石油实验地质

2008, 30(2)

Abstract(245)

Abstract:

RECONSIDERATION OF DEEP BASIN GAS IN THE WESTERN SICHUAN DEPRESSION OF THE SICHUAN BASIN

Ye Jun

2008, 30(2): 109-114. doi: 10.11781/sysydz200802109

Abstract(670) PDF-CN(388)

Abstract:
The Western Sichuan Depression of the Sichuan Basin is qualified for deep basin gas accumulation due to basin types,hydrocarbon source rock characteristics,reservoir-source combination and reservoir tightness.However,the Western Sichuan Depression is a combined basin influenced by stages of tectonic movements.Mass charges of hydrocarbon of the Xujiahe Formation of the Upper Triassic take place before reservoir tightening.Natural gas migrates under hydrodynamic and buoyancy effects,which is different from deep basin gas in accumulation mechanisms.Inversion of gas and water cannot be found in the same reservoir of the Upper Triassic.Natural gas is zoned obviously,mainly controlled by the Yanshanian and Indosinian uplifts.Distribution of gas and water is also different from deep basin gas.Water product of single well may reach 1000m³/d.Present accumulation types of natural gas of the Xujiahe Formation are mainly combination traps.Gas content and water distribution are controlled by fractures in traps and diagenetic reservoir-leaking bodies.The Xu4 reservoir is probably a residual reservoir,partially filled with water.The Xujiahe Formation of the Upper Triassic in the Western Sichuan Depre-ssion is accumulated conventionally,yet deformed by stages of tectonic movements.Though it is characterized by abnormal gas and water distribution,it does not belong to deep basin gas.

DISCUSSION OF BASIN GENETIC TYPES OF THE QAIDAM BASIN

Luo Qun

2008, 30(2): 115-120. doi: 10.11781/sysydz200802115

Abstract(1040) PDF-CN(526)

Abstract:
The Qaidam Basin is a petroliferous basin with multiple genetic types.There are many different view points about its genetic characteristics and mechanisms during different evolution stages.Based on 4 main view points,combined with regional tectonic evolution,sedimentary generation,tectonic history restoration and seismic reflection characteristics,it is concluded in this paper that,the Qaidam Basin has experienced 4 stages: rift-subsidence basin from early to middle Jurassic,compression-inflection basin from late Jurassic to Cretaceous,compression-depression basin during early Tertiary and foreland basin from late Tertiary to Quaternary.This new opinion unifies knowledge about basin genetic types and mechanisms of the Qaidam Basin.It is very important for further research of basin geology and resource evaluation.

PROGRESS ON THE SECOND EPISODE OF HIMALAYA MOVEMENT AND PRIMARY DISCUSSION ON THE EXISTING PROBLEMS IN BASINS OF EASTERN CHINA

Liu Shilin, Xiao Huanqin, Lin Ge, Lu Guoming, Zhang Desheng, Xia Yongjian, Peng Meili

2008, 30(2): 121-126. doi: 10.11781/sysydz200802121

Abstract(787) PDF-CN(568)

Abstract:
The change of subsidence model in Cenozoic petroliferous basins of Eastern China which goes from rifting subsidence stage in the Late Oligocene to whole thermal subsidence in the Early Miocene was caused by the second episode of Himalaya Movement.This movement resulted in some typical structure phenomena which are characterized by extensive unconformity in Eogene/Neogene strata,by the formations of secondary faults,and by the positive reverse structures in local areas.Accordingly,it caused the change of sedimentary systems in the up and down strata of E/N unconformity which was characterized by shore-shallow lacustrine facies,alluvial fan and fluvial-deltaic facies in the Oligocene to alluvial fan and braided fluvial facies in the Miocene.Four key problems were mainly discussed to elucidate the movement entirely,including the active period constraints,the denudation degrees,the effect on hydrocarbon reservoirs and its dynamic mechanism.Note that denudation degree research is the most important problem to this movement.Multiple methods(e.g.apatite fission track technique,vitrinite reflectance and acoustic time method) can be effectively used to reconstruct the denudation thickness of the second episode of Himalaya Movement.About this movement,there are chiefly two possible dyna-mic mechanisms.One is the transpressional mechanism related to the collision of plates;the other is the rebound mechanism of lithosphere.

