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2000 Vol. 22, No. 3

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IS CAPILLARY POWER A DRIVING FORCE FOR THE PRIMARY MIGRATION OF OIL AND GAS?
WANG Zhi-xin
2000, 22(3): 195-200. doi: 10.11781/sysydz200003195
Abstract(744) PDF-CN(486)
Abstract:
Generally speaking, during the seccodary migration of hydrocarbon, capillary power is the resistance of hydrocarbon migration when the rear-end curvature radius of the continuous oil (gas) phase is greater than the front-end's and is the driving force when the rear-end curvature radius is smaller than the front-end's because of the change of pore structure. Capillary power always tends to making the nonwetting phase occupy larger pore space. Under the joint action of buoyancy, hydrodynamic force and capillary power, oil (gas) moves intermittently. This has been verified in the physical simulation experiment.In fact, there are three types of capillary power. The first and the second types are parallel to the extensional direction of capillary, and the third is perpendicular to the wall of capillary and directs to the nonwetting phase. The third type of capillary power takes effect to increase the frictional resistance between the nonwetting phase and the throat wall, and is usually neglected in the media with wider throats (such as reservoirs). Hydrocarbon can migrate only when the driving force in the advancing direction surpasses the sum of the capillary resistance and the frictional resistance in this direction.A prevailing viewpoint says that capillary power is an important drivivng force during the primary migration of hydrocarbon from source rocks to reservoirs. So under the water-wetting condition, the oil (gas) phase will move spontaneously from small pores and thin throats to larger pores and wider throats. In this paper, the author studied this problem starting with the essence of capillary appearance and found that different types of capillary power act quite differently in source rocks comparing with in carrier beds. Because of the wider throats, the first and the second types of capillary power take main parts and the role of the third type of capillary power is often neglected in carrier beds. And in source rocks, the third type of capillary power increases greatly compared with the first and the second types because the capillary radius reduces all-roundly. This results in the steep rise of frictional resistance and makes it be the main resistance of hydrocarbon expulsion from source rocks. Therefore the viewpoint that "capillary power is a driving force for hydrocarbon expulsion" is a wrong conclusion due to unreasonable neglecting the third type of capillary power which plays a decisive role in source rocks. By studying the pore structure of argillutite, the author suggested that the pores in argillutite should be mainly "dead pores", and the hydrocarbon expulsion of source rocks should be eruptive surging through microfractures whose opening or forming and the happen of surging all have something to do with sudden and fierce tectonic movement.
THE WAY AND MODEL OF STRESS EFFECT ON HYDROCARBON EXPULSION
TONG Heng-mao
2000, 22(3): 201-205. doi: 10.11781/sysydz200003201
Abstract(595) PDF-CN(298)
Abstract:
Based on analysis of hydrocarbon expulsion mechanism in different stages, the way of stress effect on hydrocarbon expulsion is discussed, and theoretical model of hydrocarbon expulsion with stress effect is developed. By these models, the stress effect on hydrocarbon expulsion is defined on two aspects: pathway formation of hydrocarbon expulsion (microfracture) and as a power of primary oil migration (causing the change of fluid pressure of source rock). The result shows that the stress component which has main effect on hydrocarbon expulsion is maximum differential stress, and the direction of hydrocarbon expulsion is parallel to microfracture, which is parallel to maximum main stress. It is also shown that, in different kind of basins, the way and result of stress effect on hydrocarbon expulsion is different, in which compressive basin has relative bigger effect, and extensional basin has smaller one, and it is the most propitious to hydrocarbon expulsion in active tectonic stage.
THE TRANSFER ZONE WITHIN INTRA-CONTINENT SUBDUCTION OROGENIC BELT IN THE TIANSHAN, NORTHWEST CHINA
CAI Li-guo
2000, 22(3): 206-209. doi: 10.11781/sysydz200003206
Abstract(736) PDF-CN(467)
Abstract:
The Tianshan Mountains is a composite orogenic belt. The intra-continent subduction occurred under the influence of distant compressure of subduction and collision taking place between the Indian plate and the Eurasia plate in the Mesozoic-Cenozoic. The Tarim block and the Junggar block subducted in the opposite direction beneath the Tianshan Mountains. The mountains was lifted rapidly and thrust-folded from central to north and south. Intra-continent subduction foreland basins were developed, under effect of the tectonic load, in the North and South of the Tianshan Mountains. There were differences along the trend of the intra-continent subduction orogenic belt, in terms of the thickness of crust, the elevation of mountains, the intensity of earthquake etc, between eastern and western Tianshan Mountains. It was clear that the West of Tianshan Mountains was more active than the East. The Bogeda Mountains showed the intensive activity in the formation of intra-continent orogenic belt. Lift and thrust-fold belt, formed in the stage, controlled the deposition in the foreland basins developed in the two sides of the Mountains. There was comparison between the West of the Tianshan Mountains and Bogeda Mountains. All of them showed that there was a transfer zone, which transferred the shortening from the West of the Tianshan Mountains to the Bogeda Mountains, in the development of intra-continent orogenic belt. The difference of the crust shortening of western and eastern Tianshan Mountains was transferred to the Bogeda Mountains. The transfer zone balanced the differences between eastern and western Tianshan Mountains, and named as Urumqi-Kuerle transfer zone.
