石油实验地质

CLASSIFICATION OF FORELAND BASINS AND ASPECTS OF HYDROCARBON RESOURCES

GAO Chang-lin, YE De-liao, Qian Yi-xiong

2000, 22(2): 99-104. doi: 10.11781/sysydz200002099

Abstract(1606) PDF-CN(708)

Abstract:
Foreland basins can be classified into 5 types in accordance with their tectonic settings: periland foreland basin, retroarc foreland basin, broken foreland basin, hinterland foreland basin and strike slip foreland basin. Foreland basins are formed in compressional tectonic environment and show some similar characteristics of formation. Such as discordance of depocentre and subsidence centre; 3 segment of subsidence curve showing steep, gentle and steep; and 3 to 5 deformation zones as a result of compression in sediments of foreland basins, are the common characters. The filling patterns and basinal structures are different in foreland basins formed in different tectonic settings and showed different hydrocarbon potential. Periland foreland basin is flextural basin formed in subducting plate resulted from continental-continental collision. It is generally transformed from rifting basin of passive continental margin. The basin showed dual-layer structure of filling. The flysch foreland basin with great thickness was developed in the early stage and thick source rocks were deposited; and molasse foreland basin with coarsing-upward sequence was developed in the late stage and thick reserviors was formed. This kind of foreland basin is the most favorable petroliferous basins. Retroarc foreland basin was related to A-type subduction and could be transformed from retroarc rif-ting basin. Basin filling can be in dual-layer or single layer patterns. Volcanic-flysch forelang basin with thick sediments was developed in the early and source rocks were relatively thick; and volcanic-molasse foreland basin was developed in the late. This kind of foreland basin showed favorable hydrocarbon potential. The formation of broken foreland basin is due to basement involved foreland deformation, which resulted in isolated basins separated by block uplift and basement fold. The sediments is thin and hydrocarbon potential is poor in the basin. Hinterland foreland basin was formed in the interior of a plate and was far away from collisional orogenic belt. It may be related to long distance effect of collisional orogenic zone. The basin was filled in dual-or single-layer patterns and dominated by molasse foreland basin with little development of early flysch. This kind of foreland basin showed certain hydrocarbon potential.Strike-slip foreland basin was developed on both sides of main continental strike-slip system, accompanying with pull-apart basin. The basin filling pattern was single layer structured and molasse foreland basin was developed.The depocentre were obviously arranged in en echelon. Hydrocarbon potential in the basin was limited.The structures of foreland basin was asymmetric.Piedmont thrust, foreland depression, front slope and fron uplift were successively developed from orogenic ane to basin, in which distribution of hydrocarbon accu-mulation was different: a) hydrocarbon was rnainly distributed in fods of hanging wall of piedmont thrust; b)hydrocarbon was entrapped in stratigraphic and diagenetic traps in foreland depression; c) sedimentary wedge thenned or pinch out towards the front slope, so accurnulation in sand driies sealed by upper-dip pinch out orstraopaphic onlap can be formed; and d) large scale of anticline can be developed in front uplift, such as triangeare, drape anticline, and faulted fold structures and so on are habitat of hydrocarbon.

A STUDY OF PRE-CAMBRIAN BASEMENT IN THE QAIDAM BASIN

TAN Ying, LIU De-liang, YANG Xiao-yong

2000, 22(2): 105-109. doi: 10.11781/sysydz200002105

Abstract(642) PDF-CN(485)

Abstract:
Based on data of gravity survey, seismic exploration, aerial magnetical survey and surface geology, the central fault belt was identified in the Qaidam Basin. The basin was divided into two differnt parts by the fault and indicated existence of old crystaline continental kernel pre-Wutai movement. In accordance with geochemical data of intermediatoacid intrusives, a conclusion can be drawn that there was an old altyn Ocean, which expanded the scope of the paleo-Qing-Qi-Kun Ocean. The Altyn Ocean was closed during the Altgn Movement and the arc became pre-Cambrian folded accreted belts.

A NEW METHOD FOR COMPACTION CORRECTION

LI Shao-hu, WU Chong-long, WU Jing-fu, HE Da-wei

2000, 22(2): 110-114. doi: 10.11781/sysydz200002110

Abstract(785) PDF-CN(550)

Abstract:
According to the similarity and the monotonic characteristics of the compaction curves between the compacted and the decompacted states,the paleo-porosity-depth function φ'(Z) and the paleo-density-depth function ρ'(Z) was supposed.By using the principle which formation grain volume and mass have been keeping constant,the compaction correction equations has been established. Further,the decompacted thickness S and the average paleo-density ρ_s can be calculated and the grain density of the compacted and decompacted states can be kept constant.

