石油实验地质

2013, 35(5)

Abstract(563) PDF-CN(639)

Abstract:

Evaluation of selected areas for petroleum exploration in marine strata of Lower Yangtze region

Jin Zhijun, Liu Guangxiang, Fang Chengming, Zhang Changjiang, Peng Jinning

2013, 35(5): 473-479. doi: 10.11781/sysydz201305473

Abstract(1030) PDF-CN(926)

Abstract:
From Paleozoic to Mesozoic, multiple types of basins developed in the Lower Yangtze region, forming 2 sets of petroleum assemblages of marine facies (the lower one and the upper one). Influenced by the tectonic deformation and basin superposition during Indosinian-middle Yanshanian and late Yanshanian-Himalayan periods, the generation, evolution, migration and accumulation of petroleum in marine strata are very complicated. As a result, it is difficult to select favorable zones for petroleum exploration in traditional ways. Based on the theory of “source and cap rocks control hydrocarbon”, the relationships between hydrocarbon kitchen and cap rock at the end of Caledonian, the end of Indosinian, the end of middle Yanshanian and present days are discussed, and the favorable zones for petroleum accumulation and preservation are predicted. An accumulation prediction model of multiple layers, stages and elements is applied to point out favorable zones for exploration.

Hydrocarbon origin and source in east section of Dinan salient of Junggar Basin

Li Lin, Chen Shijia, Yang Disheng, Lu Jungang, Zou Hongliang, Yuan Bo, Liu Chaowei, Zhang Huanxu, Xu Huaimin

2013, 35(5): 480-486. doi: 10.11781/sysydz201305480

Abstract(925) PDF-CN(705)

Abstract:
Oil reservoirs with certain scale have been formed in the east section of Dinan salient, the Junggar Basin. The crude oils are characterized by high density and high viscosity. Several hydrocarbon-generation sags have been found in the region. Many sets of source rocks exist in the longitudinal direction, and they all have hydrocarbon supplying possibility. According to the physical and geochemical properties of crude oils, it has been concluded that the crude oils in the study area are characterized by light carbon isotope and high abundance of C₂₈ sterane. The sterane has higher maturity than crude oils themselves and Permian source rocks from the Wucaiwan Sag. The saturated hydrocarbon chromatograms of crude oils and reservoir extracts are incomplete with severe damage of light components and n-alkanes, which can be explained by biodegradation effect on mature hydrocarbon sourced from Permian of the Dongdaohaizi Sag. The analyses of natural gas composistions and carbon isotopes have indicated that the natural gas is dry gas with heavier ethane carbon isotope and lighter methane carbon isotope, and is associated with biodegraded oil. It is the mixture of crude oil degraded by bacteria and the product of high-over mature stage of Carboniferous. The next exploration direction should be extended to the Dongdaohaizi Sag, and the preserve conditions in the downward inclined part of structure are better. The common plugging of degraded heavy oil and tight reservoir could form lithologic trap, which is beneficial to capture oil and gas of high mature stage in the sag.

MaincontrollingfactorsforpetroleumaccumulationinKongqueheslope, TarimBasin

Zhao Yongqiang, Zhang Genfa, Wang Bin, Luo Yu, Zhou Yushuang, Lin Xueqing, Chen Xuyun

2013, 35(5): 487-494. doi: 10.11781/sysydz201305487

Abstract(1122) PDF-CN(867)

Abstract:
Petroleum generation in the Kongquehe slope is closely related with paleostructure during the late Caledonian Movement. Paleostructural background is the key for accumulation. The space -time matching relationship between the peak of hydrocarbon expulsion of source rock and the trap formation works as the main controlling factor. The traps with paleostructural background are favorable exploration targets. The main source rocks from Cambrian and Middle-Lower Ordovician become mature and over-mature during the middle and late Caledonian stage, and do not generate hydrocarbon during the late period. Traps are formed during the late Caledonian and the middle Yanshanian stages. The studies of accumulation stage, exploration practice and conditions of crude oil cracked gas prove that the discovered oil and gas in the Kongquehe slope may be early primary petroleum accumulations.

