石油实验地质

TECTONIC SIGNIFICANCE OF SANDSTONES AND COUPLING RELATION OF BASIN AND MOUNTAIN IN THE LATETRIASSIC-JURASSIC IN THE MIDDLE AND UPPER YANGTZE REGION

Liu Yunsheng, Guo Zhanfeng, Liang Xiwen, Yang Zhenwu

2006, 28(3): 201-205. doi: 10.11781/sysydz200603201

Abstract(933) PDF-CN(386)

Abstract:
Based on the sandstone clastic model built by Dickinson et al,the characteristics of detrital composition of the Late Triassic-Jurassic sandstones in the Middle and Upper Yangtze region are studied to determine the types of source areas.It is presented that the main provenances of the Late Triassic-Jurassic basin comes from the East Qinling and Dabie orogenic belt,Longmenshan mountain and Jiangnan obduction zone.The main types of provenances attribute to the properties of recycled orogenic belt.The variational sequences of detrital compositions are the sedimentary responses to the three times of obduction of orogenic belt in the surrounding margin of basin.The analysis on the tectonic significance of detrital composition of the Late Triassic-Jurassic sandstones shows that the Late Triassic-Jurassic basin in the southern margin of the East Qinling and Dabie orogenic belt is a foreland basin located in the foreland of a collision orogen and thrusting nappe belt.The coupling relations of basin and mountain and Mesozoic tectonic evolution in the East Qinling and Dabie orogenic belt were also discussed in this paper.

TECTONIC REVERSE OF MESOZOIC AT THE WESTERN FOOT OF HELAN MOUNTAIN AND ITS MEANING

Wang Feng, Liu Chiyang, Zhao Hongge, Yang Xingke, Weng Wangfei

2006, 28(3): 206-209. doi: 10.11781/sysydz200603206

Abstract(956) PDF-CN(375)

Abstract:
The comprehensive analysis of fractures and bedding structures in the Xiaosongshan fault indicates that,a huge tectonic reverse took place after the Late Jurassic and the Xiaosongshan ‘nappe' structure developed at the western foot of the northern part Helan Mountain is actually a slipping structure.The sedimentary feature and the basaltic environment prove that,the region is a continental rift slope.Therefore,the(massive) compressive stress in EW direction did not exist in the Early Mesozoic.Fold deformation as well as bedding shear is the result of local structural deformation caused by the slipping structure,which is obviously contractive to the typical EW trend thrusting in the west of Ordos block and should be paid attention to in research.

THE COMPARISON OF TWO TYPES OF TIGHT SAND GAS RESERVOIR

Jiang Zhenxue, Lin Shiguo, Pang Xiongqi, Wang Jie

2006, 28(3): 210-214. doi: 10.11781/sysydz200603210

Abstract(1014) PDF-CN(744)

Abstract:
The tight sand gas is one of unconventional gas, it is also an important candidate resources of conventional gas.The opinion based on the research of predecessors.After fully thinking of the background of structural evolution,and dynamical analysis the relationships between the hydrocarbon genera-tion and expulsion fastigium of source rock and tight evolution history of reservoir,divide the tight sand gas reservoir into two types: "pre-exiting deep gas" and "subsequent tight sand gas".According to the comparative analysis on reservoir forming conditions,reservoir forming characters and reservoir forming principle of this two types,generalize the reservoir forming patterns and distribution regulation.The reservoir forming patterns of "pre-exiting" deep basin gas reservoir is divided into three kinds: depression central symmetry distribution,!foreland lateral margin slope distribution and structure slope distribution."first is the conventional accumulation,but late is reconstruction" is the reservoir forming pattern of "subsequent" tight sand gas,and the pattern is divided into three phases with different reservoir forming characters and conditions.Correctively distinguish the two kinds of tight sand gas from each other is very important to guide natural gas exploration and make the right exploitation plan.

