为了探究Klinkenberg效应及不同状态的Klinkenberg因子在注CO_(2)提高煤层气采收率(CO_(2)-Enhanced Coal Bed Methane,CO_(2)-ECBM)过程中的作用,借助COMSOL有限元软件模拟分析了Klinkenberg因子为0、固定Klinkenberg因子与动态Klinken...为了探究Klinkenberg效应及不同状态的Klinkenberg因子在注CO_(2)提高煤层气采收率(CO_(2)-Enhanced Coal Bed Methane,CO_(2)-ECBM)过程中的作用,借助COMSOL有限元软件模拟分析了Klinkenberg因子为0、固定Klinkenberg因子与动态Klinkenberg因子3种状态对CO_(2)-ECBM及有效渗透率的影响,以及CH_(4)与CO_(2)压力随该因子的动态变化情况,并将CH_(4)产气量与工程实际作了对比验证。结果表明,CH_(4)与CO_(2)有效渗透率呈先缓慢增长再急速下降后逐渐趋于平缓的态势,相较于固定Klinkenberg因子或Klinkenberg因子为0,动态Klinkenberg因子影响下的CH_(4)与CO_(2)有效渗透率更大,当Klinkenberg因子为动态变量时,受不同气体的摩尔质量与动力黏度影响,CO_(2)有效渗透率小于CH_(4)有效渗透率。在动态Klinkenberg因子作用下,煤层中CH_(4)压力下降和CO_(2)压力上升均更快,当Klinkenberg因子为固定值或0时,会高估煤层内CH_(4)压力,低估CH_(4)抽采与CO_(2)压注的影响范围,并且估值均随时间增长而增大。工程验证表明,考虑动态Klinkenberg因子作用下的CH_(4)累积产气量更接近真实情况。研究成果有助于分析CH_(4)与CO_(2)有效渗透率变化趋势,预估CH_(4)抽采与CO_(2)压注的影响范围及CH_(4)产气量,在探究煤层增渗,优化井网布置,定量评价煤田产气量等方面具有理论指导意义。展开更多
Focused on the Klinkenberg effect on gas seepage, the independently developed triaxial experimental system of gas seepage was applied to conduct research on the seepage characteristics of coal seam gas. By means of ex...Focused on the Klinkenberg effect on gas seepage, the independently developed triaxial experimental system of gas seepage was applied to conduct research on the seepage characteristics of coal seam gas. By means of experimental data analysis and theoretical derivation, a calculation method of coal seam gas permeability was proposed, which synthesized the respective influences of gas dynamic viscosity, compressibility factor and Klinkenberg effect. The study results show that the Klinkenberg effect has a significant influence on the coal seam gas seepage, the permeability estimated with the method considering the Klinkenberg effect is correct, and this permeability can fully reflect the true seepage state of the gas. For the gas around the standard conditions, the influences of dynamic viscosity and compressibility factor on the permeability may be ignored. For the gas deviating far away from the standard conditions, the influences of dynamic viscosity and compressibility factor on the permeability must be considered. The research results have certain guiding significance in forming a correct understanding of the Klinkenberg effect and selecting a more accurate calculation method for the permeability of coal containing gas.展开更多
Reservoir quality from cored intervals has traditionally been described by grouping similar intervals according to rock type. The main shortcoming of this static modelling approach is that it lacks clarity and it is n...Reservoir quality from cored intervals has traditionally been described by grouping similar intervals according to rock type. The main shortcoming of this static modelling approach is that it lacks clarity and it is not conducive for setting up a dynamic simulation model. The alternative is to use a modelling approach based on Hydraulic Flow Zone Units (HFZUs). First proposed in the late 1980s and extensively published in the early 1990s such formulation uses the well-known Carman-Kozeny (C-K) equation. More recently, this approach has been extended to cover a wider range of geological formations with diverse pore structure types. In using a HFZU approach, a pre-processing step is customarily undertaken to first overburden correct the data and where necessary also to correct for the Klinkenberg effect (lower permeability formations, lab testing with gas). The study presented compares corrected and uncorrected data sets, to see if correction alters the overall outcome of HFZU analysis. Specifically, data sets are compared at three different conditions: ambient, overburden (only) corrected and finally data that has been corrected for both, overburden and Klinkenberg effects. In all cases it is the Flow Zone Indicator (FZI), an index representative of formation quality that is tracked, together with the type of relationship. Several comparative analysis examples are given for diverse formations. The results show that uncorrected data can yield a different correlation and FZI, especially for intervals that include low permeability samples. Results indicate that Overburden and Klinkenberg corrections should be applied before HFZU analysis.展开更多
It is well known that,as non-continuum gas flows through microscale porous media,the gas permeability derived from Darcy law is larger than the absolute permeability,which is caused by the so-called Klinkenberg effect...It is well known that,as non-continuum gas flows through microscale porous media,the gas permeability derived from Darcy law is larger than the absolute permeability,which is caused by the so-called Klinkenberg effect or slippage effect.In this paper,an effective definition of Knudsen number for gas flows through square arrays of circular cylinders and a local boundary condition for non-continuum gas flows are first proposed,and then the multi-relaxation-time lattice Boltzmann equation including discrete effects on boundary condition is used to investigate Klinkenberg effect on gas flow through circular cylinders in square arrays.Numerical results show that the celebrated Klinkenberg equation is only correct for low Knudsen number,and secondorder correction to Klinkenberg equation is necessary with the increase of Knudsen number.Finally,the present numerical results are also compared to some available results,and in general an agreement between them is observed.展开更多
