石油实验地质

2011, 33(6)

Abstract(1209) PDF-CN(766)

Abstract:

Reformation mechanism of high-quality carbonate reservoirs in northeastern Sichuan Basin

Luo Kaiping, Huang Zeguang, Jiang Xiaoqiong, Guan Honglin, Cao Qinggu

2011, 33(6): 559-563. doi: 10.11781/sysydz201106559

Abstract(3297) PDF-CN(885)

Abstract:
The high-quality carbonate reservoirs in Puguang Gas Field of the northeastern Sichuan Basin are mainly dolomites of reef-bank facies.Secondary intragranular and intergranular pores work as the main reservoir spaces,accompanied with significant tectonic track ways.The secondary pores generated from 2 stages of dissolution during burial history.1) The 1st stage of dissolution took place during the early burial period of mesodiagenesis,which corresponded to the early and middle Jurassic and was followed by big-scale petroleum filling.2) The 2nd stage of dissolution took place during the late burial period of mesodiagenesis,which corresponded to the late Jurassic and the early Cretaceous.Organic acid generated during organic thermal evolution and H₂S (TSR origin) solution in gypsolyte strata worked as fluid medium for the 2 stages of dissolution,respectively.Burial dissolutions can be identified from micropetrologies and diagenesis marks of reservoirs.A large number of tectonic track ways in reservoir rocks resulted from stages of tectonic movement during Meso-Cenozoic.The 2 stages of tectonic movement (the early and the middle-late Yanshan movements) occurred at the same time as the 2 stages of dissolution,which gave birth to fractures and microfractures.Rock permeability was improved and acid fluids migrated into rocks.Non-selective dissolutions happened and "fracture-dissolved pore" combination formed.Tectonic stress promoted burial dissolution,and their interactions helped reservoir reformation.The reservoir generation model named "facies-controlled distribution-tectonic stress+dissolution reformation" can be used to predict favorable carbonate reservoirs.

Reservoir diagenesis of 3rd member of Feixianguan Formation, Jiannan Gas Field

Bao Yunjie, Wang Shuyi, Jiang Xiaoqiong, Guan Honglin, Yang Zhenheng

2011, 33(6): 564-568. doi: 10.11781/sysydz201106564

Abstract(3648) PDF-CN(880)

Abstract:
Diagenesis and features of the 3rd member of Feixianguan Formation in the Jiannan Gas Field were studied taking well Jian43 as an example.Dolomitization,karstification and tectonic disruption were contributive to reservoir.Diagenesis sequence was illustrated as follows: algae agglutinate and micritization→first consolidation→atmospheric water erosion→secondary granular consolidation→neomorphism→compaction and pressolution→dolomitization→early tension fissure and filling→tectonic compression→buried erosion Ⅰ→petroleum entering→dolomite and fluorite filling as well as quartz filling and metasomatism→oil evolving to bitumen→buried erosion Ⅱ→late tension fissure→gas entering.There were 4 kinds of diagenesis environment including seabed (intertidal),atmospheric water,shallow bury and deep bury.Dolomite crystals,secondary granular consolidations,eroded fluorites,tensional fissures and pores without obvious deformation were the main identifications for buried erosions.

Accumulation conditions and controlling factors of Shaximiao Formation, Huilong area, Western Sichuan Depression

Yang Fan, Sun Zhun, Zhao Shuang

2011, 33(6): 569-573. doi: 10.11781/sysydz201106569

Abstract(3342) PDF-CN(780)

Abstract:
Based on the studies of source rock,storage,preservation and accumulation conditions for hydrocarbon,combined with tectonic history,core,seismic and drilling data,the main controlling factors for gas accumulation in Shaximiao Formation in Huilong area of the Western Sichuan Depression were analyzed.It was concluded that the study area was favorable for hydrocarbon generation,storage and capping.The main controlling factors included porous sand body with low impedance,boundary fault and effective trap.Typical sand body accumulation indicated that there were 3 kinds of typical accumulation assemblages; however,restricted by traps,gas accumulation size was limited.

