石油实验地质

2011, 33(2)

Abstract(248) PDF-CN(319)

Abstract:

2011, 33(2): 102-102. doi: 10.11781/sysydz201102102

Abstract(548) PDF-CN(297)

Abstract:

Discussion of several problems in petroleum accumulation geologic research in Tahe Oil Field

Su Jiangyu, Yu Renlian

2011, 33(2): 105-112. doi: 10.11781/sysydz201102105

Abstract(4182) PDF-CN(1050)

Abstract:
Through geologic studies of petroleum accumulation in the Tahe Oil Field,several problems referring to source rock,heavy crude accumulation as well as migration and accumulation network were discussed.Key events of petroleum accumulation in the Tahe Oil Field were charted in order.The oilfield has multiple source rocks,3 sets of regional transportation formation as well as 4 sets of vertical migrating and adjusting "highway".Systematic studies of the oilfield may illustrate the multiple stages of accumulation and adjustment,and the compound distribution of reservoir.

Main characteristics and tectonic movement ages of fractures in Niaoshan region, west of Tarim Basin

Yang Haijun, Li Yuejun, Wu Genyao, Li Yong, Zeng Changmin, Zhao Yan, Tan Zejin

2011, 33(2): 113-119. doi: 10.11781/sysydz201102113

Abstract(2890) PDF-CN(1057)

Abstract:
The EW-trending Niaoshan deep fracture locates in the west of Tarim Basin.According to seismic section analyses,the Niaoshan deep fracture as well as the Luositage deep fracture to the north both thrusted to the north during Cretaceous,and extended downwards till the Lower-Middle Cambrian gypsum-salt layer.The Niaoshan shallow fracture thrusted northwards during Pleistocene,and continued to Holocene.The Niaoshan eastern fracture sheared right-laterally mainly in Cretaceous,forming transferring structural belt in EW-trending thrust belt together with the NW-trending Haimitage deep fracture.The Niaoshan northern fracture strike-slipped right-laterally during Miocene,playing the role of shearing transfer in the thrusting of NW-trending fracture.The tectonic styles in the Niaoshan and neighboring regions ever since the late Mesozoic were summarized into 2 sets of thrusting system with varied orientations,accompanied by 2 sets of shearing transfer.The Niaoshan region might not be a beneficial region for oil-and-gas exploration.Some suggestions for explorations in fracture well-developed regions were presented.

Hydrocarbon accumulation in Silurian updip pinch out traps, Tahe region, Tarim Basin

Guo Qian, Pu Renhai, Yang Lin, Sun Guofeng, Zhu Li, Chu Xianbo

2011, 33(2): 120-123. doi: 10.11781/sysydz201102120

Abstract(3185) PDF-CN(920)

Abstract:
High-yielding oil flow was found in Paleozoic clastic rocks in Well S112-2 of Tahe region in 2005.The oil flow is on the unconformity interface between Carboniferous and Silurian;hence the origin still remains discussion.Based on core,logging and seismic data,the date,tectonic and trap features of the Well S112-2 reservoir were concluded.2 types of sandstone updip pinch out trap exist in Silurian in the region: a) tongue-shape ones,with monocline at the top of sandbody and pinchout line leading to the north;b) nose-shape ones,with nose-shape structure at the top of sandbody and straight pinchout line.The nose-shape ones are new trap types which may have similar oil-bearing features in the region.

Characteristics and evaluation of fracture-pore reservoir of Ordovician Yingshan Formation in Bachu-Maigaiti region, Tarim Basin

Zhang Fushun, Li Jianjiao, Lin Dongsheng

2011, 33(2): 124-129. doi: 10.11781/sysydz201102124

Abstract(3184) PDF-CN(993)

Abstract:
Reservoir type of the Ordovician Yingshan Formation in the Bachu-Maigaiti region and the main controlling factors for favorable reservoir generation are the keys for further petroleum explorations in the region.Based on core observation,thin-section analysis and well-logging interpretation,the Ordovician reservoir is fracture-pore type.According to trace element and carbon or oxygen isotope analyses,the reservoirs include fractures and corrosion pores formed under closed burial diagenetic conditions.Fracture generation belt controlled by the Caledonian and Hercynian movements is favorable for the Yingshan Formation reservoir distribution.Karst plateau and slope formed by long-time denudation of the Hetian ancient uplift are qualified for epidiagenetic karst reservoir generation,and are important for further exploration.

