1996 Vol. 2, No. 2

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CRUSTAL STRESS AND OIL AND GAS MIGRATION
Wang Lianjie, Zhang Lirong, Yuan Jiayin, Wang Wei
1996, 2(2): 3-10.
Abstract (134) PDF (450KB)(15)
Abstract:
In this paper are discussed the deformation of rock and the pore pressure under the action of crustal stress. The differential equation and finite element formula for fluid flow in a porous rock are described. The oil migration potentials for Liaohe oil field in North China are calculated based on crustal stress measurements and stress field modelling. The results may provide a basis for oil and gas exploration and development.
APPLICATION OF ACOUSTIC EMISSION TECHNIQUE IN DETERMINATION OF FOSSIL AND PRESENT-DAYSTRESSES IN OIL FIELDS
Sun Baoshan, Ding Yuanchen, Shao Zhaogang, Zhou Xingui, Wang Xihai, Zhang Daquan
1996, 2(2): 11-17.
Abstract (137) PDF (463KB)(16)
Abstract:
Fossil and present-day rock stresses in the Tabei, Zhongyuan, and the Keerkang Oil Fields have been measured using acoustic emission (AE) technique. It has been found by an analysis of the relationship between known oil/gas distribution and stress state that thepresent sreatest principal stress in the Tabei Oil Field is below the average of the country, and that the stress in producing wells is lower than that in the non-producing wells. Therefore, the magnitude of the current stress may serve as a criterion for distinguishing oilbearing structures, for choosing the parameters of pumping pressure, and for the division of production horizons.
PALEOSTRESS IN NORTHERN TARIM OIL FIELD ESTIMATED BY AE
Ding Yuanchen, Sun Baoshen, Wang Xihai, Shao Zhaogang, Zhou Xingui
1996, 2(2): 18-25.
Abstract (127) PDF (566KB)(19)
Abstract:
After a feasibility study of the application of AE method to the measurement of paleostress emphasis is placed on the discussion of the methods used in paleostress measurements and current stress measurements by AE in the paper.
Paleostress measurements by AE in Northern Tarim Oil Field show two-episodes of tectonic movements in the Himalayan movement three in the Yanshannian movement, and that the Himalayan was the most dominant.
STUDY OF TECTONIC STRESS CONTROL OF OIL AND GAS MIGRATION IN SECTIONS
Feng Xiangyang, Shen Shumin, Liu Wenying
1996, 2(2): 26-30.
Abstract (117) PDF (346KB)(15)
Abstract:
The formation, migration and accumulation of oil and gas forms a most important subject in petroleum geology. The oil and gas accumulation is thought to be a long continued process in the past geologic time. It seems to the authors that the action of tectonic stress may create the most important conditions to drive the migration and accumulation of oil and gas. The states of migration potentials have been simulated and calculated for a few typical sections in the northern Tarim Basin. The results obtained show that the low stress field corresponds to the areas of low migration potentials, where oil and gas pools occur.
STATISTIC ANALYSIS OF SIMILARITIES BETWEEN FENWEI AND BAIKAL RIFT SYSTEMS
Wu Zhenghan, Cui Shengqin, Wang Lianqing, Ma Yinshen
1996, 2(2): 31-40.
Abstract (118) PDF (653KB)(13)
Abstract:
Similarity factors are calculated from both field observations and remote sensing image interpretations for analyzing tectonic similarities between the Fenwei and Balkal rift systems in 7 different aspects by means of statistic methods on the basis of abundant geologic and geophysic data. The similarity factor is 0.999 for their geometry, 0.923 for the sedimentation rate at various stages of rifting, 0.635 for the total subsidence in the Cenozoic, 0.794 for fault activities during rifting, 0.813 for seismic activities and 0.766 for the shape of the Moho(between Fenwei and Balkal rift systems). Further statistic check (student-t check)shows that there is remarkable similarity between the two in 3-demensional structure framework, and historical and present activities.
An analysis of the results obtained from GPS survey and stress measurements suggests that the high similarity between the Fenwei and Balkal rift systems may be dynamically related to the large scale S-shaped extension originating from the unequal westward motion of the two N-S oriented adjoining terrains in the east Asian continent.
ACTIVITIES OF FAULTS AS DETERMINED FROM THE MICROSTRUCTURAL FEATURES OF THE CLAY GOUGE
Zhang Bingliang, Fang Zhongjing, Li Jianguo, Cui Siping
1996, 2(2): 41-46.
Abstract (295) PDF (542KB)(19)
Abstract:
Fault gouges rich in clay minerals are widely found in natural faults. The history of the activity of a fault is often recorded in the soft and easily deformed fault gouges. In the paper, a modeling of the stick-slip and creep-slip of faults with natural fault gouges is made.The nicrostructural features so produced is compared with those of natural fault gouges. An integrated analysis with the macro-seismogelogic data suggests a definite relationship between the microstructural features of fault gouges and the stick-slip or creep-slip of faults.
RESEARCH ON RELATION BETWEEN MICROSTRUCTURES AND MACROSTRUCTURES OF DEFORMED CARBONATE ROCKS
Liu Wencan, Li Dongxu, Zhang Da
1996, 2(2): 47-54.
Abstract (134) PDF (587KB)(18)
Abstract:
Although experimental researches on microfabrics of deformed carbonate rocks and their preferred orientations have been well developed, there still are difficulties in their application to the explanation of the complicated natural structural deformations. The principal aims of this study are:(1) to compare deformation behaviour and micro fabric characteristics of the deformed carbonate rocks at shallow(Tongling area) and intermediate-deep levels (Bet Huaiyang area); (2) to improve our knowledge of the microstructures of deformed carbonate rocks by relating to the results of microfabric studies. Based on the microstructures of the marbles in the contact zone of granitic intrusives, two types of emplacement mechanism of granites are identified in the Tongling area, Auhui. A study of the calcite mylonites in the ductile shear zone of Bet Huaiyang of north Da Bieshan mountain was also made.
