2002 Vol. 24, No. 6

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CHARACTERISTICS OF HYDROCARBON POOL-FORMING SYSTEMS IN THE MARINE RESIDUAL BASINS OF CHINA
ZHOU Li-qing, ZHANG Huai
2002, 24(6): 483-489. doi: 10.11781/sysydz200206483
Abstract:
Starting with the pool forming system characteristics research of hydrocarbon in the Ordos Basin,the Sichuan Basin,the Tarim Basin,the Bohaiwan Basin,Middle Lower Yangtze area,Dian Qian Gui area and other marine residual basins,it was concluded that the essential factors of hydrocarbon pool forming systems in the major marine residual basins of China were closely related to the geotectonic location of the basins and the tectonic evolutionary history the basins experienced.These basins hare characteristics as follow.a)The tectonic subsidence of prototype basins controlled the types and distribution of principal hydrocarbon source rock.b)Controlled by the tectonic evolutionary cycles of prototype basins,three kinds of effective source rock reservoir cap rock assemblages were formed.c)The paulopost tectogenesis controlled the late stage hydrocarbon generating center of a residual basin.d)The large scale inherited paleo uplifts formed in the Caledonian,the Hercynian and the Indo Chinese periods were the main target areas of hydrocarbon migration.e)The hydrocarbon generating peak periods of the Paleozoic hydrocarbon generating areas must organically match with the trap forming periods.f)The paulopost tectonic reconstruction must be moderate.Not only appropriate compressive uplifting was needed,which formed necessary storage spaces,traps and migration power and resulted in the enrichment of hydrocarbon,but also oil and gas pools did not be disrupted.g)After the paulopost tectonic reconstruction had been experinced,the late stage hydrocarbon generation and migration of basins were controlled by the tectonic patterns after reconstruction.
THE FEATURE OF MIGRATION AND ACCUMULATION FOR LARGE AND MEDIUM SIZED GAS FIELDS IN CHINA
WEI Yong-pei
2002, 24(6): 490-495. doi: 10.11781/sysydz200206490
Abstract:
There are different ways and forms for the migration and accumulation of natural sized gas in large and medium sized gas fields in major basins of China,which could be summarized as following:1.Regional tectonic movement is the most important factors for gas migration;2.Occurence of fluid potential controls the direction of gas migration and the place of accumulation;3.Natural gas is mainly migrated vertically and migrated step by step in a faulted basin,and is dominated by lateral migration in a craton,foreland or large fault sag basin,but with strong influence of vertical migration;4.Faults and unconformity surfaces are the major passways for gas migration;5.Abnormal high pressure is the drive force in high pressure basin,and thermal flow also shows some influence;6.Natural gas is normally accumulated in the updip of a basin and the paleo high.
IS TECTONIC UPLIFTING THE GENESIS OF ABNORMAL HIGHPRESSURE?
XIA Xin-yu, ZENG Fan-gang, SONG Yan
2002, 24(6): 496-500. doi: 10.11781/sysydz200206496
Abstract(1066) PDF-CN(502)
Abstract:
In many articles and works in China,tectonic uplifting was regarded as the genesis of abnormal highpressure.This opinion omitted the effects on fluid pressure by the decrease of fluid temperature and the rebound of pore volume in the process of uplifting.Calculations show that neither of the two factors can be neglected completely.Tectonic uplifting inclines to forming abnormal lowpressure rather than abnormal highpressure.Since the decrease of load and temperature in the process of uplifting makes unisostatic compaction and other factors tend to stopping,tectonic compression often becomes the most principal genesis of overpressure in uplifted areas.Therefore,caution is needed when using the seismic method to predict the distribution of abnormal pressure in the areas where tectonic uplifting happened in later and recent periods.Tectonic uplifting resulted in the disappearance of paleooverpressure in the gas bearing measures of some basins(for example,the Ordos Basin).This is mainly because of the fluid state changes caused by uplifting,not only because the gas suppling amount of hydrocarbon source rock was less than the dispersed amount of natural gas.
A CORRELATION OF DEFORMATION CHARACTERISTICS BETWEEN THE KUQA DEPRESSION AND THE SOUTHWESTERN TARIM DEPRESSION IN THE TARIM BASIN
HUANG Ze-guang, ZHAI Chang-bo, XU Hong-jie
2002, 24(6): 501-505. doi: 10.11781/sysydz200206501
Abstract:
Based on a correlation of dynamic background,deformed sequences,decollement structures between the Kuqa depression and the southwestern Tarim depression,there is obvious difference in the two areas in terms of their structural deformation.The compressional stress is dominated in the Kuqa area with little change of deformation characteristics in whole area but a decreasing vertical deformation from north to south.The southwestern Tarim depression is showed strong wrench deformation with different intensity in different parts.As a result,structural traps are poorly developed in the deep part and Maigaiti slope,and faults can not be acted as a vertical passway of hydrocarbon migration.