FORMATION CONDITIONS AND INTERNAL FEATURES OF DEEP BASIN GAS ACCUMULATIONS
ZHANG Jin-chuan, JIN Zhi-jun, PANG Xiong-qi
2000, 22(3): 210-214. doi: 10.11781/sysydz200003210
Abstract(654) PDF-CN(364)
Abstract:
Deep basin gas accumulation (DBGA) has been followed with wind interests by petroleum geologists since the being put forward of the concept DBGA (deep basin gas trap by J. A. Masters)and the breakthrough of accumulation mechanism,especially its enormous reserves. Deep basin gas accumulations are distinct from normal ones in origin mechanism,genetic features and distribution rules. The formation and distribution of DBGAs are restricted by tight sand reservoirs with low porosity,low permeability and high saturation of water. The fundamental features of DBGAs are the overturning of formation fluids and occurring of abnormal pressures. DBGAs are distinguished from normal ones in their basic principles,general characteristics and genetic sequences. DBGA is discussed thoroughly in the paper to expect to be useful for the exploration of DBGA in China.
ON FORMING CONDITIONS FOR NON-ANTICLINAL OIL AND GAS POOLS IN THE TARIM BASIN
CHEN Rong-lin
2000, 22(3): 215-219. doi: 10.11781/sysydz200003215
Abstract(525) PDF-CN(315)
Abstract:
There are favorable condition for formation of non-anticlinal oil & gas pools in the Tarim Basin. The basin underwent superimposition of the Paleozoic cratonic basin and the Ceno-Mesozoic foreland basin, in which large scale of paleo-uplift and paleo-slope were developed. Because of several transgression and regression and large scale of structural movement of subsidance and uplift in its evolution history, various complicated paleo-structural and paleogeographic environments were developed. There are several unconformity surfaces in the basin. All of these proved conditions for formation of non-anticlinal oil and gas pools, which may indicate a bright future for hydrocarbon exploration in the basin.
COMPARISON OF TECTONIC EVOLUTION OF OIL AND GAS TRAPS BETWEEN THE BACHU UPLIFT AND THE NORTH TARIM UPLIFT
HE Wen Yuan, LI Jiang-hai, QIAN Xiang-lin, HE Ji-ping, ZHENG Duo-ming, LI Jian-jun
2000, 22(3): 220-224. doi: 10.11781/sysydz200003220
Abstract(661) PDF-CN(354)
Abstract:
Both the North Tarim Uplift and the Bachu Uplift had gone through forebulge phase, so they had some similar features. By comparing their Mesozoic and Cenozoic tectonic evolution history, the authors consider Bachu Uplift has some shortcomings in collecting oil and gas: a little late of the forebulge development time, severe damage and too far away to the source of oil and gas. But Badong slope, especially the surrounding back thrust uplift zones, has some good merits such as lower post-tectonic stress, high tectonic position and many new and old traps. So Badong slope should be a focal zone in the next exploration process.
RELATIONSHIP BETWEEN FAULTING AND THE PRESERVATION OF OIL AND GAS ACCUMULATION
LUO Qun, SUN Hong-zhi
2000, 22(3): 225-231. doi: 10.11781/sysydz200003225
Abstract(523) PDF-CN(351)
Abstract:
Faulting destroying oil and gas accumulation is a widespread phenomenon.Based on the analysis of typical cases about faults destroying oil and gas accumulation in this paper,its mechanism is studied,and its classifying index system is determined.It can be divided into three categories,nine subcategories and twenty-seven types.Then,four models of faults destrotying oil and gas accumulation are established,and the geologic concept models and mathematical models for its quantative evaluation are suggested.