RELATIONSHIP BETWEEN THE MESOZOIC AND CENOZOIC TECTONIC STRESS FIELDS AND THE HYDROCARBON ACCUMULATION IN THE ORDOS BASIN

Zhang Yikai, Zhou Lifa, Dang Ben, Sun Wei

2006, 28(3): 215-219. doi: 10.11781/sysydz200603215

Abstract(682) PDF-CN(380)

Abstract:
On the basis of previous achievements,through the observation of a great deal of joints,faults and folds in field and under well and the classification of formation sequences of structures,it is studied in this paper the Mesozoic and Cenozoic tectonic stress fields and the relationship between tectonic stress fields and hydrocarbon accumulation in the Ordos Basin.The directions of the main tectonic stress fields in the basin were NW-SE,NNE-SSW and SN which controlled the first hydrocarbon migration and accumulation during the Indosinian movement.During the Yanshanian movement,it was NW-SE which controlled the second hydrocarbon migration and accumulation.During the Himalayan movement,it was NNE-SSW which controlled the final migration,adjustment and accumulation.

STRUCTURAL-DEPOSITIONAL FEATURE AND OIL-GAS RESERVOIR DISTRIBUTION IN THE TANGYUAN FAULT DEPRESSION

Ma Jinlong, Zhang Baoquan

2006, 28(3): 220-224. doi: 10.11781/sysydz200603220

Abstract(710) PDF-CN(338)

Abstract:
Developed on Premesozoic basement,the Tangyuan Fault Depression is a Mesozoic and Cenozoic Fault Depression.Basin controlled by two large faults toward NNE,cut by faults toward NW with divided zones between east and west and fault blocks between south and north.It exited Cretaceous and Paleogene two relatively dependent structure and oil-gas unit with fan delta-lake depositional system.The results illustrated that the Tangyuan Fault Depression went through three stages: early fault depression in Mesozoic,developing fault depression and late fault depression in Cenozoic.Its feature is giant sedimentary thickness,maximum 6 000 metres.Cretaceous and Paleogene are formation of interest.As a result of Yanshan event at the end of Cretaceous and Himalayas event at the late Cenozoic,prototype basin is subjected to strong deformation;prototectonics and sedimentary frames were obviously changed;oil-gas reservoirs were destroyed.Oil-gas reservoirs are principally controlled by faults and lithology.

HYDROCARBON-GENERATION HISTORY OF FAULT SUBSIDENCE-DEPRESSION PROTOTYPE SUPERIMPOSITION SYSTEM：A CASE STUDY OF QINTONG SAG IN THE NORTH JIANGSU BASIN

Xu Xuhui, Jiang Xingge, Zhu Jianhui

2006, 28(3): 225-230. doi: 10.11781/sysydz200603225

Abstract(668) PDF-CN(351)

Abstract:
The hydrocarbon-generation history of the oil and gas materials in a fault subsidence-depression basin is certainly restricted and controlled by the burial history of fault subsidence-depression prototype superimposition.The idea of petroleum reservoir-forming from hydrocarbon source rock to trap must be brought into the basin system.Based on this idea,the relationship between geologic process and its response in a basin can be determined,and the boundary conditions that the prototype controls the dynamic changes of pressure(P),volume(V) and temperature(T) are established.At the same time,the TSM basin modelling system is used so as to calculate the hydrocarbon-generation quantity and analyze the hydrocarbon-generation history.

PETROLEUM GEOLOGIC CONDITION AND EXPLORATION TARGETS IN THE SOUTHEAST OF JUNGGAR BASIN

Zhou Songbai, Liu Guangxiang

2006, 28(3): 231-235. doi: 10.11781/sysydz200603231

Abstract(738) PDF-CN(385)

Abstract:
Three basin prototypes are generated in the southeast of Junggar Basin: filling basin in the post-rift sequence(P₂-T_2-3),foredeep basin in the post-rift sequence(T₃³-J_1-2) and intracontinental foreland basin(J₃-E).There are three sets of major hydrocarbon source rocks: the Lucaogou and Hongyanchi Formations of the Upper Permian,the Huangshanjie and Haojiagou Formations of the(Upper) Triassic and the Badaowan,Sangonghe and Xishanyao Formations of the Lower and Middle Jurassic,located in the Fukang,Jimusaer,Wucaiwan and Huangcaohu Sags,forming multiple petroleum supply centers.The research region is good for petroleum preservation.Oil and gas can be explored in different blocks.The Bogda nappe structure and the two fault blocks(approximately SN and EW) are closely related to hydrocarbon generation, migration and accumulation.Hence this region is worth exploring further.

