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2004 Vol. 22, No. S1

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Recent Oil & Gas Exploration Harvests in the New Area of Petrochina and Future Challenges and Measures
ZHAO Zheng-zhang, HE Hai-qing
2004, 22(S1): 1-7.
Abstract:
Since 1998, with the construction of the three large national petroleum companies including, Petrochina, Sinopec and Cnooc, the oil gas exploration situation has taken place great change in China. The three companies will face great violent competition in international and civil market. Currently, Petrochina has dominant position among the Chinese oil companies in terms of oil gas resource, proved reserves, production output and prospect right. At the same time, it has relatively strong competitiveness as compared to international companies. In recent years, being dead against oil gas exploration actuality, Petrochina has achieved a number of important discoveries and harvests in the exploration of new area through the effective measures for comprehensive geology research, seismic technique study and preparations and wider application of advanced and suitable new exploration technology. This plays key role in the crude oil production stabilization of Petrochina, at the same time, prepares some potential targets and key work target for next exploration in new area. Next step, although the facing challenge will be more serious, through effective modus formed by continuously persistence in recent years, the exploration of new area will acquire new discoveries.
Geochemistry of Petroleum Systems in the Eastern Pearl River Mouth Basin-I:Oil Family Classification, Oil-source Correlation and Mixed Oil Analysis
ZHANG Shui-chang, GONG Zai-sheng, LIANG Di-gang, WU Ke qiang, WANG Jian-rong, SONG Fu-qing, WANG Pei-rong, WANG Hui-tong, HE Zhong-hua
2004, 22(S1): 15-26.
Abstract:
Detailed analyses of crude oils and source rock extracts indicate the presence of two, effective petroleum source rocks in the eastern Pearl River Mouth Basin of the South China Sea region. Oils derived from the lacustrine source rocks in the Eocene Wenchang Formation are characterized by abundant C30 4 methyl steranes with relatively little C19 tricyclic terpane and bicadinanes. In contrast, oils from an Eocene-Oligocene Enping Formation source typically contain significant amounts of C19 tricyclic terpane and bicadinanes, with relatively little 4-methylsteranes and high pristane/phytane ratios. However, the chemical compositions of a large number of oils do not conform to those of the unknown source rocks. consistent with the mixing of the two sources. Mixed oils occur mainly in the Huizhou Sag and along its south margin, and the highest proportion of the Enping Formation source in the mixed oils is estimated to be around 80%. Laboratory mixing experiments using selected end-member oils indicate that, even with 50 to 80% contribution from the Enping Formation source, the mixture still display sterane biomarker signatures diagnostic of the Wenchang Formation source. Therefore, the presence of abundant 4-methyl steranes is a necessary but not sufficient indicator for the Wenchang Formation source in the eastern Pearl River Mouth Basin. Although our results support the Wenchang Formation as a major source to the known oil discoveries in the study area, the contribution of the Enping Formation source to traps in the Huizhou Sag and surrounding area cannot be ignored. There is clear evidence for the recharge of Enping Formation derived oils into the early-biodegraded oil reservoirs to form light oil accumulations.
Characteristics of Organic Geochemistry of Natural Gas Accumulated in Late Stage in China
LI Jian, LUO Xia, LIU Ren-he, Hu Guo-yi, XIE Zeng-ye
2004, 22(S1): 33-38.
Abstract:
Research on natural gas formation and characteristics of organic geochemistry of gas fields in China illustrates that natural gases in China are nearly formation in late stage. Late stage formation and its type are defined in this article according to the characteristics of depressional basins in China. Characteristics of organic geochemistry of all types of primary and modified late stage gas fields are also summarized in this paper.
Geochemistry and Origin of Oil and Natural Gas in Baimiao Area of Dongpu Depression
LUO Xiao-ping, SHENG Zhong-min, PENG Bo-ying, WANG You-jie, LIN Ren-zi
2004, 22(S1): 50-55.
