石油实验地质

2013, 35(2)

Abstract(942) PDF-CN(851)

Abstract:

Hydrocarbon accumulation mechanism of tight sandstone reservoir in Jiyang Depression

Liu Chuanhu, Wang Yongshi, Han Hongwei, Wang Xuezhong

2013, 35(2): 115-119. doi: 10.11781/sysydz201302115

Abstract(1683) PDF-CN(1137)

Abstract:
The permeability of tight sandstone reservoirs is below 10×10^-3 μm². Due to the particularity of reservoir space type and characteristics, the tight sandstone reservoirs are different from normal ones in hydrocarbon accumulation mechanism. The generation conditions and accumulation features of "source-contacting gas" are studied. Based on simulation experiments, hydrocarbon accumulation mechanism is concluded according to the features of tight sandstone reservoirs in the Jiyang Depression. Overpressure charging is the main way of hydrocarbon migration and accumulation in tight sandstone reservoir. The border for overpressure transfer is the boundary for oil or gas. When overpressure gradient is larger, the distance of hydrocarbon charging and the range of trap will be larger, and the hydrocarbon saturation will be higher. Through similarity research, the tight sandstone reservoirs in the Jiyang Depression have the following characteristics. 1) Source rocks contribute to hydrocarbon continuously. Large quantity of oil and gas with poor diversity exist in source rocks or neighboring reservoirs. 2) In tight sandstone reservoirs, facies and potential control accumulation. 3) Tight reservoirs may exist widely, indicating for good exploration potential.

Hydrocarbon potential of Upper Paleozoic in Yanbian area, Jilin Province

Dong Qingshui, Zhang Kaiwen, Xu Zhi, Yu Meng, Li He, Zhang Yong

2013, 35(2): 120-126. doi: 10.11781/sysydz201302120

Abstract(1500) PDF-CN(867)

Abstract:
The research extent of the Upper Paleozoic hydrocarbon resources is low in Yanbian area of Jilin Province. Through numerous trenching samplings and geochemical tests, combining with gravity-magnetic and seismic data interpretations, the distribution of the Upper Paleozoic and the organic abundance, type and maturity of dark mudstones in the study area were studied. In Yanbian area, the Upper Paleozoic is wide distributed and is rich in dark mudstone with high organic carbon content. As a whole, the dark mudstones are medium or good source rocks, which mainly produce Ⅱ-Ⅲ kerogen but with high organic maturity. In the southwestern and northeastern parts of the study area, organic matters are over matured, and the R_o value is over 4.0%, indicating for poor hydrocarbon potential. In Tianqiaoling-Hunchun area which locate in the center of the study area, the R_o value ranges from 2.22% to 3.48%, and organic matters are during the high mature-dry gas effective gene-ration stages. The Upper Paleozoic dark mudstones in the basement of the Huichun Basin have good hydrocarbon exploration potential.

Petroleum accumulation regulations and exploration targets in Jiangling Sag, Jianghan Basin

Luo Kaiping, Qiu Qi, Ye Jianzhong

2013, 35(2): 127-132. doi: 10.11781/sysydz201302127

Abstract(1767) PDF-CN(940)

Abstract:
In the Jiangling Sag of the Jianghan Basin, the lower Xingouzui Formation served as the main source rocks, and petroleum generated mainly in the Meihuaiqiao-Zifusi syncline. The discovered oil and gas pools are featured by small trap scale, low charging extent and located around oil sources. Transformation system mainly of faults and reservoir physical property controlled petroleum accumulation. From Cretaceous to Tertiary in the Jiangling Sag, the proved rate is 12.4%, indicating for low exploration extent and good potential. The southern slope of the Jingzhou anticline, the tectonic-lithologic and lithologic traps in the Meihuaiqiao sub-Sag, Cretaceous and Precretaceous buried hill in the Wancheng fault, the volcanic reservoirs in the Gongan monocline, and the shale oil in oil source sags are the targets for future exploration.