THE SEDIMENTARY AND PALAEOGEOGRAPHIC CHARACTERISTICS OF THE UPPER ORDOVICIAN IN THE TARIM BASIN

Wang Shuyi, Huang Jiwen, Jiang Xiaoqong

2006, 28(3): 236-242. doi: 10.11781/sysydz200603236

Abstract(651) PDF-CN(436)

Abstract:
The Late Ordovician epoch is an important period of sedimentation-structure transform in the Tarim Basin.On the palaeogeographic basis of being shallow in the west and deep in the east in the Cambrian-Middle Ordovician epoch,the north-south directional sedimentary framework of uplift alternating with depression was added,forming the diamictic continental shelf deposit system in the center and west and the deep-sea trough basin deposit system in the east of Tarim Basin.Because the tectogenesis was not harmonious,the vertical diamictic continental shelf deposit system in the center and west of Tarim Basin was different from the transverse one.The vertical variation is that there are many autogenic carbonate sediments in the earlier period and that terricolous sediments are dominant in the later period.In the early and middle periods,carbonate mild slope deposit of Qiaerbake Formation and carbonate platform deposit of Lianglitage Formation developed,forming three carbonate platforms in the center and north of Tarim Basin and in Bachu-Tangwangcheng area.In the later period,the Sangtamu Formation slope-tidal flat deposit with detrital rock being dominant developed.Transversely,in the deep depression areas away from the surrounding uplifts,the Querqueke Formation turbidite deposit with diamictic outer continental shelf deep basin facies developed in the east of the diamictic continental shelf and the static water mudstone deposit with diamictic outer continental shelf deep basin facies developed in Keping,Shaxi and Awati areas.In Bachu upheaval area with shallow water body and gentle sea-bottom slope gradient,the diamictic inner continental shelf deposit developed.The supercompensated deep-sea turbidite deposit developed in the eastern deep-sea trough basin.There still exists a slope-break zone with topography greatly varing between the central and western continental shelfs.Comparing with the outer continental shelf deposit,its turbidite sequence further developed and the coarse clastics obviously increased.

HYDROCARBON MIGRATION AND ACCUMULATION CHARACTERISTICS IN THE BACHU-MAIGAITI AREA OF THE TARIM BASIN

Ma Hongqiang, Wang Shuyi, Lin Jun

2006, 28(3): 243-248. doi: 10.11781/sysydz200603243

Abstract(724) PDF-CN(388)

Abstract:
There are 2 sequences of source rocks including the Cambrian-Middle-Lower Ordovician and the Carboniferous in the Bachu-Maigaiti area of the Tarim Basin.The source rock evolution history in the Bachu Uplift is different from which in the Maigaiti Slope.The hydrocarbon migration systems include reservoir fracture,fault and unformity.The hydrocarbon accumulation in the area can be divided into 3 periods such as the late Caledonian-early Hercynian,the late Hercynian and the Himalayan.Reservoirs were destructed in the late caledonian-early Hercynian,destructed or persered in the late Hercynian and generated or adjusted again in the Himalayan.Acorrding to major hydrocarbon accumulation as well as source rocks and reservoirs,there are 4 types of hydrocarbon accumulation models in the area: a)the early hydrocarbon accumulation;b)the secondary early hydrocarbon accumulation;c)the early hydrocarbon accumulation-destruction-late accumulation again;d)the late hydrocarbon accumulation.