Abstract:
Baimiao structure in the south of Dongpu depression is a trap with rich natural gas and condensate. The reservoir has some characters of many source rocks and many periods of formation and interruption. Based on the study of primarily geolegical characters, this paper investigates the variation law of carbon isotope of methane in natural gas and density of condensate as well as the character of biomarkers in condensate, which helps discussion on origin of oil and gas and their migration direction and time to the whole reservoir, together with applying of more geochemical methods in authigenic minerals.
Study on Genesis of Crude Oil from Qaidam Basin
DUAN Yi, ZHANG Hui, ZHENG Chao-yang, WU Bao-xiang
2004, 22(S1): 61-65.
Abstract:
Qaidam basin is one of the largest petroliferous basins in the northwestern China. After 50 years oil-gas exploration, 18 oil fields have been found in this basin, which are mainly distributed in the western portion of Qaidam basin. Their geneses are always the focus in which people are interested. The physical and chemical character, oil-rock correlation and genetic mechanism are studied, it is indicated that the western Qaidam and the northern Qaidam are two different oil-generating units, that they have obviously different oil-forming environments, precursor types, maturity and source of oil. Although organic carbon abundance of source rocks is low, plant lipids are well preserved in the reducing and saline acustrine environments. Plant lipids together with soluble organic matter and kerogen can generate a significant volume of crude oil at low mature stage and be the main way to produce immature and low mature crude oils in the western Qaidam basin
An Approach to the Evolution of TOC Value for Source Rock and Its Relation to Efficiencies of Hydrocarbon Generation and Expulsion
ZHONG Ning-ning, LU Shuang-fang, HUANG Zhi-long, ZHANG You-sheng, XUE Hai-tao
2004, 22(S1): 73-78.
Abstract:
Pyrolysis and numeric modeling techniques were adopted to reveal the loss rate of total organic carbon content (TOO with source rock maturation process. The TOC loss rate was presented as DTOC = (TOC°-TOC/TOC°. While source rock is of lower efficiencies of hydrocarbon generation and exclusion, the DTOC is a negative value, i. e. in this case the TOC value mount up with maturation progress. With increase in efficiencies of hydrocarbon generation and exclusion, DTOC goes up gradually, i. e. TOC loss rate increases and source rock therefore change its TOC evolution path from a "carbon adding" process to a "carbon reduction" process. There is only the type I kerogen source rock that under the ideal condition of extremely high efficiencies of hydrocarbon generation and exclusion the range of DTOC increase ("carbon adding" process) could be significant. It is evident that the criteria of carbonate source rock which bases on the recovery of original TOC value is likely an overestimate of "carbon reduction" process. Thus, in many cases, it would sugar up originally poor source rock.
Gaseous Hydrocarbon Generation of Different Types of Source Rocks under Different Geological Conditions
JIANG Zheng-long, LUO Xia, LI Jian, HU Guo-yi, WANG Chun-yi, LI Zhi-sheng
2004, 22(S1): 84-90.
Abstract:
Gaseous hydrocarbon generation of gas source rock is a key index in evaluating gas source rock. It is also an important parameter of basin resource assessment. But there should have different gas hydrocarbon generation of the same source rock under different geological conditions. How to get gas hydrocarbon generation of a source rock? A new method that is combined thermal evaluation experiment and numerical evaluation is applied in this paper. Gas hydrocarbon generation of different types of source rocks under different geological conditions is given though above new method. It is a new and important parameters of gas resources evaluation in China.
Comparison of Experimental Results between Two Simulation Methods
GUO Jian-ying, SU Xue-feng, WANG Dong-Hang, LIU Bao-quan, YU Guo-ying, GUO Shu-zhi
2004, 22(S1): 110-117.
Abstract:
The authors carry out simulation experiment with separate heating and continuous heating, the former is equivalent to sealed system, and the other is equivalent to opened system. Comparing the oil and gas yielding in different systems, we discussed t the relationship of natural hydrocarbon generation process and both of the heating mode. The experiment indicates that total gas yielding and gaseous hydrocarbon yielding in opened system is lower than that in sealed system: and oil quantity and total oil production yielding in opened system is higher than that in sealed system. The natural hydrocarbon process is the status between the opened system and sealed system.
