2005 Vol. 27, No. 2

Display Method:
“HYDROCARBON ENRICHMENT IN FORELANDS”AND EXPLORATION DIRECTION FOR LARGE OIL AND GAS FIELDS-REDISCUSSION ON HYDROCARBON ENRICHMENT IN FORELANDS
Li Pilong
2005, 27(2): 101-103. doi: 10.11781/sysydz200502101
Abstract:
As one of areas for hydrocarbon exploration, forelands have petroleum geological conditions for hydrocarbon enrichment and accumulation. They are the most practical areas for "secondary hydrocarbon-generation", "secondary pool-formation" and "a second time adjustment and late-stage pool-formation", and they are also the most favorable areas for "rapid pool-formation" and "many times adjustment and recent pool-formation". The tectonic styles of forelands are varied. There exist certain mutual controlling and restricting relations between the enrichment and accumulation of hydrocarbon with different tectonic styles and petroleum geologicl factors. The mixed "compressional-strike slip" tectonic style is more favorable to hydrocarbon enrichment and the formation of large oil and gas fields accumulating in late (or recent)stages. On the other hand, the tilted tectonic style in long-term uplifting areas is more favorable to the preservation of "early (primary) stage oil and gas pools".
TWO PALEO-OCEANS IN THE LATE PALEOZOIC AND THEIR CONTROL TO BASINS IN CHINA
Gao Changlin, Ye Deliao, Huang Zeguang, Liu Guangxiang, Ji Rangshou, Qin Deyu
2005, 27(2): 104-110. doi: 10.11781/sysydz200502104
Abstract:
Two important geologic events took place in China during the Late Paleozoic: the Ancient Middle Asian Ocean underrode and consumed during the Late Devonian to Early Carboniferous, and the Xing-Meng orogenic belt combined the Ancient China and the Siberia Plates into the giant Ancient Asian Plate; the Palaeotethys expanded and the SES edge of ancient Asia detached. 3 types of prototype basin were generated in the Ancient Asian Craton from the Late Peleozoic to Triassic: 1)convergent edge basin, mainly in the southern edge of D(2+3)-C North Plate, one side or both sides of the D-C central orogenic belt, and the southern of P2-T South China Plate; 2)detached edge basin, distributed in the southern and northwestern edge of South China Plate and the southern edge of Tarim basin; 3)inner Craton basin, including inner platform depression, fault-depression or fault, rift and aulacogen from remaining basin.
PROTO-SEDIMENT BASIN TYPES AND TECTONIC EVOLUTION IN THE SOUTHERN EDGE OF NORTH CHINA PLATE
Yu Hezhong, Lu Fuliang, Guo Qingxin, Lü Wenzhong, Wu Jinyun, Han Shouhua
2005, 27(2): 111-117. doi: 10.11781/sysydz200502111
Abstract(1310) PDF-CN(637)
Abstract:
Type of ancestral basin in the Southern North China plate is controlled by tectonic evolution. The North China and Yangtze plates changed from open to close during the Paleozoic era to Middle Triassic epoch. The southern edge of North China Plate changed from passive continental margin(Z-O2) to uplift denude(O3-C1), then to foreland flysch basin(C2-P2).The two plates collided and formed the famous Central Orogenic Belt(T3-J1) and coupled molasses sedimentary basin. From the Middle Jurassic to Early Cretaceous, postkinematic inner-orogenic belt subsided while orogenic belt margin detached, forming complex structures of backlimb thrust and front detachment. Detached fault-depression and down-warping basin came into being, controlled by activities of the Palaeo-Pacific plate and Pacific plate in late epoch. Different type of ancestral basin in different time is important for oil-gas exploration.
FORMATION SETTINGS OF THE MESOZOIC AND CENOZOIC BASINS IN THE SOUTHERN PART OF NORTH CHINA
Lü Junxiang, Huang Zeguang, Zhai Changbo
2005, 27(2): 118-123. doi: 10.11781/sysydz200502118
Abstract:
Formation and evolution of basins in the southern part of North China are mainly controlled by activities of the Qinling-Dabie orogenic belt and the Tanlu fracture belt. Based on analysis of volcanic tectonic settings generated in Mesozoic, regional tectonic evolution characteristics during the Indosinian and Yanshan epochs, and stress field, it is proposed that, the southern part of North China area has experienced compression, strike-slip, expansion and weak extrusion, resulting in the juxtaposition and superposition of basin prototypes.