TECTONIC SYSTEM ANALYSIS OF THE FENGHUANG SHAN INTRUSIVE AND ITS EMPLACEMENT
Li Dongxu, Zhang Da, Liu Wengcan, Du Zitu
1996, 2(2): 55-65.
Abstract (138) PDF (727KB)(14)
Abstract:
In this paper, a discussing is made of the location of the Fenghuanshan pluton, in the regional tectonic regime, tectonic evolution before and after the emplacement and the dynamic conditions for the magma emplacement. The foliations and lineations both in the pluton and in the contact zone are systematically studied by measuring their magnetic fabrics, microstructures, strained inclusions and X-ray analysis of rock fabrics. As a result, it leads to the conclusion that there occurred not only dilatation due to the emplacement but also rotation of the intrusive in the late stage of the emplacement, which was controlled by the NNE sinistralshear.
A NUMERICAL ANALYSIS OF THE TECTONIC EVOLUTION OF THE TANLU FAULT ZONE
Wu Hongling, Chen Bolin, Wang Xiaofeng, Wang Wei
1996, 2(2): 66-74.
Abstract (127) PDF (657KB)(21)
Abstract:
In this paper a numerical modeling of the stress and strain fields as well as the displacement rates of the Tanlu fault zone in the principal periods of its tectonic evolution is made using the Finit Element Method for a Newtonian liquid. The causative dynamic origin, the boundary forces and the effect of rock properties on the stress fields are discussed and analysed.
This is aimed at further explaining that the repeated tectonic activity of the zone in its evolution is closely related to the motion of the North China platform.Lower Yangtze massif, the Pasific plate and the Philippine plate. Meanwhile, the geothermal anomaly accompaning the tectonic movement may also constitute one of the important dynamic factors to form the respective stress field, especially the tensile one of the fault zone.
NUMERICAL TREATMENT OF MEASURING GROUND STRESS BY THE BOREHOLE DEFORMATION METHOD USING PRE-PRESSED PROBES OF CONTACT TYPE
Zhang Fan, Pan Lizhou
1996, 2(2): 75-82.
Abstract (167) PDF (474KB)(19)
Abstract:
In current measurement of ground stress by the borehole deformation method using pre-pressed probes of contact type, the calibration of probes have been made by Hast's method and by mid-confining pressure method. Both methods have some defects in the derivation of reduced displacements. In 1984, Pan clarified it and gave the accurate formulas (See Ref.[1]). However. the formulas can not be used in practical measurements unless the parameters involved in them are numerically expressed. This paper has worked out the numerical values of the parameters through calculation with Finite Element Method. The error of traditional formulas have been estimated. By analyzing the numerical results, the majorfactors which effect the accuracy of reduced displacements as defined in Ref.[1] have beenrevealed.
NUMERICAL SIMULATION OF STRUCTURAL CONTROL OF GOLD DEPOSITS IN THE XIAODONGYANGHE AREA OF LIAONING PROVINCE
Jiang Xirong, Zhao Yinzhen, Wang Lianjie
1996, 2(2): 83-89.
Abstract (161) PDF (459KB)(14)
Abstract:
This paper studies the geological structure in the Xiaodongyanghe area, Hebei, and proposes a new method for forecasting blind gold ore bodies by means of numerical simulation.
On the basis of intensive field work, we distinguished the synmetallogenic structural system and the main metallogenic stages, leaving out the structures and geologic bodies which formed after the main metallogenic stage, and leaving in those formed during and before the main metallogenic stage for establishing the experimental model. The model experiment was conducted using finite element method to study the stress field and the stress drop which occurred before and after the synmellogenic deformation. The stress concentrations overlapping the high stress drops are regarded as forecast gold targets. The target Predicted were found to well agree with the known ore spots as well as the geochemical anomalies. Altogether ten drill holes and a drift were designed for verification.
MODELING THE MIGRATION AND ACCUMULATION OF ORE-FORMING ELEMENTS UNDER HIGH TEMPERATURES AND PRESSURES
Chen Zhengle, Zhou Xianqiang, Yang Nong, Chen Xuanhua
1996, 2(2): 90-93.
Abstract (111) PDF (287KB)(17)
Abstract:
Modelling of the migration and accumulation of ore-forming elements in rocks deformed by application of stresses are conducted at different temperatures and pressures. This is found to differ for different elements at the same temperatures and pressures and for the same element at different temperatures and pressures. And it is shown that the action of stress plays an important role in the formation of many metallic mineral deposits and their zoning.
SER DATING OF THE F1 AND F7 FAULTS IN THE ZHANGHEWAN RESERVOIR DISTRICT, HEBEI
Zhang Shukun, Sun Jiashu, Wang Xihai, Feng Yanwei
1996, 2(2): 94-96.
Abstract (109) PDF (206KB)(16)
Abstract:
ESR method was nas used for dating the F1 and F7 faults in Zhanghewan resovoir distict, Hebeiprovince. The results are comparable with that obtained by TL dating before.This indicaes the feasiblity of the method for dating Quaternary faults. As the measured age values are greater than the characteristicage value of an active fault, 1.1×104, the faults F1 and F7 do not belong to active faults. This conclusion is supported by other geological observations as well.