SOME CHARACTERISTICS OF OIL FIELDS IN THE TARIM BASIN

KANG Yu-zhu

2000, 22(2): 115-120. doi: 10.11781/sysydz200002115

Abstract(747) PDF-CN(540)

Abstract:
39 oil fields have been discovered presently in the Tarim Basin. 21 of them are large-to medium-sized, including giant Tahe oil field and Kela No.2 gas field, which indicated a very bright future for hydrocarbon exploration and development in the basin. Distribution of oil and gas pools was characterized by stacking of multiple horizons And pools can be classified into different level of types which were formed in several pool-forming periods (Early and Late Hercynian, Indosinian-Himalayan) and showed various patterns of formation. Distribution of oil fields was controlled by paleocraton basin, the Meso-Cenozoic foreland basins and structural systems. There is useful indication for hydrocation exploration in the basin in the study.

ANALYSIS ON CONTROL OF TECTONIC STYLE TO PETROLEUM IN THE QAIDAM BASIN

DAI Jun-sheng

2000, 22(2): 121-124. doi: 10.11781/sysydz200002121

Abstract(709) PDF-CN(597)

Abstract:
Based on the basic characteristic study of tectonic style in the Qaidam Basin, the control of tectonic style to petroleum is analysed in this paper from the relation between the develpment of tectonic style by stages and the distribution of hydrocarbon source rocks by areas, the petroliferous properties of tectonic style, the reformation of tectonic style to oil and gas pools, etc. It is pointed out that the hydrocarbon source rocks formed in the development stage of extensional tectonic style in the early of the Yanshanian are mainly distributed in the north of the basin, those formed in the development stage of the Tertiary compressional tectonic style distributed in the west of the basin, and those formed in the development stage of strongly-compressional tectonic style in the late of the Himalayan distributed in the middle of the basin. The growth anticline is major oil-bearing tectonics. The fault propagation anticline controlled by recoil fault is important hydrocarbon-bearing tectonics. The longitudinal bend anticline in oil-generating areas can form oil pools. And the longitudinal bend anticline in Sanhu region is gas-bearing tectonics. The pools formed by the Early-Middle Himalayan compressional tectonic style regularly reformed by the strong compressional tectonic style of the Late Himalayan. The extensional structural style on the core of anticlines has reformation effects on oil and gas pools.

EVOLUTION AND TECTONIC CHARACTERISTICS OF THE MESOZOIC BASIN IN DAGANG PROSPECT AREA

DU Xu-dong, QI Jia-fu, LU Ke-zheng, FU Li-Xin

2000, 22(2): 125-130. doi: 10.11781/sysydz200002125

Abstract(783) PDF-CN(538)

Abstract:
The Mesozoic tectonic styles in Dagang prospect area include stretch,compression,strike-slip,adjustment and those related to volcanic rock.The Early and Middle Jurassic tectonic sublayer dominated by compression has the characteristics to develop the Kongxi buried-hill structure;the Jurassic-Cretaceous tectonic sublayer dominated by weak stretch has concurrent fault depressions and basins,and has strong volcanic activities;and the Late Cretaceous tectonic sublayer dominated by weak uplift has limited distribution of basins.The time and space distribution of the Jurassic-Cretaceous basins and their deformational characteristics are related to Yanshan-Qikou-Xingang buried faulted zone and the Mesozoic Cangdong faulted zone.The deformational dynamics is controlled by the compressional settings which are caused by the minor-angle oblique subduction of the Izanagi Plate and the continent-to-continent collision betneen the Yangtze Plate and the North China Plate.