TECTONIC EVOLUTION OF THE SOUTH YELLOW SEA SINCE THE PALEOZOIC
Yao Yongjian, Xia Bin, Feng Zhiqiang, Wang Liaoliang, Xu Xing
2005, 27(2): 124-128. doi: 10.11781/sysydz200502124
Abstract:
The South Yellow Sea is a polycycle basin surperimposition forming on the pre-Sinian metamorphic rock basement of the Lower Yangtze Platform. The complex geotectonic features occur in the sea, and the proto-type basins can not been found after multiple-period tectonic reformation. Based on the data of new seismic profiles, wells, adjacent lands and the research of different periods dynamic systems, tectonic movements as well as deformation characteristics, the tectonic evolution of the South Yellow Sea can be divided into four principal stages: the Paleozoic-Triassic marine basin, the Mesozoic land basin, the Paleocene-Middle Miocene fault basin and regional depression since the Late Miocene. The south margin of the Lower Yangtze Platform linked with the South China Folded Belt during the Caledonian Movement, and the stable and wide Post-Caledonian Platform was formed. The Sulu Orogenic Zone raised between the Lower Yangtze Platform and the southeast margin of the North China Platform during the Indosinian-Early Yangshanian Movement. The Huangbei Foreland Basin was formed between the south side of the Orogenic Zone and the Central Uplift, and the Huangnan Fault Basin on the south of the Central Uplift.
FEATURES OF FLUID MIGRATION AND HYDROCARBON ACCUMULATION IN THE ACTIVE AND INTERMITTENT STAGES OF FAULT EPISODIC ACTIVITIES
Yu Cuiling, Zeng Jianhui
2005, 27(2): 129-133. doi: 10.11781/sysydz200502129
Abstract:
Periodical episodic activities of faults lead to the periodical episodic movement of fluid migration along fault zones. One episodic activity of a fault consists of two stages: the active stage and the intermittent stage. During the active stage, fluid in deep formation migrates vertically along fault zones and then flows laterally in reservoirs under the power of superpressure or seismic pump, and the fluid migrates in the mixed phase states of oil, gas and water. In the intermittent stage, when fault zones are still open and pressure in leading systems has not got to balance, fluid flows adjustively in fault zones and bilateral reservoirs until the pressure is balanced. When faults close completely, fluid flow ceases. So the transport ability of fault zones is strong in the active stage but weak in the intermittent stage. In the episodic active stage, complex hydrocarbon-accumulating zones with multiple oil-bearing measures, which contain the same formation with different oil sources or different formations with the same oil source, will form adjacent to fault zones. In the episodic intermittent stage, the redistributed oil and gas pools in leading systems lead to the intact vertical series of undersaturated oil pools, high-saturated oil pools, oil and gas pools and pure gas pools around fault zones.
ANALYSIS OF EPISODIC POOL FORMATION IN DONGLING AREA, THE SONGLIAO BASIN
Guo Shaobin
2005, 27(2): 134-137. doi: 10.11781/sysydz200502134
Abstract:
Primary organic inclusions in diagenetic minerals are widely used to determine the time of oil reservoir formation, oil expulsion, migration as well as hydrocarbon maturity. It is effective to indicate the timing and phases of hydrocarbons by integrating the analyses of the homogenization temperature and compositions of organic inclusions in diagenetic minerals with detailed modelling of paleotemperature and time-temperature burial history. As a case study, the authors examined the homogenization temperature and composition of organic inclusions in Dongling area, the Songliao Basin. The pool-forming history of reservoirs in this area we reconstructed by modelling burial and thermal history and analyzing homogenization temperature. The results indicated that there were at least three episodes of hydrocarbon pool formation and migration in the Early Cretaceous, occurring at about 85.8, 78.6 and 66 Ma respectively. The further compositional analysis of organic inclusions by Raman laser spectrum microprobe was consistent with the results from homogenization temperature analysis. Organic inclusion abundance and organic component content were lower, and the area underwent structure destruction in the late stages. These are unfavorable for present-day petroleum exploration.