文摘为了探究Klinkenberg效应及不同状态的Klinkenberg因子在注CO_(2)提高煤层气采收率(CO_(2)-Enhanced Coal Bed Methane,CO_(2)-ECBM)过程中的作用,借助COMSOL有限元软件模拟分析了Klinkenberg因子为0、固定Klinkenberg因子与动态Klinkenberg因子3种状态对CO_(2)-ECBM及有效渗透率的影响,以及CH_(4)与CO_(2)压力随该因子的动态变化情况,并将CH_(4)产气量与工程实际作了对比验证。结果表明,CH_(4)与CO_(2)有效渗透率呈先缓慢增长再急速下降后逐渐趋于平缓的态势,相较于固定Klinkenberg因子或Klinkenberg因子为0,动态Klinkenberg因子影响下的CH_(4)与CO_(2)有效渗透率更大,当Klinkenberg因子为动态变量时,受不同气体的摩尔质量与动力黏度影响,CO_(2)有效渗透率小于CH_(4)有效渗透率。在动态Klinkenberg因子作用下,煤层中CH_(4)压力下降和CO_(2)压力上升均更快,当Klinkenberg因子为固定值或0时,会高估煤层内CH_(4)压力,低估CH_(4)抽采与CO_(2)压注的影响范围,并且估值均随时间增长而增大。工程验证表明,考虑动态Klinkenberg因子作用下的CH_(4)累积产气量更接近真实情况。研究成果有助于分析CH_(4)与CO_(2)有效渗透率变化趋势,预估CH_(4)抽采与CO_(2)压注的影响范围及CH_(4)产气量,在探究煤层增渗,优化井网布置,定量评价煤田产气量等方面具有理论指导意义。
基金Projects(51104059,51204067)supported by the National Natural Science Foundation of ChinaProject(2012CB723103)supported the National Basic Research Program of China+3 种基金Project(IRT1235)supported by Innovation Team Development Plan of the Ministry of Education of ChinaProject(2013M531674)supported by China Postdoctoral Science FoundationProject(132300413203)supported by Basic and Frontier Technology Research Program of Henan Province,ChinaProject(WS2012B07)supported by the Open Project of State Key Laboratory Cultivation Base for Gas Geology and Gas Control(Henan Polytechnic University),China
文摘Focused on the Klinkenberg effect on gas seepage, the independently developed triaxial experimental system of gas seepage was applied to conduct research on the seepage characteristics of coal seam gas. By means of experimental data analysis and theoretical derivation, a calculation method of coal seam gas permeability was proposed, which synthesized the respective influences of gas dynamic viscosity, compressibility factor and Klinkenberg effect. The study results show that the Klinkenberg effect has a significant influence on the coal seam gas seepage, the permeability estimated with the method considering the Klinkenberg effect is correct, and this permeability can fully reflect the true seepage state of the gas. For the gas around the standard conditions, the influences of dynamic viscosity and compressibility factor on the permeability may be ignored. For the gas deviating far away from the standard conditions, the influences of dynamic viscosity and compressibility factor on the permeability must be considered. The research results have certain guiding significance in forming a correct understanding of the Klinkenberg effect and selecting a more accurate calculation method for the permeability of coal containing gas.
文摘Reservoir quality from cored intervals has traditionally been described by grouping similar intervals according to rock type. The main shortcoming of this static modelling approach is that it lacks clarity and it is not conducive for setting up a dynamic simulation model. The alternative is to use a modelling approach based on Hydraulic Flow Zone Units (HFZUs). First proposed in the late 1980s and extensively published in the early 1990s such formulation uses the well-known Carman-Kozeny (C-K) equation. More recently, this approach has been extended to cover a wider range of geological formations with diverse pore structure types. In using a HFZU approach, a pre-processing step is customarily undertaken to first overburden correct the data and where necessary also to correct for the Klinkenberg effect (lower permeability formations, lab testing with gas). The study presented compares corrected and uncorrected data sets, to see if correction alters the overall outcome of HFZU analysis. Specifically, data sets are compared at three different conditions: ambient, overburden (only) corrected and finally data that has been corrected for both, overburden and Klinkenberg effects. In all cases it is the Flow Zone Indicator (FZI), an index representative of formation quality that is tracked, together with the type of relationship. Several comparative analysis examples are given for diverse formations. The results show that uncorrected data can yield a different correlation and FZI, especially for intervals that include low permeability samples. Results indicate that Overburden and Klinkenberg corrections should be applied before HFZU analysis.
基金financially supported by the National Basic Research Program of China(Grant No.2006CB705804)the National Natural Science Foundation of China(Grant Nos.60773195 and 10972087).
文摘It is well known that,as non-continuum gas flows through microscale porous media,the gas permeability derived from Darcy law is larger than the absolute permeability,which is caused by the so-called Klinkenberg effect or slippage effect.In this paper,an effective definition of Knudsen number for gas flows through square arrays of circular cylinders and a local boundary condition for non-continuum gas flows are first proposed,and then the multi-relaxation-time lattice Boltzmann equation including discrete effects on boundary condition is used to investigate Klinkenberg effect on gas flow through circular cylinders in square arrays.Numerical results show that the celebrated Klinkenberg equation is only correct for low Knudsen number,and secondorder correction to Klinkenberg equation is necessary with the increase of Knudsen number.Finally,the present numerical results are also compared to some available results,and in general an agreement between them is observed.