Hydrocarbon migration and accumulation model of fractured-vuggy reservoir under unconformity surface: A case study of carbonate reservoir in Tarim Basin

Guo Qiulin, Yang Wenjing, Xiao Zhongyao, Lu Yuhong, Xie Hongbing, Gao Rili, Huang Shaoying

2013, 35(5): 495-499. doi: 10.11781/sysydz201305495

Abstract(1106) PDF-CN(820)

Abstract:
It is difficult to accurately evaluate petroleum resources or reserves in the fractured-vuggy carbonate rocks under unconformity surface using traditional volumetric method. This paper proposes a three-dimensional invasion percolation model (3D-IP) to simulate hydrocarbon migration and accumulation in fractured-vuggy carbonate rocks, based on three-dimensional geologic modeling, structure, porosity and the quantity of supplied hydrocarbon data. The model has 3 main points: (1) Trace migration paths along the direction with least resistance; (2) When an obstacle is encountered, oil and gas flow back; (3) When the balance between driving force and resistance is broken, oil and gas continue to migrate by finding the weakest points and paths. The model can make up for the inadequacy of the volumetric method. It can predict not only the amount of petroleum resources, but also their locations. By stochastic model experiment and practical application of Block S6 in Tazhong area of the Tarim Basin, this paper confirms the validity and superiority of the proposed model, and points out potential targets in Block S6, thus giving exploration direction of fractured-vuggy reservoir in the slope area.

Evidence of exposure erosion of Lower-Middle Ordovician top in Beiweixie region, middle Tarim Basin

Ma Qingyou, Sha Xuguang, Li Zongjie, Cao Zicheng

2013, 35(5): 500-504. doi: 10.11781/sysydz201305500

Abstract(987) PDF-CN(717)

Abstract:
Whether there was exposure erosion of the Lower-Middle Ordovician top in Beiweixie region of the middle Tarim Basin, it is critical to identify the controlling factors for reservoir development and exploration direction in the study area. Through the analyses of the reflection characteristics of new 3d seismic profile, R_o thermal evolution profile of drilled well, and δ¹³C, δ¹⁸O isotopes of fracture-filling calcites, it is concluded that the Lower-Middle Ordovician top may have suffered various degrees of exposure erosion in Beiweixie region under the action of the episode Ⅰ of the mid-Caledonian. Denudation degree increases approaching to the Tazhong No. Ⅰ fault belt, which enhances the oil and gas exploration potential of weathering crust karst areas of the episodeⅠof the mid-Caledonian in the study area.

Petroleum accumulation feature and history of Upper Paleozoic, Ordos Basin

Wu Qing, Xu Huazheng, Zhou Xinke, Na Weihong

2013, 35(5): 505-510. doi: 10.11781/sysydz201305505

Abstract(986) PDF-CN(702)

Abstract:
During the early burial period, the ground water of coal series in the Ordos Basin became weakly acidic, due to the release of organic acids from coal. The corrosion of oxygen-containing carboxylic acid then generated a large number of pores in aluminum silicate and made sandstone easily to be compacted. The following rise of formation temperature promoted the Al³⁺ and Si²⁺ complexation reduce to SiO₂, clay and ferrocalcite, which led to the regional sandstone densification. From the Late Jurassic to the Early Cretaceous, tectonic-thermal events resulted in the hydrocarbon generation of coal series and the vaporization of formation water, which promoted high-pressure fluid (methane and steam) flood the whole storage box. A basin-scale high-temperature and highpressure gas reservoir was founded. From the Late Cretaceous to Paleocene, the regional uplift and erosion of strata made the coal series burial depth decrease and the geothermal gradient decrease, so that vapor condensated into water, while the CH4 gas retained gradually. High-temperature and high-pressure gas reservoir was transformed into low-temperature and under-pressure reservoir.

Deep tectonic-thermal effects and inorganic gas reservoirs during Yanshanian period in volcanic basins along Yangtze River in Jiangsu and Anhui provinces

Fan Xiaolin

2013, 35(5): 511-514. doi: 10.11781/sysydz201305511

Abstract(918) PDF-CN(1009)

Abstract:
The Mesozoic volcanic basins along the Yangtze River in Jiangsu and Anhui provinces are closely related with large-scale magmatic eruption, intrusion and volcanism caused by the Yanshanian tectonic movement. According to geophysical data, deep tectonic-thermal effect during basin evolution and its geologic response are studied. The possibility for the discovery and exploration of unconventional new energy in the volcanic basins along the Yangtze River is discussed, and the potential for inorganic gas reservoirs in the volcanic basins is prospected.