THE SEQUENCE STRATIGRAPHIC MODEL BASED ON THE VARIANCE OF RIVER LEVEL——TAKE THE GUDONG OILFIELD IN THE JIYANG DEPRESSION AS AN EXAMPLE

Dong Chunmei

2006, 28(3): 249-252. doi: 10.11781/sysydz200603249

Abstract(751) PDF-CN(405)

Abstract:
Taking the upper member of Guantao Formation of the Neogene in the Zhanhua Sag of the Ji-yang Depression,the Bohaiwan Basin as an example,a study of the high-resolution sequence stratigraphy has been carried out.Based on the study,the paper presents a new principle and method for identi-fying sequence.Using the data from the sedimentary structure character,lithology,color of rocks,the changing of clay types and geochemistry elements enrichment which reflect the change of river level,mark off the flooding system tract,high water level system tract and low water level system tract.The corresponding deposition processes of parasequence sets are flooding deposition,lateral accretion and slow deposition.Based on three system tracts,the facies model of four river types are established.

PETROLEUM SYSTEMS IN THE HONGZE SAG, THE NORTH JIANGSU BASIN

Fan Wenke, Wang Jiangong, Liu Lifang, Li Guoyong

2006, 28(3): 253-258. doi: 10.11781/sysydz200603253

Abstract(744) PDF-CN(321)

Abstract:
The Hongze Sag is a middle-small rift located in the west end of North Jiangsu Basin.It can be divided into 4 petroleum systems as the Shunhe,Guanzhen,Suxiang and Jia'nan,among which the Shunhe and Guanzhen petroleum systems are favorable but distinguished.Further more,the petroleum systems of Shunhe and Guanzhen can be divided respectively into 2 accumulation systems as the northern and the southern ones.Within the accumulation system,migration takes place almost the same time as trap formation.The Sanduo Movement is the key period to control petroleum accumulation and distribution while tectonic subsidence and geothermal history are the key factors to affect abundance.Insufficient reservoirs are formed due to the later time and lower maturation of organic matters.The best plays for oil accumulation are the deep-fault belts in the Southern Guanzhen and Southern Shunhe accumulation systems,and the deep monocline belts in the Northern Guanzhen and Northern Shunhe accumulation systems.Other belts in the Northern Guanzhen and Northern Shunhe accumulation systems can also be favorable,especially the belts near source rocks.

NAPPE STRUCTURE IN FUJIAN PROVINCE

Tao Jianhua, Chen Fulong

2006, 28(3): 259-263. doi: 10.11781/sysydz200603259

Abstract(781) PDF-CN(367)

Abstract:
Surface and deep geophysical data analysis has proved the existance of nappe structures in Fujian Province.Accordingto different shapes,they can be divided into 3 types: the eastern thrust nappe belt,the central thrust fold belt and the western compressive nappe belt.Regional tectonic analysis indicates that,nappe structures in the Fujian Province were generated during the Indosinian epoch,propagated mainly during the early Yanshan epoch and decreased in the late Yanshan epoch.The nappe movement is from northwest to southeast.The formation of nappe is related to the tectonic movement of circum-Pacific continental active belt.

THE ORGANIC FACIES DISTRIBUTION AND HYDROCARBON-FORMING MODEL IN THE QIANGTANG BASIN, QINGHAI-TIBET PLATEAU

Qin Jianzhong

2006, 28(3): 264-270. doi: 10.11781/sysydz200603264

Abstract(721) PDF-CN(331)