THE CENOZOIC EVOLUTION AND PETROLEUM RESPONSE ESTIMATION IN THE QUTANG-LIBAO REGION OF THE HAIAN DEPRESSION, THE NORTH JIANGSU BASIN
Zhu Jianhui, Jiang Xingge, Xu Xuhui, Zhang Yuchang
2005, 27(2): 138-143. doi: 10.11781/sysydz200502138
Abstract:
The Qutang-Libao region lies in the south of Haian depression, the north Jiangsu.It is a Neozoic depression controlled by NE-and EW-oriented big faults. Periodic fault activities controlled deposition and sediment in the Qutang subdepression in the north and the Haibei subdepression in the south, resulting in 3 combinations of hydrocarbon generation, reservation and capping. Primary hydrocarbon terrane including the Taizhou Fm. and the Member 1 and 3 of Funing Fm. came into threshold of oil yielding after the Sanduo Fm.subsided and then entered peak era when the Member 2 of Yanchen Fm.subsided. It is estimated applying the TSM basin modelling that, Votal hydrocarbon yielding of the Qutang subdepression is about 230.54×106t,and that of the Haibei subdepression is about 149.21×106t.The hydrocarbon expelling period took place during depression development, accounting for 95% of the total discharging amout (88.837×106t).Fractures of different level generated in different period affect hydrocarbon scale.Fault belt of multiple faults near deep depression is the main target for exploration.Nose uplift in exterior slope and fault step belt may be favorable accumulation zone.
POOL-FORMING FEATURES OF OLD OIL FIELDS IN THE EAST CHINA
Tan Caiping, Liu Cuirong, Zhou Xinke, Liu Bin, Zhou Xiaojin, Cheng Xiaoling, Li Haihua
2005, 27(2): 144-150. doi: 10.11781/sysydz200502144
Abstract:
Based on analysis of source rock maturity stage, fluid-inclusions and history simulation of sedimental basin setting and thermal evolution (transient thermal flow model), it is discussed in this paper the distribution patterns of key source beds, reservoir and cap rock characteristics and their matching relationship during basin evolution period in the old fields of East China.The source-reservoir-caprock system distribution and the matching features of oil-and-gas migration, accumulation and main trap forming time and the petroleum enrichment characteristics have also been discussed.
EXPLORATION DIRECTION OF LARGE CARBONATE ROCK OIL AND GAS POOLS IN THE EAST OF THE TARIM BASIN
Liang Shengzheng, Kong Liping, Liang Yongmei, Song Xiaoying
2005, 27(2): 151-157. doi: 10.11781/sysydz200502151
Abstract:
The east of the Tarim Basin, which possesses a stratigraphic sequence of carbonate rocks in the lower part and clastic rocks in the upper part, has a tectonic development history of uplifting in the ancient stage, down-warping in the middle and stabilizing in the late. The Upper Proterozoic-Lower Paleozoic source rocks contain high abundance organic matter, and are better oil and gas resources. They have the advantages of forming large carbonate rock oil and gas pools, including good source-reservoir-caprock assemblages, and large anticline structures and stratigraphic traps. The Qunke Low Convex (called the Kongquehe Slope) in the north and the Tadong and the Luonan low convexes in the south, which are the east extension of the Tabei Uplift and the Tazhong Uplift and higher than the Tabei and Tazhong uplifts,are the direction of oil and gas migration. It was suggested that the further survey should be enforced in the Cambrian limestone anticlinal pools and the Sinian dolomite unconformity pools in the Tadong and the Qunke low convexes.
GEOLOGIC FEATURE AND MIGRATION-ACCUMULATION MECHANISM OF THE MAHAI GAS FIELD, THE QAIDAM BASIN
Liu Yuan, Luo Qun, Pang Xiongqi, Li Zilong
2005, 27(2): 158-163. doi: 10.11781/sysydz200502158
Abstract:
The Mahai gas field includes Mahai shallow layer tectonic gas accumulation and Mahai deep layer stratigraphic overlap gas accumulation with different accumulation types, forming periods, as well as main controlling forces. Gas of the two accumulations both come from the Yibei depression 40-50 km to the Mahai gas field. Fault and unconformity are the most important paths for vertical and lateral migration. The formation and evolution as well as dynamic features are different, resulting in two kinds of gas migration-accumulation mechanism models: 1)"tectonic stress drives gas to migrate along fault-conduction and forms secondary gas accumulation" for the Mahai shallow layer tectonic gas accumulation; 2)"buoyancy drives gas to migrate along fault-unconformity and forms primary gas accumulation" for the Mahai deep layer stratigraphic overlap gas accumulation. Favorable gas accumulation regions of the Qaidam basin are forecasted according to the two mechanism models.