Characteristics and origin of Cambrian dolomite, northern Tarim Basin

Xing Xiujuan, Jiao Cunli, Wang Yi, Zhang Tao, Liu Shilini

2011, 33(2): 130-136. doi: 10.11781/sysydz201102130

Abstract(3335) PDF-CN(981)

Abstract:
From the Northern Tarim Uplift to the southern margin of the Kuche Depression,the northern Tarim region is one of the largest hydrocarbon enrichment regions in the Tarim Basin.The Cambrian platform sediment is 1 000 m thick,and is an important exploration layer.Due to big thickness,various types and wide distribution,dolomite in the region is favorable for reservoir generation and is the main exploration target.Based on lithologic,isotopic and REE analyses of well cores and outcrops of Cambrian dolomites in the northern Tarim region,combined with temperature studies of fluid inclusions,it has been concluded that the Cambrian dolomites in the northern Tarim region have various structural types,including mud microcrystal,fine-medium crystal and coarse crystal.Besides penecontemporaneous and burial dolomitization effects,they were also influenced by tectonic and hydrothermal dolomitization effects,which were controlled by fault-fracture,unconformity and thermal flow,usually resulting in the coexistence of saddle dolomite and multiple hydrothermal minerals.The tectonic and hydrothermal dolomitization effects were important for favorable dolomite reservoir generation.Controlled by cycles of tectonic and diagenesis evolutions,ancient uplifts in the northern Tarim region were eroded for several times.Angular unconformity took place between Cambrian dolomite and Meso-zoic,and strong weathering crust karst effect generated.Deep and big faults worked as pathways for deep fluid to flow into dolomite.The dolomite was transformed into complex high-quality reservoir of different origin.

Generation conditions of continental shale gas in Biyang Sag, Nanxiang Basin

Chen Xiang, Yan Yongxin, Zhang Xinwen, Liu Hongtao, Xue Xiuli, Luo Xi

2011, 33(2): 137-141. doi: 10.11781/sysydz201102137

Abstract(3566) PDF-CN(1136)

Abstract:
Generation conditions of shale gas from the Hetaoyuan Formation in the Biyang Sag of the Nanxiang Basin were systematically studied according to the U.S.A marine shale gas evaluation index for the first time.The Hetaoyuan Formation extends widely with big thickness of single layer in the region.The TOC content is high and the thermal evolution degree is equivalent to that of Devonian basins in the U.S.A.The responses of gas-bearing shale in well logging are obvious.Micro-fracture and micro-pore are well-developed in shale,providing good condition for reserving.Gas is well preserved in shale.The high content of brittle minerals such as quartz is favorable for reservoir fracturing.Shale gas exploration prospect is bright in the Biyang Sag where is favorable for shale gas forming and the potential resource of shale gas is huge.

Reasons for abnormal thermal evolution of source rocks in Upper Paleozoic, southern North China

Cheng Zhe, Xu Xuhui, Wang Rongxin, Wu Minghui, Xin Lili

2011, 33(2): 142-147. doi: 10.11781/sysydz201102142

Abstract(3092) PDF-CN(876)

Abstract:
The Upper Paleozoic is widely distributed in southern North China with thick source rock and high organic abundance, mainly Ⅱ₂-Ⅲ type. Multiple stages of deformation during Indosinian, Yan-shanian and Himalayan resulted in the differences in thermal evolution degree between source rocks, which was the key factor for petroleum resource evaluation and exploration target identification in southern North China. Based on thermal evolution characteristics of source rocks in the Upper Paleozoic of the study area, the reasons for abnormal thermal evolution were found out, mainly hypozoic thermal metamorphism. Crust uplift during Mesozoic resulted in the south and north division of thermal evolution of source rocks in the Upper Paleozoic. Magmatism ever since Mesozoic was the root cause for regional high-degree thermal evolution. Regional dynamometamorphism and gravitational sliding also helped thermal evolution. Industrial petroleum resources in the Upper Paleozoic are mainly found around the edge of high thermal evolution zone, such as Yichuan of Luoyang-Xiangcheng of Juling-Luyi-Shenqiu of Tanzhuang-Niqiuji-Yanji. They are the regions favorable for Upper Paleozoic petroleum exploration in southern North China.