Relationship between natural gas accumulation and overpressure in Xujiahe Formation, Xiaoquan—Fenggu structural belt, Western Sichuan Depression

Leng Jigao, Yang Keming, Yang Yu

2011, 33(6): 574-579. doi: 10.11781/sysydz201106574

Abstract(3055) PDF-CN(960)

Abstract:
The Western Sichuan Depression is a typical overpressure foreland basin.The forming mechanism of overpressure and its relationship with natural gas accumulation still remain discussing in researches.Interval transit time has been applied to calculate formation pressures of 29 wells in the Xiaoquan—Fenggu structural belt.Combined with the measured formation pressures of 37 wells,it has been concluded in this paper the forming mechanism and classification of overpressure as well as the relationship between overpressure and natural gas accumulation and preservation.1) Obvious overpressure has been found in Xujiahe Formation of the Xiaoquan—Fenggu structural belt.The 2nd and the 4th members of Xujiahe Formation belong to different pressure system.The neighbor-source overpressure mechanism is obvious.2) Undercompaction and hydrocarbon generation effects are the main causes for overpressure in the study area.3) 3 types of overpressure distribution have been found,including the Xinchang,the Hexingchang and the Fenggu ones.4) Natural gas accumulation is closely related to overpressure in Xujiahe Formation of the Xiaoquan—Fenggu structural belt.The PLS (pressure leakage strata) close to the top of OPC (overpressured compartment) is rich in natural gas.5) Studies of residual pressure for caprock breakthrough have indicated that the 2nd member of Xujiahe Formation is favorable for natural gas pre-servation all around the study area while the 4th member is unfavorable for preservation in the northeast of Xinchang and the southeast of Fenggu.

Discovery significance of Triassic dark mudstone rich in organic carbon, well AB1, Avat area, Tarim Basin

Lü Haitao, Geng Feng, Wu Qiqiao

2011, 33(6): 587-591. doi: 10.11781/sysydz201106587

Abstract(3506) PDF-CN(868)

Abstract:
In well AB1 of Avat area of the Tarim Basin,lacustrine dark mudstones rich in organic carbon have been found in Triassic.The abundance of organic matter pyrolyzed from rock ranges from medium to high; however,the organic matter is still in the immature and low-mature stages.Studies of sedimentary,tectonic background and thermal evolution history have indicated that several factors control the generation of effective source rock in Triassic of the platform-basin region.1) The deep and half-deep lacustrine facies are the most favorable,and the shore and shallow lacustrine facies the second.2) Dark mudstones should be thick and widespread enough.3) Buried over 5 500 m deep.During the early Triassic,Avat area was in lacustrine background.Triassic in the study area is buried deep presently.According to thermal evolution simulation as well as studies of seismic and sedimentary facies,the area of effective source rocks in Avat is 2 600 km².

Dynamic analysis and accumulation process recovery of typical reservoirs in Zhenjing region, south of Ordos Basin

Yin Wei, Hu Zongquan, Li Song, Liu Zhen, Shang Xiaofei, Zhang Huazhao

2011, 33(6): 592-596. doi: 10.11781/sysydz201106592

Abstract(3717) PDF-CN(886)

Abstract:
The dynamic analyses of typical reservoirs in Zhenjing region of the southern Ordos Basin have been carried out based on pore evolution history recovery,petroleum generation history thermal simulation and fluid inclusion analyses.The Chang8 lithologic traps were formed since the late Jurassic (160 Ma).The Chang7 source rocks began to generate petroleum at the end of Jurassic (140 Ma) and achieved the peak at the end of early Cretaceous (100 Ma).The Chang8 reservoirs were formed during 2 stages,including the medium of early Cretaceous (130 Ma) and the beginning of late Cretaceous (90 Ma).The times for trap formation,petroleum generation and reservoir formation matched well,which was favorable for the formation of Chang8 reservoirs.The charging and accumulation processes of petroleum were recovered according to the studies of tectonic evolution.A dynamic evolution model illustrating the process of reservoir formation was made,characterized by "multiple stages of accumulation,mainly formed during the middle stage and late stage adjustment".

