石油实验地质

BASIC FORMING MODELS OF THE CENOZOIC BIOGAS POOLS IN CHINA

Zhou Liqing, Liu Chiyang

2005, 27(1): 1-7. doi: 10.11781/sysydz200501001

Abstract(752) PDF-CN(484)

Abstract:
Under the control of geotectonic evolution zonality and paleogeographic and paleoclimatic zonality of the Cenozoic, five kinds of basic forming models of biogas pools were developed in the Cenozoic basins of China. The first pools are in salt lakes and inland salt lakes in the circumstances of highlands, high latitude, high elevation and cold and dry climate, which are located in large intermontane strike-slip compressional down-warped basins in the northwestern part of China. The second are in inland brackish water and fresh water lakes under humid tropic and subtropical zone climate, which are located in ultra small intermontane strike-slip extensional rift basins in the southwestern part of China. The third are the Quaternary biogas pools in plain, estuarine facies and large delta facies areas in the southeast coastal subtropical zones of China. The forth are mixed-genetic biogas pools in the eastern strike-slip extensional rift basins of China. The fifth are the Upper Tertiary-Quaternary biogas pools in the poor-trophic shallow littoral areas of tropic and subtropical zones, which are on the quasi-passive continental margins of the South China Sea.

AN APPROACH TO THE STUDY OF INVERSION POINTS AND TANGENCY-IN POINTS FOR OROGENY AND COUPLED/DECOUPLED BASIN DEVELOPMENT

Wu Genyao, Ma Li

2005, 27(1): 8-17. doi: 10.11781/sysydz200501008

Abstract(685) PDF-CN(412)

Abstract:
The study of orogeny and coupled/decoupled basin development regarded orogeny and basin development as a whole and explored a uniform kinematic process and geodynamic mechanics between the both. The key of methodology for the study was to grasp, correctly and practically, inversion points and tangency-in points, the former representing obvious changes of tectonic patterns or styles, and the latter constituting a key link connecting basins with orogeny. For the inversion points, we should, first of all, understand the essential problems of orogeny and coupled/decoupled basin development in a given regional framework. In addition, the tectonic features of Chinese continent decided the difficulties and complexities of discerning inversion points, which supported, in turn, a wide platform for the study of tengency-in points. The tangency-in points might be decided by a poly-direction, poly-visual angle, poly-level and poly-aspect means, in which the orogenic types and structural styles should be the first important and necessary one. As the road one must take for the study of inversion points and tangency-in points, a combination of "normal succession" and "reversal succession" was emphasized, with stress on the study of "reversal succession". Namely, regional evolution and basin development should be worked from the ancient to the present, and the oil-gas accumulation analysed from the young structural layers to the older ones. The paper introduced some experiences to compile some profiles, perpendicular to the regional tectonic strike, across both an orogen and neighbouring basins. With the inversion points and tangency-in points being embodied in the basin research, the alternation of basin generations as well as tectonic patterns and structural styles in each generation should be correctly distinguished, particularly, to distinguish the basin generations changed in the periods of main tectono-thermal events. The prerequisite for understanding basin generations was to constrain a geohistorical phase and to stipulate a basin definition. The advances in the study of inversion points and tangency-in points for orogeny and coupled/decoupled basin development must open up a new prospect of the basin research, and then draw a new inspiration in the oil-gas exploration of relict marine basins.

RESEARCH ON THE TECTONO-THERMAL EVOLUTION OF THE BAISE BASIN, GUANGXI PROVINCE

Liao Zongting, Jiang Xinge, Li Ran, Chen Yuekun

2005, 27(1): 18-24. doi: 10.11781/sysydz200501018

Abstract(810) PDF-CN(516)