Exploration prospects of the Carboniferous and Permian in the southern North China

Xu Xianghua, Chen Xinjun, Lei Ming, Li Shujun, Zhou Xiaojin, Wu Minghui

2011, 33(2): 148-154. doi: 10.11781/sysydz201102148

Abstract(3065) PDF-CN(876)

Abstract:
Based on the study of the covered structures and analysis of the hydrocarbon evolution types in coal-bearing strata of southern North China, it was showed that there was good hydrocarbon source in the Carboniferous-Permian sequence. The thickness of original middle layer in coal-bearing strata, the Triassic and Jurassic-Cretaceous, was relatively thin. Some Neogene sags showed favorable potential such as three covered structures and late hydrocarbon generation. The coal-forming gas accumulation could be formed in the secondary hydrocarbon generation of Himalayan stage, so it was showed the good exploration prospects in southern North China. Based on the coal-forming gas accumulation features, the evaluation principle was proposed and some gainful exploration targets were evaluated.

Reservoir evaluation and effective pay thickness study of carbonate reservoir in Jiyang Depression, Bohai Bay Basin

Lu Guoming

2011, 33(2): 155-159. doi: 10.11781/sysydz201102155

Abstract(3836) PDF-CN(880)

Abstract:
Due to strong heterogeneity, various reservoir spaces and types as well as complicated formation structure and combination, it is difficult to evaluate reservoir and divide effective pay thickness for reservoir calculation in carbonate reservoir. Based on analyses of reservoir types and rock-electricity characteristics of carbonate buried-hill in the Jiyang Depression, using normal well-logging and imaging as well as nuclear magnetic logging technology, we qualitatively identified and quantitatively interpreted fracture, cave and pore. The effect of fracture, cave and pore was judged, and the division standard for effective pay thickness was established. A set of evaluation method suitable for the effective pay thickness of carbonate buried hill reservoir in the Jiyang Depression was put forward. Taking into consideration of the particularity and the drilling features of carbonate buried hill reservoir, a method for selecting effective pay thickness of reservoir unit was proposed.

Distribution and evolution of thermal field in middle and upper Yangtze region

Wang Hongjiang, Liu Guangxiang

2011, 33(2): 160-164. doi: 10.11781/sysydz201102160

Abstract(2012) PDF-CN(1014)

Abstract:
Based on 16 thermal evolution (R_o-H) profiles in the middle and upper Yangtze region, using methods such as R_o inversion, R_o-ΔR_o and the highest paleogeotem perature method, temperature gradients from the early Paleozoic to the beginning of late Paleozoic, the late Paleozoic to the Middle Triassic, the Late Triassic to Jurassic were restored. The corresponding temperature gradient distribution was also mapped. Thermal field distribution and evolution are closely related to regional structure, basin system and thermo-tectonic events. From the early Paleozoic to the beginning of late Paleozoic, the Middle and upper Yangtze region belonged to cratonic depressional basin. Heat flow value was low and increased from craton to passive continental margin. From the Late Paleozoic to the Middle Triassic, controlled by regional extension, continental margin subsidence and intracontinental rift had high heat flow value, and low value remained in craton. From the Late Triassic to Jurassic, foreland basin generated. High value existed in tectonic active area (foreland thrust belt, basement-involved detachment and cap rock detachment zones) and decreased into foreland basin.