Abstract:
The main Mesozoic marine hydrocarbon source rocks developed in J_3x,J₂b,J_2x and J_3s formations in the Qiangtang Basin,Qinghai-Tibet Plateau.Macro-algae are the main hydrocarbon-forming organisms in these hydrocarbon source formations.The Ⅱ₁ and Ⅱ₂ organic facies developed in the J_3s and J₃b formations.The Ⅱ₁,Ⅱ₂ and lignosa organic facies developed in the J_2x formation.They are getting poorer and poorer from the center of the basin or depressions to the northeast of the basin.In the J_3x formation all types of above mentioned organic facies developed.The Ⅰ or Ⅱ₁ organic facies gradually transited into lignosa organic facies from the south and north of the basin or depressions towards the central uplifted area.The source rocks in the center of the Qiangtang Basin are in the middle to late stages of mature and the Jurassic Ⅱ₁ organic facies are the most favorable oil-generation facies.The source rocks in the center and west of the north Qiangtang Depression are in the stage of high-mature and the Jurassic Ⅱ₁ organic facies are the favorable condensate oil-or light oil-and gas-generation facies.The Ⅱ₁ organic facies in the J_3x formation in the Qiangtang Basin are over mature at present.They are the favorable gas-generation facies.

THE THERMAL EVOLUTION HISTORY AND OIL AND GAS GENERATION HISTORY OF MAIN SOURCE ROCKS IN THE NANPANJIANG BASIN

Zhao Mengjun, Zhang Shuichang, Zhao Ling, Liu Peichu

2006, 28(3): 271-275. doi: 10.11781/sysydz200603271

Abstract(803) PDF-CN(528)

Abstract:
The restoration of oil and gas generation is very difficult since the over mature source rock experienced multi-stage tectonic movements in the Nanpanjiang Basin.The paper has discussed the thermal evolution history and oil and gas generation history of the main source rock based on two chemical kinetics methods.By the study of source thermal evolution,it shows that the source rock of Middle and Lower Devonian entered into over mature stage in Late Hercynian to Early Indosinian and had different thermal evolution in different areas.And by the study of oil and gas generation,it shows that the crude oil from Middle and Lower Devonian source rock cracked completely into methane gas in the end of Late Permian or the beginning of Early Triassic in the east of Nanpangjiang Basin and in Late Triassic in the west of Nanpanjiang Basin.

STUDY ON GEOCHEMICAL TRACKING FOR THE PERIODS OF RESERVOIR-FORMING OF OIL AND GAS IN THE TAHE OILFIELD

Gao Bo, Liu Wenhui, Fan Ming, Zhang Dianwei, Nan Qingyun

2006, 28(3): 276-280. doi: 10.11781/sysydz200603276

Abstract(705) PDF-CN(403)

Abstract:
The geochemical characteristics of oil and natural gas contain a lot of information on organic matter of source rocks,evolution of hydrocarbon generation,hydrocarbon migration direction and hydrocarbon reservoir-forming stages.Based on systematic research of the geochemical characteristics of crude oil and natural gas from the Tahe Oilfield,the reservoir-forming stages of the Tahe Oilfield was discussed.The geochemical characteristics of the crude oils from the Tahe Oilfield are very similar,which imply that the oils are derived from the same source.The characteristics of the oil from the Tahe Oilfield reveal that it had been underwent two oil infilling stages of which the former infilling oil had relative lower maturity and was strongly biodegraded and the later infilling oil had high maturity.The natural gas from the Tahe Oilfield belongs to the typical petroliferous gas with high maturity,which falls into mature to overmature.The geochemical characteristics of natural gas from the Tahe Oilfield reveals that it had two stages of charging.The first was gas associated with crude oil and the second was pyrolysis dry gas.So there at least exists 3 times of hydrocarbon charging in the Tahe Oilfield.

CHARACTERISTICS OF CARBON AND SULFUR ISOTOPES IN CRUDE OIL AND OIL-SOURCE CORRELATION IN THE TARIM BASIN

Zheng Bing, Gao Renxiang

2006, 28(3): 281-285. doi: 10.11781/sysydz200603281

Abstract(708) PDF-CN(411)