Abstract:
Baise basin is a typical strike-slip and pull-apart basin that was formed in the Tertiary Period. It is the tectonic background and main reason why the Baise Basin was formed. The collision of the India Plate and the Eurasian Plate made the Youjiang fracture belt left-handed strike slip(20-50 Ma ago) first, then right-handed strike slip (20 Ma till now). The basin includes three depressions (the Tiandong Depression, the Toutang Depression and the Liantang Depression) and two uplifts (the Nabi Uplift and the Nage Uplift). The three depressions were formed in the places where the left stage stagger NW fractures turning left overlapped and arrayed, and the two uplifts were formed in the places where the left stage stagger NW fractures turning left overlapped and arrayed. The three main periods of tectonic evolution includes the Liuniu-Dongjun pull-apart period, the Nadu-jianduling pull-apart period, and the Late Jiandu-ling-Quaternary epi-pull-apart period. Each period had its own apparently different characteristics. Although the scale of the basin is small, there are better oil source rocks and the conditions of reservoirs and cover rocks. The main problem about influencing oil-gas formation is that the degree of thermal evolution is lower. The thermal evolution of the Baise Basin was modelled based on vitrinite reflectance R_o, apatite fission tracks and fluid inclusions. The modelling results showed that the gradient of thermal evolution was lower. the Nadu Formation is the only oil-generating strata with low maturity. The oil-generating strata of the rest formations are not mature. The basic characteristics of thermal evolution in the basin were that paleotemperature increased with the subsidence and sedimentation of the Tiandong Depression from 55 Ma ago first, and achieved the highest during 25-30Ma ago, then decreased gradually with the slow lifting of the crust. The low thermal evolution of the basin is one of the most important factors resulting in poor prospective oil-gas.

TECTONIC CHARACTERISTICS AND PETROLEUM DISTRIBUTION OF THE TARIM FORELAND BASIN

Kang Yuzhu

2005, 27(1): 25-27. doi: 10.11781/sysydz200501025

Abstract(703) PDF-CN(559)

Abstract:
The Mesozoic-Cenozoic foreland basin is quite common in the Tarim basin with great potential for oil and gas. By now,10 fields have been found. Evolution of the Tarim foreland basin can be divided into 3 stages: early stage, late stage and intracontinental integration. According to dynamic characteristics, it can also be divided into single foreland, double forelands and strike-slip foreland basins. Tectonic deformation is complicated and the main tectonic style is compressional reversing fracture. Horizontally it can be divided into overthrust zone, fault-fold zone, depression zone and slope zone.Oil and gas are mainly distributed in the fault-fold and slope zones.

PALEO-GEOTHERMAL FIELD AND TECTONIC-THERMAL EVOLUTION IN THE CHUXIONG BASIN OF CHINA

Wang Guoli, Cai Liguo, Wang Jiyang, Shi Xiaobing

2005, 27(1): 28-31. doi: 10.11781/sysydz200501028

Abstract(738) PDF-CN(590)

Abstract:
The evolution of geothermal field and tectonic-thermal activities were all consistent with tectonic events in the Chuxiong Basin. The heat flow values of the basin in the Late Triassic was similar to that of retro-arc basins in the world, but the thermal field and thermal gradient were slightly lower. The thermal gradient and thermal current were gradually weakening in the Jurassic and the Early Cretaceous as compared with those in the Late Triassic in the basin, which were close to the values of thermal flow in crato-nic basins. The thermal gradient and thermal flow were rapidly raised in the Cenozoic as intra-continent strike-slip activities and magmatic injection happening along deep faults. The formation of high thermal field in the basin was the result of tectonic-heat activities.

STUDY ON DEEP BASIN GAS IN THE WESTERN SICHUAN DEPRESSION, THE SICHUAN BASIN

Chen Zhaoguo

2005, 27(1): 32-38. doi: 10.11781/sysydz200501032

Abstract(739) PDF-CN(527)

Abstract:
Natural gas in deep basin reservoirs is one type of tight sandstone gas pools, and its exploration strategy is wholly different from normal reservoirs due to its special characteristics and mechanism of gas accumulation. Is there any deep basin gas in tight clastics of continental facies in the Western Sichuan Depression? There were much different arguments about that. The gas accumulation mechanism and gas reservoir characteristics in the Westem Sichuan Depression were compared with those of deep basin gas reservoirs in North American. It was considered that typical characteristics of deep basin gas had not been discovered in the Upper Triassic reservoirs. The gas accumulation mechanism of the Western Sichuan Depression is different from those of deep basin gas reservoirs. The complex gas accumulation model of "normal accumulotion in the early stage and modification in the late" was suggested.

THE JURASSIC PETROLEUM SYSTEM IN THE KASHI DEPRESSION OF THE TARIM BASIN

Li Tiejun, Luo Xiaorong

2005, 27(1): 39-43. doi: 10.11781/sysydz200501039

Abstract(551) PDF-CN(498)

Abstract:
Based on studies on source, reservoir, seal rocks and traps of petroleum system, thermal evolution of source rock and tectonic evolution of the Kashi Depression are analyzed and modeled. Evolution of the Jurassic petroleum system in Kashi Depression can be divided into primary stage and rebuilt one, with different time and space range in different stages. Different oil space range suggests different exploration techniques. For primary petroleum system in the inner parts of depression, the target should be aimed at lithological traps. But for mountain front belts, the concentration should be structural traps.