Petroleum geologic features and exploration targets in Anda region, Songliao Basin

Zhao Bo

2011, 33(2): 165-170. doi: 10.11781/sysydz201102165

Abstract(4052) PDF-CN(1033)

Abstract:
Based on geologic, drilling, seismic and geochemical data, it was analyzed in this paper the tectonic evolution, source rock, sediment, reservoir-cap combination, oil-water relationship as well as accumulation type and characteristics in Anda region. Petroleum geologic features in the region were concluded as follows. Organic matter abundance of source rock is high, favorable for hydrocarbon generation and migration. Physical properties of sandbody reservoir in distributary channel are good, providing room for hydrocarbon accumulation. The favorable combination of reservoir and cap rock helps hydrocarbon accumulation and preservation. Fracture which leads to source rock works as pathway for hydrocarbon migration. Overpressure in mudstone in the 1st member of the Qingshankou Formation drives hydrocarbon to migrate. In the study area, water locates at the bottom and oil locates at the top. Reservoirs are mainly fault-lithology and lithology-tectonic ones. The Fuyu oil layer in the region is controlled by mature source rock, overpressure in the 1st member of the Qingshankou Formation, favorable migration pathway and reserve condition. Further exploration target in the region was pointed out.

Characteristics of volcanic reservoir of Yingcheng Formation in east Changling Fault Depression, Songliao Basin

Shi Yingmin, He Dengfa, Shi Shengqun

2011, 33(2): 171-176. doi: 10.11781/sysydz201102171

Abstract(2439) PDF-CN(905)

Abstract:
Explorations of volcanic reservoir have achieved great success in the east of the Changling Fault Depression of the Songliao Basin in the past few years. Gas is found in the Yingcheng Formation in many wells. Volcanic reservoir is the key for natural gas accumulation. Based on core, logging and testing data, volcanic reservoir was analyzed from origin and evaluated. Due to low porosity and permeability, pores and fractures are well connected in volcanic rock, providing relatively good condition for accumulation. Especially in rhyolite and tuff, there exist multiple types of pores and fractures, including both primary ones generated during diagenetic stage and secondary ones transformed by later slacking. Reservoir parameters are closely related to rock density, rather than burial depth. Different volcanic facies have different reservoir condition due to different composition. The overflow and outbreak phases are favorable for reservoir formation. Besides, weather-worn may influence reservoir formation. Unconformities are also beneficial for reservoir formation.

Physical properties and influencing factors of volcanic rock reservoir, Yingcheng Formation, Changling Fault Depression

Zhang Yanxia, Wang Baohua, Lu Jianlin

2011, 33(2): 177-181. doi: 10.11781/sysydz201102177

Abstract(3471) PDF-CN(947)

Abstract:
Volcanic rock of the Yingcheng Formation in the Changling Fault Depression has made great contribution to increase reserve and production. Based on analyses of physical property, pore structure and seepage characteristics of volcanic rock reservoir, it has been concluded that volcanic rock reservoir in the region has low and extra-low porosity and permeability. Fracture seepage dominates in gas reservoir. Lithologic property, lithofacies and epigenesis effect of volcanic rock are the main controlling factors for physical property. Secondary pores and fractures generated during epigenesist, and were the key factors for reservoir deformation and improvement.

Identification of chief hydrocarbon source rocks based on n-alkane distribution patterns in western Qaidam Basin

Song Zhenxiang, Zhou Shixin, Mu Yapeng, Chen Zhao

2011, 33(2): 182-187. doi: 10.11781/sysydz201102182

Abstract(3333) PDF-CN(914)

Abstract:
The n-alkane distribution of crude oils from the western Qaidam Basin is characterized by even-to-odd (C₁₈—C₂₈) predominance. Source rocks from the region are mainly characterized by odd-to-even predominance. Based on n-alkane distribution pattern, combined with single molecule carbon isotope analysis, comparing crude oil with source rock, it was discussed in this paper the main source rocks in the western Qaidam Basin. The correlation of n-alkane distribution and single molecule carbon isotope analysis illustrated that the chief hydrocarbon source layer was E₂₃ and the secondary layers were E₁₊₂ and N₃₁ in deep region. Meanwhile, the chief hydrocarbon source layer was N₁ and the secondary layer was N₂ in shallow region. Hydrocarbon potential analysis showed that those samples with even-to-odd (C₁₈—C₂₈) predominance possessed higher TOC, bitumen "A", total hydrocarbon content and conversion ratio, displaying huge hydrocarbon generating potential.