Burial and thermal histories of northeastern Sichuan Basin：A case study of well Puguang 2

Wu Qun, Peng Jinning

2013, 35(2): 133-138. doi: 10.11781/sysydz201302133

Abstract(1580) PDF-CN(945)

Abstract:
The thermal maturity index (TTI) was applied in well Puguang 2 to recover the burial and thermal histories of the northeastern Sichuan Basin. In this way, the thermal evolution of source rocks and the hydrocarbon generation and migration processes in the study area were discussed. The maturity of source rocks evolved until the end of Cretaceous. Source rocks in the Lower Cambrian gave birth to hydrocarbon only from the Late Permian to the Late Triassic. Source rocks from the Upper Ordovician to the Lower Silurian gave birth to hydrocarbon rapidly from the Middle Triassic to the Late Triassic and also during the Middle Jurassic. Source rocks in Permian gave birth to hydrocarbon rapidly during the Late Triassic and the Middle Jurassic. All the above-mentioned source rocks experienced at least 2 hydrocarbon generation peaks, including the oil (liquid hydrocarbon) generation during the mature stage and the cracking of liquid hydrocarbon to gas during the high-mature stage.

Petroleum geologic conditions and accumulation history of Middle Devonian, southern Guizhou province

Wang Jinyi, Wang Yanqing, Peng Jinning, Liu Guangxiang, Gao Lin

2013, 35(2): 139-145. doi: 10.11781/sysydz201302139

Abstract(1658) PDF-CN(838)

Abstract:
In the Dushan Formation of the Middle Devonian in the southern Guizhou province, the mudstone source rocks of trough-basin facies are widespread with high organic abundance. The average organic carbon content is 3.02%. Most of the kerogens are of type Ⅱ₁, and some are of type Ⅰ, indicating for excellent hydrocarbon generation conditions. In carbonate and sandstone reservoirs, intergranular, intergranular pores and cracks develop well. Cap rocks distribute widely and are preserved well, indicating for strong sealing capacity. Petroleum shows prove that, in both carbonate and sandstone reservoirs in the Middle Devonian, uneven organic matter or asphalt infillings can be found. The homogenization temperatures of fluid inclusions in the Dushan Formation show that the study area has experienced 2 phases of hydrocarbon charging. At the end of Devonian, the southern Guishou province was the uplifting area of the Ziyun Movement, hence was favorable for petroleum charging during the early Carboniferous. Petroleum migrated along cracks to the reef flat limestone reservoirs and the littoral sandstone reservoirs in platforms and platform edges.

Influence of pre-Paleogene tectonics on Upper Paleozoic-Mesozoic source rocks in Bohai Sea area

Zhou Jing, Lü Dawei, Chen Long, Li Zengxue, Liu Haiyan, Zheng Xue

2013, 35(2): 146-150. doi: 10.11781/sysydz201302146

Abstract(1981) PDF-CN(742)

Abstract:
The Bohai Sea area can be divided into 5 structural layers. The distribution of Carboniferous, Permian and Mesozoic strata was studied, indicating for close relationship between stratigraphic distribution and basin evolution. Due to the subduction of the continental margin orogeny of the northern Xingmeng ocean activities in the Late Paleozoic (the Hercynian Movement), and influenced by a number of transgression, source rocks became better from north to south gradually. From the Late Paleozoic to Triassic, source rocks became worse because of the Indosinian Movement. The Yanshan Movement during Mesozoic resulted in a large number of inland warped lake deposition in the area and excellent source rocks of large quantity generated in the center of lake basin.