Abstract:
Based on the fractionation of carbon and sulfur isotopes in the process of petroleum generation and evolvement,the crude oils and their sources in the Tarim Basin have been discussed.The δ¹³C of crude oil inherited the one of its biologic matrix.The δ¹³C value of marine crude oil is less than-32‰ or more than-24‰,and the δ¹³C value of continental crude oil is from-32‰ to-24‰.The organic sulfur in crude oil originates from the sulfate in source rock.But the δ³⁴S value of mature crude oil with temperature being higher than 80-120 ℃ is 3‰-4‰ lighter than the δ³⁴S value of the sulfate in source rock.The crude oils in the Tarim Basin can be classified into four types according to the characteristics of carbon and sulfur(isotopes) as well as other physical and chemical properties of crude oil.The second is 21‰-26‰ and δ¹³C value is less than-32‰.It is typical marine crude oil.The second is Permo-Carboniferous crude oil whose δ³⁴S value is 5‰-7‰ and δ¹³C value is less than-32‰.It is also marine crude oil,but the biologic matrix is poor.The third is Triassic-Jurassic crude oil whose(δ³⁴S) value is 10‰-14‰ and δ¹³C value is about 26‰.It is typical continental crude oil.The fourth is mixed oil of the above three types of crude oil.Its δ³⁴S value is between that of marine and continental oil.The mixed oil composed of Cambrian-Ordovician and Permo-Carboniferous crude oil has characteristics of marine oil,and the mixed oil composed of Cambrian-Ordovician and Triassic-Jurassic crude oil has characteristics of mixed oil facies.The mixed oil composed of Permo-Carboniferous and Triassic-Jurassic crude oil has not yet been discovered.

AN EXPERIMENTAL INVESTIGATION OF DYNAMIC AND STATIC ELASTIC PARAMETERS OF COMPACTED CLASTICS, THE NORTHEAST SICHUAN BASIN, CHINA

Li Zhiwu, Liu Shugen, Luo Yuhong, Gong Changming, Shan Yuming, Liu Weiguo

2006, 28(3): 286-291. doi: 10.11781/sysydz200603286

Abstract(767) PDF-CN(321)

Abstract:
The ultrasonic wave velocities and mechanical parameters of compacted clastics of Upper Triassic and Middle Jurassic in the northeast Sichuan Basin,with current burial depths ranging from 320 0 m to 420 0 m,aremeasured simultaneously under simulated formation conditions(including temperature,pore pressure,confining pressure,air-dried or saturated by water,and different directions of samples).The composition and structure of rock are the inherent factors determining the velocities and mechanical parameters,with the velocities and Young's modulus decreasing along with the increases in clay content and porosity.Generally,the velocities and dynamic elastic moduli of samples parallel to bedding are greater than those perpendicular to bedding,while the Poisson's ratio is an exception.The velocities,dynamic Young's modulus and bulk modulus increase along with the decrease in temperature and increase in effective confining pressure,while the Poisson's ratio shows no evident rule to the changing of temperature,and increase for air-dried samples and decrease for samples saturated with brine as the effective confining pressure increases.Both P-wave and S-wave velocities increase firstly and then decrease along with the increase in additional axial stress,with the maximum velocities corresponding respectively to 80% and 50% ultimate compressive strength of sandstones.The P-wave velocity and dynamic elastic moduli of samples saturated by brine are greater than those of air-dried samples,with the exception of(S-wave).The dynamic Young's moduli of all samples are greater than the static Young's moduli,but the dynamic and static Poisson's ratios show no such rule.

STUDY AND APPLICATION OF LIQUID/SOLID COUPLE MODEL IN DOUBLE POROSITY MEDIA SYSTEMS

Zhou Dehua, Ge Jiali

2006, 28(3): 292-295. doi: 10.11781/sysydz200603292

Abstract(754) PDF-CN(390)

Abstract:
The 2 fields of fluid flowing and stress simultaneously play roles in the pore-fracture media(during) hydrocarbon exploration.The coupling effects may change the reservoir formation parameters and affect the liquid distribution.Therefore,it is necessary to utilize a liquid/solid couple model to analyze the fluid flowing behavior in double porosity media.This model has been made thanks to the concept of effective stress.Finite Element Method and limited difference are utilized to gain solutions.The influence of couple effect on accumulation is stated as follow: higher pressure coefficient,poorer formation nature,and more remarkable liquid/solid couple effects.The effect will gradually disappear as the development time prolongs,therefore,it is not necessary to take into account the liquid/solid couple effects in all double porosity media reservoirs.

