Quantitative thickness estimation below tuning thickness is a great challenge in seismic exploration. Most studies focus on the thin-beds whose top and bottom reflection coefficients are of equal magnitude and opposit...Quantitative thickness estimation below tuning thickness is a great challenge in seismic exploration. Most studies focus on the thin-beds whose top and bottom reflection coefficients are of equal magnitude and opposite polarity. There is no systematic research on the other thin-bed types. In this article, all of the thin-beds are classified into four types： thin-beds with equal magnitude and opposite polarity, thin-beds with unequal magnitude and opposite polarity, thin-beds with equal magnitude and identical polarity, and thin-beds with unequal magnitude and identical polarity. By analytical study, an equation describing the general relationship between seismic peak frequency and thin-bed thickness was derived which shows there is a Complex implicit non-linear relationship between them and which is difficult to use in practice. In order to solve this problem, we simplify the relationship by Taylor expansion and discuss the precision of the approximation formulae with different orders for the four types of thin-beds. Compared with the traditional amplitude method for thin-bed thickness calculation, the method we present has a higher precision and isn＇t influenced by the absolute value of top or bottom reflection coefficient, so it is convenient for use in practice.展开更多
Thin-bedded turbidites are important hydrocarbon-bearing reservoirs in many mature fields throughout the world.The type of turbidite depositional setting strongly influences vertical and horizontal continuity of the r...Thin-bedded turbidites are important hydrocarbon-bearing reservoirs in many mature fields throughout the world.The type of turbidite depositional setting strongly influences vertical and horizontal continuity of the reservoir.However,distinguishing between lobe and levee associated thin-bedded turbidites remains challenging due to their generally similar facies characteristics.This study aims to contribute some insights to this problem by conducting a detailed bed-scale facies analysis on the Early Miocene Temburong Formation exposed at Kampung Bebuloh,Labuan Island,Malaysia,which may uncover features that can help in differentiating between both depositional types.Six facies are recognized in the Temburong Formation,which are interpreted as low density turbidites(F1-F4),hybrid event beds(F5),and sustained turbidites(F6).Detailed facies and ichnology analysis reveal features which are consistent with a lobe fringe deposit rather than leveeassociated environment interpretation,including tabular bed geometries,presence of hybrid event beds,and the absence of thick-bedded channel-fill sandstones.Five facies associations are identified and interpreted as representing sub-environments within an overall lobe depositional setting.A diverse trace fossil assemblage,comprising the Nereites ichnofacies is consistent with a deep marine environment.Further identification of the Paleodictyon and Nereites sub-ichnofacies indicates a distal turbidite system setting,most likely lobe fringe.Based on the thick accumulation of FA2 and FA3 and no distinct observable vertical trend,the Early Miocene Temburong Formation in Labuan is interpreted as turbidites deposited at the fringes of lobe complexes rather than a single lobe fringe.Earlier works into the Temburong Formation in SW Labuan proposed a middle slope to proximal basin floor setting where the thin-bedded intervals were interpreted as potentially representing either levee deposits or the fringes of confined lobe deposits.Conversely,the Temburong Formation at Kampung Bebuloh exhibits characteristics of an unconfined lobe setting,suggesting an evolutionary change in depositional conditions over time.展开更多