Hydrocarbon origin and distribution regularity in Fulin sub-Sag, Zhanhua Sag, Bohai Bay Basin

Wang Xiuhong

2013, 35(2): 151-156. doi: 10.11781/sysydz201302151

Abstract(1788) PDF-CN(832)

Abstract:
Based on the studies of biomarker distribution and composition of crude oils in the Fulin sub-Sag of the Zhanhua Sag of the Bohai Bay Basin, there are 3 types of crude oil in the study area. The crude oils of type Ⅰ mainly exist in the east of the sub-sag, characterized by low Pr/Ph ratio, high gammacerence content as well as low diasterane and 4-methyl-sterane contents. They are originated from source rocks in the upper subsection of the 4th member of the Shahejie Formation in the east of the sub-sag. The crude oils of type Ⅱ mainly locate in the center of the sub-sag, featured by high Pr/Ph ratio, low gammacerence content and high diasterane content. The origin for oil and gas is different vertically. Hydrocarbon in the middle and shallow reservoirs is mainly originated from source rocks in the lower subsection of the 3rd member of the Shahejie Formation in the Gunan sub-Sag while hydrocarbon in the deep reservoir is mainly originated from source rocks in the lower subsection of the 3rd member of the Shahejie Formation in the Fulin sub-Sag. The crude oils of type Ⅲ mainly distribute around fault belts in the central sub-sag, featured by low maturity, high Pr/Ph ratio, medium gammacerence content, high C₂₈ sterane content as well as low pregnane and diasterane contents, which show mixed-oil characteristics of source rocks from both the 1st member of the Shahejie Formation in the Gunan sub-Sag and the lower subsection of the 3rd member of the Shahejie Formation in the Fulin sub-Sag.

Characteristics and origin of dolomite reservoirs in Lower Ordovician Yingshan Formation, northern slope of Tazhong uplift, Tarim Basin

Zheng Xingping, Liu Yongfu, Zhang Jie, Zheng Jianfeng

2013, 35(2): 157-161. doi: 10.11781/sysydz201302157

Abstract(1814) PDF-CN(805)

Abstract:
At present, the rich oil-and-gas resources discovered in the Ordovician Yingshan Formation in the northern slope of the Tazhong uplift of the Tarim Basin mainly exist in limestone karst fracture-cave reservoirs which are controlled by the unconformities on the top of the Yingshan Formation. With the deepening of exploration, dolomite reservoirs in the Yingshan Formation have been found in some new exploratory wells, and the reservoir spaces mainly include intercrystal pores, solution pores and vugs. Dolomite reservoirs have good physical properties and are thick locally; however, their horizontal comparisons are poor. According to core, slice observation, cathodoluminescence, REE and isotopic analyses, the favorable dolomite reservoirs in the Yingshan Formation had experienced buried dolomitization and strong dissolution, and was influenced by hot fluid in the late stage. Distributed widely and controlled by underground fluid activities, the dolomite reservoirs are the key types and targets for explorations in carbonate reservoirs in the Yingshan Formation in the northern slope of the Tazhong uplift of the Tarim Basin.

Features and influencing factors of Chang 7 reservoir of Yanchang Formation in Hujianshan area, Ordos Basin

Yao Jingli, Chen Shijia, Lu Jungang, Zhang Huanxu, Liu Chaowei, Tang Haiping, Wang Gang, Zhang Bowei

2013, 35(2): 162-166. doi: 10.11781/sysydz201302162

Abstract(1693) PDF-CN(886)

Abstract:
The Chang 7 strata in the Ordos Basin were regarded as source rocks in the past. Plenty of industrial oil wells have been found in the Chang 7 strata of the Yanchang Formation in Hujianshan area of the Ordos Basin in recent years; however, the reservoirs are unevenly distributed and have different industrial productivities. Based on rock thin section, cast thin section, mercury penetration and physical property analyses, the features of the Chang 7 reservoir were studied, and the influencing factors were discussed. Arkose and lithic arkose sandstones are most common in the Chang7 strata. The main interstitial materials are ferroan calcite and hydromica. Residual intergranular pore and dissolved pore are the dominant reservoir spaces. The Chang 7 reservoir is a low porosity and ultra-low permeability reservoir with micro-throat and poor physical property. The main affecting factors include quartz content, size of detrital grain, depositional micro-facies and diagenesis, etc.