Controlling factors for deep fluid activity and prediction of positive effect area in middle Tarim and Bachu regions

Meng Qingqiang, Zhu Dongya, Xie Qilai, Jin Zhijun

2011, 33(6): 597-601. doi: 10.11781/sysydz201106597

Abstract(3355) PDF-CN(964)

Abstract:
Volcanic activities and deep faults caused deep fluid activities in the Tarim Basin.Volcanic activities gave birth to deep fluids,and deep faults provided pathways for deep fluids to migrate upwards.In the middle Tarim and Bachu regions,Permian volcanic rocks were widespread.Around well Zhong1 of the middle Tarim region and in faults such as Tumuxiuke,Selibuya,Kangtakumu and Mazhatage of Bachu region,volcanic activities were the most active.During the late Hercynian,the faults Tazhong Ⅰ,Tazhong well 10 and Tazhong Ⅱ in the middle Tarim region and the faults Tumuxiuke,Selibuya,Kangtakumu and Mazhatage in Bachu region were active faults for deep fluid activities.In this way,the middle Tarim and Bachu regions with active deep fluid were favorable for carbonate reservoir corrosion in the lower Paleozoic.

Features and controlling factors of BSR in Shenhu area, South China Sea

Gong Jianming, He Yuhua, Yan Guijing, Yang Chuansheng, Li Gang, Yuan Chunfang

2011, 33(6): 602-606. doi: 10.11781/sysydz201106602

Abstract(2087) PDF-CN(808)

Abstract:
The high-resolution seismic reflection profiles from gas hydrate drilling zones of Shenhu area in South China Sea were interpreted precisely so as to analyze the features and the controlling factors of BSR (Bottom Simulating Reflector).It has been concluded that gas hydrate and BSR are closely related.In the study area,BSR is characterized by multi-axes and is discontinuous.The amplitude of BSR is mainly controlled by the free gas underneath the base of gas hydrate stable zone.BSR in Shenhu area might be influenced by the vertical combination of gas hydrates of different origins.

Structure of carbonate platform margin and characteristics of reef and their controlling factors in western deep-water region of South China Sea

Chen Lei, Lu Yongchao, Wang Zhenfeng, Sun Zhipeng

2011, 33(6): 607-612. doi: 10.11781/sysydz201106607

Abstract(3346) PDF-CN(1118)

Abstract:
Reefs are favorable for petroleum accumulation and their inner structure and generation environment have been the study focuses of geologists.Studies of the structure of the carbonate platform margin of the southern uplift of the western deep-water region of the South China Sea have indicated that,there are 2 types of platform margin structure (symmetrical and asymmetrical) and 3 types of platform margin style (fault-controlling,faulted flexure and carbonate ramp).Based on the analyses of seismic profiles,the generation styles and features of reef controlled by different platform margin structures have been studied.The structures of carbonate platform margin and the characteristics of reef are mainly controlled by regional tectonic differences,palaeogeomorphologies,ancient monsoons and sea level changes.

Comprehensive two dimensional gas chromatography and time-of-flight mass spectrometry of hydrocarbon in crude oil：application of inverse column set

Li Shuifu, Hu Shouzhi, Cao Jian, He Sheng, Ma Jun, Wang Xulong, Zhang Dongmei, Chen Yuyao

2011, 33(6): 645-651. doi: 10.11781/sysydz201106645

Abstract(2539) PDF-CN(939)

Abstract:
Petroleum hydrocarbons,which span a wide range of boiling point and polarity,are very complicated.The comprehensive two dimensional gas chromatography and time-of-flight mass spectrometry is one of the most effective methods to separate complex mixtures.An inverse column set was used to analyze petroleum hydrocarbons,and to distinguish some critical compounds,providing data for the comprehensive two dimensional gas chromatography and time-of-flight mass spectrometry of hydrocarbons in crude oil.It was concluded that,the inverse column set worked perfectly in separating two dimensionally the saturated hydrocarbons,especially isoalkane and cyclane with low molecular weight.It could be used to distinguish the UCMs (unresolved complex mixtures) from saturated hydrocarbons of biodegradation oil.

Characteristics and geologic implication of fluid inclusions of Carboniferous Huanglong Formation in well Paishen 1, Jianghan Plain

Sheng Xiancai, Guo Zhanfeng

2011, 33(6): 652-656. doi: 10.11781/sysydz201106652

Abstract(2620) PDF-CN(839)