A REDISCUSSION ON THE EXPLORATION PROSPECT OF COAL BED GAS IN CHINA

CHI Wei-guo, WU Song-gin

2000, 22(2): 131-135. doi: 10.11781/sysydz200002131

Abstract(688) PDF-CN(462)

Abstract:
Encouraging achievements have been obtained from the exploration of coal bed gas in china. In many areas, an industrial breakthrough has been made in exploation and development tests, and large scale coal bed gas fields have been discovered. But there exists technical problems and different opinions to the exploration and development which mainly reflect the influence from the gelogic conditions of coal bed gas. From the geologic conditions which affect the exploration of coal bed gas, the author studied the mineability of coal bed gas resources and considered that the area whose coal bed gas resources can be developed by the drainage gas-collecting method is limited at the present. This is mainly controlled by the mineability of coal bed gas. The mineability of coal bed gas mainly depends on coal texture, formation pressure and hydrogeologic conditions. In this paper, three hydrogeologic types of coal bed gas and their distributive regions were suggested for the first time, different influence caused by different hydrogeologic types to the mineability of coal bed gas was analysed, and the prospect to the comprehensive exploration and development of coal bed gas was discussed. Also, the author gave some advises to the later exploration work of coal bed gas.

MAJOR FACTORS CONTROLLING THE ENRICHMENT OF THE UPPER PALEOZOIC NATURAL GAS IN THE ORDOS BASIN

ZHAO Lin, XIA Xin-yu, DAI Jin-xing, HONG Feng

2000, 22(2): 136-139. doi: 10.11781/sysydz200002136

Abstract(664) PDF-CN(561)

Abstract:
The Upper Paleozoic gas source rocks in the Ordos Basin have the sustained ability to provide gas from the Triassic to the present. They still have considerable gas-expulsion amount after the Early Cretaceous. The sustained gas-provision ability and the large gas-expulsion amount of the Upper Paleozoic gas source rocks are favorable conditions for the enrichment and accumulation of the Upper Paleozoic natural gas. They show that the Ordos Basin have the material basis to form deep-basin gas. From the Triassic to the Early Cretaceals, the Upper Paleozoic natural gas in the Ordos Basin migrated northward in a large scale; after the Early Cretaceous, the natural gas migrates and accumulates nearby. This create advantageous gas-source conditions for bearing gas in the large areas of the basin. The sand bodies of distributary channels and river-mouth sandbars in the Lower Shihezi-Shanxi Formation, which is distributed in the four large scale fluvial-deltaic sedimentary systems, have best physical properties. The channel sandbodies in these sedimentary systems are favorable places to the enrichment of natural gas. Stable tectonic setting as well as good seeling ability of regional and direct covers forms advantageous conditions to the preservation of the Upper Paleozoic natural gas. The key factor to the accumulation of the Upper Paleozoic natural gas. in the Ordos Basin is the distribution of favorable sand bodies. To strengthen the prediction of distribution for the sandstone reservoir of the Shihezi-Shanxi Formations has important significance to the exploration of the Upper Paleozoic natural gas.

SECONDARY HYDROCARBON GENERATION OF COAL AND ACCUMULATION OF COALBED METHANE IN THE EAST MARGIN OF THE ORDOS BASIN

TANG Da-zhen, WANG Ji-liu, ZHANG Jun-feng, HUANG Wen-hui

2000, 22(2): 140-145. doi: 10.11781/sysydz200002140

Abstract(716) PDF-CN(628)

Abstract:
The studies of the allocation of tectonics, geotherm and coal metamorphic evolution indicated that to the Late Paleozoic coals in the east margin of the Ordos Basin, the production rate of coalbed methane is observably high and the time of gas generation is relatively centralized within the sections affected by abnormal geotherm of the Yanshan Period magma. The secondary hydrocarbon generation controlled the intensity of gas generation and determined the superior conditions of accumulation and conservation of coalbed methane as well.

STUDY OF THE WEST-EAST TREND NATURAL GAS ACCUMULATION ZONE IN THE MIDDLE OF THE ORDOS BASIN, CHINA

FANG Guo-qing, LIU De-liang

2000, 22(2): 146-151. doi: 10.11781/sysydz200002146

Abstract(619) PDF-CN(459)

Abstract:
The discovered industrial gas fields, like Liujiazhuang, Shenglijing, Changqing, Zhenchuanbu and Wubu in the Oudos Basin are all located in the west-east trend tectonic belt of the Middle. There are gas showings or a small amount of gas flows in only rare wells in the other regions of the basin. Their reservoirs are the Ordovician carbonate rock or sandstone and thin-bedded limestone in the Carboniferous and the Permian coal measures strata. The gas sources are pure gas pools and are all related to the Ordovician or the Carboniferous and the Permian hydrocarbon source rocks. They show good identity. Industrial gas fields zonally distributed in west-east trend in the middle of the basin is not accidental. It reflects the controlling action of the middle tectonic belt to the pool-formation and distribution of these fields. Taking the middle tectonic belt as setting and linking their same or similar genetic background together, theas fields can be included into the west-east trend natural gas accumulation zone of the Middle. Obviously, this zone is the most favorable target for natural gas exploration.

