A quantitative evaluation model that integrates kerogen adsorption and clay pore adsorption of shale oil was proposed,and the evaluation charts of adsorption-swelling capacity of kerogen(Mk)and adsorbed oil capacity o...A quantitative evaluation model that integrates kerogen adsorption and clay pore adsorption of shale oil was proposed,and the evaluation charts of adsorption-swelling capacity of kerogen(Mk)and adsorbed oil capacity of clay minerals(Mc)were established,taking the 1st member of Cretaceous Qingshankou Formation in the northern Songliao Basin as an example.The model and charts were derived from swelling oil experiments performed on naturally evolved kerogens and adsorbed oil experiments on clays(separated from shale core samples).They were constructed on the basis of clarifying the control law of kerogen maturity evolution on its adsorption-swelling capacity,and considering the effect of both the clay pore surface area that occupied by adsorbed oil and formation temperature.The results are obtained in four aspects:(1)For the Qing 1 Member shale,with the increase of maturity,Mk decreases.Given Ro of 0.83%–1.65%,Mk is about 50–250 mg/g.(2)The clay in shale adsorbs asphaltene.Mc is 0.63 mg/m^(2),and about 15%of the clay pore surface is occupied by adsorbed oil.(3)In the low to medium maturity stages,the shale oil adsorption is controlled by organic matter.When Ro>1.3%,the shale oil adsorption capacity is contributed by clay pores.(4)The oil adsorption capacity evaluated on the surface at room temperature is 8%–22%(avg.15%)higher than that is held in the formations.The proposed evaluation model reveals the occurrence mechanisms of shale oils with different maturities,and provides a new insight for estimating the reserves of shale oil under formation temperature conditions.展开更多
The common microscale to nanoscale pore types were introduced and divided into organic and inorganic pores to estimate their contributions to porosity in the Lower Silurian Longmaxi Formation shale of southeast Chongq...The common microscale to nanoscale pore types were introduced and divided into organic and inorganic pores to estimate their contributions to porosity in the Lower Silurian Longmaxi Formation shale of southeast Chongqing. Following the material balance principle, the organic porosity values, which changed with formation subsidence and thermal evolution, were calculated using chemical kinetics methods and corrected via the organic porosity correction coefficient, which was obtained from field emission scanning electron microscopy. Grain density values were determined using the contents and true densities of compositions in the shale samples. The total porosity was calculated based on the grain and bulk densities. The inorganic porosity was determined from the difference between the total porosity and organic porosity at the same depth. The results show that inorganic pores mainly contain microfractures, microchannels, clay intergranular pores, intercrystalline pores and intracrystalline pores in the Lower Silurian Longmaxi Formation shale of southeast Chongqing. Organic pores mainly include organopore and fossil pore. The total porosity, organic porosity and inorganic porosity of organic-rich shale samples can be quantitatively evaluated using this method. The total porosity, organic porosity and inorganic porosity values of the Longmaxi Formation shale samples from the well Pyl in southeast Chongqing lie in 2.75%-6.14%, 0.08%-2.52% and 1.41%-4.92% with average values of 4.34%, 0.95% and 3.39%, respectively. The contributions of the inorganic pores to the total porosity are significantly greater than those of the organic pores.展开更多
The mechanical properties such as Young's modulus, hardness and fracture toughness of Lower Silurian Longmaxi shale samples from Youyang area in southeast Chongqing, China were investigated using dot matrix nanoin...The mechanical properties such as Young's modulus, hardness and fracture toughness of Lower Silurian Longmaxi shale samples from Youyang area in southeast Chongqing, China were investigated using dot matrix nanoindentation measurements. With the help of field emission scanning electron microscope(FESEM) and energy dispersive X-ray fluorescence spectroscopy(EDS), the indentation morphology and mineral composition in indentation area were quantitatively analyzed. According to mechanical strength classification, a micromechanical model with three components was introduced and the Mori-Tanaka model was used to upscale mechanical parameters from nano-scale to centimeter-size scale, which were further compared with uniaxial compression results. The