The National Gas Hydrate Program expeditions(NGHP-01 and-02)have conclusively proven the presence of hydrate deposits on the eastern coast of India.The novelty of the present study lies in its investigation of the ric...The National Gas Hydrate Program expeditions(NGHP-01 and-02)have conclusively proven the presence of hydrate deposits on the eastern coast of India.The novelty of the present study lies in its investigation of the richest gas hydrate deposit(hydrate saturation[Sh]>0.75),NGHP-01-10D,in the Krishna-Godavari(KG)Basin,India.The study presents a first look at the long-term gas production viability using a single vertical well,subjected to variations in production interval and bottom hole pressure.Specifically,we compared the gas production at bottom hole pressures of 3-6 MPa and production intervals of 20-40 m.The results indicate production rates that are technically feasible but lower than commercially acceptable standards.Increasing the bottom hole pressure drawdown from 6 MPa to 3 MPa increased the gas production from 1297 m^(3)/d to 4902 m^(3)/d(i.e.,more than tripling the average daily gas production).Meanwhile,while expanding the production interval from 20 m to 40 m led to an increase in gas production,it also resulted in higher water production.As a result,the average gas-to-water ratio(RGW)decreased from 9.5 to 5.3 with the expansion of the production interval,thereby highlighting the need to optimize the interval length.Furthermore,the spatial evolution of certain thermodynamic parameters,including pressure,temperature,and phase saturation(methane,water,and hydrate),underscores the critical role of heat transfer from the UB.Our study findings offer valuable insights for long-term production forecasting,the delineation of phase evolution patterns,and the identification of potential flow barriers that may impede deliverability.展开更多
Natural gas hydrates(NGH)are found in marine sediments on continental and island slopes,deep-water sediments of inland lakes and seas,and polar sediments on continents and continental shelves.NGH constitutes the large...Natural gas hydrates(NGH)are found in marine sediments on continental and island slopes,deep-water sediments of inland lakes and seas,and polar sediments on continents and continental shelves.NGH constitutes the largest hydrocarbon resource on Earth,representing a reservoir of sustainable fuel owing to the possibility of a so-called CO_(2)-CH_(4)replacement process.If CO_(2)is injected into NGH sediments,CH_(4)is released and CO_(2)hydrate formed.The extraction of gas from NGH,combined with carbon capture,presents significant potential advantages in the energy infrastructure and various economic and political contexts,aligning with future green policies.This study contributes to the advancement of knowledge by reviewing the findings of a three-year Italian research project focused on methane recovery and carbon dioxide disposal in NGH.The consortium comprises seven multidisciplinary Italian partners.This study introduces a novel process wherein the CO_(2)-CH_(4)replacement process is integrated with methane purification and CO_(2)recirculation,which has been experimentally tested and represents a new advancement in gas hydrate science.Experimental tests at the microscopic and macroscopic levels showed that the efficiency of the process strongly depends on the mutual influence of the properties of water,sediment,and the involved gaseous species.Energy evaluations show that the ratio between the energy spent to complete an entire cycle of replacement and recirculation over the stored energy in the recovered methane is 17%,resulting in a beneficial energy balance,while economic analysis shows that the transition could generate—even in the short term—large high-impact cash-out.展开更多
文摘The National Gas Hydrate Program expeditions(NGHP-01 and-02)have conclusively proven the presence of hydrate deposits on the eastern coast of India.The novelty of the present study lies in its investigation of the richest gas hydrate deposit(hydrate saturation[Sh]>0.75),NGHP-01-10D,in the Krishna-Godavari(KG)Basin,India.The study presents a first look at the long-term gas production viability using a single vertical well,subjected to variations in production interval and bottom hole pressure.Specifically,we compared the gas production at bottom hole pressures of 3-6 MPa and production intervals of 20-40 m.The results indicate production rates that are technically feasible but lower than commercially acceptable standards.Increasing the bottom hole pressure drawdown from 6 MPa to 3 MPa increased the gas production from 1297 m^(3)/d to 4902 m^(3)/d(i.e.,more than tripling the average daily gas production).Meanwhile,while expanding the production interval from 20 m to 40 m led to an increase in gas production,it also resulted in higher water production.As a result,the average gas-to-water ratio(RGW)decreased from 9.5 to 5.3 with the expansion of the production interval,thereby highlighting the need to optimize the interval length.Furthermore,the spatial evolution of certain thermodynamic parameters,including pressure,temperature,and phase saturation(methane,water,and hydrate),underscores the critical role of heat transfer from the UB.Our study findings offer valuable insights for long-term production forecasting,the delineation of phase evolution patterns,and the identification of potential flow barriers that may impede deliverability.
基金funded by the Italian Ministry of University and Research(MUR)under the Prin 2017 Framework-Research Projects of Relevant National Interest 2019-2023The research in Antarctica has been partially supported by the Programma Nazionale di Ricerche in Antartide(PNRA).3.
文摘Natural gas hydrates(NGH)are found in marine sediments on continental and island slopes,deep-water sediments of inland lakes and seas,and polar sediments on continents and continental shelves.NGH constitutes the largest hydrocarbon resource on Earth,representing a reservoir of sustainable fuel owing to the possibility of a so-called CO_(2)-CH_(4)replacement process.If CO_(2)is injected into NGH sediments,CH_(4)is released and CO_(2)hydrate formed.The extraction of gas from NGH,combined with carbon capture,presents significant potential advantages in the energy infrastructure and various economic and political contexts,aligning with future green policies.This study contributes to the advancement of knowledge by reviewing the findings of a three-year Italian research project focused on methane recovery and carbon dioxide disposal in NGH.The consortium comprises seven multidisciplinary Italian partners.This study introduces a novel process wherein the CO_(2)-CH_(4)replacement process is integrated with methane purification and CO_(2)recirculation,which has been experimentally tested and represents a new advancement in gas hydrate science.Experimental tests at the microscopic and macroscopic levels showed that the efficiency of the process strongly depends on the mutual influence of the properties of water,sediment,and the involved gaseous species.Energy evaluations show that the ratio between the energy spent to complete an entire cycle of replacement and recirculation over the stored energy in the recovered methane is 17%,resulting in a beneficial energy balance,while economic analysis shows that the transition could generate—even in the short term—large high-impact cash-out.
