2011 Vol. 17, No. 2

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THOUGHTS OF STRATEGIC HYDROCARBON SURVEY ON SUPERIMPOSED BASINS IN CHINA
ZHOU Xin-gui, LIU He-fu, WANG Zong-xiu, ZHANG Lin-yan, HUANG Chen-jun, LI Hui-jun, YAN Xi-li, MA Li-cheng
2011, 17(2): 111-120.
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Abstract:
During the 20th Century, most hydrocarbon reserves were found in Meso-Cenozoic continental rifts and foreland basins in China. While in the 21st Century, the increase points of reserves are transferring to Paleozoic marine carbonates in craton basins. The discoveries of Great Tahe Petroleum Field, and Great Sulige and Puguang Natural Gas Fields indicate the favorable exploration prospect of the Pre-Mesozoic marine carbonate in continental China, which is the essential strategic succeeding scope of hydrocarbon resources exploration in China. However, almost all the hydrocarbon-bearing basins in China are superimposed basins, their special exploration situations have caused the slow increase of hydrocarbon reserves. Seeing from the present hydrocarbon exploration extent, the future work will develop toward two aspects, one is in search of new exploration areas, new scopes, new strata and new types, the other is to speeding up the prospect evaluation of the hydrocarbon resources in new areas of the main hydrocarbon-bearing basins. These two aspects require not only the support of newly developed detecting techniques, more importantly, require the updating of the conception and recognizing, using new theories and new thoughts to break through the recognizing of the complex geological tectonic rules controlling the reserving state of the hydrocarbon in the deep of the superimposed basins and instruct the hydrocarbon exploration and evaluation strategically. Basin analysis → petroleum system → hydrocarbon bearing zone → prospect evaluation is the main rhythm of recognizing and predicting new exploration areas and reservoir potential evaluation in superimposed basins. And the basins with characters of integrality, slight reconstruction, and favorable seal boundary are main targets of new exploration area initial evaluation and strategic district selection. The main exploration direction and research field was discussed at the end of the paper.
GEOLOGICAL CHARACTERISTICS AND EXISTING PROBLEMS OF LARGE GAS FIELDS FOUND RECENTLY IN CHINA
LI Hui-jun, ZHOU Xin-gui, ZHANG Lin-yan
2011, 17(2): 121-131.
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Abstract:
In the beginning of 21st century, natural gas exploration has been developing rapidly in China, with rapidly increasing of proven reserves and more and more newly found large gas fields, mainly located in 6 gas provinces, such as Ordos, Sichuan, Tarim, Qaidam, Songliao and Pearl River Mouth basins. The features of source rocks, reservoirs and traps of the large gas fields are summarized in this paper. It is concluded that the natural gas exploration in China has been developing from monism (oil type gas-generating) theory to plurality (oil-type, coal-derived and inorganic gas-generating) theories. The coal-derived gas becomes the major resource. Large gas fields can form at every stage of source rock evolution, and may distribute in clastic, carbonate and volcanic reservoirs with major in clastic reservoir and little in volcanic reservoir, and mainly structural-stratigraphic and minor structural traps. Based on the discussion of source rock, reservoir, and reservoiring, the 6 gas provinces are suggested to be main territories of natural gas exploration in the early 21st century in China.
DRIVING EFFECT OF THE CRUSTAL STRESS ON PETROLEUM MIGRATION
WANG Lian-jie, SUN Bao-shan, WANG Wei, QIAO Zi-jiang, WANG Hong-cai, SUN Dong-sheng
2011, 17(2): 132-143.
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Abstract:
Oil and gas migration mechanics driven by the crustal stress and constitutional equation and flowing equation are discussed in this paper. Take the Dongying depression of Shengli oil field as an example, this study models the crustal stress and migration potential field at the central zone of the anticline. The results show that the anticline has a well corresponding relation between oil and gas migration, and low stress zone or low potential zone. Most reservoirs occur in low stress zone or low potential zone, indicating the control of crustal stress over the migration and reservoiring of oil and gas. Based on the distribution of crustal stress and migration potential fields, the oil-favored areas predicted in this study will provide scientific guide for oil exploration and development.
POTENTIAL OF THE DEEP OIL-GAS RESERVIOR-FORMING AND EXPLOITATION DIRECTION IN JIZHONG DEPRESSION
ZHANG Lin-yan, FAN Kun, HUANG Chen-jun, MENG Qin-wei, LIU He-fu
2011, 17(2): 144-157.
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Abstract:
The tectonic evolution and superimposing-transformation process of prototype basin are the basic conditions and controlling factors of hydrocarbon accumulation in deep layer of Jizhong depression. Effective hydrocarbon source rocks and preservation conditions of oil and gas are the two key factors for assessment and prediction of different types of hydrocarbon accumulation. The modes of"Paleozoic auto-genous and auto-reserved"and "new bed-generating and old bed-storing buried hill-type"are the most important two potential fields of deep hydrocarbon exploration in Jizhong depression.
EVOLUTION OF PALEOZOIC SEDIMENTATION OF THE JUNGGAR BASIN
KANG Zhi-hong
2011, 17(2): 158-174.