experimental results show that there is a positive linear correlation between Young's modulus and hardness and between the Young's modulus and the fracture toughness under nano-scale; the Young's modulus, hardness and fracture toughness perpendicular to the bedding are slightly lower than those parallel with the bedding. According to data statistics, the mechanical properties at the nano-scale follow Weibull distribution feature and the dispersion degree of hardness results is the highest, which is mainly due to shale anisotropy and nanoindentation projection uncertainty. Comparing the results from nanoindentation test, with those from upscaling model and uniaxial compression test shows that the mechanical parameters at the nano-scale are higher than those from upscaling model and uniaxial compression test, which proves mechanical parameters at different scales have differences. It's because the larger the core, the more pores and internal weakness it contains, the less accurate the interpreted results of mechanical parameters will be.展开更多
On the basis of the characterization of microscopic pore-throats in shale oil reservoirs by high-pressure mercury intrusion technique, a grading evaluation standard of shale oil reservoirs and a lower limit for reserv...On the basis of the characterization of microscopic pore-throats in shale oil reservoirs by high-pressure mercury intrusion technique, a grading evaluation standard of shale oil reservoirs and a lower limit for reservoir formation were established. Simultaneously, a new method for the classification of shale oil flow units based on logging data was established. A new classification scheme for shale oil reservoirs was proposed according to the inflection points and fractal features of mercury injection curves: microscopic pore-throats(less than 25 nm), small pore-throats(25-100 nm), medium pore-throats(100-1 000 nm) and big pore-throats(greater than 1 000 nm). Correspondingly, the shale reservoirs are divided into four classes, I, II, III and IV according to the number of microscopic pores they contain, and the average pore-throat radii corresponding to the dividing points are 150 nm, 70 nm and 10 nm respectively. By using the correlation between permeability and pore-throat radius, the permeability thresholds for the reservoir classification are determined at 1.00× 10^(-3) μm^2, 0.40×10^(-3) μm^2 and 0.05×10^(-3) μm^2 respectively. By using the exponential relationship between porosity and permeability of the same hydrodynamic flow unit, a new method was set up to evaluate the reservoir flow belt index and to identify shale oil flow units with logging data. The application in the Dongying sag shows that the standard proposed is suitable for grading evaluation of shale oil reservoirs.展开更多
Inspired by the successful development of shale oil/gas exploration in North American, multiple continental oil fields in China have vigorously put forward its evaluation and exploration of shale oil. However, the out...Inspired by the successful development of shale oil/gas exploration in North American, multiple continental oil fields in China have vigorously put forward its evaluation and exploration of shale oil. However, the outcomes of shale oil drilling in China are not well as expected.展开更多
1 Introduction The importance of the unconventional petroleum is increasingly prominent, with the rising demand of oil and gas in the economic and social development and the gradual consumption and depletion of conven...1 Introduction The importance of the unconventional petroleum is increasingly prominent, with the rising demand of oil and gas in the economic and social development and the gradual consumption and depletion of conventional oil and gas resources. Compared with the shale and coal-bed gas reservoir, tight reservoir has better fracturing capability.展开更多
1 Introduction Petrological characteristics （such as brittle mineral content）, miero-nanoscale porosity, total organic carbon and organic matter maturity of shale play important roles in the accumulation and explora...1 Introduction Petrological characteristics （such as brittle mineral content）, miero-nanoscale porosity, total organic carbon and organic matter maturity of shale play important roles in the accumulation and exploration of shale gas. The nanometre pores in shale are mostly organopores （pores within organic matters in shale） created from hydrocarbon generation during formation subsidence and thermal evolution （Loucks et al., 2009; Liu et al., 2011; Chalmers et al., 2012）.展开更多
