2010 Vol. 16, No. 3

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REVIEW ON THE HISTORY, EXPERIENCES AND LESSONS FROM PETROLEUM DISCOVERY IN ORDOS BASIN (Ⅰ):IMPLICATIONS OF THE TALK BY LI SIGUANG IN 1968
SUN Zhao-cai
2010, 16(3): 223-236.
Abstract (240) HTML (274) PDF (1364KB)(10)
Abstract:
The history of oil and gas exploration in Ordos Basin is long.Before the founding of new China, few of oil and gas surveying has been done in the basin.A lot of systematic petroleum geological survey and exploration began after the founding of new China.During the 14 years from 1955 to 1968, a large number of geological data have been accumulated, but neither commercial petroleum has been found, nor definite prospects or targets have been determined.Since 1969, according to the instruction of "return to Ordos Basin", the petroleum exploration came back to Ordos Basin from Weihe and Hetao Graben.Six Jurassic oil fields in Qingyang, Huachi and Wuqi, five large oil fields over hundred-million tons in northern Yan'an-Wuqi, and a large Ordovician gas field in centre of the basin had discovered successively.History of petroleum exploration in Ordos Basin showed that oil and gas discovery comes from geologist's idea.We should attach great importance to basic geologic survey.Application of geologic surveying methods and exploration procedure must have pertinence.Neither can simplify the complicated issues, nor can generally approach the special problems.The exploration areas must be determined according to the actual situation.
FROM PETROLEUM DISCOVERY IN ORDOS BASIN (Ⅱ):FROM BASIN STYLES TO THE PROSPECTS OF PETROLEUM EXPLORATION IN ORDOS BASIN
SUN Zhao-cai
2010, 16(3): 237-245.
Abstract (160) HTML (82) PDF (1133KB)(9)
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Ordos Basin is one of the earliest areas to find petroleum in China.For a long time, few of petroleum has been discovered in the basin because of both its structural characteristics and ultra low porosity and permeability in Triassic Yanchang Formation.As a result, the explorationists were lost in a dilemma with "oil shows in every hole, but no oil flow in all holes".In recent 20 years, along with the concept of oil exploration in foreland basins, remarkable breakthrough has been made in the several basins in western China.The study for foreland basins in western China is still at an early stage.We should further researched on the generalities of foreland basins in the future.
GENERAL CHARACTERISTICS OF THE MESOZOIC-CENOZOIC TECTONICS IN EASTERN CHINA
LIN Zong-man
2010, 16(3): 246-259.
Abstract (189) HTML (103) PDF (2339KB)(34)
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In this paper, the author divided the Mesozoic-Cenozoic in eastern China into six tectonic-sedimentary cycles.The movement occurred in the Late Jurassic was a style-changed movement.In addition, the author further divided the tectonic deformation history of this region into two deformation phases (T-J) and one transitional phase (K1).During the two deformation phases, two types of basins and two tectonic systems developed.There exists extensive tectonic unconformity, which shows that the duel structures are basic characteristics of Mesozoic-Cenozoic geotectonics in eastern China.
ANALYSIS ON FRACTURE POTENTIAL FOR DIFFERENT TYPES OF ROCKS IN ARCHEAN BURIED HILL: A CASE STUDY OF LIAOHE WESTERN SAG
CAI Guo-gang, TONG Heng-mao
2010, 16(3): 260-270.
Abstract (196) HTML (183) PDF (910KB)(6)
Abstract:
The Archean crystallization metamorphic rocks are important reservoir rock types in buried hill, and fracture developmental potential for different types of Archean metamorphic rocks have not been yet clearly recognized.Based on a large number of rock mechanics experiments, core fracture observation, imaging logging data, and oil field production practices, the fracture developmental potential for different types of Archean metamorphic rocks has been analyzed.Rock mechanics test results show that the mechanical properties are changable in different Archean lithology, e.g., the brittleness coefficient generally decreases with increase of dark minerals.In addition, rock mechanics parameters are closely related to the loading direction in gneiss which bear well-developed oriented structure.The brittleness coefficient fb gets greater when the angle between gneissosity and the loading direction changes from less than 45° into greater than 45°.A large number of oil production practice data show that shear fracture is more often seen in the gneiss with oriented structure, while tension fracture in the granulite without oriented structure.According to the comprehensive analysis, the development potential of shear fracture in different rocks can be arranged as:gneiss class > mixed granite class > amphibolite; while that of tension fracture as: mixed granite class, light granulite > gneiss class > amphibolite.
STRUCTURAL DIVISION OF MARINE MESOZOIC-PALEOZOIC IN LOWER YANGTZE REGION AND ITS SIGNIFICANCE FOR PETROLEUM EXPLORATION TARGETS
LI Ya-hui, DUAN Hong-liang, TAN Ying
2010, 16(3): 271-280.