METER-SCALE CARBONATE CYCLES IN THE BACHU FORMATION OF THE LOWER CARBONIFEROUS IN THE TARIM BASIN

QI Yong-an, HU Bin

2000, 22(2): 152-155. doi: 10.11781/sysydz200002152

Abstract(746) PDF-CN(417)

Abstract:
Two kinds of meter-scale carbonate cycles are developed in the Bioclastic Limectone Member of the Bachu Formation in the Lower Carboniferous of the Tarim Basin,i.e. the intertidal-supratidal cycle and the subtidal-supratidal cycle.According to the characteristics of sedimentology and the analysis of the Fischer Plot, the cycles are formed in the upland system domain of the 3^rd order sequence and controlled by Milankovitch-induced high-frequency sea-level fluctuation. The dolomitic limestone reservoirs developed with needlehole-like solution openings may be related to the short-term exposure of carbonate platforms caused by the high-frequency sea-level fluctuation.

CHARACTERISTICS OF GEOTEMPERATURE FIELD AND MATURITY HISTORY OF SOURCE ROCKS IN LUNPOLA BASIN, XIZANG(TIBET)

YUAN Cai-ping, XU Si-huang

2000, 22(2): 156-160. doi: 10.11781/sysydz200002156

Abstract(698) PDF-CN(421)

Abstract:
Lunpola Basin, developed on Yensan basement, is an extensional Eogene continental basin. It started relatively later than other Cenozoic basins in eastern China, ended at the end of Oligocene Epoch, and then uplifted until present. Its deposition period was short. It also took place a short uplifting period at the end of Eocene Epoch. Lunpola Basin is a typical HOT Basin, in which geothermal gradient was higher than 50℃/km, and temperature was decreased as Qingzang plateau elevating. Special characteristics of structure, sedimentary history and geotemperature field made source rocks of Niubao formation in the basin bury shallow and mature fast. All of those are favorable for hydrocarbon generation and expulsion. But Petroleum exploration has shown that Lunpola Basin was reformed by succeeding structure and fracture and the primary reservoir was damaged. So it is unfavorable for preserving great amount reserves of oil and gas.

A MODEL FOR FORMATION OF OIL POOLS IN THE ZHAOXIAN ANTICLINE OF THE CENTRAL HEBEI DEPRESSION

LIU Da-ting, ZHANG Shu-juan

2000, 22(2): 161-166. doi: 10.11781/sysydz200002161

Abstract(733) PDF-CN(397)

Abstract:
The Zhaoxian anticline is a new oil-bearing structure discovered in 1998, with 1300×10⁴t of oil reserve. The total area of the anticline is 70km² and trap area 55.2km². During the progressive exploration and development, the anticline was studied in detail and the control factors on formatim and distribution of oil pools were clearly definited in accordance with reservior description. Three kinds of oil pools were classified, including structural, lithological-structural and structural-lithological oil pools. The study may provide some valuable suggestions for future exploration and development of the anticline.

CALCULATION OF HYDROCARBON-GENERATING TEMPERATURE AND ITS APPLICATION TO EXPLORATION

ZHU Yang-ming

2000, 22(2): 167-171. doi: 10.11781/sysydz200002167

Abstract(704) PDF-CN(499)

Abstract:
According to the steady-state catalytic model for the origin of light hydrocarbon proposed by Mango,2,4-/2,3-dimethylpentane ratio is a pure temperature parameter.Based on the paleogeotemperature, the thermal history and the analytical data of light hydrocarbon for source rocks, Bement and Mango et al. established the functional equation between the light hydrocarbon temperature parameter and the burial temperature and applied it to the calculation of hydrocarbon-generating temperature. The hydrocarbon-generating temperature has broad application to the research fields of oil & gas exploration and reservoir geochemistry. It can be used to study the evolutionary degree, migration distance,pool-forming time,the property of self-generation and self-accumulation,the threshold of hydrocarbon expulsion etc.In this paper, the generating temperature of the marine and continental hydrocarbons from the Tarim Basin are calculated, and their generating depth and maturity are estimated. They are verified by other geological and geochemical data.