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Abstract:
Junggar basin, located at the northern part of Xinjiang, covers an area of 13 × 104 km2. To date, more than 30 oil and gas fields have been discovered. Many years'research shows that the basin has a pre-South China System crystallized metamorphosed basement. Under the control of Latitudinal and Xiyu systems and NE-trending structural system, Paleozoic sediment widely developed. They are characterized by deep rifting during South China and shallow and deep sea marine deposition of cratonic basin during Ordovician, deep sea deposition of compressed craton basin during Silurian and Devonian, shallow-terrestrial facies sedimentation of intracraton rifting basin during Carboniferous and Permian.
EAST ASIAN MONSOON CHANGES DURING THE HOLOCENE———RECORDS FROM THE SOUTHEASTERN LOESS PLATEAU
XU Chen-xi, HAO Qing-zhen, YANG Shi-ling, ZHAO Shu-jun, ZHOU Xin, GE Jun-yi, XIAO Guo-qiao
2011, 17(2): 175-184.
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Abstract:
The influence of global warming on East Asian Monsoon (EAM) has received intensive concern, and studies on history of EAM could provide important climate analogue in the warmer temperature context.Five loess-paleosol sequences in the southeastern Loess Plateau were sampled to address the history of EAM during the last 20 ka.The intensity of EAM was weak from 18 to 12 ka B.P., increased rapidly in the interval of 12-10 ka B.P, and reached highest points during 10-6 ka B.P., and declined after 6 ka B.P.The proxies of summer monsoon, magnetic susceptibility and paleo-weathering intensity in this study is basically timely consistent with the geological records in different part of EAM region.The insolation of low-latitude northern hemisphere is main control factor of EAM, although changes of EAM lagged variations of insolation of low-latitude northern hemisphere.The lag may be induced by several important boundary conditions (e.g., scales of polar ice sheet in northern high latitudes, sea level changes, interaction between sea and atmosphere in low latitudes) of EAM to insolation and interaction between components of climate system.Additionally, our studies showed that magnetic susceptibility (MS) and maximum FeD/FeT values in same section were not in same position of soil profiles, with lower position of maximum FeD/FeT value than that of MS in relatively strong weathering area.Compared with MS, FeD/FeT ratio can better reflect the intensity of EAM.
RUN-THROUGH ALONG THE ESTUARY OF THE YALONG RIVER-JINGPINGZI REACH OF THE JINSHA RIVER
XU Qin-mian, YANG Da-yuan Yang, GE Zhaoshuai
2011, 17(2): 185-199.
Abstract (199) HTML (104) PDF (1587KB)(12)
Abstract:
Based on the study of the fluvial geomorphology along the Jinsha river from the estuary of Yalongjiang to Jinpingzi by using the methods of sedimentology, geomorphology and chronology, combining with the character of geomorphology and the Cenozoic sediment in this region, we suggest that the development of reach can be divided into four stages, i.e, 1) the river developing on the plateau (7-4.2 Ma), 2) the lake and basin developing on plateau (4.2-1.1 Ma), 3) the ancient water system developing (1.1-0.73 Ma), and 4) the eastward flowing of Jinsha river (0.73 Ma). 7-4.2 Ma, the river developed after planation surface discomposed.The two steep slopes of 1800-2000 m and 1600-1800 m had formed after the river incised planation surface of 2000 m, and the pebble layer underlying the Formation depositing had formed.The ancient Shenyu river run through Jinsha river, entered into the ancient Zhangjiu river, and converged into the Dianchi lake. 4.2-1.1 Ma, Xigeda formation, and Huili and Huidong basins developed.the ancient Cheng river probably converged into Yuanmou basin and began to form Yuanmou formation.These ancient lake in Panzhihua area and Yuanmou did not link.The ancient Shenyu river divagated and flawed eastward, but not run through. 1.1-0.73 Ma, the ancient Shenyu river run through and formed the Jinsha river.Intensive headward erosion took place toward the ancient Cheng river, so the platform did not form in area of 1400 m along Luonong to Jinpingzi of Jinsha river.The ancient Yalong and Cheng rivers converged into Yuanmou basin. 0.73 Ma, the Jinsha river captured the ancient Cheng and Yalong rivers, and run through this area.The developed of Yuanmou formation finished. 0.73 Ma to now, the bank of 1200-1400 m along Jinsha river had formed steep slop under speedy incising of the river.Terraces has began to form since the late middle Pleistocene.
NUMERICAL SIMULATION OF THE STRAIN LOCALIZATION OF A CIRCULAR TUNNEL AT DIFFERENT ELASTIC MODULI
WANG Xue-bin, WANG Wei, PAN Yi-shan
2011, 17(2): 200-210.
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Abstract:
Strain localization processes of a circular tunnel at different elastic moduli are modeled by use of FLAC where the solution is based on equations of motion. In the present calculation, the tunnel is excavated after the model is loaded to reach a static equilibrium state. The numerical results show that at low and moderate elastic moduli, the movement of the surrounding rock toward the center of the tunnel is apparent once the tunnel is excavated, generating many fracture bands, V-shaped notches and shorter shear bands. The analyses and numerical simulations based on static equilibrium, which may yield unsafe solutions, cannot be applied to these cases. When the elastic modulus is lower, the capacity of the surrounding rock maintaining uniform circumferential or loop deformation is worse, and the axially-symmetrical deformation mode is easier to be broken and broken earlier. Although the failed number of elements is not monotonic with an increase of the elastic modulus, in general, as the elastic modulus is increased, the failed number of elements decreases, and the maximum shear strain increment is decreased monotonically and rapidly.

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