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2003 Vol. 25, No. 5

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FORMATION AND DISTRIBUTION OF THE PALEOZOIC MARINE CARBONATE-ROCK POOLS IN CHINA
DOU Li-rong, WANG Yi-gang
2003, 25(5): 419-425. doi: 10.11781/sysydz200305419
Abstract(843) PDF-CN(384)
Abstract:
The superimposing distribution of many sets of the Paleozoic marine source rocks and the further overlying of the Meso-Cenozoic continental strata resulted in the multi-source and multi-stage formation of the Paleozoic oil and gas pools in China.Hydrocarbon source rocks are distributed in craton basins and in-tracratonic rift basins.Carbonate rocks are major reservoirs, and argillaceous rocks are major local and regional caprocks.The hydrocarbon phases of the basins except for the Tarim Basin are dominated by dry gases including pyrolysis gases from kerogen and crude oil because of tectonic-thermal events.According to the characteristics of reservoirs, carbonate rock pools were divided into four types, that is, carbonate rocky-beach pools, uncomformity-karst pools, biohermal pools and diagenetic pools.Among them, carbonate rocky-karst pools and the beach-phase pools developed in high-energy environments are the most important types of oil and gas pools.Faults, unconformities and paleouplifts control the spatial distribution of oil and gas, and the distribution of oil and gas is diachronous.
THE FAULT SYSTEM CHARACTERISTICS AND HYDROCARBON EXPLORATION STRATEGY IN QAIDAM BASIN
SUN De-jun, LUO Qun
2003, 25(5): 426-431. doi: 10.11781/sysydz200305426
Abstract(801) PDF-CN(359)
Abstract:
The base fault pattern of the Qaidam Basin determined the basin's tectonic evolution and its sedimentary development, and resulted in 3 distinguishing fault structure systems of the north edge, the middle and the Kunbai.The north-edge fault system shows a anti-S shape in plane, and in section the fault system displays a series of reverse fault belts having a south-dip direction and lining many syndepositional structures like steps controlled by the fault system.They are effected by Qilan mountain tectonic stress field on the north.The Kunbei fault system are composed of some press fault-depressions and fault-step belts in the south of the basin.Its formation is controlled by Kunlun mountain tectonic stress field on the south.The middle fault system has a common structure of a swelling press form both side faults as its important feature.It is effected by two stress fields of Qilan mountain and Kunlun mountain in the same period.The faults play very important roles in hydrocarbon accumulation and distribution.It was pointed out that future hydrocarbon exploration in the basin is the middle part-middle fault structure system according to the fault controlling law on hydrocarbon accumulation in the basin and its petroleum geologic conditions, especially the Ebonang-Yikeyawuru, Yahu-Taijnail tectonic belts and middle-south swelling region.Petroleum exploration of the Qaidam Basin may make a huge breaktrough in these areas.
STUDY ON THE DYNAMIC MODE AND ITS SIMULATION IN THE FORMATION OF LONGMEN MOUNTAIN-WEST SICHUAN FORELAND BASIN SYSTEM, CHINA
LIU Shu-gen, LUO Zhi-li, ZHAO Xi-kui, YUE Guang-yu, LIU Shu, LI Tian-bin, SONG Hong-biao
2003, 25(5): 432-438. doi: 10.11781/sysydz200305432
Abstract(776) PDF-CN(622)
Abstract:
The paper has further discussed the dynamic mode of Longmen Mountain-West Sichuan Foreland Basin System, which is Longmenshan subduction (simply called L-type Subduction).It is further confirmed through the physical simulation and mathematic simulation that L-type subduction existed in the a-rea.The gravity and adjustment of deep material had taken an important role in the process of the formation and evolution of Longmen Mountain-West Sichuan Foreland Basin System.The dynamic source, formatting L-type Subduction, was from the deep.The deep dynamic force took the role depending on the main deep faults.There is a tendency that the relative displacement of the main faults decreased from the deep to the shallow.The plastic and soft layers and the sliding on them had taken an important role in the formation and evolution of Longmen Mountain-West Sichuan Foreland Basin System.The horizontal relative displacement of Mantle plastic layer is usually greater than the horizontal relative displacement of Crust plastic layers.