Differences of petroleum geological conditions between eastern and western basins in Algeria

Liu Qiong, Hu Xiaolin, Yu Shui, Hao Liye, Zhang Yingde, Peng Jiayong

2013, 35(2): 167-173. doi: 10.11781/sysydz201302167

Abstract(1678) PDF-CN(893)

Abstract:
Based on several years of petroleum exploration and development in Algeria, the most of petroleum production are from the eastern basins on the Saharan Platform, while the western basins have large prospecting potential but with low exploration degree. The eastern and western basins are evidently different from each other in their sedimentary fillings, source rocks, reservoirs, traps, petroleum properties and accumulation models. Analysis suggests that large anticline traps related to fault belts are advantageous to find natural gas accumulation in the western basins with low exploration degree. By comparison, due to high exploration degree and exploration difficulties, oils in middle and small size structural traps or lithologic-structural traps should be targeted in the eastern basins.

Controlling of tectonic evolution on hydrocarbon occurrence in PreCaspian Basin

Liang Shuang, Wang Yankun, Jin Shutang, Wang Zhen, Zheng Junzhang

2013, 35(2): 174-178. doi: 10.11781/sysydz201302174

Abstract(2188) PDF-CN(985)

Abstract:
The PreCaspian Basin, which is one of the richest oil and gas basins in central Asia, is located in the southeast of the East European platform. According to the development of central Asia areas, the tectonic evolution of the PreCaspian Basin has been divided into four stages including the rift, passive continental margin, convergence and depression. Based on the study of tectonic evolution, it is discussed in this paper the relationships between the evolution and the source rocks, reservoirs-seals, traps, hydrocarbon migration and accumulation. Tectonic evolution has played an important role in reservoir forming. Under the effection of tectonism, attributed to the paleotectonic form for this basin, the two sets of main source rocks developed along the edge of the basin and nearby the bioherm uplift, while the main high-quality reservoirs in the Caspian Basin distributed on the carbonate platform. Meanwhile, the subsalt anticlines, bioherm traps and the development of salt tectonic traps are controlled by tectonism. Besides, fault and unconformity offered the main migration pathways for oil and gas.

Hydrocarbon generation and expulsion pattern of different types of excellent source rocks

Qin Jianzhong, Shen Baojian, Tenger, Zheng Lunju, Tao Guoliang, Fu Xiaodong, Zhang Linglong

2013, 35(2): 179-186. doi: 10.11781/sysydz201302179

Abstract(1853) PDF-CN(931)

Abstract:
Semi-closed pyrolysis experiments were conducted in order to evaluate what controls the hydrocarbon generation and expulsion efficiency for three types of excellent source rocks (siliceous, calcareous and clay ones). Each type of source rock has different relative hydrocarbon expulsion efficiencies in the stage of early-middle oil window, where siliceous source rock has the highest oil expulsion efficiency and oil expulsion quantity, reaching to 50%, and the expelled products are dominated by heavy oil. This is followed by calcareous source rock, about 30%. The oil expulsion efficiency of clay source rock is the lowest, about 4%-11%. During the middle-late maturation stage, siliceous source rock tends to achieve the highest expulsion efficiency first, followed by calcareous source rock (65%) and then clay source rock. During the late and high-mature stage, the oil expulsion efficiencies of siliceous and calcareous source rocks do not change obviously, while the oil expulsion efficiency of clay source rock increases rapidly from 20% to 90%. The models of hydrocarbon generation and expulsion of three types of excellent source rocks are different in the stage of early-middle oil window.