Depositional system of Lower Jurassic Baitianba Formation in northwestern Sichuan Basin

He Jiang, Hu Xin, Zhang Benjian, Yin Hong, Ma Hualing, Nie Zhou, Feng Chunqiang, Chen Chao, Chen Bo

2013, 35(5): 515-522. doi: 10.11781/sysydz201305515

Abstract(1190) PDF-CN(704)

Abstract:
Glutenite reservoirs are widespread in the Baitianba Formation of the Lower Jurassic in the northwestern Sichuan Basin, showing a new field for expanding exploration of intrabasinal clastic rock gas pools. Based on detailed field profile observation, tracking contrast of strata and glutenite, and fine description of typical phase sequence, systematic studies of geologic background, source distribution, depositional system and evolution mode have been carried out. During the late Triassic, the Indosinian Movement laid the palaeostructure pattern of “steep west and gentle north” in early deposits of the Lower Jurassic in the northwestern Sichuan Basin. In the front of the Micang Mountain in the northeast, there was a closed stair-step thrust fold belt and the deformation intensity decreased progressively to the basin, which was favorable for the long distance transportation of deposits and served as the main sources. In the Longmen Mountain in the northwest, compressive orogenic activities took place, leading to steep terrain. Different sizes of alluvial fans formed from seasonal mountain stream before mountain, serving as the secondary sources. From mountain front to basin center, a depositional system from alluvial fan, fan delta to lacustrine developed.

Different distribution of lacustrine facies and its controlling factors during rifting stage, ZhuⅠand Zhu Ⅲ Depressions, Pearl River Mouth Basin

Liu Zhifeng, Wang Shenglan, Yin Binhao, Zhang Yang, Xiao Lingli

2013, 35(5): 523-527. doi: 10.11781/sysydz201305523

Abstract(1091) PDF-CN(881)

Abstract:
The distribution of lacustrine facies during rifting stage in the Zhu Ⅰ and Zhu Ⅲ Depressions of the Pearl River Mouth Basin shows that lacustrine facies spread much more widely in the Zhu Ⅰ Depression. It might be explained by the smaller extensional level of the Zhu Ⅲ Depression. The extensional level of a depression is affected by many factors, such as stress orientation, basement lithology and region faults. The differences of basement lithology, sag distribution, large potential fault below Cenozoic and sag-controlling fault orientation lead to the different extensional level of the Zhu Ⅰ and Zhu Ⅲ Depressions, and further control the different distribution of lacustrine facies.

Sedimentary characteristics of tight oil reservoir in Permian Lucaogou Formation, Jimsar Sag

Si Chunsong, Chen Nenggui, Yu Chaofeng, Li Yuwen, Meng Xiangchao

2013, 35(5): 528-533. doi: 10.11781/sysydz201305528

Abstract(1260) PDF-CN(949)

Abstract:
In the Permian Lucaogou Formation in the Jimsar Sag, lake and delta facies strata deposited, and rocks mainly include mudstone, carbonate and fine-grained clastic rock. Two tight oil cookies developed. The lower cookies are mainly in fine-grained clastic rocks, and generate in the microfacies of delta front distal bar and sheet sand. The upper cookies are mainly in crabonate rocks, and generate in the microfacies of beach bar of shore shallow lake. The upper and lower cookies are thick and widespread, indicating giant potential for tight oil reservoir.

Influence of reservoir bed heterogeneity on hydrocarbon accumulation: Taking beach-bar sandstone of upper fourth member of Eocene Shahejie Formation in Boxing oilfield as an example

Guo Song, Tan Lijuan, Lin Chengyan, Li Hongnan, Lü Xiuxiang

2013, 35(5): 534-538. doi: 10.11781/sysydz201305534

Abstract(888) PDF-CN(861)

Abstract:
Based on the analyses of logging data and experiment, it is discussed in this paper the reservoir bed heterogeneity and its effects on hydrocarbon accumulation in the upper fourth member of Eocene Shahejie Formation of the Boxing oilfield. The result shows that the beach-bar reservoir bed with thin interbedded sandstone has strong heterogeneity. Hydrocarbon distribution and property are extremely uneven. Influenced by diagenesis, beach-bar sandstone shows strong heterogeneity, leading to different reservoir bed qualities in different areas. Reservoir bed quality has a good correspondence with hydrocarbon-bearing property, and reservoir bed heterogeneity controls the accumulation and distribution of hydrocarbon as well as oil saturation. Simulated experiment indicates that the relationship between driving force and resistance has effects on hydrocarbon accumulation feature and weakens the control of hydrocarbon accumulation by reservoir bed heterogeneity to a specific extent.