GAS RESOURCE OF BOHAI BAY AND ITS SURROUNDING AREAS
WANG Gou-chun, ZHANG Hou-he
2003, 25(5): 439-444. doi: 10.11781/sysydz200305439
Abstract(733) PDF-CN(337)
Abstract:
Gas resource in offshore part and its surrounding Huanghua, Liaohe and Jiyang depressions in Bohai Bay Basin showed their own characteristics.The offshore is an important part of the basin with special geological character, which is extension of the three depressions.Tanlu fault belt passing through the offshore part played a very important part in hydrocarbon formation and accumulation.Gas generation was controlled by kerogen types and their evolution level.Onshores Dagang and Liaohe oil gas provinces showed favourable gas potential, but Shengli oil province is dominated by oil as a result of tremendous type I kerogen and low maturity.The offshore is a favourable area for gas generation and preservation due to rich source rocks, high maturity and overpressure.Gas resource in offshore is enormous.
FORMATION CHARACTERISTICS OF LARGE-MIDDLE LITHOLOGIC-STRUCTURAL COMPOSITE OIL AND GAS FIELDS IN THE QIAN’AN-CHANGLING DEPRESSION OF THE SONGLIAO BASIN
ZHOU Li-qing, ZHANG Huai
2003, 25(5): 445-451. doi: 10.11781/sysydz200305445
Abstract(627) PDF-CN(392)
Abstract:
Many sets of high-quality source rocks and delta-front-facies sandstone reservoirs were developed in the Lower Cretaceous of the Qian an-Changling Depression in the southern part of the Songliao Basin.And upper, middle and lower three sets of pool-forming assemblages were formed.The Huazijing Terrace in the eastern part of the Depression possessed various advantageous conditions to form large-middle struc-tural-lithologic composite traps: a) multiphase delta-front-facies areas were intersecting and superimposing each other, and the lateral facies changes and updip thinning-out of lithology often occurred; b) the differentiation of south and north inherited sedimentary microfacies generated on the background of paleotopog-raphy-the buried paleouplift zone in Qiannan area; c)paulopost tectonic movement resulted in the elevation of the East Songliao Basin, and made the eastern sandbodies mass updip thinning out; d)paulopost tectonic movement resulted in a series of minor faults, screening off the updip direction of sandbodies; e) large scale of oblique water current formed organic allocation with regional structural patterns; and f) diagenesis resulted in the compaction of reservoirs.Lithologic-structural composite traps formed in the Nen-jiang and Mingshui perieds, and matched well with large scale of hydrocarbon migration periods.This provided good conditions to form a group of large-middle structural-lithologic composite oil and gas fields in the Huazijing Terrace.
FORMATION AND DISTRIBUTION OF OIL AND GAS POOLS IN BOXING AREA OF THE DONGYING DEPRESSION, THE BOHAIWAN BASIN
JIANG You-lu, RONG Qi-hong, SONG Jian-yong, SU Yong-jin, TAN Li-juan
2003, 25(5): 452-457. doi: 10.11781/sysydz200305452
Abstract(651) PDF-CN(483)
Abstract:
This paper discussed the formation conditions, types and distribution characteristics of oil and gas pools in the southwestern part of the Dongying Depression, the Bohaiwan Basin.Affected by the special geologic background, the study area has good conditions for pool formation and has a variety of oil and gas pools.There are many excellent reservoirs in the area, but the oil and gas sources are not sufficient.Oil and gas in the area are concentrated in the positive structural belts controlled by faults and paleo-up-lifts.The oil and gas reservoirs are deep and relatively oil-enriched in the east and the north parts, and are shallow and relatively gas-enriched in the west and the south parts.The reservoirs of hydrocarbon have obvious zonation, and tectonic background and hydrocarbon-source conditions have important controlling effects on the enrichment of oil and gas.
OIL AND GAS FIELDS IN BURIAL HILLS OF TARIM BASIN
KANG Yu-zhu
2003, 25(5): 458-463. doi: 10.11781/sysydz200305458
Abstract(553) PDF-CN(421)
Abstract:
A new petroleum exploration domain has been started after well Shacan-2, which was drilled in the Paleozoic marine carbonates in northern Tarim Basin, was successful in September 1984.Especially, as Tahe oilfield was discovered and proved, exploration and research work for the Paleozoic burial hill were greatly strengthened and much progress was made.Some theoretical problems on petroleum exploration of Chinese Paleozoic marine carbonates were solved, and distribution and prospecting of oilfields in paleo-burial hill were pointed out.