Organic geochemical characteristics and thermal evolution maturity history modeling of source rocks in Eocene Hetaoyuan Formation of Biyang Sag, Nanxiang Basin

Dong Tian, He Sheng, Lin Sheqing

2013, 35(2): 187-194. doi: 10.11781/sysydz201302187

Abstract(1985) PDF-CN(806)

Abstract:
In the Biyang Sag of the Nanxiang Basin, effective hydrocarbon source rock system mainly develops in the lagoon or salt lake facies strata in the lower and upper parts of the 3rd member of the Hetaoyuan Formation. The source rocks include dark gray, brown gray, gray mudstones, calcareous mudstones and dolomitic mudstones. The average organic carbon contents of the lower and the upper parts of the 3rd member of the Hetaoyuan Formation are 1.60% and 2.23%, respectively. Kerogens of the lower part of the 3rd member of the Hetaoyuan Formation are mainly of type Ⅱ, and part of them are of type Ⅲ. In the upper part of the 3rd member of the Hetaoyuan Formation, kerogens are mainly of type Ⅱ₁, and part of them are of types Ⅰ and Ⅲ. Pr/Ph ratio which illustrates depositional environment is low and gammacerane content is high. Organic matter maturity values (R_o) range from 0.5% to 1.4%, indicating for oil generation stage with current threshold depth of approximately 1 820 m. In the southern steep slope and deep depression, source rocks at the bottom of the 3rd member of the Hetaoyuan Formation enter the threshold for hydrocarbon generation at 37 Ma, and the corresponding depth and temperature are 2 500 m and 100℃. At the top of the upper part, the threshold for hydrocarbon generation is at 23 Ma, and the corresponding depth and temperature are 1 950 m and 90℃. The average organic carbon content of the 2nd member of the Hetaoyuan Formation is 1.85%. Organic matter types are mainly Ⅰ and Ⅱ, having not entered the mature threshold.

Characteristics of fluid inclusions and timing of hydrocarbon accumulation in Longtan reservoirs in Huangqiao region, Lower Yangtze Basin

Li Jianqing, Xia Zailian, Shi Haiying, Hua Caixia, Wang Xin

2013, 35(2): 195-198. doi: 10.11781/sysydz201302195

Abstract(1616) PDF-CN(799)

Abstract:
In the Longtan Formation of the Upper Permian in Huangqiao region of the Lower Yangtze Basin, there are 2 stages of fluid inclusion. The fluid inclusions of stage Ⅰ mainly generated during the early-middle period of quartz overgrowth, and generally located along micro-fractures within a linear zone. The fluid inclusions of stage Ⅱ mainly generated after quartz overgrowth, and distributed along micro-fractures which cut through quartz overgrowth. The homogenization temperature of fluid inclusions was 75-120℃, and the peak was 75-85℃. Analyses of geothermal evolution, burial history and hydrocarbon generation-expulsion history revealed that the main hydrocarbon generation period of the Longtan Formation source rocks was in Cretaceous, and oil charging mainly occurred in Jurassic (188-160 Ma) and from the Late Cretaceous to Paleocene (60-43 Ma). The Longtan reservoir mainly formed at the end of Cretaceous.

Analysis of shale fluid experiment data

Wang Min

2013, 35(2): 199-201. doi: 10.11781/sysydz201302199

Abstract(1513) PDF-CN(1167)

Abstract:
There is still no clear standard in determining oil volume of continental basin shale in domestic and abroad due to the lack of coring data and systematic research. Therefore the deeply understanding of fluid distribution law in shale is also lacked. Based on the laboratory conditions today, the water content, oil content and porosity of shale are measured by the atmospheric dry distillation method and the helium method. The experimental results show that the pore fluid distribution law in shale is different from conventional sandstone. 1) The sum of water saturation and oil saturation is greater than 100% in shale; 2) With the increasing of porosity, oil volume is also increasing while water volume is constant. A reasonable explanation for the phenomenon is given by analyzing the experiment methods and conditions. This understanding might be significant for the in-depth research and understanding of unconventional shale reservoir.