An Obvious Example of Redox Reaction in the Process of Oil and Gas Generation-the formation of carotane
MA Su-ping, HE Jian-qiao, XIA Yan-qing
2004, 22(S1): 124-128.
Abstract:
In the whole process of forming hydrocarbon, there exist the joining and removal of hydrogen or oxygen atom and heteroatom from the beginning to end. Therefore, redox reaction takes place in the whole process. The formation of carotane is the result of the hydrogen addition of carotene, and this process is very typical redox reaction, which needs plenty of hydrogen. Through the pyrolysis experiments, it is discovered that the carotane formation demands ample reductant. If absent, even the environment does not belong to oxidation environment, the carotene also can not form carotane. Saturated cyclic steroid and terpenoid compound is the better reductant. Carotane has the very close relation with cricoids biomarkers. Therefore, we can affirm that saturated cyclic steroid and terpenoid compound is the reductant in the formation process of the carotane. Actually, the carotene which can be oxidized very easily to be the oxidant in some environments. So, organic acid, alcohol and ketone etc.,can be reduced and form hydrocarbon, which should not be problematic.
Research on the Accumulative Layers of As and Hg Elements in Columnar Profile of Soil in Beijing City
WANG Ya-ping, PEI Tao, XU Chun-xue, CHEN De-xing
2004, 22(S1): 135-139.
Abstract:
Based on the contents and distribution of Hg and As elements in the columnar profile of soil in Beijing area, this paper discusses the migration characters, mechanism of accumulation and dissipation in lengthways, and prohes the potential danger that the migration of Hg and As elements may cause to the environment, i. e. forming the possibility of" chemical time bomb". After surveying the soil borehole in Nanyuan, we found that pH value changed acutely and contents of heavy metals increased drastically in the soil stratum from 13. 66 to 16. 00 meters depth, which is deduced as the major accumulation stratum of contamination.
Contents
The Causative Assemblages of Oil Pools Based on Hydrocarbon Generation and Accumulation Process in Terrestrial Rift Basin:A case study from Shengtuo Oilfield
ZHANG Lin-ye, LIU Qing, ZHANG Chun-rong, WANG Ru, KONG Xiang-xing, LI Zheng
2004, 22(S1): 8-14.
Abstract:
The relation assemblage of oil pools and its effective hydrocarbon source rocks is the key factor in the study of pool-forming process, and to elucidate its controlling factors will do much help in the exploration and forecasting of the remaining unfound reservoirs. In this article Shengtuo oilfield with 39 years of exploitation history in the east of China is taken as an example for the study. Based on oil and source correlation, the time and space assemblages of oil reservoirs and its hydrocarbon generation and accumulation process are studied, and a new research procedure for subtle reservoir exploration is put forward. The study indicates Shengtuo oilfield is mainly sourced from excellent hydrocarbon source rocks, that is the oils from Area Ⅰ , and Area Ⅲ are mainly sourced from Es4 while the oils from Area I is sourced mainly from Es3. Reservoir water chemistry and fault system studies imply that Shengbei fault is the most important vertical conduit, since it is a source fault connecting the effective source rocks and the reservoir. As the oil pools found before are all else-sourced, it is believed that self-sourced oil pools with certain size should exist in the deep part of Paleogene and the burial hills on the steep slope.
Geochemistry Study on Gas-source Correlation of Natural Gas
LIU Wen-hui, ZHANG Dian-wei, WANG Xiao-feng, NAN Qing-yun
2004, 22(S1): 27-32.
