The permeability and its horizontal anisotropy induce a critical influence on staged CH_(4) output inhibition process.However,a quantitative evaluation of this influence has been rarely reported in the literature.In t...The permeability and its horizontal anisotropy induce a critical influence on staged CH_(4) output inhibition process.However,a quantitative evaluation of this influence has been rarely reported in the literature.In this work,the impact of horizontal anisotropic permeability on CO_(2)-ECBM was numerically investigated.The variation in the staged CH_(4) output inhibition was analyzed.The ideal displacement profile of the CO_(2)-ECBM process was established for the first time.Moreover,the variation in CH_(4) output of different wellbores was discussed.The results showed that 1)low-permeable or weak-anisotropic reservoirs were not conducive to enhanced CH_(4) recovery owing to long inhibition time(>1091 days)and high inhibition level(>36.9%).As permeability and anisotropy increased,due to the accelerated seepage of free water,the hysteresis time and inhibition time could decrease to as short as 5 days and 87 days,respectively,and the inhibition level could weaken to as low as 5.00%.Additionally,the CH_(4) output and CO_(2) injection could increase significantly.2)Nevertheless,high permeability and strong anisotropy easily induced CO_(2) breakthrough,resulting in lower CH_(4) production,CO_(2) injection and CO_(2) storage than expected.While maintaining high efficiency of CO_(2) storage(>99%),upregulating CO_(2) breakthrough concentration from 10%to 20%might ease the unfavorable trend.3)Along the direction of fluid flow,the ideal displacement profile consisted of CO_(2) enriched bank,CO_(2) and CH_(4) mixed bank,CH_(4) enriched bank,and water enriched bank,whereas a remarkable gap in the displacement profiles of the dominant and non-dominant seepage directions was observed.4)The potential of CH_(4) output might vary greatly among different wellbores.The producers along the dominant seepage direction held more potential for CH_(4) recovery in the short-term,while those along the non-dominant seepage direction avoided becoming invalid only if a long-time injection measure was taken for the injectors.These findings pave the way to understand fluid seepage in real complex reservoirs during CO_(2)-ECBM and conduct further field projects.展开更多
Ammonia nitrogen (NH4+-N) is one of the three main forms of total nitrogen (TN). Most studies have estimated the load of TN from nonpoint sources instead of one specific form. The relationship between land use and con...Ammonia nitrogen (NH4+-N) is one of the three main forms of total nitrogen (TN). Most studies have estimated the load of TN from nonpoint sources instead of one specific form. The relationship between land use and concentrations of NH4+-N in runoff was analyzed using the hydraulic analysis functions of a Geographic Information Systems (GIS), and the annual loads of NH4+-N in the Xitiao River catchment were estimated according to model results. The results suggested that the calculated annual loads of NH4+-N...展开更多
基金the National Natural Science Foundation of China(Grant No.42141012)the National Key R&D Program of China(No.2018YFB0605600)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘The permeability and its horizontal anisotropy induce a critical influence on staged CH_(4) output inhibition process.However,a quantitative evaluation of this influence has been rarely reported in the literature.In this work,the impact of horizontal anisotropic permeability on CO_(2)-ECBM was numerically investigated.The variation in the staged CH_(4) output inhibition was analyzed.The ideal displacement profile of the CO_(2)-ECBM process was established for the first time.Moreover,the variation in CH_(4) output of different wellbores was discussed.The results showed that 1)low-permeable or weak-anisotropic reservoirs were not conducive to enhanced CH_(4) recovery owing to long inhibition time(>1091 days)and high inhibition level(>36.9%).As permeability and anisotropy increased,due to the accelerated seepage of free water,the hysteresis time and inhibition time could decrease to as short as 5 days and 87 days,respectively,and the inhibition level could weaken to as low as 5.00%.Additionally,the CH_(4) output and CO_(2) injection could increase significantly.2)Nevertheless,high permeability and strong anisotropy easily induced CO_(2) breakthrough,resulting in lower CH_(4) production,CO_(2) injection and CO_(2) storage than expected.While maintaining high efficiency of CO_(2) storage(>99%),upregulating CO_(2) breakthrough concentration from 10%to 20%might ease the unfavorable trend.3)Along the direction of fluid flow,the ideal displacement profile consisted of CO_(2) enriched bank,CO_(2) and CH_(4) mixed bank,CH_(4) enriched bank,and water enriched bank,whereas a remarkable gap in the displacement profiles of the dominant and non-dominant seepage directions was observed.4)The potential of CH_(4) output might vary greatly among different wellbores.The producers along the dominant seepage direction held more potential for CH_(4) recovery in the short-term,while those along the non-dominant seepage direction avoided becoming invalid only if a long-time injection measure was taken for the injectors.These findings pave the way to understand fluid seepage in real complex reservoirs during CO_(2)-ECBM and conduct further field projects.
基金the National Key BasiResearch Project of China (No. G2002CB410807)the National Natural Science Foundation of China (No40571146)
文摘Ammonia nitrogen (NH4+-N) is one of the three main forms of total nitrogen (TN). Most studies have estimated the load of TN from nonpoint sources instead of one specific form. The relationship between land use and concentrations of NH4+-N in runoff was analyzed using the hydraulic analysis functions of a Geographic Information Systems (GIS), and the annual loads of NH4+-N in the Xitiao River catchment were estimated according to model results. The results suggested that the calculated annual loads of NH4+-N...