The Daqing exploration area in the northern Songliao Basin has great potential for unconventional oil and gas resources,among which the total resources of tight oil alone exceed 109 t and is regarded as an important r...The Daqing exploration area in the northern Songliao Basin has great potential for unconventional oil and gas resources,among which the total resources of tight oil alone exceed 109 t and is regarded as an important resource base of Daqing oilfield.After years of exploration in the Qijia area,Songliao Basin,NE China,tight oil has been found in the Upper Cretaceous Qingshankou Formation.To work out tight oil’s geological characteristics,taking tight oil in Gaotaizi oil layers of the Upper Cretaceous Qingshankou Formation in northern Songliao Basin as an example,this paper systematically analyzed the geological characteristics of unconventional tight oil in Gao3 and Gao4 layers of the Qijia area,based on the data of the geological survey,well drilling journey,well logging,and test.It is that three sets of hydrocarbon source rocks(K2qn1,K2qn2+3,and K2n1)develop in the examined area,and exhibit excellent type I and II kerogens,high organic matter abundance,and moderate maturity.The reservoir is generally composed of thin-bedded mudstone,siltstone,and sandstone,and presents poor porosity(average 8.5 vol.%)and air permeability(average 4 mD).The main reservoir space primarily includes intergranular pores,secondary soluble pores,and intergranular soluble pores.Three types of orifice throats were identified,namely fine throat,extra-fine throat,and micro-fine throat.The siltstone is generally oil-bearing,the reservoirs with slime and calcium become worse oil-bearing,and the mudstone has no obvious oil-bearing characteristics.The brittleness indices of the sandstone in the tight oil reservoir range from 40%to 60%,and those of the mudstone range from 40%to 45%,indicating a better brittleness of the tight oil reservoir.Based on the study of typical core hole data,this paper gives a comprehensive evaluation of the properties of the tight oil and establishes a tight oil single well composite bar chart as well as the initial evaluation system with the core of properties in the tight oil reservoir.This study has theoretical guiding significance and practical application value for tight oil exploration and evaluation in the Qijia area.展开更多
砂岩油气储层在地震剖面上一般表现为“亮点”,但钻探发现四川盆地中江气田的一些砂岩储层在地震剖面上表现为“暗点”,不易识别。这里依据钻测井资料,采用地震正演模拟方法分析了这些储层地震响应表现为“暗点”的机制,认为是Ⅱb类AVO(...砂岩油气储层在地震剖面上一般表现为“亮点”,但钻探发现四川盆地中江气田的一些砂岩储层在地震剖面上表现为“暗点”,不易识别。这里依据钻测井资料,采用地震正演模拟方法分析了这些储层地震响应表现为“暗点”的机制,认为是Ⅱb类AVO(Amplitude variation with offset)响应砂岩在特定厚度的薄层调谐作用下,在叠前道集中发生了极性反转,从而使得原本在叠后剖面上应为较“亮点”的反射变成了“暗点”。针对这种储层隐蔽机制,采用高分辨处理与AVO分析相结合的方法,成功识别出了消隐的河道砂储层,为“暗点”型薄砂岩储层的识别提供了可参考的成功范例。展开更多
基金supported by National Key S&T Special Projects of Marine Carbonate 2008ZX05000-004CNPC Projects 2008E-0610-10
文摘Quantitative thickness estimation below tuning thickness is a great challenge in seismic exploration. Most studies focus on the thin-beds whose top and bottom reflection coefficients are of equal magnitude and opposite polarity. There is no systematic research on the other thin-bed types. In this article, all of the thin-beds are classified into four types： thin-beds with equal magnitude and opposite polarity, thin-beds with unequal magnitude and opposite polarity, thin-beds with equal magnitude and identical polarity, and thin-beds with unequal magnitude and identical polarity. By analytical study, an equation describing the general relationship between seismic peak frequency and thin-bed thickness was derived which shows there is a Complex implicit non-linear relationship between them and which is difficult to use in practice. In order to solve this problem, we simplify the relationship by Taylor expansion and discuss the precision of the approximation formulae with different orders for the four types of thin-beds. Compared with the traditional amplitude method for thin-bed thickness calculation, the method we present has a higher precision and isn＇t influenced by the absolute value of top or bottom reflection coefficient, so it is convenient for use in practice.
基金Farah Syafira Burhanuddin reports financial support was provided by ConocoPhillips Company.