OCCURRENCE CHARACTERISTICS AND SIGNIFICANCE OF CARBONIFEROUS AND PERMIAN IN THE SHENGLI OIL FIELD, THE BOHAI BAY BASIN

Miao Jiujun, Zhang Xinguo, Zhang Yanxia, Qiu Qi, Li Kuang

2008, 30(2): 127-132. doi: 10.11781/sysydz200802127

Abstract(662) PDF-CN(350)

Abstract:
Carboniferous and Permian strata in the east of Jiyang and Linqing Depressions(the Shengli Oil Field) of the Bohai Bay Basin are zoned and blocked from east to west and zoned from north to south,influenced by multi-compressions during the Indosinian-Yanshanian stage and extensions during the Himalayan stage.Compression uplifts during the Indosinian-Yanshanian stage are strong in the northeast and weak in the southwest.Extensional uplifts during the Himalayan stage are large in the southeast and small in the northwest.Various "blocks" of different sizes,shapes and depths are formed.Blocks in the northeast are small and faulted while those in the southwest are big and jointed.In addition,superimposition of the two stages of tectonic movements has changed Carboniferous and Permian residual block bodies into "wedge shape".Multi-compressions,uplifts and erosions during the Indosinian-Yanshanian stage and the following tectonic reverse result in the gradually thinning trend in the east and west of blocks.Strong extensions during the Himalayan stage make blocks deep in the north and shallow in the south.Blocks are thinning in the deep northern flank like wedges and gradually uplifting in the south.The above-mentioned characteristics have relatively great impact on late hydrocarbon generation(mainly secondary hydrocarbon generation) and accumulation in Carboniferous and Permian in the Shengli Oil Field,the Bohai Bay Basin.

ANALYSIS OF HYDROCARBON SOURCE CONDITIONS IN MARINE FACIES PETROLEUM EXPLORATION IN SOUTH CHINA-A CASE STUDY IN THE JIANGHAN PLAIN REGION

Luo Kaiping, Ding Daogui, Lü Jianhong, Liu Guangxiang

2008, 30(2): 133-137. doi: 10.11781/sysydz200802133

Abstract(814) PDF-CN(307)

Abstract:
Geologic conditions and characteristics of marine facies petroleum in South China have put forward new contents and requirements for petroleum source condition analysis.For late accumulations,prescription of source rocks is more important than their original characters.Spurning the former rules which adhere to parameters,source condition analysis and source rock evaluation should be based on source rock evolution history research and focus on stage and prescription studies.When effective source rocks and generation regions are confirmed,exploration targets can be chosen.In marine facies strata in the Jianghan plain region,sealing system rebuilt from late Yanshanian to early Himalayan period is the main exploration target.Superimposition of rift-subsidence basins makes Permian source rocks become mature and Lower Paleozoic source rocks again produce petroleum.Permian carbonate source rocks are the main effective source rocks.From Wufeng Formation of Upper Ordovician to Longmaxi Formation of Lower Silurian is the second effective.Main source regions locate in the Jiangling and Qianjiang sags.

FAULT CHARACTERISTICS OF HEISHANDUN AREA OF THE ERDOS BASIN AND ITS CONTROL OF OIL AND GAS

Zhang Weihua

2008, 30(2): 138-143. doi: 10.11781/sysydz200802138

Abstract(690) PDF-CN(293)

Abstract:
There are two overlying structural systems in Heishandun working area of the Erdos Basin.They borders at around reflector T8 as show on seismic data.Among which the upper system is the target.It can be divided into three level fractures in terms of scale.The primary and second order fractures are mainly reverse faults extended down to the source rocks in south to north direction.The third order fractures are mostly intrabed normal faults.Faults and local structures were formed predominantly at early Yanshanian,and hydrocarbon expulsed at late Yanshanian.The primary and second order fractures,which connect oil sources and control local structures,play an active role in the accumulation of hydrocarbon.In combination with postdrill assessment,it is concluded that local structures are the controlling factor to the formation of hydrocarbon reservoir,and faulted anticlines are the favourable places for hydrocarbon accumulation.The primary and second order fractures play the main role in the initial allocation of hydrocarbon,whereas the third order intrabed fractures play an important role in the reallocation of hydrocarbon.