Application of colonial inclusions geochemistry in oil-and-gas origin study

Mi Jingkui, Zhang Shuichang, He Kun

2011, 33(2): 188-192. doi: 10.11781/sysydz201102188

Abstract(3400) PDF-CN(853)

Abstract:
Although the geochemical characteristics of colonial inclusions do not work as well as those of single inclusion in oil-and-gas origin and accumulation analyses, they are still reliable and important ways to study oil-and-gas origin at present. Studies of the geochemical characteristics of colonial inclusions in sandstone reservoir (Silurian, the Tarim Basin) and carbonate reservoir under salt layer (Ordovician, the Ordos Basin) indicated that, the biomarkers of crude oil from inclusions in sandstone reservoir (Silurian, the Tarim Basin) were the same as those of present saved crude oil which originated from the middle and upper Ordovician. The geochemical characteristics of gas in under-salt inclusions (well Longtan1, the lower Paleozoic, the Ordos Basin) were different from those of gas from the central gas fields. δ¹³ C₂ could not demonstrate natural gas origin due to big changes. The geochemical comparison between gas from inclusions and gas from gas pools proved that the natural gas found in the lower Paleozoic of the Ordos Basin was coal origin.

Relationship between reservoir bitumen and hydrocarbon migration in Dabei region, Kuqa Foreland Basin

Zhuo Qingong, Zhao Mengjun, Xie Huiwen, Fang Shihu, Li Mei

2011, 33(2): 193-196. doi: 10.11781/sysydz201102193

Abstract(3217) PDF-CN(963)

Abstract:
Based on systematic analyses of microscopic characteristics, thermal maturation and biomarker compounds of reservoir bitumen, it was discussed in this paper the bitumen origin as well as the hydrocarbon migration and accumulation in Dabei region of the Kuqa Foreland Basin. A little black resin bitumen was observed in microscopic fractures of sandstone reservoir under salt bed of the Kumugeliemu Group in Dabei region. 2 groups of bitumen were found in well Dabei202, with reflectivity of 1.07% and 0.47%. 1 group of bitumen was found in well Tubei1, with reflectivity of 0.43%, and its content was very rare. Solid bitumen in reservoir was the result of mixed precipitation of oil and gas of different origin and stage. Therefore, natural gas in Dabei region is not originated from crude oil cracking. At least 3 stages of hydrocarbon charging took place in under-salt traps such as Dabei1 and Dabei2. Crude oil in ancient reservoir migrated into shallow sandstone along the Kelasu thrust fault in the north, and then accumulated in the Dawanqi anticline. Reservoir bitumen was found in well Tubei1 near the Kelasu thrust fault, indicating that sandstone worked as the pathway for hydrocarbon migration. Hydrocarbon might accumulate in the higher part of the fault block. The research illustrated the origin of natural gas in the Kelasu structural belt, and might guide ancient reservoir exploration in the region.

Grouped fluid inclusion composition analysis and application in Shaya Uplift

Xu Jin, Zheng Lunju, Jia Cunshan, Xi Binbin

2011, 33(2): 197-201. doi: 10.11781/sysydz201102197

Abstract(2787) PDF-CN(891)

Abstract:
The improved composition analysis method for grouped fluid inclusion may collect gas, light and heavy hydrocarbons at the same time. Liquid nitrogen is used to freeze samples and break them into single minerals, keeping crystal form unchanged. Ball milling is applied to open fluid inclusion whose components and properties are protected during this process. Composition analyses of free hydrocarbon, adsorbed hydrocarbon and petroleum inclusion in 9 reservoir samples from the Shaya Uplift have indicated that, the compositions of gas and light hydrocarbon in inclusions may be used judge sample maturity. The biomarker and carbon isotope of liquid hydrocarbons may show the differences in sedimentary environment and accumulation.