SEDIMENTARY FACIES OF MIDDLE JURASSIC XISHANYAO AND TOUTUNHE FORMATIONS IN THE SANGEQUAN AREA OF JUNGGAR BASIN
GAO Lei, ZHU Xiao-min, LÜ Xue-yan
2003, 25(5): 464-468. doi: 10.11781/sysydz200305464
Abstract(605) PDF-CN(421)
Abstract:
Based on analysis of individual well sedimentary facies with numerous seismic data, logging data, paleobiologic data and other test data integratedly, the sedimentary styles of facies, shape and distribution of sandbodies were clarified and sedimentation variation principles and control factors of sedimentation in Middle Jurassic Xishanyao and Toutunhe Formation were discussed in the Sangequan area of Junggar Basin.Results showed that delta and lake deposits were occurred under warm and humid climate in Middle Jurassic, which was dominated by powerful distributaries channel deposit.When water retreated southward there was large proportion of swamp developed on delta plain.Sangequan area becomes a important target due to its close to western well Pen-1 source sag and is rich in good quality sandbody in the west and south.
STRATIGRAPHIC SEQUENCE AND HYDROCARBON POTENTIAL IN LILE BASIN
ZHANG Li, LI Wen-cheng, ZENG Xiang-hu
2003, 25(5): 469-472. doi: 10.11781/sysydz200305469
Abstract(550) PDF-CN(522)
Abstract:
Development of Meso-Cenozoic stratigraphic sequence in Lile Basin was studied.It was considered that relative thick Triassic-Cretaceous was widely developed in the basin and showed medium to good potential of hydrocarbon generation, which was one of the main source rocks in the basin.The Cenozoic is completely developed with biggest thickness of 6 000m in the basin.The favourable source rocks for gas were developed in Paleocene to Middle Eocene.
POOL-FORMING PERIODS AND GAS SOURCES OF WEIYUAN GASFIELD
DAI Jin-xing
2003, 25(5): 473-480. doi: 10.11781/sysydz200305473
Abstract(1036) PDF-CN(626)
Abstract:
Weiyuan gasfield is not only the great gasfield with the oldest reservoirs (the Sinian Dengying Formation) and the oldest source rocks (the Cambrian Jiulaodong Formation) in China but also one of the gas pools with the oldest geologic ages in the world.Though the ages of reservoirs and source rocks in this gasfield were very old, the natural gas in it accumulated and pool-formed very late, in the Himalayan period.There are various opinions concerning the gas origin of the field.One is inorganic origin, which believes the natural gas including hydrocarbon gases maybe come from the deep of the Earth because of the high He and Ar contents in gas pools and the high mean 40Ar/36Ar value of up to 7 000.The other is organic origin, which is divided into three viewpoints: a) the gas pools in the Dengying Formation are cracking gases from its own algal dolomite; b)the gas sources mainly come from the caprocks of the Dengying gas pools, that is, the Jiulaodong Formation; c)the gas pools of the Dengying Formation are mixed gases from the Dengying dolomite and the Jiulaodong argillutite.According to δ13C1 < δ13C2 and δ13C1 < -31‰ in the gas pools of the Dengying Formation, it is concluded that the hydrocarbon gases are organic origin.The Dengying Formation has the average TOC value of only 0.12%, so is difficult to become effective source rocks;and the Jiulaodong Formation has the average TOC value of 0.97%, so the hydrocarbon gases should come from it.The R/Ra values of 0.021 and 0.022 in gas pools suggest the crust-source inorganic origin of helium.It the meantime, as the uranium and thorium mineral contents are low in the Sinian dolomite and higher in the Jiulaodong Formation, the helium in gas pools also mainly comes from the uranium and thorium decay of the Jiulaodong Formation.As a result, the natural gas in the Dengying Formation is mainly organic origin gases from the Jiulaodong Formation.