文摘Thin-bedded turbidites are important hydrocarbon-bearing reservoirs in many mature fields throughout the world.The type of turbidite depositional setting strongly influences vertical and horizontal continuity of the reservoir.However,distinguishing between lobe and levee associated thin-bedded turbidites remains challenging due to their generally similar facies characteristics.This study aims to contribute some insights to this problem by conducting a detailed bed-scale facies analysis on the Early Miocene Temburong Formation exposed at Kampung Bebuloh,Labuan Island,Malaysia,which may uncover features that can help in differentiating between both depositional types.Six facies are recognized in the Temburong Formation,which are interpreted as low density turbidites(F1-F4),hybrid event beds(F5),and sustained turbidites(F6).Detailed facies and ichnology analysis reveal features which are consistent with a lobe fringe deposit rather than leveeassociated environment interpretation,including tabular bed geometries,presence of hybrid event beds,and the absence of thick-bedded channel-fill sandstones.Five facies associations are identified and interpreted as representing sub-environments within an overall lobe depositional setting.A diverse trace fossil assemblage,comprising the Nereites ichnofacies is consistent with a deep marine environment.Further identification of the Paleodictyon and Nereites sub-ichnofacies indicates a distal turbidite system setting,most likely lobe fringe.Based on the thick accumulation of FA2 and FA3 and no distinct observable vertical trend,the Early Miocene Temburong Formation in Labuan is interpreted as turbidites deposited at the fringes of lobe complexes rather than a single lobe fringe.Earlier works into the Temburong Formation in SW Labuan proposed a middle slope to proximal basin floor setting where the thin-bedded intervals were interpreted as potentially representing either levee deposits or the fringes of confined lobe deposits.Conversely,the Temburong Formation at Kampung Bebuloh exhibits characteristics of an unconfined lobe setting,suggesting an evolutionary change in depositional conditions over time.
基金funded by the shale oil and gas geological survey project in Quemoco sag,Qiangtang Basin of China Geological Survey(DD20221855,DD20230315).
文摘The Daqing exploration area in the northern Songliao Basin has great potential for unconventional oil and gas resources,among which the total resources of tight oil alone exceed 109 t and is regarded as an important resource base of Daqing oilfield.After years of exploration in the Qijia area,Songliao Basin,NE China,tight oil has been found in the Upper Cretaceous Qingshankou Formation.To work out tight oil’s geological characteristics,taking tight oil in Gaotaizi oil layers of the Upper Cretaceous Qingshankou Formation in northern Songliao Basin as an example,this paper systematically analyzed the geological characteristics of unconventional tight oil in Gao3 and Gao4 layers of the Qijia area,based on the data of the geological survey,well drilling journey,well logging,and test.It is that three sets of hydrocarbon source rocks(K2qn1,K2qn2+3,and K2n1)develop in the examined area,and exhibit excellent type I and II kerogens,high organic matter abundance,and moderate maturity.The reservoir is generally composed of thin-bedded mudstone,siltstone,and sandstone,and presents poor porosity(average 8.5 vol.%)and air permeability(average 4 mD).The main reservoir space primarily includes intergranular pores,secondary soluble pores,and intergranular soluble pores.Three types of orifice throats were identified,namely fine throat,extra-fine throat,and micro-fine throat.The siltstone is generally oil-bearing,the reservoirs with slime and calcium become worse oil-bearing,and the mudstone has no obvious oil-bearing characteristics.The brittleness indices of the sandstone in the tight oil reservoir range from 40%to 60%,and those of the mudstone range from 40%to 45%,indicating a better brittleness of the tight oil reservoir.Based on the study of typical core hole data,this paper gives a comprehensive evaluation of the properties of the tight oil and establishes a tight oil single well composite bar chart as well as the initial evaluation system with the core of properties in the tight oil reservoir.This study has theoretical guiding significance and practical application value for tight oil exploration and evaluation in the Qijia area.
文摘砂岩油气储层在地震剖面上一般表现为“亮点”,但钻探发现四川盆地中江气田的一些砂岩储层在地震剖面上表现为“暗点”,不易识别。这里依据钻测井资料,采用地震正演模拟方法分析了这些储层地震响应表现为“暗点”的机制,认为是Ⅱb类AVO(Amplitude variation with offset)响应砂岩在特定厚度的薄层调谐作用下,在叠前道集中发生了极性反转,从而使得原本在叠后剖面上应为较“亮点”的反射变成了“暗点”。针对这种储层隐蔽机制,采用高分辨处理与AVO分析相结合的方法,成功识别出了消隐的河道砂储层,为“暗点”型薄砂岩储层的识别提供了可参考的成功范例。