TLC-FID to predict viscosity of heavy oil in reservoir

Wang Shuangqing, Sun Weilin, Shen Bin, Wang Lei

2011, 33(2): 202-205. doi: 10.11781/sysydz201102202

Abstract(2059) PDF-CN(879)

Abstract:
A thin layer chromatography-flame ionization detection (TLC-FID) technique was introduced in this paper to predict the viscosity of heavy oil in reservoir. The new method was convenient, efficient and economic. It took 3 steps. First, representative heavy oil samples were collected from oilfield, and the relative mass-to-area responses of aliphatic, aromatic, resin and asphaltene fractions of oil were determined respectively through preparing the fractions with column liquid chromatograph. Second, TLC-FID analysis and viscosity test of a certain amount of heavy oil samples were carried out, establishing an exponent mathematical relationship between them. Finally, viscosity of the to-be-predicted heavy oil could be calculated with TLC-FID data of the extract of oil sand according to above relationship. The method was practiced to establish viscosity profile of single well in an oil production area of China through analyzing 27 heavy oils from the area and 152 extracts of oil sands from the well, and the result achieved was reasonable.

Pore throat characteristics of extra-ultra low permeability sandstone reservoir based on constant-rate mercury penetration technique

Gao Hui, Xie Wei, Yang Jianpeng, Zhang Chuang, Sun Wei

2011, 33(2): 206-211. doi: 10.11781/sysydz201102206

Abstract(3142) PDF-CN(1270)

Abstract:
Based on constant-rate mercury penetration technique, micro pore throat characteristics of extraultra low permeability sandstone reservoir of the Yangchang Formation in the Ordos Basin were analyzed, and the alterations of pore throat characteristic parameters were also quantitatively characterized. Pore radiuses were similar, usually 100～200 μm, and the peak values were about 140 μm. Compared to those in the extra-low permeability reservoir, distribution ranges of throat in the ultra-low permeability reservoir were narrow. Throats less than 1 μm accounted for large amount, and were more sensitive to permeability. Distribution ranges of pore throat radius ratio were wide and permeability had big influence on input mercury saturation of throat in ultra-low permeability reservoir. The differences of pore throat characteristics between extra-and ultra-low permeability sandstone reservoir mainly lay in throats. 3 variation periods were identified on overall capillary pressure curves. Each period was affected by pore or throat in different extent due to different permeability. Throats should be focused on in the ultra-low permeability reservoir during the middle and latter stages.

Experimental study of stress sensitivity in abnormal overpressure gas reservoir

Pan Weiyi, Lun Zengmin, Wang Weihong, Liu Hua

2011, 33(2): 212-214. doi: 10.11781/sysydz201102212

Abstract(2864) PDF-CN(925)

Abstract:
In abnormal overpressure reservoir, pressure coefficient is high and percolation flow mechanism is different from those of conventional reservoir. During development, rock may deform, influencing production greatly. So, it is very important to carry out stress sensitivity research in abnormal overpressure reservoir. With superhigh pressure core displacement method, stress sensitivity experiments were done in matrix, fracture filled and fractured core samples. It is concluded that abnormal overpressure reservoir is very sensitive to stress. As net confined pressure increases, permeability decreases quickly at first, and then becomes stable, corresponding to power exponent form. Matrix core has the strongest stress sensitivity, fracture filled core the second, and fractured core the worst. Rock in deforms weakly when stressed, mainly plastic. The stress sensitivity of core is irreversible.

Ultimate potential resource prediction and exploration target in East Depression, Baise Basin

Luo Yi, Cai Xunyu, Lü Liyong

2011, 33(2): 215-218. doi: 10.11781/sysydz201102215

Abstract(2561) PDF-CN(900)

Abstract:
The confirmed recoverable oil resource was estimated to be 37.59% in the East Depression of the Baise Basin. By means of reservoir scale sequence, the ultimate potential resource of the depression was predicted, indicating 35 reservoirs and 2 836×10⁴ t reserves remained to be discovered. 11 undiscovered reservoirs (total reserves 1 622×10⁴ t) had the reserves of more than 100×10⁴ t. 24 undiscovered reservoirs (total reserves 1 214×10⁴ t) had the reserves of less than 100×10⁴ t. The difference between predicted and actual oil reserves was less than 10%. The resources remained to be discovered mainly located in covered oil reservoirs in the Central Sag, delta sandbodies and beach-bar sandbodies in the Southern Slope, pre-Tertiary buried hill, glutenite and red bed in the steep slope and shale in the Nadu Formation.

2011 Vol. 33, No. 2

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