PETROLEUM GEOLOGIC CONDITIONS AND EXPLORATION PROSPECTS OF CARBONIFEROUS IN THE EAST OF QAIDAM BASIN

Zhang Jianliang, Zhong Jianhua, Li Yahui, Duan Hongliang, Li Xuejing, Ying Chengming

2008, 30(2): 144-149. doi: 10.11781/sysydz200802144

Abstract(755) PDF-CN(364)

Abstract:
Based on organic geochemistry analysis of source rocks,combined with regional geologic survey and seismic data interpretation,it is discussed in this paper geologic conditions and exploration prospects of Carboniferous in the east of Qaidam Basin.Carboniferous is widely distributed in the region with large residual thickness.There are many categories of hydrocarbon source rocks.Dark-colored mudstones belong to good source rocks with 1.85% of organic carbon,type-Ⅱ₂ and Ⅲ organic matters and moderate maturity.And carbonates belong to moderate source rocks with 0.42% of organic carbon,type-Ⅱ organic matters and moderate maturity.All source rocks are in the peak period of oil generation and expulsion and have strong hydrocarbon generation ability,except for those in the Zongwulong mountain front belt and the Dulan area,where thermal evolution degree is too high.With moderate-good source rocks,several reservoir beds and capping formations as well as good trap conditions,Carboniferous in the east of Qaidam Basin has experienced the process of hydrocarbon generation,migration and accumulation,hence is favorable for petroleum exploration.The Delingha Depression is most favorable for hydrocarbon generation with good Carboniferous source rocks and large residual thickness.The Zongwulong mountain front structural belt and the Tuonan fault terrace belt are prospective areas.

STUDY OF GROUND STRESS FIELD AND NATURAL FRACTURE FIELD OF YAOYINGTAI Oil field IN THE CHANGLING SAG OF THE SONGLIAO BASIN

Zhang Fengdong, Ma Shou

2008, 30(2): 150-153. doi: 10.11781/sysydz200802150

Abstract(705) PDF-CN(343)

Abstract:
Combined with the development of fractured hydrocarbon reservoir of Yaoyingtai Oil field in the Changling Sag of the Southern Songliao Basin,the paper quantitatively analyzes the ground stress field and the natural fracture field,and sets up an areal model to simulate the tectonic stress field and compares it with the actually measured ground stress value by taking the reservoir structure as the study object so as to obtain the distribution characteristics of the stress field.Based on the palaeotectonic stress field formed in the reservoir fracture and the theory of elasticity,by using of the fracture criteria of rock,it determines and predicts the group,azimuth and density of the reservoir tectoclase.The study of the development distribution of stress field and natural fracture field determines the well groups for the field experiment and instructs the fracturing treatment and the design optimization and field application of the well pattern arrangement for the field development.

HYDROGEOCHEMICAL REGULARITY OF PETROLIFEROUS BASINS

Zhao Kebin, Liu Chongxi, Li Wei

2008, 30(2): 154-161. doi: 10.11781/sysydz200802154

Abstract(794) PDF-CN(321)