Abstract:
Gas-source correlation is an important task for natural gas exploration and oil-gas theoretic research. Isotopic geochemistry is an effective means for gas-source contrast, especially carbon and hydrogen isotopes, which have been widely used to trace source rocks, to identify the deposit conditions of parent substance, to calculate the evolution stage of source rocks and the process of reservoirs forming, and to estimate mixed gas. In this paper we summarize some methods, that is, to trace the source rocks of natural gas by using, carbon hydrogen and rare gas isotopic character; to trace gas source by using the mathematic model of methane and evolution stage; to identify the deposit conditions of parent substance and the process of reservoirs forming by using the hydrogen isotopic character of methane; to identify the possible source of deep area by using rare gas isotopic character and to calculate the mixing ratio by using the function of time-accumulation-emotion.
The Origin of Condensate and Oil-type Gas from Deep Reservoir in the North of Songliao Basin
FENG Zi-hui, FENG Zhi-qiang, LIU Wei, WANG Xue, GUAN Qiu-hua
2004, 22(S1): 45-49.
Abstract:
The discovery of condensate and oil-type gas from deep reservoir increased the exploring potential of petroleum in the north of Songliao basin. Applying the analytical technologies of biomarker and carbon isotope of individual compounds, combining with geological background, the geochemical characteristics of condensate, oil-type gas and solid bitumen was discussed. The condensate was generated from coals and coal-measure source rocks in deep formation of the basin. The former is characterized by high content of aromatic hydrocarbon and heavy carbon isotope of individual compounds. The latter is characterized by high content of saturated hydrocarbon and light carbon isotope of individual compounds. However, the result of correlating biomarker indicates that the both condensate are derived from the same source rock-Shahezi formation. The carbon isotope of methane of oil-type gas is light, generally less than -45‰. The difference of carbon isotope between methane and ethane is obvious belonging to natural gas from oil cracking. The mixture of oil-type gas and coal-type gas in deep reservoir may be the one major reason of reverse in hydrocarbon carbon isotope series of deep natural gas. The TOC is 0. 08%-0. 16%, the HI is 49-297 mg/ g, Ro is about 1. 87% for the solid bitumen in deep volcanic reservoir. It shows that potential of generating hydrocarbon of the solid bitumen is low nowadays, oil was cracked to natural gas during the later period of high mature stage, corresponding geologic age is about the sedimentary time between the Nenjiang formation and Mingshui formation (80-65 Ma). The fact of oil transforms into natural gas enlightens that the exploration of deep natural gas should put the study of pero-reservoir into consideration.
Study on Oil-prone and Gas-prone Property of Coal-measure Source Rocks
CHENG Ke-ming, XIONG Ying, LIU Xin-yue
2004, 22(S1): 56-60.
Abstract:
Relative content of oil-prone carbon (Co) and gas-prone carbon (Cg) in kerogen are detected using solid-state 13C nuclear magnetic resonance spectra analysis. Co and Cg can be used to directly distinguish whether source rocks tend to generate oil or gas during "liquid hydrocarbon window". Although the kerogen of coal-measure source rock is characteristic of predominant humic type, Co is more than Cg among aliphatic carbon of the kerogen, so the source rocks still tend to generate oil. According to relative content of Co and Cg from solid state 13C nuclear magnetic resonance spectra analysis, the paper answers why Middle-Lower Jurassic coal-measure source rock of Xinjiang Yanqi basin tend to generate oil based on the mechanisms of hydrocarbon generation.
Origin of Oils from Well Tadong 2 in Tarim Basin
XIAO Zhong-yao, HUANG Guang-hui, LU Yi-hong, ZHANG Qiu-cha, WU Yi
2004, 22(S1): 66-72.
Abstract:
Oils from Well Tadong2, Tarim Basin, characteristic of high density, high viscosity and heavy carbon isotopic composition, are marine oils due to compositional features of light hydrocarbons, cyclicterpanes, steranes and triaromatic steranes. It can be seen that oils from Well Tadong2,Tarim Basin, are derived from Cambrian source rocks based on age-specific biomarker correlation studies. Recent oil compositional characteristics are probably related with the influence of high temperature geologic thermal event evidenced by pyrobitumen within reservoirs, PAH in aromatic fractions and carbon isotopic composition of alkanes
Study on Key Parameters of Natural Gas Resource Assessment
LIU Cheng-lin, LIU Ren-he, LUO Xia, XIE Zeng-ye, LI Jian, ZENG Qing-meng
2004, 22(S1): 79-83.