Based on the microscopic pore-throat characterization of typical continental tight reservoirs in China,such as sandstone of Cretaceous Qingshankou and Quantou formations in Songliao Basin,NE China sandy conglomerate o...Based on the microscopic pore-throat characterization of typical continental tight reservoirs in China,such as sandstone of Cretaceous Qingshankou and Quantou formations in Songliao Basin,NE China sandy conglomerate of Baikouquan Formation in Mahu area and hybrid rock of Lucaogou Formation in Jimusaer sag of Junggar Basin,NE China the theoretical lower limit,oil accumulation lower limit,effective flow lower limit and the upper limit of tight oil reservoirs were defined by water film thickness method,oil bearing occurrence method,oil testing productivity method and mechanical balance method,respectively.Cluster analysis method was used to compare the differences in pore-throat structure of different tight reservoirs,determine the grading criterion of tight reservoirs,and analyze its correlation with the limit of reservoir formation.The results show that the boundary between tight reservoir and conventional reservoir corresponds to the upper limit of physical properties,the boundary of classⅡand classⅢtight reservoirs corresponds to the lower limit of effective flow,the boundary of classⅢand classⅣtight reservoirs corresponds to the lower limit of reservoir forming,and the theoretical lower limit of tight reservoir corresponds to the boundary between tight reservoir and non-reservoir.Finally,the application results of the grading evaluation criterion show that the tight oil productivity is highly controlled by the type of tight reservoir,and classⅠand classⅡtight reservoirs are the favorable sections for high production of tight oil.展开更多
1 Introduction The Williston Basin is one of the most successful basins in exploration and development of shale oil and gas in North America with abundant logging and geochemical data. A total of three chief source ro...1 Introduction The Williston Basin is one of the most successful basins in exploration and development of shale oil and gas in North America with abundant logging and geochemical data. A total of three chief source rocks are respectively developed in the Ordovician, the Devonian-Lower Carboniferous and the Cretaceous.展开更多
Quantificational characterization of the microscopic pore structure is the key to evaluating tight reservoirs. Since tight reservoirs mainly develop nano-pores which are difficult to fully characterize pore throats＇ ...Quantificational characterization of the microscopic pore structure is the key to evaluating tight reservoirs. Since tight reservoirs mainly develop nano-pores which are difficult to fully characterize pore throats＇ distribution by single conventional experimental method, there＇s an urgent need to establish a characterization method by jointing several conventional experimental methods.展开更多
基金Supported by the National Natural Science Foundation of China(42102154,41922015,42072147)China Postdoctoral Science Foundation(2021M690168)Postdoctoral Innovation Talent Support Program of Shandong Province(SDBX2021004).
文摘A quantitative evaluation model that integrates kerogen adsorption and clay pore adsorption of shale oil was proposed,and the evaluation charts of adsorption-swelling capacity of kerogen(Mk)and adsorbed oil capacity of clay minerals(Mc)were established,taking the 1st member of Cretaceous Qingshankou Formation in the northern Songliao Basin as an example.The model and charts were derived from swelling oil experiments performed on naturally evolved kerogens and adsorbed oil experiments on clays(separated from shale core samples).They were constructed on the basis of clarifying the control law of kerogen maturity evolution on its adsorption-swelling capacity,and considering the effect of both the clay pore surface area that occupied by adsorbed oil and formation temperature.The results are obtained in four aspects:(1)For the Qing 1 Member shale,with the increase of maturity,Mk decreases.Given Ro of 0.83%–1.65%,Mk is about 50–250 mg/g.(2)The clay in shale adsorbs asphaltene.Mc is 0.63 mg/m^(2),and about 15%of the clay pore surface is occupied by adsorbed oil.(3)In the low to medium maturity stages,the shale oil adsorption is controlled by organic matter.When Ro>1.3%,the shale oil adsorption capacity is contributed by clay pores.(4)The oil adsorption capacity evaluated on the surface at room temperature is 8%–22%(avg.15%)higher than that is held in the formations.The proposed evaluation model reveals the occurrence mechanisms of shale oils with different maturities,and provides a new insight for estimating the reserves of shale oil under formation temperature conditions.