RESERVOIR SPACE EVOLUTION OF VOLCANIC ROCKS IN THE YINGCHENG FORMATION OF THE XUJIAWEIZI FAULT DEPRESSION, THE SONGLIAO BASIN

Liu Weifu, Zhu Xiaomin

2005, 27(1): 44-49. doi: 10.11781/sysydz200501044

Abstract(660) PDF-CN(556)

Abstract:
Commercial gas streams were obtained from volcanic rocks in the Yingcheng Formation of the Xujiaweizi Fault Depression, the Songliao Basin, but the output of each well was different. It was not only related to the distribution of volcanic rocks, but also related to the developing degree of accumulating spaces in volcanic rock reservoirs. The study of core, thin section and scanning electron microscope data showed that the main accumulating rock types of the study area were various volcanic lava and volcanic breccia, and the accumulating spaces included primary and secondary two kines. Though the primary accumulating spaces took the small proportion, they provided fovorable conditions for paulopost reconstruction. The development and evolution of volcanic rock accumulating spaces can be divided into four stages. The first is the forming stage of primary accumulationg spaces, and the secondary is weathering and leaching stage. These two stages are dominated by construction. The third is shallow-burying and structural fracture developing stage, with coexisting of construction and destruction, but dominated by construction. The fourth is deep-burying stage, which is dominated by destruction.

RELATIONS BETWEEN THE EARLY PERMIAN MAGMATIC ROCKS AND HYDROCARBON ACCUMULATION IN THE CENTRAL TARIM

Zhu Yixiu, Jin Zhijun, Lin Changsong, Lü Xiuxiang, Xie Qilai

2005, 27(1): 50-54. doi: 10.11781/sysydz200501050

Abstract(569) PDF-CN(621)

Abstract:
Characteristics, distribution patterns and hydrocarbon accumulation relations of the Early Permian magmatic rocks in the Central Tarim have been studied with well geological data and core and rock testing and analysis information. Types, lithofacies, occurrences, development and distribution of the Early Permian magmatic rocks in the studied area are discussed in this paper. Relations between the hydrocarbon generation and accumulation and the Early Permian magmatic activity in the area are shown. The activity does not destroy oil and gas formation and accumulation, but is favorable for a large quantity of hydrocarbon to generate from source rocks, as the high thermal fluid brought by magma activity could increase ancient geothermal gradient, and accelerate the evolution history of source rocks. Also, magmatic activity could result in the formation of more channels for oil and gas migration and accumulation, and form many secondary pores and fissures. In addition, magmatic rocks could seal hydrocarbons in traps and pools.

SEDIMENTARY FACIES TYPES OF THE THIRD MEMBER OF THE SHAHEJIE FORMATION IN THE PALEOGENE OF THE DONGYING DEPRESSION, THE BOHAIWAN BASIN AND THEIR DISTRIBUTION CHARACTERS ON PLANE

Lin Huixi, Yan Jihua, Yuan Wenfang, Chen Shiyue

2005, 27(1): 55-61. doi: 10.11781/sysydz200501055

Abstract(639) PDF-CN(647)

Abstract:
Based on the synthetical analysis of geological, logging and seismic data, the sedimentary facies types of the third member of the Shahejie Formation in the Paleogene of the Dongying Depression, the Bohaiwan Basin and their distribution characters on plane were studied roundly and systematically. The results showed that seven types of sedimentary facies were developed in this area, that is, fan delta, delta, inshore subaqueous fan, sublacustrine fan, shore shallow lake, half-deep lake and deep lake facies. During the Early and Middle Sha-3 periods, fan delta facies and inshore subaqueous fan facies were developed on the northern steep slope zone of the Dongying Depression, delta facies and fan delta facies on the southern gentle slope zone, the Dongying and the Gaoqing delta deposits along the east-west axis, and sublacustrine fan facies in half-deep lake and deep lake environments within the basin. During the Late Sha-3 period, the lake basin shrinked. With various skeleton sandbodies expanding from basin margins to interior of the basin, the range of half-deep lakes and deep lakes reduced gradually to form favorable hydrocarbon reservoirs.