UNUSUAL DISTRIBUTION OF STABLE CARBON ISOTOPE COMPOSITIONS FOR N-ALKANES OF ORDOVICIAN AND TRIASSIC CRUDE OILS FROM LUNNAN OILFIELD, TARIM BASIN, NW CHINA：PALEOENVIRONMENTAL IMPLICATIONS
LU Hong, SUN Yong-ge, PENG Ping-an
2003, 25(5): 481-486. doi: 10.11781/sysydz200305481
Abstract(564) PDF-CN(481)
Abstract:
Compound specific carbon isotope analysis was conducted for crude oils collected from a drilling well and the entire oilfield at Lunnan, Tarim Basin, NW China, and the results demonstrated that there was an unusual distribution of δ13C showing that carbon isotope was enriched in Ordovician oils and depleted in Upper Triassic oils.This unusual distribution is consistent with the distribution and evolution of carbon isotope of crude oils from all over the world in geological history, and cannot be explained by simply utilizing conventional models based on the differences in organic facies or sources, maturity, depositional environment, or migration fractionation, etc..in consideration of the great span in geologic times-cale between Ordovician and Triassic periods.It is illustrated from a survey of geochemical literature that the unusual distribution of stable carbon isotope of crude oils was associated with the global paleoenviron-mental changes such as in atmospheric CO2 and algae growth rates, etc., and was indeed resulted from the combination of the positive excursion of δ13C values in Ordovician period and the negative excursion in Triassic period.Crude oils, as a product of sedimentation and a kind of fossil fuels, recorded the paleoenvir-onmental and paleoclimatical changes in geological history, their stable carbon isotope is also controlled by these changes.
SEQUENCE STRATIGRAPHIC GEOCHEMISTRY-A NEW PROGRESS OF GEOCHEMISTRY
LI Mei-jun, ZHOU Dong-sheng
2003, 25(5): 487-491. doi: 10.11781/sysydz200305487
Abstract(862) PDF-CN(494)
Abstract:
Sequence stratigraphic geochemistry is a new progress of geochemistry.It mainly studies the occurrence, distribution and geochemical characteristics of source rocks under a sequence stratigraphic framework.The concept of sequence stratigraphic geochemistry was proposed by Peters et al.in 2000, and was effectively used in hydrocarbon exploration practice.Combining geochemistry with sequence stratigraphy, it can be used to study the distribution and geochemical characteristics of source rocks from a sequence standpoint and the changing rules of the geochemical characteristics of source rocks with the sea (lake) level.It can also make the genetic classification of crude oil under a sequence stratigraphic framework on the basis of oil-oil and oil-source correlation, and study the characteristics of hydrocarbon migration and accumulation.It can be eventually used to direct hydrocarbon exploration.During the course of sequence-stra-tigraphic-geochemical research, the setup of a sequence stratigraphic framework is the base, and the high-resolution analyses of biomarkers are the key.The study of sequence stratigraphic geochemistry is necessary in the exploration of continental fault lake basins in East China, where the exploration is focused on seeking for unconventional hydrocarbon accumulations such as subtle or deep reservoirs.
COLLECTION, QUANTITATIVE ANALYSIS AND CARBON ISOTOPIC ANALYSIS METHODS OF MINOR/TRACE HYDROCARBON GASES
LIU Jin-zhong, XIANG Tong-shou
2003, 25(5): 492-497. doi: 10.11781/sysydz200305492
Abstract(572) PDF-CN(495)
Abstract:
In the study of hydrocarbon-generation dynamics, it is needed to make quantitative analysis, qualitative anakysis and simple-hydrocarbon carbon-isotopic analysis on minor or trace hydrocarbon gases generated from thermal simulation.The gases in gold tubes were collected and quantified by a Toepler mercury pump, and then were sent into a gas chromatogaph to make compositional analysis.The residual gases were collected and transferred so as to make carbon isotopic analysis.In this paper, the detailed structure and operating mechanism of the system were introduced, and several factors affecting analysis precision were discussed.
STUDY ON THE STRESS SENSITIVITY OF PERMEABILITY IN FRACTURE-PORE DUAL MEDIA BY THE FULL SIMULATION EXPERIMENT
XIANG Yang, XIANG Dan, HUANG Da-zhi
2003, 25(5): 498-500. doi: 10.11781/sysydz200305498
Abstract(606) PDF-CN(486)
Abstract:
The holodiameter full-simulation blow-down exploitation experiment was done under the conditions of 75MPa of overburden pressure, 120℃ of formation temperature, 30MPa of formation pressure and water saturability.The results revealed that in fracture-pore dual media, the increase of production pressure drop resulted in the increase of effective overburden pressure and the decrease of fracture height, which caused the demage of gas permeability in reservoirs.It was showed that the higher the permeability was, the greater the damage of permeability was.On this basis, the critical production pressure drops for different types of reservoirs were suggested.