GEOTHERMAL HISTORY RECONSTRUCTION OF ZHANHUA SAG, JIYANG DEPRESSION

CHENG Ben-he, XIANG Xi-yong, MU Xing

2000, 22(2): 172-174. doi: 10.11781/sysydz200002172

Abstract(665) PDF-CN(459)

Abstract:
Based on available well temperatures and vitrinite reflectance (R^o) data, geothermal history of zhanhua sag,Jiyang Depression was reconstructed with synthesizing lithosphere-scale and basin-scale multi-linear model offered in this paper. The study result indicates: (1) the heat flow evolution curve shows a general tendency of decreasing slowly interrupted by two picking up periods that shapes‘a saddle’from the Paleocene to the Present. The calculated heat flow is about 83.6 mW/m² in the early Paleocene corresponding to active rift region, however, the present heat flow gets down to 63mW/m² as the global average value. (2) the main oil bearing layers experienced long term slowly heating process, subsequently, it is still at the ‘oil generation window', and has a wide range depth for oil existence. So, the geothermal evolution background is favorable to oil generation. The conclusion can also be further proofed by the rifting model of Bohaiwan Basin, and is useful to oil exploration in this area.

PHYSICAL PROPERTY CHARACTERISTICS OF CAP ROCKS IN THE SOUTHEASTERN PART OF THE SONGLIAO BASIN

CHEN Qiang-lu

2000, 22(2): 175-179. doi: 10.11781/sysydz200002175

Abstract(645) PDF-CN(422)

Abstract:
The cap rocks in the southeastern part of the Songliao Basin are dominated by argillite. The Lower Cretaceous Qingshankou Formation and its upper lacustrine-facies mudstone are good regional cap rocks in the northern part of the area. The upper mudstine of the Quansan(K₁g³) and Quaner(K₁g²) Members is not only the regional cover of the area, but also the critical cover of its underlying gas reservoirs. The breakthrough pressure of the cover is greater than the residual pressure of gas pools and the displacement pressure of reservoir rocks, and the gas-sealing height is greater than the height of gas pools. So, effective sealing is formed. The relationship between the sealing mechanism of cap rocks and the texture of micropores shows that the styles of the cap rocks are dominated by the compound style of microfissures and micropores.

AN APPROACH TO THE TECHNICAL ECONOMIC RESEARCH OF MINOR-LAYER RESIDUAL OIL

XIE Cong-jiao, AI Jing-xu, LI Xi-yu

2000, 22(2): 180-183. doi: 10.11781/sysydz200002180

Abstract(607) PDF-CN(420)

Abstract:
The conventional way to study minor-layer residual oil is to calculate the present saturability of residual oil according to the static and dynamic data and allocate it to the minor layers so as to determin the potential residual oil regions in the whole oil area macroscopically. In this paper, the principle of balance of profit and loss is applied to analyse the low-efficient oil wells with low residual oil saturability microscopically from the technical economic angle, and the range and horizon of distribution for residual oil is pointed out further. This also provides basis for the decision of oil field development.

DEVELOPMENT OF SOFTWARE FOR SIMULATION OF FORMATION DAMAGE BY USING THE OBJECT-ORIENTATION METHOD

CAO Yan-rong, XU Shi-jing, WANG Ru-cheng, LU Xian-cai

2000, 22(2): 184-188. doi: 10.11781/sysydz200002184

Abstract(711) PDF-CN(381)

Abstract:
Simulation of formation damage is an active field in software development in petroleum industry. At present, most programer use function decomposition or data flow approach to develop their software, but there are many limitation in those two methods: they make problems complex, bad communication between programer and geologist and few recycle of the software. So, a new method was suggested in the paper, i.e. object-oriented software development for simulation of formation damage. The geological reality was expressed by objeet. The property and law of geological reality are object's attribute and service, and interaction of objects can be implemented by message connection, thus, they form an organic unit.

TREATMENT AND REINJECTION OF OILFIELD WASTE WATER：A CASE STUDY AND ITS PROSPETS

LIU Bin, WANG Da-wei

2000, 22(2): 189-192. doi: 10.11781/sysydz200002189

Abstract(628) PDF-CN(370)

Abstract:
By introducing a case study of waste water treatment and reinjection in an oilfield,the authors discussed the installation and technology available to waste water control,and affects of changeable operational loads on sewage treating system,which in turn will make a more flexible design of oilfield waste water treatment.In order to deal with the 3 major issues related to water quality,i.e.corrosin,blockage and scale,a rational use of reagents is suggested.Additionally,the prospects of waste water control were propoed.

2000 Vol. 22, No. 2

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