Controlling factors and hydrocarbon significances of Miocene carbonate buildups in Central Luconia Basin

Ma Liangtao, Wang Chunxiu, Zheng Qiugen, Lei Baohua

2013, 35(5): 539-544. doi: 10.11781/sysydz201305539

Abstract(1072) PDF-CN(1043)

Abstract:
During the Middle -Late Miocene, the Central Luconia Basin was characterized by the extensive development of carbonate buildups. Tectonic activity strength, palaeogeomorphology, sea level alternation and the influx of terrestrial material dominated the development of carbonate buildups. 1) The basin remained stable throughout the Middle-Late Miocene, thereby facilitating carbonate deposition. 2) From Oligocene to the Early Miocene, due to extensional and strike-slip tectonics, it was formed in this area the NE-SW trending graben and horst which dominated the type and distribution of carbonate buildups. 3) The cycle of carbonate buildup growth was related to the cycle change of sea level. 4) From the late stage of the Middle Miocene to Pliocene, terrestrial materials migrated from the south and southeast of the basin, suppressed the growth of carbonate buildups, resulting in the plane difference of reservoir physical property. Finally, the reservoir-cap combination features and the controlling factors for petroleum accumulation in carbonate buildups were analyzed.

Content distribution and isotopic composition characteristics of sulfur in marine source rocks in Middle-Upper Yangtze region

Fu Xiaodong, Qiu Nansheng, Qin Jianzhong, Tenger, Liu Wenhui, Wang Xiaofang

2013, 35(5): 545-551. doi: 10.11781/sysydz201305545

Abstract(897) PDF-CN(814)

Abstract:
Marine hydrocarbon source rocks in the Middle-Upper Yangtze region are rich in sulfur compared with terrestrial source rocks. Significant differences exist in sulfur content of source rocks in different formations or in the same formation with different lithology. There are obvious positive correlations between sulfur content and TOC of source rock. Sulfur in marine source rock exists mainly in form of organic sulfur and pyritic sulfur. Elemental sulfur is common in soluble extracts of marine source rock, but it has a variable content and occupies a lower percentage of total sulfur content. The δ³⁴S value of sulfur in marine source rock has a broad variation range from -35‰ to 30‰. The average values of δ³⁴S of organic sulfur and elemental sulfur are negative with -8. 68‰ and -5. 65‰ respectively, and those of pyritic sulfur and sulfate sulfur are positive with 4. 15‰ and 2. 19‰ respectively.

Geochemical characteristics of crude oil and oil-source correlation in Yanchang Formation in Xingzichuan Oilfield, Ordos Basin

Bai Yubin, Gao Zhendong, Li Zhongfeng, Zhang Zhisheng, Zhu Jie, Zheng Hui

2013, 35(5): 552-558. doi: 10.11781/sysydz201305552

Abstract(777) PDF-CN(723)

Abstract:
There are significant differences between the crude oil in different horizons of Yanchang Formation, as is shown by the property, group composition, gas chromatography of saturated hydrocarbon, biomarker of terpane and sterane, comprehensive geological analyses. The crude oil properties of Chang-4+5 and Chang-6 are generally consistent and isogenous, whose difference may be related to migration fractionation effect and crude oil maturity. However, there exist obvious variances in the crude oil property between Chang-9 or Chang-10 and Chang-4+5 or Chang-6, indicating different maternal properties. The crude oils in Chang-9 and Chang-10 have relatively higher maturity, mirrored by the biomarkers of Ts/ Tm, C₂₉ββ / (ββ+αα) and αααC₂₉20S / (20S+20R), etc. The content of regular sterane in the crude oils in Chang-9 and Chang-10 shows different genesis. Thus, the comprehensive geological analyses and oil-source correlation manifest that the crude oils in Chang-4+5 and Chang 6 come from the source rocks of Chang-7, while the crude oils in Chang-9 generate from the Lijiapan shale, and the crude oils in Chang-10 may stem from the effective source rocks of Chang-92.