POOL-FORMING MECHANISM AND MIGRATION AND ACCUMULATION PATTERNS OF HYDROCARBON IN NORMAL PRESSURE HALFGRABEN-TYPED FAULT DEPRESSIONS

Yao Hefa, Lin Chengyan, Ren Lihua, Xu Huazheng, Jin Xiuju

2005, 27(1): 62-66. doi: 10.11781/sysydz200501062

Abstract(684) PDF-CN(502)

Abstract:
The Gaoy ou Depression in the North Jiangsu Basin is a Cenozoic halfgraben-typed fault depression.Its hydrocarbon pools are do minated by normal pressure,which have the characters of multi-stage evolution and the two stages of pool formation early in the Sanduo period of the Paleogene and late in the Yancheng period of the Neogene and develop reticulated,bedded and faulted three types of conduit systems and lateral,vertical and branchy three kinds of hydrocarbon migration and accumulation patterns.The hydrocarbon migration and accumulation is mainly later al in the K₂t—E₁f Formation of slope zones,branchy in the E₂d-E₂s Formation of deep depressed zones and vertical in faulted zones which including shallow (Ny),medium(K₂t—E₁f) and deep three sets of petroleum measures.

COMPARISON OF GENETIC AND STATISTICAL METHODS FOR PETROLEUM RESOURCE ASSESSMENT

Zhou Zongying, Bai Senshu, He Hong

2005, 27(1): 67-73. doi: 10.11781/sysydz200501067

Abstract(837) PDF-CN(620)

Abstract:
Genetic method, statistical method and their relevant mathematic models, basic features and applicability and confines are contrasted in this paper. In fact, genetic method mainly represented by basin simulation technology is a kind of comprehensive method for petroleum geology analysis, which not only quantitatively estimates petroleum resources, but also provides many sorts of valuable outcome maps. But from now on, some further research should be taken urgently to improve petroleum migration and accumulation module, so as to enhance the reliability of resource estimation. Statistical method establishes relevant mathematical models to estimate petroleum resources in the exploration area with higher exploration maturity, according to the changing trend of petroleum reserves (output) or supposing that, pool size submits to a certain distribution function. Some kinds of utility models of statistic method are introduced, such as lognormal distribution, truncated shifted Pareto distribution, generalized Pareto distribution, pool size sequence and Weng's life cycle. In practice, many kinds of models should be chosen to make crosswise verification according to petroleum geology condition and exploration maturity, so as to ensure the reliability of estimation result.

MODELS OF HYDROCARBON GENERATION AND EXPULSION FROM VARIOUS MARINE SOURCE ROCKS

Qin Jianzhong, Liu Baoquan

2005, 27(1): 74-80. doi: 10.11781/sysydz200501074

Abstract(595) PDF-CN(560)

Abstract:
The 17 models of original and secondary hydrocarbon generation and expulsion from marine source rocks have been established. The work has been done on the basis of the thermal-pressure simulated experiment on ten samples selected from Mesozoic marine source rocks in the Qinghai-Xizang Plateau, and the Proterozoic marine source rocks in Jibei. The total hydrocarbon quantity, as well as the ratio of hydrocarbon generation, generated from kerogen in marine source rocks decreases gradually from type Ⅰ to Ⅱ₁, Ⅱ₂ kerogen and solid bitumen. At the same time, the oil quality becomes lighter and lighter, and the gas drier and drier. The efficiency of oil expulsion increases gradually from hydrocarbon-rich shale to marlite, limestone and solid bitumen. Both the total quantity and the ratio of hydrocarbon generation from them show a downward trend. The oil-gas ratio in total hydrocarbon increases gradually from solid bitumen to hydrocarbon-rich shale, marlite and limestone. The quantity of oil-gas generation and expulsion, the total quantity and the ratio of hydrocarbon generation decrease gradually, but the oil-gas ratio in total hydrocarbon increases with the reduction of the content of organic matter in the marine source rock(TOC=0.2%-1.0%).