Reserve growth potential and exploration measures of oil-rich faulted basins in eastern China

Cheng Zhe, Xu Xuhui, Zou Yuanrong, Min Bin, Li Na

2013, 35(2): 202-206. doi: 10.11781/sysydz201302202

Abstract(1747) PDF-CN(677)

Abstract:
Based on the analysis of the resources and exploration potential of oil-rich faulted basins in the eastern work area of SINOPEC, it is found that these oil-rich basins are still in the peak of oil reserve growth. Through the study of reserve component, subtle reservoirs, such as stratigraphic, lithologic reservoirs, et al, and complex small fault block reservoirs are main exploration targets. The key zones still have large spaces for reserve growth. The main countermeasures of oil exploration at present are to strengthen the study of difference and quantitative evaluation of different reservoirs to deepen the understanding of hydrocarbon accumulation law and to carry out the secondary 3D seismic acquisition (including high resolution).

Flow unit division based on reservoir architecture：taking Fuyu-Yangdachengzi Formation in blocks Dong5-9 of Fuyu Oilfield as an example

Jiang Ping, Lü Mingsheng, Wang Guoting

2013, 35(2): 213-219. doi: 10.11781/sysydz201302213

Abstract(1585) PDF-CN(807)

Abstract:
Aiming at revealing the distribution of sandbody and the rule of fluid flowing in the Fuyu-Yangdachengzi Formation of the Fuyu Oilfield, the Fuyu Formation was divided into compound channel, single channel and accretion, and the Yangdachengzi Formation was divided into single channel, point bar and lateral accretion through hierarchical analysis. The relationship between architecture surfaces and flow barriers was summarized. Based on parameters such as porosity, permeability, FZI, remaining oil saturation and water driving index, four types of flow units with their own judging standard were classified as to the Fuyu-Yangdachengzi Formation. Combining with reservoir architecture, there were five genetic types of flow unit. The relationship between flow unit and dynamic data demonstrated that the flow unit could forecast productivity, instruct the distribution of remaining oil and the effectiveness of producing.

Experimental simulation of burial dissolution of clay-bearing carbonate

Zhang Juntao, Wu Shixiang, Tang Dehai, Long Shengxiang

2013, 35(2): 220-223. doi: 10.11781/sysydz201302220

Abstract(1677) PDF-CN(665)

Abstract:
The burial dissolution process of claybearing carbonate was simulated with experiment in order to analyze the enrichment and occurrence of clay mineral. As the increase in pressure and temperature, clay mineral content increased at first and then decreased, with 80-160℃ as the turning point. Clay mineral mainly existed in crack, inclusion and residual crack. Dissolution rate increased as temperature and pressure increased, and obtained the biggest value at 160℃ and 48 MPa in experiment. The influence of clay content in carbonate on dissolution rate was not obvious, while the occurrence of clay mineral played a more important role. As dissolution continued, clay mineral delayed the increase of dissolution rate at 80-120℃; however, the influence weakened as temperature and pressure continued increasing.

Dynamic evaluation of oil-and-gas resources of Lishu Fault Depression in Songliao Basin

Zhang Xi, Song Zhengxiang, Xu Wen, Li Zhongbo

2013, 35(2): 224-230. doi: 10.11781/sysydz201302224

Abstract(2042) PDF-CN(859)

Abstract:
Based on the latest exploration progress of the Lishu Fault Depression in the southeastern uplift of the Songliao Basin, combined with seismic, drilling and geochemical testing data, it was evaluated in this paper the organic geochemical features of hydrocarbon source rocks in the study area. The distribution characteristics and hydrocarbon generation potential of source rocks were also analyzed. By means of basin simulation and reservoir scale sequence methods, reserve amount was calculated and resource potential was predicted. The calculation results were compared with the previous evaluations, and the reasons for resource amount changes were discussed.

2013 Vol. 35, No. 2

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