RESEARCH OF AUTOMATIC MODELLING ON 3D DIGITAL STRATIGRAPHIC FRAMEWORK BASED ON BORING DATA
LIU Qing-wu, WU Chong-long, LI Shao-hu
2003, 25(5): 501-504. doi: 10.11781/sysydz200305501
Abstract(813) PDF-CN(452)
Abstract:
The research of automatic modelling on three-dimension (3D) digital stratigraphic framework is a preliminary approach to the 3D automatic modelling of geologic bodies.Based on doring data, the automatic modelling was divided into two processes independent each other in the perpendicular and parallel directions of stratigraphic interfaces by numerical and non-numerical calculation such as digitization, trigonometric division and stratigraphic correlation.At first, linear interpolation was used to model stratigraphic framework cells automatically.Then, the models of framework cells were conformed according to numerical relations among them so as to form stratigraphic framework bodies.
STUDY ON THE GEOLOGICAL MODEL OF RESERVOIR HETEROGENEITY IN LOW-PERMEABILITY SANDSTONE OIL POOLS
XING Zheng-yan
2003, 25(5): 505-507. doi: 10.11781/sysydz200305505
Abstract(713) PDF-CN(509)
Abstract:
Based on the comprehensive geological study of Niu-20, Chun-41, Zhuang-74 and Daluhu low-permeability sandstone oil pools, the research content and method of the geological model on the reservoir heterogeneity of low-permeability sendstone oil pools in Shengli oil district were sumarized systematically in this paper.This modol takes full use of 3-D seismic, geologic, drilling, logging and testing data.Quantitative research is the major method, and the study of stratigraphic, structural and reservoir models is the base.The study of fracture models is the key, which including the study of field and core fractures, fracture density research by logging, fracture trend prediction by paleo-tectonic stress field simulation, fracture connectivity research by modern stress field simulation and the effect analysis of fracture direction and resservoir fractures on oilfield development.The study of the geological model on reservoir heterogeneity mainly includes the establishment of the logging data interpretation model and the study of interlayer, in-trastratal and plane heterogeneity.The model has good application effects in Shengli oil district.
SEVERAL PROBLEMS IN STUDY OF DEVELOPMENT PROGRAMME OF ORDOVICIAN CARBONATE RESERVOIRS IN TAHE OILFIELD, TARIM BASIN
LU Xin-bian
2003, 25(5): 508-512. doi: 10.11781/sysydz200305508
Abstract(628) PDF-CN(550)
Abstract:
The Ordovician carbonate reservoirs in Tahe oilfield are dominated by karst-fractures carbonates with special characteristics.The favourable reservoirs were mainly distributed below 1-120m of weathering crust of Lower Ordovician.The reservoirs showed obvious diversities and severe heterogeneity.In order to design suitable development programme, some concepts such as fissured cave system, reservoir heterogeneity, and determining of double medium, reservoir stochastic modelling and importance of reservoir performance were analyzed and discussed.
IDENTIFICATION AND PREDICTION OF VOLCANIC BODIES IN TAZHONG AREA OF THE TARIM BASIN
ZHANG Chuan-lin
2003, 25(5): 513-516. doi: 10.11781/sysydz200305513
Abstract(504) PDF-CN(447)
Abstract:
Four periods of volcanics were developed from Permian to Presinian in Tazhong area of the Tarim Basin, which seriously infleunced the structural traps and preservation of hydrocarbon accumulation in the area.It was the main reason of drilling failure of wells TZ18, 21, 22 et al.To avoid exploration risk, several methods for identification and prediction of volcanics were proposed.A good result was obtained during drilling of well Zhong-1 as a result of successful prediction of structure under volcanic body.
STUDY OF GEOLOGICAL MODEL OF GAS RESERVOIRS IN CHUANXI DEPRESSION OF SICHUAN BASIN
XU Guo-ming
2003, 25(5): 517-520. doi: 10.11781/sysydz200305517
Abstract(648) PDF-CN(417)
Abstract:
The Chuanxi Depression is located in the eastern slope of Longmen mountain nappe belt, the west of Sichuan Basin.Gas reservoirs were mainly developed in Upper Triassic to Lower Cretaceous clastic sequences.Aanalysis of attributes of seismic reflection, correlated well interpretation, 3D reservoir visualization, constrained sparse spike inversion and stadmod inversion played an important role in reservoir characterization.Application of above technologies gained good result in construction of geological model of gas reservoirs in Chuanxi Depression.

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