Abstract (115) HTML (88) PDF (1127KB)(8)
Abstract:
According to the basement features, structural deformation, depth of the Indo-surface and characteristics of depocenters and subsidence centers, the Lower Yangtze region has been divided into 5 first-order geological structure zones and 17 second-order zones mainly In terms of structural stability, effective preservation, and late-stage hydrocarbon generation, the second-order zones have been assessed.The Lower Paleozoic favorable zones for exploration include the late-stage uplifting stable region in centeral part of southern Yellow Sea (Ⅰ2), the late-stage subsiding deep thrust region in Jiangdu-Dongtai-southern part of the South Yellow Sea (Ⅰ3), the late-stage subsiding deep thrust region in Taixing-Haian (Ⅱ1), the late-stage subsiding lower nappe region in Nantong-south part of South Yellow Sea (Ⅱ2), and the late-stage subsiding lower nappe region around the Taihu Lake (Ⅱ4); the Upper Paleozoic favorable zones for exploration include, the latestage subsiding deep thrust region in North Yellow Sea (Ⅰ1), the late-stage subsiding deep thrust region in Jiangdu-Dongtai-south part of South Yellow Sea, (Ⅰ3), the late-stage subsiding deep Lower Paleozoic-involved thrust region in Binhai-Dafeng (Ⅰ4), the late-stage subsiding deep thrust region in Taixing-Haian (Ⅱ1); the most favorable zones for Indo-surface exploration include the late-stage subsiding deep thrust region in North Yellow Sea (Ⅰ1), the late-stage subsiding deep Lower Paleozoic-involved thrust region in Binhai-Dafeng (Ⅰ4), the late-stage subsiding deep Lower Paleozoic-involved thrust region in Jinhu-Gaoyou (Ⅰ5), and the late-stage subsiding deep thrust region in Taixing-Haian (Ⅱ1).
SEDIMENTARY SYSTEM FOR THE SECOND MEMBER OF SHAHEJIE FORMATION, BONAN SAG
LI Li-bo, WU Fa-dong, JIANG Da-wei, PENG Gang
2010, 16(3): 281-293.
Abstract (169) HTML (91) PDF (1477KB)(5)
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According to the theories of sequence stratigraphy, with the object of understanding genetic facies of the well cores, a study of fan delta sedimentary system has been made to discuss the main characteristics of reservoir rocks based on subdivision and correlation of the second member of Shahejie Formation.The results suggested that this member is well developed in the interior of Bonan sag, but lacks its lower part in the marginal parts because of uplift and insufficient supply source.In the study area, the second member of Shahejie Formation is formed in shallow-water lake and composed of fan delta deposits.In western and northern parts of the area, it occurs as smallscale near-shore subaqueous fan deposits.The reservoir rocks in the member are mainly siltstone, sandstone and pebbly sandstone indicative of fan-delta front edge.In southeast part of the area, the reservoir displays favorable physical properties and is closely related with oil and gas accumulation.
GEOLOGIC CHARACTER AND EVOLUTION OF THE ACCOMMODATION ZONE IN THE JIZHONG DEPRESSION
LAO Hai-gang, WU Kong-you, CHEN Qing-hua
2010, 16(3): 294-309.
Abstract (242) HTML (117) PDF (1761KB)(12)
Abstract:
According to the accommodation structure theory, in combination with the analysis on geological map and paleo-fall, five accommodation zones and seven structure forms have be recognized in Jizhong Depression.The synthetic approaching-type accommodation zone can occur as nose structure, horst and transform fault, e.g., it occurs as nose structure exist in fault segment joints, but as coexistence of transform fault and transverse salient in the joints of faults controlling depression.The synthetic overlap-type accommodation zone transfers strain in the form of trend slope.The synthetic collateral-type accommodation zone reforms the Hexiwu buried hill belt in the form of warping.The convergent collateral-type accommodation zone develops in Yanling area in the form of low uplift.The convergent approaching-type accommodation zone, typically observed in the Maozhou hub zone, forms double-layer deformation system, which comprises a bottom of fault bifurcation oblique slip and an upper of wide cup zone.In the geological evolution, a relation of ebb and flow can be obserbed among the activity intensities of the faults which play the part of accommodation.With the effect and reformation of accommodation zone, a migration path for oil and gas, with ancient structural ridge as dominant migration pathway, can be formed on the slop of buried hill.
RELATIONSHIP BETWEEN STRUCTURAL STRESS FIELD AND DEVELOPMENT OF FRACTURES IN FORELAND THRUST BELT
SONG Yong, FENG Jian-wei, DAI Jun-sheng, LIU Xu, BIAN Bao-li, LI Ming
2010, 16(3): 310-324.
Abstract (294) HTML (100) PDF (1193KB)(11)
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Aiming at the difficulties in predicting the fractures in strata in thrust belt, by selecting the fracture criteria suitable for the Wuxia foreland thrust belts under study, this paper has defined a relation of mechanical parameters with the current stress field and the paleostress field during the formation of the fractures, Based on the study on the Permian reservoir fracture, we have finished a quantitative calculation for fracture aperture and other parameters and drawn a map of distribution of each formation.The results show that structural stress and lithology paly a crucial part in development of the fractures; generally the fractures with greater fractural parameters are relatively easy to form in the areas with evidently different structural stresses; and near the high part of principal faults more fractures are developed, and the strata are more tuffaceous and argillaceous, fine-grained, with more fractures developed.