基金Financial supports from the National Science Foundation of China(grants No.41530315,41302101 and 41330313)the National Science and Technology Major Project of China(grant No.2016ZX05061)+1 种基金the Natural Science Foundation of Shandong Province(grant No.ZR2016DL07)the Fundamental Research Funds for the Central Universities(grant No.18CX02071A)
文摘The common microscale to nanoscale pore types were introduced and divided into organic and inorganic pores to estimate their contributions to porosity in the Lower Silurian Longmaxi Formation shale of southeast Chongqing. Following the material balance principle, the organic porosity values, which changed with formation subsidence and thermal evolution, were calculated using chemical kinetics methods and corrected via the organic porosity correction coefficient, which was obtained from field emission scanning electron microscopy. Grain density values were determined using the contents and true densities of compositions in the shale samples. The total porosity was calculated based on the grain and bulk densities. The inorganic porosity was determined from the difference between the total porosity and organic porosity at the same depth. The results show that inorganic pores mainly contain microfractures, microchannels, clay intergranular pores, intercrystalline pores and intracrystalline pores in the Lower Silurian Longmaxi Formation shale of southeast Chongqing. Organic pores mainly include organopore and fossil pore. The total porosity, organic porosity and inorganic porosity of organic-rich shale samples can be quantitatively evaluated using this method. The total porosity, organic porosity and inorganic porosity values of the Longmaxi Formation shale samples from the well Pyl in southeast Chongqing lie in 2.75%-6.14%, 0.08%-2.52% and 1.41%-4.92% with average values of 4.34%, 0.95% and 3.39%, respectively. The contributions of the inorganic pores to the total porosity are significantly greater than those of the organic pores.
基金Supported by the National Natural Science Foundation of China(51704324,41728004,U1762213)China National Science and Technology Major Project(2016ZX05061)
文摘The mechanical properties such as Young's modulus, hardness and fracture toughness of Lower Silurian Longmaxi shale samples from Youyang area in southeast Chongqing, China were investigated using dot matrix nanoindentation measurements. With the help of field emission scanning electron microscope(FESEM) and energy dispersive X-ray fluorescence spectroscopy(EDS), the indentation morphology and mineral composition in indentation area were quantitatively analyzed. According to mechanical strength classification, a micromechanical model with three components was introduced and the Mori-Tanaka model was used to upscale mechanical parameters from nano-scale to centimeter-size scale, which were further compared with uniaxial compression results. The experimental results show that there is a positive linear correlation between Young's modulus and hardness and between the Young's modulus and the fracture toughness under nano-scale; the Young's modulus, hardness and fracture toughness perpendicular to the bedding are slightly lower than those parallel with the bedding. According to data statistics, the mechanical properties at the nano-scale follow Weibull distribution feature and the dispersion degree of hardness results is the highest, which is mainly due to shale anisotropy and nanoindentation projection uncertainty. Comparing the results from nanoindentation test, with those from upscaling model and uniaxial compression test shows that the mechanical parameters at the nano-scale are higher than those from upscaling model and uniaxial compression test, which proves mechanical parameters at different scales have differences. It's because the larger the core, the more pores and internal weakness it contains, the less accurate the interpreted results of mechanical parameters will be.
基金Supported by the National Natural Science Foundation of China(41330313,41402122)China National Science and Technology Major Project(2017ZX05049004-003)+1 种基金Research Project Funded by the SINOPEC Corp.(P15028)Fundamental Research Funds for the Central Universities(15CX05046A,15CX07004A,17CX02074)
文摘On the basis of the characterization of microscopic pore-throats in shale oil reservoirs by high-pressure mercury intrusion technique, a grading evaluation standard of shale oil reservoirs and a lower limit for reservoir formation were established. Simultaneously, a new method for the classification of shale oil flow units based on logging data was established. A new classification scheme for shale oil reservoirs was proposed according to the inflection points and fractal features of mercury injection curves: microscopic pore-throats(less than 25 nm), small pore-throats(25-100 nm), medium pore-throats(100-1 000 nm) and big pore-throats(greater than 1 000 nm). Correspondingly, the shale reservoirs are divided into four classes, I, II, III and IV according to the number of microscopic pores they contain, and the average pore-throat radii corresponding to the dividing points are 150 nm, 70 nm and 10 nm respectively. By using the correlation between permeability and pore-throat radius, the permeability thresholds for the reservoir classification are determined at 1.00× 10^(-3) μm^2, 0.40×10^(-3) μm^2 and 0.05×10^(-3) μm^2 respectively. By using the exponential relationship between porosity and permeability of the same hydrodynamic flow unit, a new method was set up to evaluate the reservoir flow belt index and to identify shale oil flow units with logging data. The application in the Dongying sag shows that the standard proposed is suitable for grading evaluation of shale oil reservoirs.