GAS CHROMATOGRAPHIC ANALYSIS OF SIMULATED BIODEGRADED SATURATED HYDROCARBON

Zhang Qu, Liang Shu, Zhang Zhirong, Ba Liqiang, Zhen Lunju

2005, 27(1): 81-84. doi: 10.11781/sysydz200501081

Abstract(662) PDF-CN(550)

Abstract:
For crude oil, the influence of biodegradation is very important. Biodegradation of crude oil was simulated by aerophile bacteria, and the saturated hydrocarbon of the products was aralyzed by GC. It was shown that the n-alkanes would be biodegraded first, and the value of Pr/C₁₇ and Ph/C₁₈ would be increased, but the value of OEP and Pr/Ph would be kept no changes. When the isoprenoids (Pr, Ph) began to be biodegraded, the value of Pr/C₁₇ and Ph/C₁₈ would be reduced, and the value of Pr/Ph and OEP could not be measured or they were not the true value. After crude oil has been biodegraded, the parameters of saturated hydrocarbon in GC analysis should be changed. Lighter the crude oil is, faster will it be biodegraded.

NITROGEN AS AN INDEX OF OIL-GAS PRESERVATION CONDITIONS IN MARINE STRATA

Chen Anding

2005, 27(1): 85-89. doi: 10.11781/sysydz200501085

Abstract(611) PDF-CN(592)

Abstract:
This paper shows some examples of gas rich in nitrogen in the marine strata of South China, explains their distribution characteristics, and discusses various source and formation mechanism of nitrogen. It is pointed out that, nitrogen in natural gas usually comes from biological detritus decomposed by bacteria, low temperature pyrolysis of kerogen, gas migration, nitrate-mineral decomposition and atmosphere, but nitrogen in marine strata is mainly from atmosphere. Nitrogen in natural gas indicates connection of surface with underground, therefore, it could be an effective index for oil-gas reservoir.

EROSION THICKNESS RESTORATION OF UNCONFORMITIES IN THE XIHU SAG, THE SHELF BASIN OF EAST CHINA SEA

Wang Zhen, Zhang Mingli, Wang Ziyu, Wu Fadong, Wang Lisheng

2005, 27(1): 90-93. doi: 10.11781/sysydz200501090

Abstract(660) PDF-CN(544)

Abstract:
Since the final stage of Cretaceous, the Xihu Sag has undergone paar stage, depression stage and regional subsidence stage, developing several extensive surfaces of unconformity (seismic reflection sequence:) T₂⁰,T₂⁴,T₃⁰, etc. This paper explains the basic principles and calculating methods of obtaining erosion amount using sonic velocity and vitrinite reflectance data of the Xihu Sag. It also analyses the influence of strata erosion on petrloeum accumulation, probing into the applicability of those methods.

STUDY ON PREDRILLING RESERVOIR QUALITY PREDICTION-TAKING WANGJIATUN REGION, THE SONGLIAO BASIN AS AN EXAMPLE

Qu Aiying, Meng Yuanlin, Xiao Lihua, Ying Xiulan, Yang Junsheng, Li Chen, Luo Xianying

2005, 27(1): 94-97. doi: 10.11781/sysydz200501094

Abstract(611) PDF-CN(489)

Abstract:
Predrilling reservoir quality prediction includes porosity prediction and permeability prediction. The porosity of clastic rock reservoirs is determined by both sedimentary facies and diagenesis. But for the same sedimentary facies or the similar lithology, the porosity of reservoirs is mainly controlled by diagenesis. According to this, a model of porosity prediction for clastic rock reservoirs using diagenetic index I_D was established, with the predicting error of less than 2%. The Deng-3 Member (K₁d³) in Wangjiatun region, the Songliao Basin was taken as an example to illustrate the application of this model. The reservoirs were composed of lithic arkose and feldspathic litharenite, and were deposited in shallow river facies. At present, the reservoirs in northeastern Wangjiatun region are in the late diagene-tic stage B, with the maxi-mum porosity of 14%-16%; and the reservoirs in western Wangjiatun region are in the late diagenetic stage C, with poorer reservoir petrophysical properties and the maximum porosity of 10%-12%.

THERMAL-INDUCED ROCK CRACKING AND ITS SIGNIFICANCE IN ENGINEERING

Han Xuehui, Chu Zehan, Zhang Yuanzhong

2005, 27(1): 98-100. doi: 10.11781/sysydz200501098

Abstract(693) PDF-CN(567)

Abstract:
Thermal-induced rock cracking is a common phenomenon when sedimentary and igneous rocks are in high temperature environments. It can impact on flow transportation features in rocks through the reconstruction of pore and fissure structure. Based on the review of its study status, this paper emphasized its significance in the fields of oil exploitation and nuclear waste storage.

2005 Vol. 27, No. 1

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