SIGNIFICANCE OF OIL SHALE IN THE EOGENE PETROLEUM RESOURCE EVALUATION OF THE JIYANG DEPRESSION, THE BOHAIWAN BASIN
Luo Jiaqiang, Sheng Zhongmin
2005, 27(2): 164-168. doi: 10.11781/sysydz200502164
Abstract:
It was found in recent years that the formation of hundred million ton scale of oilfields was related to the oil shale of the lower sub-member of the 3rd member of the Shahejie Formation (for short Es3)in the Jiyang Depression on the bases of the detailed correlation of oil and gas to source rocks, and the important contribution of oil shale to hydrocarbons was understood again. There is a great amount of oil shale containing Botryococcus braunii and Coccolithophorida these algae-enriched layers of great hydrocarbon potential in the upper sub-member of Es4 and Es3 of the Jiyang Depression, it is an important contributor to hydrocarbons. Lateral migration was the important mode of primary hydrocarbon migration in oil shale. The existence of book structure, especially when oil shale cut by faults, was probably the main cause of the great enhancement of hydrocarbon discharge efficiency. Oil shale was separately basin-modelled and calculated in the Eogene petroleum resource evaluation of the Jiyang Depression, and its total amount resources was 13.8×108t.
EFFECTS OF ABNORMAL HIGH-PRESSURE ON THE HYDROCARBON-FORMING MECHANISM OF SOURCE ROCKS AND THE MIGRATION AND ACCUMULATION OF OIL AND GAS
Zhuo Qingong
2005, 27(2): 169-172. doi: 10.11781/sysydz200502169
Abstract:
The abnormal high-pressure of fluid controls the hydrocarbon-forming mechanism of source rocks and the migration and accumulation of oil and gas. Overpressure promoted the hydrocarbon generation of sulphur-rich source rocks in the upper sub-member of Es4; by contraries, it restrained the hydrocarbon generation of sulphur-poor source rocks in the middle and lower sub-members of Es3. Thus, in the former situation, hydrocarbon generated and discharged early, its maturity was lower, and it filled the peripheral and top traps of sags; in the latter, hydrocarbon generated and discharged late, its maturity was higher, and it filled the inner and lower traps of sags. The abnormal hygh-pressure of fluid also formed passages for hydrocarbon migration and accumulation. For the future, the forecast of subtle transportation systems is the key of exploration for lithological reservoirs.
GEOLOGICAL RESEARCH OF HIGH-SPEED AND HIGH-EFFECTIVE DEVELOPMENT OF SHUANGHE OILFIELD, THE NANXIANG BASIN
Sun Chong, Tang Xiaofen, Guo Enchang, Xu Hao
2005, 27(2): 173-177. doi: 10.11781/sysydz200502173
Abstract:
Shuanghe oilfield is not only a million-ton scale oilfield which has been earlier put into production in the Biyang Depression but also one of high-effectively developed onshore oilfields in China. Now it has been sliding into an oil-production decline stage with super-high water-cut. During 13-years stable production period, Shuanghe oilfield has been achieved better development effects and economic benefits through going on the premise of understanding geological characteristics and taking a measure of well pattern consummation and flood pattern modification in order to make the most use of sand capacity and keep producing in high speed (more than 2.0%) and high effectiveness from beginning to end. This article analyzes the mode of high-speed and high-effective development of Shuanghe oilfield and summarizes a set of effective development experiences for uncompartmentalized oilfields in order to use for reference to other similar types of oilfield development.
FORMATION PRESSURE PREDICTION IN THE BAISHUITOU OIL REGION
Wang Qingkui, Song Jianguo, Wang Xinqiang, Wang Heqiang
2005, 27(2): 178-180. doi: 10.11781/sysydz200502178
Abstract:
Technology of acoustic logging prediction and inspection is used in this paper to study formation pressure. Through study of formation pressure, the relationship between hydrocarbon reservoir and abnormal high pressure is mostly understood. Abnormal high pressure and pressure distribution regulation are recognized. Drilling level is improved greatly thanks to the study results. All these progress have made obvious economic profit. And it has significant application value in preventing engineering accidents, decreasing stratum pollution and saving drilling cost in the process of drilling.
