Hunan Province,the middle Yangtze region.The reflectance of reservoir bitumen from the Lower Ordovician to the Upper Cambrian Zhuitun Formation ranged from 3.09% to 4.08%.The bitumen was rich in H and C,poor in O,and was highly mature.From the Lower Ordovician to the Upper Cambrian,geochemical characteristics of bitumen were similar,indicating the same source.Oil-source correlation studies with biomarker and carbon isotope showed that the bitumen in the Wangcun paleo-reservoir mainly originated from the Lower Cambrian source rocks.

New explorations of petroleum preservation conditions in marine sequences, South China—concept and research methods of ‘preservation system’

Wo Yujin, Wang Xinwei, Yuan Yusong, Li Shuangjian, Zhou Yan, Gao Bo, Zhang Rongqiang, Zhang Dianwei

2011, 33(1): 66-73. doi: 10.11781/sysydz201101066

Abstract(2900) PDF-CN(770)

Abstract:
The reservoirs in South China are characterized by mixed-sources,multiple kitchens as well as multi-stages of accumulation,deformation and destruction.It is necessary to explore new description methods and research ideas of petroleum preservation studies.A new concept of 'preservation system' and its research methods were put forward in this paper.The 'preservation system' is a unity of geological factors,geological functions and processes,and reservoir formation associated with preservation conditions in a geological unit.This system has an integrate source-cover condition,the same or similar geological structure and fluid characteristics,and the consis-tent preservation(or destruction)process of oil-and-gas reservoir.A preservation system is an oil-and-gas exploration unit,and its scope corresponds to a second-class or a third-class tectonic unit of a basin.The study content of the preservation system includes 4 basic features(geological structure types,cover functions,source-cover dynamic relationships and fluid characterizations)and 1 comprehensive evaluation system.The new concept and research methods may meet the needs of oil-and-gas explorations in South China or similar polycyclic basins.

Research on cap rock, pressure seal and abnormal pressure system

Liu Weixin, Cheng Qiuquan, Fan Ming

2011, 33(1): 74-80. doi: 10.11781/sysydz201101074

Abstract(3781) PDF-CN(760)

Abstract:
Based on studies of the Mesozoic unconventional tight sandstone gas reservoirs in the western depression of the Sichuan Basin,it was found that sealing capability of caprocks depends on not only micropores,but also fractures and pore fluid pressures.Researches of the Tertiary oil and gas reservoirs in the western depression of the Liaohe Basin proved that undercompacted mudstones worked as effective overpressure sealing for hydrocarbon accumulations.Therefore,caprock seals were divided into 3 types:micropores,micofractures and undercompacted ones with overpressure sealing.A new parameter(the ratio of oil saturation to its corresponding capillary pressure)was used to distinguish microfracture caprocks from micropore ones.Abnormal pressure sealing of pore fluid was usually caused by mudstone undercompaction,which was radically different from normal micropore sealing mechanism of compacted mudstone.The undercompacted mudstone sealing played an important role in shallow-medium buried accumulations,especially in shallow gas accumulations.Development of micropore caprocks might bring about the formation of compartments which took place in medium-deep buried horizons,and affected hydrocarbon migration and accumulation greatly.According to their origin,abnormal pressure systems were divided into 4 types:the sealed(compartments),the expulsion-delayed(overpressure zones related to undercompacted mudstones),the top-sealed and expulsion-delayed,and the invaded.Based on researches of abnormal pressure and overpressure sealing,it was concluded that the optimal targets of exploration were the compartments with huge volume,high pressure coefficient and low pressure gradient,as well as the traps immediately below main overpressure sealing surfaces of undercompacted zones.These concepts are summarized as abnormal pressure sealing controlling hydrocarbon accumulations.