TRI-DIMENSIONALLY MULTI-MEDIA SAMPLING AND ITS APPLICATION IN THE HYDROCARBON GEOCHEMICAL EXPLORATION IN THE NORTH YELLOW SEA BASIN

Cai Feng, Sun Ping, Gong Jianming, Chen Jianwen

2006, 28(3): 296-301. doi: 10.11781/sysydz200603296

Abstract(708) PDF-CN(273)

Abstract:
Under the different environment conditions,the availability of the geochemical indicators is largely affected by different factors,thus leading to the differences of the application for different media samples.Being aimed at the characteristics of different media samples,the samples from marine bottom sediments,bottom seawater and lower air were collected by using the tri-dimensionally multi-media sampling method.By using this useful sampling method,as well as the multi-indicators integrative analysis,the results of the samples from different media and depth can be validated and reinforced and the disturbing effects of different factors could be well eliminated.The result can provide the foundation for hydrocarbon resource evaluation.By using this method in the North Yellow Sea Basin,three classes of geochemical anomalous areas have been determined and several potential hydrocarbon targets have been brought forward,which have the good correlation with existing oil and gas areas and geological analytical results.

QUANTITATIVE CALCULATION OF HYDROCARBON EXPULSIVE COEFFICIENT OF COAL FORMATION——TAKE WELL KANGGU-4 IN THE EAST OF LINQING DEPRESSION AS AN EXAMPLE

Xu Chunhua, Kong Fanshun, Wang Xinhui

2006, 28(3): 302-306. doi: 10.11781/sysydz200603302

Abstract(587) PDF-CN(292)

Abstract:
Coal formation is not only an important source rock but also a kind of important reservoir of coal-formed gas.In a definite thermoevolutional degree,the generated gas quantity and methane quantity are also definite.The adsorption quantity and the expulsion quantity are convertible and in a dynamic equilibrium state.The method of calculating compulsive coefficient can be obtained according to this understanding.In this article,a method to calculate the gas-generated quantity was put forward based on the thermal-pressure simulating tests,by which the gas-generated quantities of different microlithotypes in different coal formations in different areas can be determined.At the same time,a way to determine the coal formation absorption quantity is introduced briefly.The curve showing the relations of coal formation methane content and it's metamorphic grade and burial depth developed by Kim was fitted using computer.A series of curves showing the relationship between burial depth and absorption quantity during different evolutional periods are gotten.These can be used to predict gas-generated quantities.All the methods have been used to calculate the gas-generated quantity of Permo-Carboniferous coal formation and absorption coefficient in well Kanggu-4 area in the east of Linqing Depression.The calculated methane quantity matches the simulated methane quantity with the error less than 5%.The calculated hydrocarbon expulsive coefficients are increased with increased maturities,from 77% in the low evolutional period to 99% in the high evolutional period.

STUDY OF REFRACTURING TECHNOLOGY IN LOW-PERMEABILITY SANDSTONE RESERVOIR

Tan Shihai

2006, 28(3): 307-310. doi: 10.11781/sysydz200603307

Abstract(596) PDF-CN(602)

Abstract:
The propped fracture generated during primary fracturing induces a stress field that changes original stress field and further reorients new fracture during refracturing,the extension direction is still controlled by stress status.By means of altering confining pressure,hydraulic fracturing simulation experiment proves the possibility of new fracture generation during refracturing.Temporarily blocked refracturing is applied in the Ansai oilfield of the Ordos Basin: a temporary blocking agent is injected during old fractures reopening to form a high-pressure environment and newly generated fracture connects the natural micro fractures which establishes new high-conduction fracture system with later added proppant and enlarges the oil-draining area.Pilot fracture monitor and effect analysis prove the generation of new fractures during refracturing.

2006 Vol. 28, No. 3

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