文摘Inspired by the successful development of shale oil/gas exploration in North American, multiple continental oil fields in China have vigorously put forward its evaluation and exploration of shale oil. However, the outcomes of shale oil drilling in China are not well as expected.
文摘1 Introduction The importance of the unconventional petroleum is increasingly prominent, with the rising demand of oil and gas in the economic and social development and the gradual consumption and depletion of conventional oil and gas resources. Compared with the shale and coal-bed gas reservoir, tight reservoir has better fracturing capability.
基金Financial support from the National Science Foundation of China(Grant No.41302101,41330313)the 973 Prophase Special Program of China(Grant No.2011CB211701)
文摘1 Introduction Petrological characteristics （such as brittle mineral content）, miero-nanoscale porosity, total organic carbon and organic matter maturity of shale play important roles in the accumulation and exploration of shale gas. The nanometre pores in shale are mostly organopores （pores within organic matters in shale） created from hydrocarbon generation during formation subsidence and thermal evolution （Loucks et al., 2009; Liu et al., 2011; Chalmers et al., 2012）.
基金Supported by the National Science and Technology Major Project(2016ZX05046-001-005)National Natural Science Foundation of China(41922015)。
文摘Based on the microscopic pore-throat characterization of typical continental tight reservoirs in China,such as sandstone of Cretaceous Qingshankou and Quantou formations in Songliao Basin,NE China sandy conglomerate of Baikouquan Formation in Mahu area and hybrid rock of Lucaogou Formation in Jimusaer sag of Junggar Basin,NE China the theoretical lower limit,oil accumulation lower limit,effective flow lower limit and the upper limit of tight oil reservoirs were defined by water film thickness method,oil bearing occurrence method,oil testing productivity method and mechanical balance method,respectively.Cluster analysis method was used to compare the differences in pore-throat structure of different tight reservoirs,determine the grading criterion of tight reservoirs,and analyze its correlation with the limit of reservoir formation.The results show that the boundary between tight reservoir and conventional reservoir corresponds to the upper limit of physical properties,the boundary of classⅡand classⅢtight reservoirs corresponds to the lower limit of effective flow,the boundary of classⅢand classⅣtight reservoirs corresponds to the lower limit of reservoir forming,and the theoretical lower limit of tight reservoir corresponds to the boundary between tight reservoir and non-reservoir.Finally,the application results of the grading evaluation criterion show that the tight oil productivity is highly controlled by the type of tight reservoir,and classⅠand classⅡtight reservoirs are the favorable sections for high production of tight oil.
文摘1 Introduction The Williston Basin is one of the most successful basins in exploration and development of shale oil and gas in North America with abundant logging and geochemical data. A total of three chief source rocks are respectively developed in the Ordovician, the Devonian-Lower Carboniferous and the Cretaceous.
基金supported by the National Basic Research Program of China(Grant No.2014CB239005-001)the National Natural Science Foundation of China(Grant No.41402109)
文摘Quantificational characterization of the microscopic pore structure is the key to evaluating tight reservoirs. Since tight reservoirs mainly develop nano-pores which are difficult to fully characterize pore throats＇ distribution by single conventional experimental method, there＇s an urgent need to establish a characterization method by jointing several conventional experimental methods.