Prediction of Triassic gypsum cap rocks in Tongnanba region of Northeast Sichuan Basin

Wei Shuijian, Feng Qiong, Feng Yin, Yuan Shukun

2011, 33(1): 81-86. doi: 10.11781/sysydz201101081

Abstract(2877) PDF-CN(632)

Abstract:
Based on detailed stratigraphic correlation,gypsum-salt rock petrophysical analyses and forward mo-deling,it was identified in this paper the seismic response characteristics of gypsum-salt cap rocks in Tongnanba region of the Northeast Sichuan Basin.With neural network seismic facies analysis method,the beneficial facies distribution of cap rocks was figured out.Using 3-D seismic attribute analysis,wavelet frequency interpretation and density inversion technologies,a set of prediction method suitable for the gypsum-salt cap rocks in the region was proposed.The relationship between cap rocks and petroleum in the region was analyzed.There were 3 suits of gypsum-salt cap rocks in the region,among which the gypsum-salt cap rocks from the 4th,5th Members of the Jialingjiang Formation to the 1st Member of the Leikoupo Formation were the best beneficial regional cap rocks due to big thickness,well crawling and self-sealing to faults;however,the sealing conditions were affected by fault activities.Fault activities increased from south to north,resulting in more risks for fault-sealing in the north.

Evaluation standard of mudstone caprock combining specific surface area and breakthrough pressure

Fan Ming, Chen Hongyu, Yu Lingjie, Zhang Wentao, Liu Weixin, Bao Yunjie

2011, 33(1): 87-90. doi: 10.11781/sysydz201101087

Abstract(3188) PDF-CN(745)

Abstract:
Based on summaries of previous analyses of evaluation standard of mudstone caprocks,it was analyzed in this paper the conventional physical parameters of mudstone samples from marine carbonate area in South China.It was concluded that the conventional physical parameters could not accurately evaluate the seal capability of mudstone caprocks.A new template to evaluate seal capability combining specific surface area and breakthrough pressure was proposed,providing relatively objective evaluation for seal capability of caprocks.

Seal mechanism of cap rocks

Yu Lingjie, Fan Ming, Liu Weixin, Zhang Wentao, Chen Hongyu

2011, 33(1): 91-95. doi: 10.11781/sysydz201101091

Abstract(2670) PDF-CN(775)

Abstract:
Seal mechanism of cap rocks was analyzed with self-designed instrument for gas breakthrough pressure experiment.As to the same siltstone sample,breakthrough pressure was the same even though the sample length was different.Therefore,cap rock thickness does not affect capillary seal capacity in geology application.In experiment,different water pressure was imposed constantly to one end of the sample,resulting in the increase of gas breakthrough pressure,which was equivalent to the imposed water pressure.According to illustrations of overpressure formation mechanism,the overpressure had made it more difficult for gas to break through the lower tight formation and the extra pressure was equivalent to overpressure of the undercompacted formation.

Simulation experiment of water-rock interaction in Silurian mudstone cap formation and its significance in Southeast Sichuan Basin

Zhang Juntao, Wu Shixiang, Li Hongtao, Liu Zhili

2011, 33(1): 96-99. doi: 10.11781/sysydz201101096

Abstract(3778) PDF-CN(702)

Abstract:
The influence of water-rock interaction of cap rock on reservoir formation and hydrocarbon preservation under different environments was analyzed with simulation experiment of water-rock interaction.The mudstone cap rock samples from the Silurian Longmaxi Formation in the Southeast Sichuan Basin were selected to react with freshwater and acetic fluid under different temperature and pressure conditions of 30℃,1 MPa;80℃,20 MPa and 160℃,40 MPa,respectively.Under normal temperature and pressure,the interaction between mudstone and fresh water was very weak,suggesting that the interaction was not destructive to cap rock under weak hydrodynamic force;however,acetic fluid under high temperature and pressure was more destructive than fresh water under normal conditions.Yet the solubility of mudstone was much lower than that of carbonate under the same conditions.In the study area,when hydrothermal fluid moved,more fluid was occluded in carbonate and reacted with rock because of low permeability and solubility of the Silurian mudstone.

Well logging identification of gypsum cap rocks in middle-upper Yangtze region

Feng Qiong, Wei Shuijian

2011, 33(1): 100-104. doi: 10.11781/sysydz201101100

Abstract(2494) PDF-CN(636)

Abstract:
Based on well logging response characteristics of gypsum cap rocks in the middle-upper Yangtze region,with geology,well logging,core analysis and logging data,it was established in this paper a logging interpretation model of gypsum cap rock parameters using the core calibration logging method.The gypsum cap rocks in the study region were interpreted and evaluated.A new set of logging identification method suitable for gypsum cap rocks in the Northeast Sichuan Basin was put forward.The qualitative identification and the quantitative evaluation of cap rocks were done,offering important basis parameters for the geophysical prediction researches of cap rocks.

2011 Vol. 33, No. 1

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