EVALUATION OF HYDROCARBON GENERATING POTENTIAL OF THE MIDDLE AND LOWER JURASSIC COAL IN NORTHWEST CHINA
LIU Guang-xiang, PAN Wen-lei, SHAO Hai-ning
2000, 22(3): 232-235. doi: 10.11781/sysydz200003232
Abstract(602) PDF-CN(298)
Abstract:
The Middle and Lower Jurassic with thick coal seam is widely distributed in Northwest China.The statistical and measured organic macerals of coal indicated that high content of hydrous desmocollinite is of gene-ral phenomenon with its average ratio to total organic maceral up to 18% in the region although content of exinite in coal usually is not high.Hydrous desmocollinite and exinite in coal are the principal material for hydrocarbon generation.Based on comparison coefficient of organic geochemical parameters of coal,hydrocarbon generating potential of coal in the area was evaluated.It was pointed out that hydrocabon generating potential of coal was excellent in many basins in the area,where was favourable for petroleum exploration.
ON DIVISION OF THE JURASSIC SEQUENCE STRATIGRAPHY IN THE JUNGGAR BASIN
ZHANG Man-lang, ZHANG Qin, ZHU Xiao-min
2000, 22(3): 236-240. doi: 10.11781/sysydz200003236
Abstract(720) PDF-CN(431)
Abstract:
Some divisions of the Jurassic sequence stratigraphy in the Junggar Basin are comparied, and problems in sequence divisions are discussed. Based on the systematic studies of the Jurassic sequence stratigraphy on East Fukang Slope and the near area, a new division of the Jurassic sequence stratigraphy is proposed,which includes six stratigraphic sequences or two tectonic sequences.
APPLICATION OF CHEMICAL REACTION KINETICS TO CALCULATION OF QUANTITY OF OIL-GENERATION FOR IMMATURE SOURCE ROCKS OF QIANJIANG FORMATION IN THE JIANGHAN BASIN
PU Xiu-gang, JIANG Ji-gang
2000, 22(3): 241-244. doi: 10.11781/sysydz200003241
Abstract(690) PDF-CN(290)
Abstract:
Based on relationships between the apparent activation energy (AAE) and hydrocarben generating rate,the frequency factor and AAE,which were derived from pyrolysis analysis of immature source rocks in the study area,a model of chemical reaction kinetics (MCRK) was established.MCRK can be used to calculating hydrocarbon generating rate and the generation amount at random depth and generating intensity in random intervals of source rocks.By using this model,the current cumulative oil generating intensity and amount for immature source rocks of Qianjiang formation were calculated in JJ,QQ,XX Depressions,the Jianghan Basin.It showed that MCRK is suitable for calculation of oil generating quantity as comparing with other methods.
PETROLEUM GEOLOGICAL CHARACTERISTICS AND OIL-PROSPECT EVALUATION OF THE TRIASSIC AND THE JURASSIC IN THE QIANGTANG BASIN, TIBET
HU Ming-yi, GONG Wen-ping, WEN Zhi-gang, XIAO Chuan-tao, YAO Zheng-dao, ZHANG Shang-feng
2000, 22(3): 245-249. doi: 10.11781/sysydz200003245
Abstract(580) PDF-CN(328)
Abstract:
The Qiangtang Basin, which is developed on the Pre-Devonian crystalline basement and the Upper Paleozoic epimetamorphic folded basement, is a composite residual basin dominated by the Mesozoic marine deposit. It consists of the North Qiangtang Geotectogene, the Central Mole Track and the South Qiangtang Geotectogene three secondary tectonic units, and mainly developed the Triassic and the Jurassic two sets of source rock-reservoir-cap rock assemblages. The Triassic and the Jurassic assemblages developed well in the North Qiangtang Geotectogene. There is scarcely the Jurassic assemblage and the Triassic assemblage is only distributed in the pitching parts within the Central Mole Track. In the South Qiangtang Geotectogene, the Ttiassic assemblage developed well, and the Jurassic assemblage exists well in some regions. The hydrocarbon exploration practice in the Qingzang Plateau shows that the oil prospect of this area depends on the strong and weak of tectonic movement and the good and bad of preservation conditions. Considered the information of source rock-reservoir-cap rock assemblages, the Qiangtang Basin can be divided into three types of prospective oil lands: the North Qiangtang Geotectogene favorable region, the South Qiangtang Geotectogene favorable region and the Central Mole Track subfavorable region.
