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
The research progress of isotopic fractionation in the process of shale gas/coalbed methane migration has been reviewed from three aspects: characteristics and influencing factors, mechanism and quantitative character...The research progress of isotopic fractionation in the process of shale gas/coalbed methane migration has been reviewed from three aspects: characteristics and influencing factors, mechanism and quantitative characterization model, and geological application. It is found that the isotopic fractionation during the complete production of shale gas/coalbed methane shows a four-stage characteristic of “stable-lighter-heavier-lighter again”, which is related to the complex gas migration modes in the pores of shale/coal. The gas migration mechanisms in shale/coal include seepage, diffusion, and adsorption/desorption. Among them, seepage driven by pressure difference does not induce isotopic fractionation, while diffusion and adsorption/desorption lead to significant isotope fractionation. The existing characterization models of isotopic fractionation include diffusion fractionation model, diffusion-adsorption/desorption coupled model, and multi-scale and multi-mechanism coupled model. Results of model calculations show that the isotopic fractionation during natural gas migration is mainly controlled by pore structure, adsorption capacity, and initial/boundary conditions of the reservoir rock. So far, the isotope fractionation model has been successfully used to evaluate critical parameters, such as gas-in-place content and ratio of adsorbed/free gas in shale/coal etc. Furthermore, it has shown promising application potential in production status identification and decline trend prediction of gas well. Future research should focus on:(1) the co-evolution of carbon and hydrogen isotopes of different components during natural gas migration,(2) the characterization of isotopic fractionation during the whole process of gas generation-expulsion-migration-accumulation-dispersion, and(3) quantitative characterization of isotopic fractionation during natural gas migration in complex pore-fracture systems and its application.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
1 Introduction The unconventional shale oil - gas energy, with a huge resource potential, has attracted lots of attention in the world. The occurrence, a accumulation ability and even the flow of the shale oil - gas a...1 Introduction The unconventional shale oil - gas energy, with a huge resource potential, has attracted lots of attention in the world. The occurrence, a accumulation ability and even the flow of the shale oil - gas are seriously affected by characteristics of the reservoir space.展开更多
Nanometer-scale pores exist in the shale, causing that shale has complex reservoir spaces, which results in a poor connectivity among various pores. In addition, because of the complex mineralogical compositions, ther...Nanometer-scale pores exist in the shale, causing that shale has complex reservoir spaces, which results in a poor connectivity among various pores. In addition, because of the complex mineralogical compositions, there is a variety of fluid occurrence state in the pores of the shale, causing that it is difficult to do experimental research for shale.展开更多
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.
基金National Postdoctoral Innovative Talent Support Program(BX20220062)National Natural Science Foundation of China(41672130 and 41972123)SINOPEC Corp.(P17027-3)。
文摘The research progress of isotopic fractionation in the process of shale gas/coalbed methane migration has been reviewed from three aspects: characteristics and influencing factors, mechanism and quantitative characterization model, and geological application. It is found that the isotopic fractionation during the complete production of shale gas/coalbed methane shows a four-stage characteristic of “stable-lighter-heavier-lighter again”, which is related to the complex gas migration modes in the pores of shale/coal. The gas migration mechanisms in shale/coal include seepage, diffusion, and adsorption/desorption. Among them, seepage driven by pressure difference does not induce isotopic fractionation, while diffusion and adsorption/desorption lead to significant isotope fractionation. The existing characterization models of isotopic fractionation include diffusion fractionation model, diffusion-adsorption/desorption coupled model, and multi-scale and multi-mechanism coupled model. Results of model calculations show that the isotopic fractionation during natural gas migration is mainly controlled by pore structure, adsorption capacity, and initial/boundary conditions of the reservoir rock. So far, the isotope fractionation model has been successfully used to evaluate critical parameters, such as gas-in-place content and ratio of adsorbed/free gas in shale/coal etc. Furthermore, it has shown promising application potential in production status identification and decline trend prediction of gas well. Future research should focus on:(1) the co-evolution of carbon and hydrogen isotopes of different components during natural gas migration,(2) the characterization of isotopic fractionation during the whole process of gas generation-expulsion-migration-accumulation-dispersion, and(3) quantitative characterization of isotopic fractionation during natural gas migration in complex pore-fracture systems and its application.
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.
基金supported by Natural Science Foundation of China(41330313)China petroleum and chemical corporation(P14068)
文摘1 Introduction The unconventional shale oil - gas energy, with a huge resource potential, has attracted lots of attention in the world. The occurrence, a accumulation ability and even the flow of the shale oil - gas are seriously affected by characteristics of the reservoir space.
基金financially supported by the Natural Science Foundation of China(Grant No.41330313)the Natural Science Foundation of China(Grant No.41172 134)+1 种基金the Fundamental Research Funds for the Central University(Grants No.13CX05013A and No.15CX020 86A)the Research Project Funded by the SINOPEC Corp.(Grant No.P14068)
文摘Nanometer-scale pores exist in the shale, causing that shale has complex reservoir spaces, which results in a poor connectivity among various pores. In addition, because of the complex mineralogical compositions, there is a variety of fluid occurrence state in the pores of the shale, causing that it is difficult to do experimental research for shale.