Abstract:
The hydrogeochemical evolution regularity of oil and gas accumulation in an artesian basin has been studied by taking the artesian basin as a whole.Some new understandings are gained as follows: 1) The horizontal movement of the underground water within the basin causes the hydrogeochemical compositions to change regularly from the water recharge area to the water discharge area,providing the hydrogeological basis for studying both the relationship among oil,gas and water,and the distribution regularity of oil and gas accumulations.2) Two distinct hydrogeological systems exist in the artesian basin,which are controlled by the sub-structures of the basin.3) The runoff characteristics,the drive energy and the geochemical compositions of the penetration water and the sedimentary water within the artesian basin may differ obviously,and may exert different effects on the generation,the migration,the accumulation and the dispersion of oil and gas.And the front interface of the two kinds of water can act as the geographical border of the oil accumulations with different properties.4) The shallow hydrogeochemical effects related to oil and gas may distribute in various hydrogeological units of the artesian basin,especially in the oil-controlling fault zones and the oil-generative centers.In a whole,the characteristics and the distribution regularity of the hydrogeochemical anomaly are closely related to oil and gas,and can be used to evaluate the oil and gas prospects,as well as to predict the favorable zones for oil and gas to accumulate.

GEOCHEMICAL CHARACTERISTICS AND EXPLORATION POTENTIAL OF MIDDLE ORDOVICIAN PINGLIANG FOMATION IN THE ORDOS BASIN

Sun Yipu, Wang Chuangang, Wang Yi, Yang Weili, Xu Huazheng, Liu Wenbin, Wu Tianhong

2008, 30(2): 162-168. doi: 10.11781/sysydz200802162

Abstract(822) PDF-CN(440)

Abstract:
Pingliang Fomation source rocks of Middle Ordovician include 80 to 200 meters mudshale and marlstone,which distributed in Zhuozishan,Well Liuqing 7,Well Kushen 1,Shibangou,Well Huan 14,Pingliang,Longxian,Xunyi and Yaoxian,formed in platform slope facies around the western and southern margin of Ordos Basin.The organic matter of Pingliang Fomation source rocks is mainly typeⅠkerogen with-29.95‰ δ¹³C value,neary 100% Ity value,and greater than 3 saturated to aromatic hydrocarbon rate of "A".TOC value is more than 0.2%.The mean contents of "A"and hydrocarbon generation potential(S₁+S₂) are up to 232×10^-6,380×10^-6 and 0.42,0.37 mg/g respectively,corresponding to outcrop and drill core samples from the western margin of Ordos Basin.The organic matter is at stage of high to post maturity with Ro value between 1.60% and 2.60%,except samples from the western thrust zone.Pyrolysis simulating experiment results show that hydrocarbon resource amount of Pingliang Fomation source rocks is 0.433 8 billion tons oil equivalent in history.The central paleouplift supplied not only the oil and gas convergence belt,but also accumulation reservoir.The eastern part of Tianhuan Depression and northern part of Weibei Uplift are prospective exploration regions in future.

MOLECULAR TRACING OF OIL FILLING IN LIANGJIALOU AREA, THE BOHAI BAY BASIN

Wang Guangli, Zhang Linye, Chen Zhilin, Song Changyu, Wang Ru, Wang Tieguan

2008, 30(2): 169-173. doi: 10.11781/sysydz200802169

Abstract(726) PDF-CN(305)

Abstract:
Liangjialou Oil field is a deep-water turbidite fan developed in the middle part of the 3rd member of Shahejie Formation(Es3) in the Dongying Sag of the Jiyang Depression,the Bohai Bay Basin.The detailed oil-source correlation study shows that oil in this Oil field mainly sources from two sets of excellent source rocks formed under different depositional environments in the lower part of Es3 and the upper part of Es4.Two geochemical indicators,the molecular maturity and the nitrogen compound,are used to study the roles in tracing the crude oil families from different sources.The results show that two ratios of the molecular tracers,the benzocarbazole and the 4-/1-methyl dibenzothiophene(MDBT),both indicate that oil in Liangjialou Oil field has 3 main filling points,with oil migrating vertically and laterally from the northwest,the northeast and the south respectively along the existing faults and sand bodies into the northern,the middle and the southern Liangjialou Oil field.Biomarkers in oil inclusions suggest that oil originated from Es4 had filled into this Oil field earlier than that from Es3,although the filling events of both sources of oil occurred in the same Minghuazhen Formation of the Neocene period.