PREDICTION METHOD OF RESERVOIR FRACTURES IN THE CHENGBEI 30 BURIED-HILL OF SHENGLI OILFIELD
WANG Duan-ping, ZHANG Jing-xuan
2000, 22(3): 250-255. doi: 10.11781/sysydz200003250
Abstract(625) PDF-CN(360)
Abstract:
As fossil buried-hill reservoirs have complex lithology and have experienced weathering and leaching as well as multiple tectonism, the identification and evaluation of their housing space is always a geological puzzle to be overcome. The evaluation of fossil buried-hill fracture reservoirs is especially difficult. Taking the Lower Paleozoic carbonate rocks and the Archaeozoic gneiss reservoirs in the Chengbei 30 Fossil Buried-hill as objects of study, the authors presented creatively a set of evaluation and prediction methods for buried-hill fracture reservoirs through comprehensive study by means of the quantitative core description, the laboratory analysis, the logging analysis, the seismic correlation analysis and velocity analysis, etc. These methods have directive significance for the study of the same kinds of reservoirs.
SEISMIC REFLECTION FEATURES AND DISTRIBUTION LAW OF VOLCANIC ROCKS IN THE YINGSHAN FAULT DEPRESSION OF THE SONGLIAO BASIN
LIU Wei-fu, SUN Li-xin, LIU Shuang-long
2000, 22(3): 256-259. doi: 10.11781/sysydz200003256
Abstract(642) PDF-CN(443)
Abstract:
Commercial gas stream bas been discovered in the Jurassic volcanic rocks of the Yingshan Fault Depression.Deep volcanic rocks then become another target stratum for hydrocarbon exploration in the Songliao Basin.To predict the distribution of volcanic rocks by seismic information is an only effective way to find out gas reservoirs in volcanic rocks when with few drilling wells.By use of seismic data and combined with the geology of drilling wells,the distribution of volcanic rocks can be studied.The distributive range and thickness of volcanic rocks can be predicted by their seismic reflection features,and the distributive law can be analysed by strata whose geology is revealed through well drilling.Therefore the formation and distribution of volcanic rocks can be understood.This has very important significance for the gas reservoir research of the Jurassic volcanic rocks in the Yingshan Fault Depression of the Songliao Basin.
HYDROTHERMAL CONVECTION MODEL OF GROUNDWATER AND THE CORRESPONDING HYDROCARBON-ACCUMULATION MODEL FOR THE NORTH SONGLIAO BASIN
WANG Jian-rong
2000, 22(3): 260-264. doi: 10.11781/sysydz200003260
Abstract(667) PDF-CN(316)
Abstract:
The movement of groundwater related to hydrocarbon in the North Songliao Basin can be divided into two stages: the movement of sedimentary water and the convection of infiltration water and juvenile water.The TDS (total dissolved solids) of groundwater in the marginal area of the basin increases with depth.It shows a low-high-low phenomenon in the middle area.In the central area of the basin,it decreases with depth. The "reversed" distributive rule of TDS for the groundwater in this area is contributed to the hydrothermal convection of groundwater.According to the hydrocarbon-accumulation model based on the hydrothermal convection geologic model of groundwater in the basin,there are three types of hydrocarbon-accumulation sites.The margin of the basin is the rapid change area of groundwater flow,in which the hydrocarbon carried by groundwater accumulates into pools in favorable traps (type C).The middle of the basin is the "dead circulation" area limited by Ⅲ-Ⅲ' flowline,in which fluid has no exchange with the outside and good hydrocarbon-preservation conditions exist (type B).The upper part of the central area in the basin is the regional drainage area of groundwater which is advantageous to hydrocarbon accumulation (type A2),and the lower part is the confluence area of two flow systems which is liable to form hydrocarbon accumulation (type A1) and is the possible distributive area of inorganic-genetic gas pools.The three types of hydrocarbon pools (type A,B and C)belong to different hydrocarbon systems respectively.
CHARACTERISTICS AND GENETIC MECHANISM OF FORMATION PRESSURE IN THE WUYANG SALT-LAKE BASIN
LI Lan-bin, SUN Jia-zhen, CHEN Wen-li, YANG Yun-fei, LI Li-xian
2000, 22(3): 265-269. doi: 10.11781/sysydz200003265
Abstract(598) PDF-CN(361)
Abstract:
Based on the particularity of stratigraphic structure for the salt-mud interbeds of the Wuyang Continental Salt-lake Basin,the authors discussed the genetic mechanism of anomalous fluid pressure in the basin starting with its destributive characteristics combined with the burial history and thermal evolutionary history of the basin.The calculated results of pressure reveal that the anomalous fluid pressure in the salt-lake basin can be classified into shallow,middle and deep three sets of pressure-sealing systems,that is the gradational and transitional moderately anomalous high pressure system in shallow beds,the mutiple sets of low-degree anomalous high pressure system in middle salt-mud interdeveloping members and the abrupt high-degree anomalous pressure system in deep beds.The formation of anomalous pressure is mainly related to the undercompaction that the fluid in nonpenetrative beds cannot drain off due to non-isostatic compaction result from rapid subsidence.It also has something to do with hydrothermal pressure-enhancement,organic matter converting into hydrocarbon,tectonic compression,etc.