Abstract:
There are mainly 4 key parameters of natural gas resource evaluation, including gas production rate, migration-accumulation coefficient, play evaluation parameters, and recovery rate. First, gas production rate charts of biotic gas, coal, mudstone, and carbonate are built up through biotic gas simulation experiments and pyrolyses. Second, the relationship of migration-accumulation coefficient and different geologic parameters is K = 0. 298 - 0. 0025S + 0. 218C - 0. 00223T - 0. 00236D + 0. 0009H - 0. 2867V + 0. 000104R (K-migration-accumulation coefficient, S-age of source rock, C TOC, T-critical moment, D-thickness of Cap, H-depth of cap, N-times of unconformities, R-age of reservoir rock). Third, play evaluation parameter system and classification standards are built up based on lots of statistics. In the end, recovery rate of 5 types of natural gas reservoirs are analyzed and the results are: recovery rate of gas drive-clastic reservoirs is (75%-90%), water drive-clastic ones 50%-70%, gas drive-carbonate ones 80%-95%, water drive-carbonate ones 55%-80%, and tight ones 40%-55%.
Gas Generation Experimental Research of Shales, Coal, Bitumen and Oil
WANG Yun-peng, GENG An-song, LIU De-han, XIONG Yong-qiang, SHEN Jia-gui
2004, 22(S1): 106-109.
Abstract:
Gas generation simulated experiments of the satand samples of shale (marine and oil shale), coal, bitumen and oil are performed in the closed system. Gas yield, peak stage and molecular composition of the different precursors in different thermal maturation stages. The gas generation mechanism and regulations of different precursors and the influence of precursor types and the thermal maturation degree are researched. The results of this paper provide the experimental basis to the indentification of the effective source rocks.
The Application of the Test Technique on ReservoirGeochemistry in Daqing Oilfield
FANG Wei, ZHANG Ju-he, FENG Zi-hui, HUANG Chun-yan
2004, 22(S1): 118-123.
Abstract:
It is introduced that the development process of four new techniques on reservoir geochemistry and applied result in the exploration and development. The analytical scope of components in crude oil is increased from C1-C40to C1-C100 by High Temperatures Gas Chromatography Technique. The separation and examination of phrrolic nitrogen compounds in petroleum is realized by the Separation and Test Technique of the nitride. It has already been completed to distinguish water-oil reservoir. Chromatogram fingerprint technique is firstly used in the calculation of allocation ratio of crude oil with four layers when oil well production. In past two years, many of actual application in Daqing oil-field show these techniques played the important role in the research of oil and source rock correlation, petroleum migration, water-oil reservoir distinction, and well deliverability monitor.
The Application Research of Multi-element Simulated Distillation by Gas Chromatography-Atomic Emission Detection in Geology
LIANG Bing, WANG Yong-li, LI Chen
2004, 22(S1): 129-134.
Abstract:
The study of multi-element simulated distillation for C, H, S, N, Ni, V and Fe in crude oil by gas chromatography-atomic emission detection was introduced. The distortion of various boiling point samples for injector insert of different shapes was examined, the effects of non-linear response and correction of H element on accurate detection of simulated distillation were also discussed. The correction curve of boiling point of n-alkane ranged from n-C12 to n-C98 were established, the calibration factor of each element was obtained. The result indicates that the measuring error of boiling point for n-alkane was than 1℃, the simulated distillation data of standard samples were in good agreement with the standard values. The results show that characters of multi-element simulated distillation of crude oil which have abundant information were obvious, the characters have comparable data of benchmark, all kinds of petroleum can be elucidated in detail, their source and kind can be confirmed too, therefore, the new means that can distinguish the comparable mode between oil and oil, oil and source was obtained.
2004, 22(S1): 140-142.
Abstract: