石油实验地质

POLICY, WAY OF THINKING AND AREA SELECTION

Sun Zhaocai

1989, 11(4): 301-313. doi: 10.11781/sysydz198904301

Abstract(467) PDF-CN(298)

Abstract:
The reason that the productivity and reserves of natural gas fall behind may not be attributed to "more stress on oil than gas" in our work,rather. It is important to encourage the policy of energy resources with emphasis on exploration; and to establish "four new concepts" (new way of thinking, new area, new realm and new depth) which is based on new way of thinking; and above all, it is critical to carefully select areas as regards to the generation and preservation of hydrocarbons. Nearly 20 years, the fact that "theory always lagged behind practice" is due to the continuous confinement of thinking by traditional geoscience concepts as fixistic ideas, pre-war geological knowladge during major oil/gas findings. Taking Tarim and East China Sea as examples, the discussion is centered on whether the two basins are intracratonic basins or remanent back arc basins. The author advocates the concept of back arc basins, and suggests they are most important selected areas in China for the exploration of giant gas fields at the present.

MOLASSE AND GLOBAL TECTONICS

Xia Bangdong, Fang Zhong, LÜ Hongbo, Yu Jinhai

1989, 11(4): 314-319. doi: 10.11781/sysydz198904314

Abstract(831) PDF-CN(768)

Abstract:
Molasse is a sedimentary assemblage which is characteristic of clastic sediments and rapid accumulation on the front of mountain mass. There are three types according to their dynamic backgrounds. divergence(stretching) type, related to the crustal cracking, 2.convergence (compressional) type, related to the collision of lithospheric plates; 3. transformational shearing) type, related to stretch-rifting basin controlled by strike-slip faults. The three types of molasse are genetically related to the models of Welson moun-tain building cycles, on the account of: 1.different types of molasse formed in different stages of Welson cycles; 2.each type of molasse has its own peculiarities, due to the differences in dynamics and kinematics of platesj 3.different mineral products formed in different molasses because of the displacement and enrichment of the elements in the crust.

STRUCTURE OF BACK THRUST BLOCK ON THE NORTH PART OF TARIM BASIN AND HYDROCARBON ACCUMULATION

Tang Liangjie

1989, 11(4): 320-330. doi: 10.11781/sysydz198904320

Abstract(740) PDF-CN(329)

Abstract:
Back thrust block structures reffered to two or more serieses of back thrust faults with opposite inclination in space and in-between blocks, which were dominant in the deformational forms in the vast area of northern part of Tarim basin. Six major structural belts of back thrust blocks were determined in the area, which, according to the structural features of the basement, properties of petrology and the evolution of stress field, can be divided into four types, i.e, compressed back, basal control, strike-slip fracture control and faulted fold thrusts. Compressional environment used to dominate over the tectonics of the area, resulted in back thrust to anti-thrust, with mountain range and rising belt being held between the former, while basin and depressing area being placed in the latter. Major sourced depressions were controlled by anti-thrust, and the rises of back thrust block were favourable for hydrocarbon accumulation. With the basis of tectonic and sedimentary evolutions of Tarim basin, the author considered that eight types of hydrocarbon pools may exist, thus the area is of petroleum prospects.

ON THE LOW VELOCITY LAYER AND CONRAD SURFACE WITHIN THE CRUST OF SOUTHERN PARTS OF CHINA

Hu Dezhao, Yun Lingling, Jiang Yongji, Wang Liangshu, Xu Mingjie

1989, 11(4): 331-340. doi: 10.11781/sysydz198904331

Abstract(603) PDF-CN(374)

Abstract:
Analogies are drawn between the models of crustal structure and velocity distribution on the basis of explosion seismological data of the southern parts of China. Further, the distributions of low velocity layer and Conrad surface (or Conrad discontinuity) within the crust, which are relative to the formation and evolution of tectonics of active continental margins, are discussed. (1) Conrad surface exists extensively in the crust of southern China. The velocity of the longitudinal waves under Conrad surface is about 6.8-7.0km/s. Hence, it make known that medium under Conrad surface consist of basalt, and probably contains a high proportion of ultrabasic rocks. The depth of Conrad surface is 23.4km in Shui county and Huangmei county, Hubei provnce, and becomes gradually intc shallow from the inner parts of Continent to the Coast in Qidony County Jiangsu Province and in Shantou, Guangdong Provinces, it is 14.3km and 22km respectively. (2) The layer of granite with velocities of 6.0-6.3km/s overlaies on Conrad surface. In the bottom of granite layer, there is probably a low velocity layer with thickness of 3-5km. Such as Lower Yangzi area is thus the district in which low velocity layer is possessed. Existence of low velocity layer makes Conrad surface into strong reflective.surface because of higher contrast of wave impedences between low velocity layer and basalt layer. The crust of paleoisland-arc (Wuyi Mountain) expresses to be two layers, nowadays we have not received information about low velocity layer yet. (3) In coast area the average P velocity of crust is about 6.32km/s, which is higher than one of other areas, hence it is considered to be corresponding to big relative thickness of basalt layer or a high proportion of ultrabasic rocks in the crust. This is the first characteristic of transitional crustal structure. The second is the thin crustal thickness, little velocity gradient with depth, low contrast of velocity from layer to layer and lacks low velocity layer generally. For the reasons above, there is the feature which expresses no fullness of crustal evolution and differentiation. Sometimes is difficult to distinguish Conrad surface in these areas. (4) In the area of the eastern parts of Hunan Province, there is the crust of the type with rift valley during Mesozoic-Cenozoic. In which the Conrad surface is clear, and low velocity layer is lack. The depths of Conrad surface and Moho are shallow (16.8km and 28.6km respectively), and the P velocity on the top of mantle is merely 7.86km/s as well.

ON THE ORIGIN, DISTRIBUTIVE PATTERN AND TECTONIC CONTROL OF SILICEOUS ROCKS IN GUFENG AND DALONG FORMATIONS, SOUTH CHINA

Zhu Hongfa, Qin Deyu, Liu Cuizhang

1989, 11(4): 341-348. doi: 10.11781/sysydz198904341

Abstract(884) PDF-CN(492)

Abstract:
The paper discussed about the time and space, distributive pattern and sedimentary characteristics of the radiolarian siliceous rocks in Permian Gufeng and Dalong Formations of south China massif. The accumulation of the siliceous rocks is the result of the convection of hot and cold sea water in the deep falldown faulted subsidence near the equator, which began at the late stage of early Permian when regular fracturing and separation due to south-north tension took place all over the south China massif.

CHARACTERISTICS OF SEDIMENTARY DIAGENESIS FOR RESERVOIR ROCKS OF VOLCANIC CONGLOMERATES IN URHO FORMATION AND RELATIONSHIP WITH HYDROCARBON ACCUMULATION

Zhang Pohu

1989, 11(4): 349-359. doi: 10.11781/sysydz198904349

Abstract(557) PDF-CN(245)

Abstract:
With the discussion on the characteristics of sedimentary diagenesis for conglomerates of peidmont diluvial fan facies on the dry basin margin, the inner relations of the resolution, solution and porosity evolution of authi-genic zeolites with hydrocarbon accumulation in sandstone enriched in volcanic elastics with poor minerals and low textural maturities were explained. The author related the reservoirs for oil fields with conglomeratic rocks in Urho system to minor fissure-pore type (secondary pores). Authigenic zeolites are index minerals for the growing band of secondary pores. In the direction of stream line of palaeo-river channel on the fan waist and the sector, and in the updip of source rocks along Karamay-Urho rift, there are conglomeratic bodies within which good collocation of lithological assemblage of cap-reservoir-trap and ideal structural deposition were formed, which are favou-rable for the formation of commercial oil and gas pools.

1989, 11(4): 360-360. doi: 10.11781/sysydz198904360

Abstract(454) PDF-CN(213)

Abstract:

FAVOURABLE REGION AND CONDITIONS FOR PETROLEUM EXPLORATION OF LOWER PALAEOZOIC IN LESHAN-LONGNUSI PALAEO-UPLIFT AREA

Zhao Xikui

1989, 11(4): 361-368. doi: 10.11781/sysydz198904361

Abstract(595) PDF-CN(342)

Abstract:
With synthetic studies of informations of geology, geophysics and dri-lling, the author thought that Leshan-Longnusi uplift was influenced by several tectonic movements during Caledonian period and was controlled by border faults. It experienced erosion at the end of Guangxi movement, thus became fixed in the form of sedimentary-erosional palaeo-uplift. There are favourable conditions for oil and gas generation in lower palaeozoic of the area, and due to frequent transgressions and regressions, numerical sedimenting gaps and faulting activities, good reservoir rocks and various lithological traps, slight unconformitive traps and burial traps would be found on the southeast of the uplift, which confirmed the area is promissing for petroleum exploration.

STUDY ON BURIAL HISTORY OF THE STRATA IN JIANGHAN BASIN

Luo Xiaorong, Chen Heli, Wang Jiahua, Wang Fengqin

1989, 11(4): 369-378. doi: 10.11781/sysydz198904369

Abstract(682) PDF-CN(354)

Abstract:
The compaction model suitable for Jianghan Basin was established, and different compactive correcting formala were chosen for different types of rocks. Furthermore, the erosional thickness of the strata in the end of late Tertiary was restored with the conversional relation of acoustic time and porosity. Using the method of "backstripping", compactive restoration was progressively made for the strata in each well, and charts respective for plane development, variations in thickness and burial history were also complished. The large amonnt of computation and charting work for the study were done by computer.

A QUEST FOR A NEW PARAMETER IN PETROLEUM EXPLORATION GEOCHEMISTRY

J. W. Smith, T. D. Gilbert, B. D. Batts

1989, 11(4): 379-389. doi: 10.11781/sysydz198904379

Abstract(642) PDF-CN(309)

Abstract:
Primary Australian terreestrially-derived crudes are characterised by high wax and n-alkane contents.These characteristics, as determined by hydrogenation and hydrous pyrolysis, appear to be unrelated to either the chemical or petrographic compositions of Victorian brown coal lithotypes. Furthermore, since relationships between chemical and petrographic composition are obscure, a re-examination of current concepts which relate these established source rock parameters to liquid hydrocarbon generating potentials is warranted. The content of thermally stable, longer chain, n-alkyl components in source rocks is introduced as the critical factor in determining whether these rocks have the potential to generate typical Australian waxy crudes or hydrocarbon gases. Modifications to this general concept are required by the thermal stability of directly substituted longer chain n-alkyl aromatics and hydroaromatics. These appear to be sources of light hydrocarbons and gases, rather than oils. Inherent weaknesses in the experimental techniques of hydrogenation and hydrous pyrolysis have hindered the collection of data, but the concept that n-alkane potential is a critical factor in determining the petroleum-generating potential of immature source rocks is being pursued using techniques modified for the determination of their total heteroatom-bonded n-alkyl contents.

MEASUREMENT OF RESIDUAL HYDROCARBON C₅—C₃₅ IN ROCKS WITH THE METHOD OF COLLECTION ON CAPILLARY COLUMN

Wu Jie, Zhang Yijia

1989, 11(4): 390-393. doi: 10.11781/sysydz198904390

Abstract(592) PDF-CN(213)

Abstract:
In the study, the new technique of hydrocarbon condensation on capillary column was mainly applied, with the quartz inner tube of the injector in chromatographic analyser as sample tube. Residual hydrocarbon C₅-C₃₅ in rock samples were expelled by carrier gas in pneumatolytic chamber at controlled temperature (250℃), which condensated on the head of capillary column, and then programme temperature started for chromatographic analysis. Tests show that the chromatographs and data obtained by the method are practical in identifying oil, gas, and water formations. Meanwhile the method would be used in whole hydroearbon (C₅-C₃₅) analysis.

STUDY ON THE POTENTIAL INFORMATION LOSES AND THE POTENTIAL METHODS IN THE RESOURCES ESTIMATION OF PETROLEUM

Xiong Weigang, Cheng Jinhua

1989, 11(4): 394-400. doi: 10.11781/sysydz198904394

Abstract(522) PDF-CN(200)

Abstract:
This paper is to analyze multiaspects and multiseries in petroleum accessment, and to study the undeterministic knowledge and qualitative laws used by petroleum geologists and to conclude that there is the potential information loses in the processes of thinking and description. It is important to make extensive investigation about the knowledge structures and thinking peculiarities of the experts, and to sum up the qualitative laws and message transmition, which would be helpful for petroleum geology in the extent of qualitative description of mere experience toward more scientific description combined with qualitative and quantitative methods; and which would be useful in introducing new ideas and methods for the development of petroleum geology.

ORDERED COLONY OF FOSSIL SPORE-POLLEN

Tong Guobang, Lin Jinxuan, Chen Zuyin

1989, 11(4): 401-407. doi: 10.11781/sysydz198904401

Abstract(539) PDF-CN(297)

Abstract:
Using three kinds of ordered colonizing methods (optimum decollation, ordered point group, and ordered graph theory), the authors dealt with the zoning problem for spore-pollen. Acurate data were taken from Sukai No.10 well in Hebei. The results show that the three methods are efficient in moldling the evolution of palaeo-vegatation, but each has its peculiarities.

1989 Vol. 11, No. 4

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