CHARACTERISTICS OF UPPER JURASSIC SUOWA FORMATION SOURCE ROCK IN THE QIANGTANG BASIN OF NORTHERN TIBET

Du Baiwei, Chen Ming

2008, 30(2): 174-178. doi: 10.11781/sysydz200802174

Abstract(808) PDF-CN(352)

Abstract:
Over 200 oil and gas shows were discovered so far in the Qiangtang Basin,of which including 5 oil shows and much oil shale shows.It indicates that the source rocks have favorable conditions to form gas and oil in the Qiangtang Basin.The mainly source rock of Upper Jurassic Suowa Formation is carbonate rocks in the Qiangtang Basin.It's thickness is from tens meters to hundred meters.The mean content of organic caborn is 0.1% to 1.90%.It is mainly middle to good source rock.The following source rock of Upper Jurassic Suowa Formation is mudstone.It's mean content of organic caborn is 3.71% to 27.14%. It is mainly good source rock,only distributes in the middle and west of the North Qiangtang Depression.The organic matter type is Ⅱ₁ through kerogen analysis.The vitrinite reflectance is 0.94% to 2.7%.The source rock is at stage of mature to post maturity.The source rock of Suowa Formation was uplifted and denuded because of the effect of tectonic movement.The research results show that Suowa Formation source rock has bad contribution to hydrocarbon accumulation in the whole Qiangtan Basin.But it is still important hydrocarbon source rock in the west and northeast of the North Qiangtang Depression.

THERMAL SIMULATION STUDY OF CRUDE OIL FROM WELL S74 IN THE TARIM BASIN(Ⅰ)-GEOCHEMICAL CHARACTERISTICS OF THE SIMULATION PRODUCTS

Liu Guangxiang

2008, 30(2): 179-185. doi: 10.11781/sysydz200802179

Abstract(894) PDF-CN(371)

Abstract:
A thermal simulation experiment of the heavy crude oil from Well S74 in the Tarim Basin has been conducted.The hydrocarbon families and the isotopes of the crude oil,the residual extract and the expelled oil have been analyzed.The saturated hydrocarbons have been detected by gas chromatography and gas chromatography-mass spectrometry,and the carbon isotope analysis of the alkane gases has been carried out.The results indicate that: 1) The compositional structure of the saturated hydrocarbons and the biomarkers of sterane and terpane of the residual extract change significantly with the increase of the simulation temperature,whereas the compositional structure of the saturated hydrocarbons and the biomarkers of sterane and terpane of the expelled oil do not change so significantly with the simulation temperature,except at 350 ℃ where anomalies occur.2) The carbon isotopes of the residual extract and its fractions increase gradually with the simulation temperature,whereas those of the expelled oil do not change so regularly with the simulation temperature.3) The carbon isotopes of the alkane gases also increase gradually with the simulation temperature,and the carbon isotope values at various simulation temperature points distribute as the normal sequence.

ANALYSIS ON OIL SOURCE OF LOWER PALAEOZOIC CRUDE OIL FROM KAILI AREA IN GUIZHOU PROVINCE

Gao Lin, Liu Guangxiang

2008, 30(2): 186-191. doi: 10.11781/sysydz200802186

Abstract(684) PDF-CN(389)

Abstract:
The geochemical characteristics of the Lower Palaeozoic crude oil from Kaili and its adjacent areas in Guizhou Province has been analyzed with emphasis in this paper based on the characteristics of the source rocks of the same areas.The results show that the stable carbon isotopic composition of the Lower Palaeozoic crude oil and oil sand is similar to that of the Lower Palaeozoic source rock extract,but obviously different from that of the Permian source rock extract,indicating that the crude oil is more closely related to the Lower Palaeozoic source rocks.While the biomarker parameters of the crude oil and the oil sand,such as the regular sterane,the tetracyclic terpane and the gammacerane/C₃₁-hopane,are more related to those of the Permian source rocks,indicating that the oil from the Lower Palaeozoic and the oil sand may be the mixture of oils generated from the Lower Palaeozoic and the Permian source rocks.The formation process of the mixture oil has also been discussed based on the structural-sedimentary evolution history and the hydrocarbon generation history of the source rocks in the study area.