MIGRATION CHARACTERISTICS OF OIL AND GAS OF THE LOWER CRETACEOUS, THE ERLIAN BASIN
Fang Jie
2005, 27(2): 181-187. doi: 10.11781/sysydz200502181
Abstract:
Systemic research on oil and gas migration activities of main hydrocarbon generation sags in the Erlian basin is made based on experiment data from mud and sand. Migration characteristics of oil and gas is summarized as below: 1)Hydrocarbon discharge ratio of 2 sets of mature source rocks (K1ba and K1bt1) in the Lower Cretaceous is about 32%-72%, thus estimated as the main hydrocarbon discharge stratum. The type Ⅰ hydrocarbon generation sag which has entered the peak stage is favorable for hydrocarbon (generation and discharge. 2)Based on mudstone) compression curve and clay mineral change, the rapid compression stage is the most favorable era for hydrocarbon discharge(primary migration). 3)Hydrocarbon generation zone of only the type Ⅰ sag is matched with mud rapid compression stage, forming good relation between hydrocarbon generation and migration. 4)Source fault and unconformity surface are the main channels for secondary migration, especially the K1bt1/K1ba surface. 5)Hydrocarbon migration effect of the Wuliyasitai sag is the best, with that of the A'nan, Saihantala, Erennaoer sags worse. Crude oil in the Bayindulan and Jiergalangtu sags has not experienced long distance migration.
OIL-SOURCE CORRELATION AND MIGRATION REGULARITIES IN THE CHEXI SAG, THE JIYANG DEPRESSION
Kong Xiangxing, Zhang Linye, Xu Sihuang
2005, 27(2): 188-193. doi: 10.11781/sysydz200502188
Abstract(1084) PDF-CN(444)
Abstract:
Based on comprehensive study of source rock, geochemical characteristics of crude oil, correlation of oil and source and hydrocarbon migration pattern of the Eogene in Chexi sag, this paper draws several conclusions. Source rock in the lower-middle Es3 (the third member of Shahejie formation of Eogene) which is buried 2 800-3 000 m below is the major source rock in Chexi sag. Source rock in the upper Es3 and Es1 which is buried 2 200 m below has some potential of immature oil. At present, most crude oil comes from the high-grade source rock of lower Es3. Sporadic petroleum discoveries are related to source rock of the middle Es3, upper Es3 and Es1. Petroleum generated from source rock of the lower Es3 at first migrated vertically through faults to reservoir beds in Es2. Later, because that the vertical pathway was sealed, petroleum migrated laterally to reservoir beds in the upper Es4 or buried hill reservoir. These reservoir beds below source rock of the lower Es3 area the most important area for future exploration.
A TECHNIQUE FOR DYNAMIC POOL-FORMING SIMULATION OF COALBED GAS
Wang Hongyan, Liu Honglin, Sun Yu, Li Guizhong, Li Jun
2005, 27(2): 194-196. doi: 10.11781/sysydz200502194
Abstract:
Based on the high-temperature and high-pressure core analysis technique, considering the adsorption and desorption characters of coalbed gas and combined with the pool-forming simulation technique of conventional natural gas, a pool-forming simulation instrument of coalbed gas was set up. By this instrument, the major factors affecting coalbed gas preservation, such as the effects of systematic temperature and pressure changes, the diffusion, migretion and dispersion of free gas, the effects of different hydrodynamics and the dissolution of formation water to coalbed gas, were determined. Through quantitative analyses and grade classification, a pool-forming model of coalbed gas was established.
STUDY ON THE STRESS SENSIBILITY OF RESERVOIR POROSITY
Gao Boyu, Zhou Yongyi, Peng Shimi
2005, 27(2): 197-202. doi: 10.11781/sysydz200502197
Abstract(652) PDF-CN(1109)
Abstract:
The porosity of reservoir rocks is one of the most essential and important formation parametersin pool development. As we know,during the development of reservoirs,the formation pressure is reducing,that is to say,the effective overlying pressure is increasing. Porosity is stronger effected by porositystress sensibility. Study porosity stress sensibility has important meanings to reservoir development. Thispaper presented a porosity stress sensibility model in theory by means of porosity volumetric strain ,brought forward a parameter named porosity stress sensibility coefficient,then took it as a method to evaluate porosity stress sensibility. This parameter is based on the change of pore compression coefficient,soit can describe porosity stress sensibility more accurately than using pore compression coefficient. Combining theoretical rules with the experiment,the theory was proved to be true by the experiment of porositystress sensibility under the simulating formation situation.