Geochemical characteristics of crude oil from lower Kalpintag Formation in SH9 well area, northern slope of middle Tarim Basin

Ma Zhongyuan, Huang Wei, Li Jingjing, Yang Suju, Zhu Xiuxiang, Zhang Li

2013, 35(5): 559-563. doi: 10.11781/sysydz201305559

Abstract(706) PDF-CN(787)

Abstract:
In the lower Kalpintag Formation in SH9 well area in the northern slope of the middle Tarim Basin, medium-light black oil has been discovered for the first time and is characterized by low viscosity, low sulphur content, low pour point and high wax content. The total hydrocarbon content and the saturated/ aromatic hydrocarbon ratio are high, while the carbon isotope is light, usually less than -31‰. Normal alkane totally shows the features of single peak and front peak types. The preservation of normal alkane is relatively complete with slight “drum kits” (UCM peak), showing slight degradation characteristics. The CPI value is 1.04 ~ 1.05 and the Pr/ Ph value is 0.84 ~0.94. Normal alkane has no odd-even predominance and has apparent phytane advantage. Regular sterane shows “V” type distribution. The relative content of C₂₈20R sterane is less than 25% and the content of C₂₉ sterane is higher than that of C₂₇ sterane. The relative contents of rearranged sterane, ascending pregnane and pregnane is relatively higher. The abundance of tricyclic terpane series is higher than that of hopane series, and the C₂₃ tricyclic terpane has abundance advantage in tricyclic terpane. The content of gammacerane is also higher. In the crude oil, sulfur fluorine is rich while triaromatic dinosterane and dinosterane are lack. Maturity parameter shows that the oil is mature. The Middle and Upper Ordovician serve as the main sources while the Middle and Lower Cambrian contribute little.

Discussion on methods of shale gas exploration evaluation

Liu Chaoying

2013, 35(5): 564-569. doi: 10.11781/sysydz201305564

Abstract(1034) PDF-CN(1135)

Abstract:
The methods and parameters for shale gas exploration evaluation of petroleum companies at home and abroad are discussed. The key elements for shale gas exploration evaluation are studied, focusing on enrichment and admissibility. An evaluation model of “enrichment probability-resource value” is established and some calculation formulas are proposed. The evaluation results are classified. Some blocks of SINOPEC in southeastern Sichuan Basin are evaluated by means of this method.

Experimental simulation of calculation on coefficient of downhole hydrocarbon gas dissolved into drilling fluids and its application on formation evaluation

Yang Mingqing, Li Sanguo, Wang Chengbiao

2013, 35(5): 579-582. doi: 10.11781/sysydz201305579

Abstract(906) PDF-CN(601)

Abstract:
When drilling bit has cut through strata, crushed rocks and gases are carried to ground by drilling fluid. Some of them are dissipated in the air immediately, and some are dissolved in drilling fluid. To detect the dissolved volume and volume fraction of hydrocarbon gas components is one of the most important methods to discover and evaluate oil-and-gas shows. Different hydrocarbon gas components have different dissolving capacities. And reservoir cannot be discovered and evaluated timely and accurately if the dissolving test of various hydrocarbon gases is just done. For this reason, a “dissolving coefficient” and its solving method are proposed for the first time. Through the dissolving test of various hydrocarbon gases with a rotary simulation device of drilling fluid in high temperature and high pressure, we recognize the dissolving coefficient in these circumstances. According to the dissolving coefficient, the true content of a certain hydrocarbon composition is calculated. This will be advantageous to discover and evaluate oil-and-gas shows timely and accurately.

Experimental study on threshold pressure gradient of CO2 miscible flooding in low permeability reservoir

Zhang Xing, Yang Shenglai, Wen Bo, Li Fangfang, Chen Hao, Nie Xiangrong, Ding Jingchen

2013, 35(5): 583-586. doi: 10.11781/sysydz201305583

Abstract(941) PDF-CN(729)

Abstract:
Threshold pressure gradient exists in the development of low permeability reservoir. The process of CO₂ miscible flooding is very complicated, demanding further research. It can be divided into 4 zones including original oil phase zone, frontal phase zone of gas injection, miscible oil phase zone and trailing phase zone of gas injection. Indoor short core experiments are used to study the threshold pressure gradient of different flooding. Studies show that the pressure gradient-flow diagrams of low permeability core are in concave distribution which is divided to nonlinear flow and linear flow. The main factors of threshold pressure gradient are fluid viscosity, effective permeability, fluid density, gas oil ratio, and so on. The threshold pressure gradient and core permeability are based on power function, and the index is about -0.482.

2013 Vol. 35, No. 5

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