STUDY ON GENERATION OF HYDROGEN SULFIDE BY SIMULATION EXPERIMENT

Xie Zengye, Li Zhisheng, Wang Chunyi, Hao Cuiguo

2008, 30(2): 192-195. doi: 10.11781/sysydz200802192

Abstract(799) PDF-CN(380)

Abstract:
A simulation experimental study on the generation of hydrogen sulfide(H₂S) by using the high pressure reactor within a closed system has been conducted and reported earlier,but the H₂S generated is very little,or too little to be detected.A novel quartz tube simulation method is thus developed to simulate the generation of H₂S with an open system.Some chemical reagents,such as hexane,calcium sulfate,sulfur and pyrite,are used to investigate the generation of H₂S in the simulation experiment;and a kind of low mature marlstone is also used to simulate the generation of H₂S during the generation of hydrocarbon.The results show that calcium sulfate may react with hexane under high temperatures but not easily,and the H₂S amount generated is little;the elemental sulfur can react easily with hexane under relatively low temperatures,generating large amounts of H₂S;pyrite can also react with hexane and generate large amounts of H₂S,mainly due to the reaction of the elemental sulfur released under high temperatures with hydrocarbons.The low mature marlstone can generate large amounts of H₂S during the hydrocarbon generation simulation,because of its high content of pyrite.The successful simulation of the generation of H₂S provides an important experimental basis for the study on the genetic mechanism of H₂S.

A NEW METHOD FOR CALIBRATING HYDROGEN ISOTOPE OF WORKING STANDARD GAS

Yang Huamin, Tao Cheng, Ba Liqiang, Li Guangyou, Zhang Meizhen

2008, 30(2): 196-199. doi: 10.11781/sysydz200802196

Abstract(610) PDF-CN(251)

Abstract:
The accuracy of hydrogen isotope analysis results needs a kind of working standard gas as a prerequisite.The steel-bottled hydrogen gas can be used as the working standard gas to measure the stability and the error of the instrument during the analyses of hydrogen isotopes.The hydrogen isotope fractionates greatly during the experiment,making the calibration of the standard working gas more important.Based on the theoretical results calculated from the hydrogen isotopic fractionation equilibrium equation of the H₂-H₂O(ι)system,the calibration of the working standard gas has been carried out in the experimental analysis of the hydrogen isotope of the natural water.The results are consistent with those analyzed by the Cr reduction method under high temperature conversion conditions.Two kinds of national standard water,Gbw04401 and Gbw04403,are used to testify the effectiveness of the calibration method.The results show that both the accuracy and the precision of this calibration method accord with the demands,and thus it can be used for hydrogen isotope analysis.

EXPERIMENTAL STUDY OF THERMOCHEMICAL SULFATE REDUCTION ON THE SULFURETED HYDROGEN

Dai Jinyou, Chen Anding, He Shunli

2008, 30(2): 200-202. doi: 10.11781/sysydz200802200

Abstract(751) PDF-CN(347)

Abstract:
In order to explore the condition of thermochemical sulfate reduction on sulfureted hydrogen,selected samples of gypsum,formation water and natural gas in Ordos Basin and maked experiment in airtight kettle.The result of the experiments indicated,the thermochemical sulfate reduction need add formation water,besides gypsum and hydrocarbon.Amount of a sulfureted hydrogen produced and corresponsive temperature or time are relation of direct proportion.During experiment with fractionation of ₃₄S isotope,and fractional strength be reduced with rise temperature.The study showed,besides gypsum and hydrocarbon,high temperature,airtight reductive environment and formation water are necessary condition of thermochemical sulfate reduction.Above five conditions are foundation of found regional model of sulfureted hydrogen.