Abstract:
The Jianghan Plain is one of the under-explored regions in southern China.Fracture (vug) fillings and aplite dolomites in cores of Huanglong Formation in well Paishen 1 of the study area were analyzed systematically using polarizing microscope,fluorescence microscope and cooling-and-heating bench.Abundant brine water inclusions and hydrocarbon-bearing brine water inclusions were found in the samples.Studies of the formation periods of single sample indicated that,dolomites,calcite veins and aplite dolomites all contained multiphase inclusions,mainly generated from multiphase filling or the mineral remains of early inclusions.Based on homogenization temperature distribution and the mineral types of host as well as the time of various veins (vugs),the inclusions were divided into 5 phases corresponding to homogenization temperature intervals 74.7-86.4,94.6-106.5,111.1-131.8,141.3-152.9 and 158-162.6 ℃,respectively.Combined with the studies of burial and thermal histories,it was concluded that inclusions were formed from the late Triassic to Cretaceous,and were influenced by stages of tectonic movement.From the late Indosinian Movement to the early Yanshanian Movement,gaseous hydrocarbon charged; however,the charging rates were smaller than the dispersing rates,and accumulations failed to form.

Distribution feature of micro-pore and throat and evaluation of movable oil in extra-low permeability reservoir：A case study in Yingcheng Formation, Shiwu Oil Field

Chen Zhihai

2011, 33(6): 657-661. doi: 10.11781/sysydz201106657

Abstract(2071) PDF-CN(1002)

Abstract:
Based on the laboratory analyses of porosity and permeability as well as the measurement of capillary pressure by mercury injection,the features of micro-pore and throat in extra-low permeability reservoirs have been studied.The micro-pore and throat radius is small,and the distribution of pore and throat is characterized by strong heterogeneity,resulting in the low permeability of reservoir and the high saturation degrees of irreducible water and oil.Movable oil in micro-pore and throat is defined using border formation theory.The threshold for movable oil has been found,by means of which movable and unmovable oils by water drive can be distinguished in extra-low permeability reservoir.The eva-luation of Yingcheng Formation in the Shiwu Oil Field has been carried out using the above-mentioned method,and the result is in accordance with that of nuclear—magnet resonance.

Hydrocarbon generation potential of lower Paleozoic source rocks in southwestern margin of Ordos Basin

Zhu Jianhui, Lü Jianhong, Miao Jiujun, Yuan Dongshan, Zhang Yanxia

2011, 33(6): 662-670. doi: 10.11781/sysydz201106662

Abstract(4205) PDF-CN(1130)

Abstract:
Carbonate and clastic source rocks generated in continental margin environment at the southwestern margin of the Ordos Basin during the early Paleozoic.Explorations proved that the lower Paleozoic source rocks experienced higher hydrocarbon generation even though their organic matter abundance was low.Good source rocks (usually type Ⅰ and Ⅱ) were found in weak-reducing and reducing bathyal environment with high salinity content.Cambrian source rocks generated hydrocarbon during Triassic and had limited contribution to the present reservoirs.The source rocks in Majiagou and Pingliang Formations of Ordovician generated hydrocarbon during Jurassic and Cretaceous.Ordovician source rocks are in high evolution stage,represented by the carbonate rocks in Majiagou Formation as well as the dark mudstones and carbonate rocks in Pingliang Formation.The hydrocarbon generation quantity of the lower Paleozoic is 172.87×10¹² m³,while in the north it exceeds 40×10⁸ m³/km²,and in the south it amounts to 30×10⁸ m³/km².

A vacuum filtrating device and technique to separate authigenic illites from sandstone reservoirs with microporous membrane

Zhang Youyu, Luo Xiuquan

2011, 33(6): 671-676. doi: 10.11781/sysydz201106671

Abstract(2518) PDF-CN(934)

Abstract:
The separation of authigenic illite is a key point in the K-Ar dating of authigenic illite in sandstone reservoir.High speed and ultra-high speed centrifuges are used home and abroad.In this paper,a new method using microporous membrane and vacuum filtration is introduced,which is outstanding for easy operation,fast speed,high efficiency and good quality.The device structure,assemblage and operation instruction are illustrated firstly.And secondly,the characteristics or innovations in 5 aspects of the device and the technological procedure are described in details.Finally,the separating efficiency,quality,application situation and prospect of the device and the technique are discussed.Series of technological problems of the elder vacuum filtrating device,such as miscellaneous operation,low efficiency and poor practicality,have been overcome by the 5 innovations.The new device could be developed into formed equipment for daily use and for scientific research and experimentation,providing a new method for authigenic illite separation,and also have a broad potential applicability in the future.

2011 Vol. 33, No. 6

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