PERMEABILITY OF FRACTURED RESERVOIRS IN THE JINGBEI BURIED-HILL POOL, CENTRAL LIAONING PROVINCE：A RENORMALIZATION GROUP APPROACH
SHAN Ye-hua, GE Wei-ping
2000, 22(3): 270-275. doi: 10.11781/sysydz200003270
Abstract(636) PDF-CN(329)
Abstract:
The renormalization group method coupled on the percolation theory provides an effective way to calculate fracture connectivity and to describe the scale dependence of rock permeability. An example is taken from the fractured reservoirs of sandstone and dolomite in the Jingbei buried-hill pool within central Liaoning province, Northeast China. In the　cores of A67 well, total fracture probabilities calculated within the core scale may be larger than 0.5 or the　critical probability for 2D-fracture network. This indicates the utmost connection of fracture networks in reservoirs, thus corresponding to the abundance of pores in sandstones. On the other hand, these fractured reservoirs are overprinted by numerous faults in the pool. Whether conductive or not, small faults referred to as those under the resolution, will undoubtfully have an impact on the reservoir permeability. Modified renormalization group method is herein used. If small faults are inconductive,calculated permeabilities decrease from 22mD in fractured matrix to several mD within the scale of well spacing; and if conductive, increase with the observation scale.
AN ARTIFICIAL NEURAL NETWORK-BASED METHOD FOR EVALUATING THE OIL PROSPECTS OF ROCKS
LIU Yong-jian, SHEN Jun, LIU Yi-jian, WANG Lin
2000, 22(3): 276-279. doi: 10.11781/sysydz200003276
Abstract(589) PDF-CN(313)
Abstract:
The calculating method of neural networks is a new way to discuss problems by simulating the mechanism of activities of human body network systems. Based on the SOM artificial neural network model advanced by T. Kohonen, an artificial network model for evaluating the oil prospects of rocks is built in this paper by taking the main reservoirs of Cainan oil field in the Junggar Basin as an example. The case study indicates that the method of artificial neural networks has good performance and is an effective way to evaluate the oil prospects of rocks.
HIGH TEMPERATURE GAS CHROMATOGRAM OF HIGH MOLECULAR WEIGHT HYDROCARBONS FROM CRUDE OIL AND ROCK EXTRACTS
HUANG Hai-ping
2000, 22(3): 280-284. doi: 10.11781/sysydz200003280
Abstract(631) PDF-CN(510)
Abstract:
By using high temperature GC analysis of high wax oil and rock extracts in Damintun Depression,the distribution and composition of high molecular weight hydrocarbons (HMWHs) were determined.Except for high molecular weight n-alkane,complete isoparaffin or cycloparaffinic hydrocarbons were observed in hydrocarbon of C40 above.Their abundance and distribution are controlled by thermal evolution of source rocks.It proved direct evidence of origin of high wax oil as a result of detection of HMWHs.
COMPARISON OF ANALYTICAL RESULTS FOR TWO SAMPLING METHODS OF NITROGEN IN AMMONIA FROM OIL FIELD WATER
ZHAO Feng-san
2000, 22(3): 285-286. doi: 10.11781/sysydz200003285
Abstract(504) PDF-CN(229)
Abstract:
The data of nitrogen in ammonia from oil field water are very different by different sampling methods.If samples was preprocessed by 1:1H2SO4,the analytical results were much higher than the value of samples without preprocessing.
DIGITAL GRAPHICS USED IN THE EXPLORATION OF HYDROCARBON IN THE TARIM BASIN
GAI Xing, LIU Bin, LIU Min-yan
2000, 22(3): 287-288. doi: 10.11781/sysydz200003287
Abstract(620) PDF-CN(224)
Abstract:
New fruits are achieved constantly in the hydrocarbon exploration and development of the Tarim Basin. Among these, the computer digital graphics is a powerful tool serving the object.

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