BALANCED CROSS-SECTION RESTORATION AND TECTONIC EVOLUTION ANALYSIS IN THE BINXIAN SAG, THE SONGLIAO BASIN

Bi Suping, Zhang Qinglong, Wang Liangshu, Chen Zhuxin, Xie Guoai, Xu Shiyin, Cui Yingbin

2008, 30(2): 203-206. doi: 10.11781/sysydz200802203

Abstract(848) PDF-CN(387)

Abstract:
Based on strata data analysis,with balanced cross-section technique,choosing 4 NS-trending cross-sections in the Binxian Sag in the east of Songliao Basin,seismic analysis sections are restored in this paper.Extension quantity,rate and velocity for each evolution stage are calculated.The Binxian Sag has experienced at least 4 evolution stages:fault,fault-depression,depression and tectonic inversion.Results have indicated that,extension velocities during the fault and fault-depression stages are higher,about 0.21 and 0.2 mm/a respectively.Deformation intensity in the center of Binxian sub-Sag is stronger than the margin.

EFFECTIVENESS ANALYSIS OF THE OIL AND GAS GEOCHEMICAL EXPLORATION INDICATORS OVER A KNOWN HYDROCARBON RESERVOIR-A CASE STUDY FROM A SUBTLE FAULT BLOCK OIL RESERVOIR IN LINNAN AREA, THE BOHAI BAY BASIN

Jiang Tao, Chen Yinjie, Zhao Kebin, Wang Lifeng, Huang Xin

2008, 30(2): 207-211. doi: 10.11781/sysydz200802207

Abstract(616) PDF-CN(401)

Abstract:
The effectiveness of the oil and gas geochemical exploration indicators includes the stability of the geochemical field of the indicators,the efficiency of the indicators in reflecting the underground oil and gas,and the reproducibility of the geochemical anomalies.A follow-up study of the geochemical indicators over a subtle fault block oil reservoir in Linnan area,the Bohai Bay Basin,including acid-extraction hydrocarbon,headspace hydrocarbon and alteration carbonate,has been conducted.The results show that the geochemical indicators of the acid-extraction methane,the heavier acid-extraction hydrocarbons,and the alteration carbonate have stable geochemical field in the study area;whereas the geochemical fields of both the headspace methane and the heavier headspace hydrocarbons are less stable.The study also indicates that the acid-extraction methane and the alteration carbonate are the main effective geochemical indicators above the subtle fault block oil reservoir,while the headspace methane is the minor effective geochemical indicator.The special geological role of faults in the oil reservoir geolo-gical system and the effect of faults on the anomaly distribution regularity of the acid-extraction methane have been discussed,and the halo anomaly pattern of this geochemical indicator has been determined over the subtle fault block oil reservoir.

STUDY OF CO₂ MISCIBLE FLOODING TECHNIQUE IN THE CAOSHE OIL FIELD, THE QINTONG SAG, THE NORTHERN JIANGSU BASIN

Yu Kai, Liu Wei, Chen Zuhua

2008, 30(2): 212-216. doi: 10.11781/sysydz200802212

Abstract(797) PDF-CN(412)

Abstract:
The Taizhou Formation reservoir in the Caoshe Oil Field of the Qintong Sag of the Northern Jiangsu Basin is a complex fault block reservoir.Border faults work as good barrier while internal ones are unbounded,resulting in communication of reservoirs.Injection of CO₂ in laboratory experiment obviously expands crude oil and reduces viscosity,hence is qualified for CO₂ miscible flooding.Before gas injection,there are many problems with flooding pattern of the Taizhou Formation reservoir.For example,the division of development series is too simple;interlayer contradicts with each other;well pattern in some region is not perfect;plane productions are unbalanced;and vertical production degrees are different,et al.Dynamic monitoring after CO₂ injection has proved that,gas entry profiles of gas injection well are improved;formation reaches the minimum miscibility pressure;heavy components in crude oils are produced;and production in the whole region is stable and advancing.

2008 Vol. 30, No. 2

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