PETROLEUM SYSTEM AND EXPLORATION STRATEGY IN SHAYA UPLIFT OF THE NORTHERN TARIM BASIN
YUN Lu, JIANG Hua-shan
2002, 24(6): 506-511. doi: 10.11781/sysydz200206506
Abstract:
There are two petroleum systems in Shaya uplift:southern one with marine source rocks and the other with terrestrial source rocks in the north.The two systems showed different characteristics in terms of key time,trap types of oil and gas pools,and occurrence.The major plays occurred in sequences older than the Jurassic in marine petroleum system,such as in Tahe area.The exploration targets are dominated by the Lower Ordovician buried hills or overturn anticline,the Triassic anticline-fault block and low amplitude anticline around salt dome,and the Carboniferous composite stratigraphic and structural traps.The major exploration targets in terrestrial petroleum system,such as in Yakela and Luntai areas,are mainly occurred in the Tertiary and Late Cretaceous structural traps and the Jurassic and Early Cretaceous stratigraphic traps.However,some attention should be paid to the Lower Paleozoic buried hills and overturn anticline in the area between Yanan fault and Luntai fault.
GENETIC TYPES OF THE NATURAL GAS IN THE NORTHEAST AND THE EAST OF SICHUAN BASIN
LIU Guang-xiang, TAO Jing-yuan, PAN Wen-lei, LÜ Jun-xiang
2002, 24(6): 512-516. doi: 10.11781/sysydz200206512
Abstract:
Based on study of the component and its carbon isotope of natural gas samples from the Northeast and the East of Sichuan Basin,the genetic types of the natural gas in different regions are different.Natural gas in the Northeast was mainly derived from the over matured source rocks with type Ⅱ-Ⅲ1 kerogen;besides,it is supposed that type Ⅱ-Ⅲ1 organic matter makes more contribution than that of type Ⅰ1-Ⅰ2 type kerogen in this region.However,natural gas samples from Jiannan gas field(Upper Permian and Lower Triassic)showed that they were mainly generated by over matured source rocks with kerogen typesⅠ1-Ⅰ2 and part of gas showed characteristic of sapropelinite and humic organic matter origin.Furthermore,natural gas in Carboniferous pool was from the secondary cracking of oil derived from Silurian source rocks.
CHARACTERISTICS OF DIAGENETIC SECONDARY MINERALS IN THE SANDSTONE OF THE SONGLIAO BASIN
YANG Gui-fang, ZHUO Sheng-guang, TENG Yu-hong, NIU Ben, E Jun-jie
2002, 24(6): 517-522. doi: 10.11781/sysydz200206517
Abstract:
During the diagenetic process of sandstone,secondary minerals were up to more than 20 kinds.The formation of secondary quartz,albitite,calcite and laumontite affected the storage physical properties of sandstone in different degrees.The SiO2 forming secondary quartz mainly came from the transformation of dissolved clay mineral in clastic feldspar.Secondary feldspar was related to the albitization process of feldspar,the albitization of plagioclase began at the early stage of diagenesis,and the albitization of K feldspar can only underway under higher diagenetic conditions.Secondary calcite was mainly inorganic CaCO3 deposit in the early stage of diagenesis.Laumontite was stable mineral in the late diagenetic stage,and was related to the albitization in the late stage of diagenesis.
A STUDY ON RESERVOIR HETEROGENEITY IN TAIXING Oil field, NORTHERN JIANGSU BASIN
XIAO Wei
2002, 24(6): 523-526. doi: 10.11781/sysydz200206523
Abstract:
The main producing horizons in Taixing Oil field,northern Jiangsu Basin are characterized by strong heterogeneity,which resulted in poor development result.It is necessary to study the reservoir heterogeneity quantitatively in order to make sure the reservoir connectivity between the water injector and producer.By calculating the variation function and analyzing the variation parameters,3D reservoir parameter models were proposed and simulated.The heterogeneity of each reservoir can clearly be recognized by the models,which provi ded an useful information for development of the Oil field.
TYPES OF PASSAGE SYSTEM AND ANALYSIS OF EVOLUTION OF ITS CAPABILITIES IN TEMPORAL AND SPATIAL RANGE
ZHAO Zhong-xin, WANG Hua, GUO Qi-jun, GAN Hua-jun, HAN Jin-yang, TIAN Xiao-xue
2002, 24(6): 527-532. doi: 10.11781/sysydz200206527
Abstract:
Petroleum migration was classified into direct and indirect migration based on the studying of its migrating characteristics and the classification of passage system.And the indirect migration was further classified.The inhomogeneity of migrating capabilities of a passage system in spatial and its influent factors such as porosity,permeability,faults,crude fractures and unconformity were analysed.It could be concluded that the migra ting capabilities of a passage system was episodic in very long time,but different passage system showed varied properties in a short time.Only diversified types of passage system were placed in their suitable locations temporally and spatially,could a commercial hydrocarbon accumulation be formed.
OVERPRESSURE TRANSFERENCE:CONCEPT AND WAYS
LIU Xiao-feng
2002, 24(6): 533-536. doi: 10.11781/sysydz200206533
Abstract:
Overpressure transference may be a kind of widespread phenomenon in overpressure sedimentary basins.Overpressure transference is the increasing of pore fluid pressure in other pressure systems caused by the flow of overpressure fluid released or leaked from overpressure systems.Base on the orientation of overpressure transference,vertical and lateral two types of overpressure transference were divided.The overpressure resulting from overpressure transference was named transference overpressure.The ways of overpressure transference include the injection of overpressure fluid,the migration of overpressure fluid along permeable sandbodies and the dilatation of overpressure compartments.
MOLECULAR GEOCHEMICAL CHARACTERISTICS OF THE SECONDARY PETROLEUM MIGRATION
DENG Jin-hui, SHI Ji-an, WANG You-xiao, WANG Qi, GUO Xue-lian
2002, 24(6): 537-540. doi: 10.11781/sysydz200206537
Abstract:
Oil samples of different migration distances were obtained from the extraction of the simulation expe riment.The saturated and aromatic hydrocarbon fractions in these oil samples were made GC/MS analysis.The results of the stuey on the fractionation effects of n-alkane,alkyl phenanthrene,alkyl sulfur fluorene and alkyl fluorene in the early stage of the secondary petroleum migration revealed that the n-alkane with very little polarity was subjected greater influences from the physical adsorption of clay mineral after entering drainage layers full of water.This resulted in the decreasing trend of nC18-/nC19+ peak value ratio within a certain migration distance.When the equilibrium of physical adsorption was reached,the peak value ratio of nC18-/nC19+ had an obvious increasing trend.Affected by geologic chromatographic effects,alkyl phenanthrene,alkyl sulfur fluorene and alkyl fluorene in the aromatic fractions with greater polarity presented obvious migration fractionation effects of high molecular hysteresis.The n-alkane and aromatic fractions were subjected physical adsorption at first in the early stage of the secondary petroleum migration,and the action on n-alkane was far greater than on aromatic fractions either in time or in space.The knowledge obtained from the experiment provided powerful research basis for the rational and effective evaluation of hydrocarbon migration processes.
DISCUSSION ON THE SECONDARY HYDROCARBON-GENERATION MECHANISM OF COAL
GONG Se, LI Jian, ZHANG Ying, LUO Xia
2002, 24(6): 541-544. doi: 10.11781/sysydz200206541
Abstract:
In this paper,the secondary hydrocarbon generation mechanism of the Upper Paleozoic coal in the South Huabei Basin was studied using a new kind of quantitative evaluation method for gas source rock.Two series of thermal simulation experiments were conducted,that is,the successive hydrocarbon generation thermal simulation and the stepwise hydrocarbon generation thermal simulation(simulating the process of subsidence uplifting subsidence).Besides,the characteristics of secondary hydrocarbon generation for coal rock were also discussed.
STUDY ON THE EXPERIMENT AND MECHANISM OF RAISING THE RECOVERY RATIO OF COALBED METHANE BY GAS INJECTION
TANG Shu-heng, YANG Qi, TANG Da-zhen, SHAO Xian-jie, WANG Jiang
2002, 24(6): 545-549. doi: 10.11781/sysydz200206545
Abstract:
In this paper,the mechanism of raising the recovery ratio of coalbed methane by gas injection was discussed.It was considered that injected gases not only enhanced reservoir energy.but also completed with coalbed methane for adsorption or replaced and expelled coalbed methane.As a result,the recovery ratio of coalbed methane was raised.By the isothermal adsorption and desorption experiments of coal samples to pure CH4 gas as well as CH4-N2 and CH4-CO2 two binary gases,their Langmuir equations were obtained respectively,and their maximum theoretical recovery ratio was compared and analysed.The results revealed that the maximum theoretical recovery ratio of binary gases in coal beds was much higher than that of pure coalbed methane under the condition of the same gas content.
EXTRACTION METHOD AND SIGNIFICANCE OF AUTHIGENIC CLAY MINERALS IN SEDIMENTARY ROCKS FOR K-Ar AGE DATING
HUANG Bao-ling, WANG Da-rui, LIU Yu-lin, MIAO Guo-jun
2002, 24(6): 550-554. doi: 10.11781/sysydz200206550
Abstract:
A new method was used to separate authigenic clay minerals in sedimentary rocks-a repetitive free zing thawing process.The aim of this process was to disaggregate rock samples using the volume expansion of water that impregnates samples.The new method can avoid the shortcoming that a conventional crushing produces an over crushing of the larger grains of a rock,creating artificially clay sized particles which become intimately mixed with the natural clay component of the rock.For the most of our samples,fractions smaller than 1μm,the new method already remove the presence of K feldspar,while the conventional method can not achieve;In addition,with the reduction of grain size,the content of detritus illite in clay mineral component decreased gradually.For our samples,in the most of fractions smaller than 0.2μm,the content of detritus illite 5%,in some of them,the detritus illite already removed.
ESTIMATION OF ANCIENT SUBSURFACE TEMPERATURES WITH THE APATITE FISSION TRACKS IN JIYUAN DEPRESSION, NORTH CHINA BASIN
ZHAO Wei-wei, JIN Qiang, WANG Wei-feng
2002, 24(6): 555-560. doi: 10.11781/sysydz200206555
Abstract:
By measuring apatite fission tracks,the paleo geotemperature gradients in the Mesozoic and Tertiary in the Jiyuan Depression,North China Basin were estimated.The annealing temperatures of the apatite fission tracks were 67-74℃ and 114-125℃ corresponding to the Tertiary samples and Mesozoic samples respectively.Based on the anneal modeling method,the calculated subsurface temperature gradients were 2.9℃/100m in the Mesozoic,and 3.1℃/100m in the Tertiary respectively.The different temperature gradients between the Mesozoic and Tertiary were resulted from different tectonic movements in the studied area,where a great lake depre ssion(with lower temperature gradient)was formed in Mesozoic,and become a rift(with higher temperature gradient)in Tertiary.These temperature gradients were applied successfully in assessment of thermal evolution of organic matters of source rocks,and in estimation of generated petroleum quantity in the Jiyuan Depression.Therefore,estimation of paleo geotemperatures with apatite fission tracks is an useful tool in rebuilding basin thermal evolution,even in the basin with different tectonic natures.
OPTIMUM ESTIMATION OF THE AMOUNT OF EROSION BY POROSITY DATA:A CASE STUDY ON MINFSHUI FORMATION OF CHANGLING DEPRESSION, SONGLIAO BASIN
HE Jiang-qi, ZHOU Zu-yi, JIANG Xing-ge
2002, 24(6): 561-565. doi: 10.11781/sysydz200206561
Abstract:
A new approach is introduced for the optimum estimation of the amount of erosion using primary porosity data.The method is applied on both the mudstone and sandstone from Mingshui Formation of Changling depression in southern Songliao basin.The two estimations yield similar results of about 500m of erosion.Considerations that should be taken into account in geological application are discussed at the end of the paper.
THE PREPARATION OF THIN SECTION FOR OIL-SATURATED ROCK SAMPLES
SUN Guo-zhong
2002, 24(6): 566-567. doi: 10.11781/sysydz200206566
Abstract:
Preparation of thin section of oil saturated rock sections of different reservoirs,such as sandstone,conglomerate and carbonate rock,must adopt different technologies to maintain original structure of rock samples and original distribution of oil.The key is how to make rock samples concrete.Usually samples may be soaked and concreted in epoxy resin under the conditions of normal pressure and vacuum or normal temperature and normal pressure.For the incompact and oil saturated rock samples,it is necessary to concrete and fix them on the slide glass by glue 502 or epoxy resin and grind them flat at first,then the thin sections can be made.
DAMAGES OF INJECTION WATER QUALITY TO RESERVOIRS IN TAIXING Oil field AND THEIR COUNTERMEASURES
LIU Bin, YANG Qi, TAN Shi-hai
2002, 24(6): 568-572. doi: 10.11781/sysydz200206568
Abstract:
The factors and mechanisms of damages of injection water quality to reservoirs are analysed,based on the characteristics of reservoirs and fluids from Taixing Oil field.It is considered that water absorptivity is mainly affected by water sensitive damages and precipitation and scaling caused by the incompatibility between injection and formation waters.The key to improved water quality lies in economic and effective autiexpander and anti scale being dosed timely,regularly and quantitatively.