Both the EU and China remain committed to safeguarding the multilateral trading system,which is in alignment with the bilateral and common interests of the world.
On March 24,the international symposium themed“Strengthen the Role of the United Nations and Promote Multilateralism”was held in Beijing.The event was hosted by the Ministry of Foreign Affairs of China,and supported...On March 24,the international symposium themed“Strengthen the Role of the United Nations and Promote Multilateralism”was held in Beijing.The event was hosted by the Ministry of Foreign Affairs of China,and supported by China Institute of International Studies(CIIS),the United Nations Association of China.展开更多
After the 2008 global financial crisis, the global governance architecture underwent significant changes, accompanied by transformations in political, economic, diplomatic, and social spheres. What we had learnt since...After the 2008 global financial crisis, the global governance architecture underwent significant changes, accompanied by transformations in political, economic, diplomatic, and social spheres. What we had learnt since the end of World War Ⅱ was unable to make sense of the evolution and direction of this architecture.展开更多
In an era marked by rising protectionism and geopolitical tensions,the world faces a stark choice:embrace multilateral cooperation or succumb to unilateral hegemony.The United States’punitive tariff policies have exp...In an era marked by rising protectionism and geopolitical tensions,the world faces a stark choice:embrace multilateral cooperation or succumb to unilateral hegemony.The United States’punitive tariff policies have exposed the negative effect of economic coercion and isolation.Meanwhile,China’s commitment to openness,innovation,and shared prosperity offers a contrast,a testament to the enduring vitality of multilateralism and global integration.展开更多
Today,the world is undergoing profound changes unseen in a century,and a host of global challenges continue to emerge.The international community urgently requires effective global governance.As Chinese President Xi J...Today,the world is undergoing profound changes unseen in a century,and a host of global challenges continue to emerge.The international community urgently requires effective global governance.As Chinese President Xi Jinping has pointed out,multilateralism is the inevitable choice for addressing the world’s difficulties and challenges.1 However,various negative trends in international politics are undermining or impeding the effectiveness of multilateralism and aggravating the global governance deficit.Against this backdrop,it is essential to reassess the importance of multilateralism in global governance,identify the challenges it faces,and explore feasible pathways for collective action to advance global governance.展开更多
Due to high energy density,clean combustion products and abundant resources,natural gas hydrates(NGHs)have been regarded as an important clean energy source with the potential for large-scale development and utilizati...Due to high energy density,clean combustion products and abundant resources,natural gas hydrates(NGHs)have been regarded as an important clean energy source with the potential for large-scale development and utilization.However,pilot tests in NGHs show that their production rates are far below commercial needs.Multilateral well technology may lead to a solution to this problem because it can dramatically expand the drainage area of production wells.This paper presents the practical rate transient analysis for multilateral horizontal wells in NGHs.In developing solution to the diffusivity equation of multilateral horizontal wells in NGHs,the superposition principle and reciprocity are applied.We wrote the governing equation in cylindrical coordinates to describe the NGH flow process.We used the moving boundaries and dissociation coefficients to model the solid-to-gas transition process in hydrates.To obtain solutions for flow in hydrate reservoirs,we used Laplace transforms and the Stehfest numerical inversion method.Superposition principle and Gaussian elimination are applied to obtain the desired solution for multilateral horizontal wells.We validated our proposed model with a commercial numerical simulator.By performing sensitivity analyses,effects on production behavior of the number of branches,dissociation coefficient,radius of the region with dissociated hydrate,and dispersion ratio are determined.A synthetic case study is conducted to show the typical production behaviors.展开更多
In order to accurately predict the productivity of herringbone multilateral well,a new productivity prediction model was founded.And based on this model,orthogonal test and multiple factor variance analysis were appli...In order to accurately predict the productivity of herringbone multilateral well,a new productivity prediction model was founded.And based on this model,orthogonal test and multiple factor variance analysis were applied to study optimization design of herringbone multilateral well.According to the characteristics of herringbone multilateral well,by using pressure superposition and mirror image reflection theory,the coupled model of herringbone multilateral well was developed on the basis of a three-dimensional pseudo-pressure distribution model for horizontal wells.The model was formulated in consideration of friction loss,acceleration loss of the wellbore and mixed loss at the confluence of main wellbore and branched one.After mathematical simulation on productivity of the herringbone multilateral well with the coupled model,the effects of well configuration on productivity were analyzed.The results show that lateral number is the most important factor,length of main wellbore and length of branched wellbore are the secondary ones,angle between main and branched one has the least influence.展开更多
Multilateral wells promise cost savings to oil and fields as they have the potential to reduce overall drilling distances and minimize the number of slots required for the surface facility managing the well.However,dr...Multilateral wells promise cost savings to oil and fields as they have the potential to reduce overall drilling distances and minimize the number of slots required for the surface facility managing the well.However,drilling a multilateral well does not always increase the flow rate when compared to two single-horizontal wells due to competition in production inside the mother-bore.Here,a holistic approach is proposed to find the optimum balance between single and multilateral wells in an offshore oil development.In so doing,the integrated approach finds the highest Net Present Value(NPV)configuration of the field considering drilling,subsurface,production and financial analysis.The model employs stochastic perturbation and Markov Chain Monte-Carlo methods to solve the global maximising-NPV problem.In addition,a combination of Mixed-Integer Linear Programming(MILP),an improved Dijkstra algorithm and a Levenberg-Marquardt optimiser is proposed to solve the rate allocation problem.With the outcome from this analysis,the model suggests the optimum development including number of multilateral and single horizontal wells that would result in the highest NPV.The results demonstrate the potential for modelling to find the optimal use of petroleum facilities and to assist with planning and decision making.展开更多
Wellbore failure can occur at different stages of operations. For example, wellbore collapse might happen during drilling and/or during production. The drilling process results in the removal of an already stressed ro...Wellbore failure can occur at different stages of operations. For example, wellbore collapse might happen during drilling and/or during production. The drilling process results in the removal of an already stressed rock material. If the induced stresses near the wellbore exceed the strength of rock, wellbore failure occurs. The production process also changes the effective stresses around the wellbore. Such changes in stresses can be significant for high drawdown pressures and can trigger wellbore failure. In this paper, the Mohr–Coulomb failure criterion with a hyperbolic hardening is used. The model parameters are identified from triaxial compression tests. The numerical simulations of laboratory tests showed that the model can reproduce the mechanical behaviour of sandstone. In addition, the simulations of multilateral junction stability experiments showed that the model was able to reproduce yielding and failure at the multilateral junction for different levels of applied stresses. Finally, a numerical example examining multilateral junction stability in an open borehole during drilling and production is presented. The results illustrate the development of a localized failure zone proximate to the area where two wellbore tracks join, particularly on the side with a sharp approaching angle, which would significantly increase the risk of wellbore collapse at the junction.展开更多
While the spread of COVID-19 in China is under control,the pandemic is developing rapidly around the world.Due to the normal migration of population,China is facing the high risk from imported cases.The potential spec...While the spread of COVID-19 in China is under control,the pandemic is developing rapidly around the world.Due to the normal migration of population,China is facing the high risk from imported cases.The potential specific medicine and vaccine are still in the process of clinical trials.Currently,controlling the impact of imported cases is the key to prevent new outbreak of COVID-19 in China.In this paper,we propose two impulsive systems to describe the impact of multilateral imported cases of COVID-19.Based on the published data,we simulate and analyze the epidemic trends under different control strategies.In particular,we compare four different scenarios and show the corresponding medical burden.The results can be useful in designing appropriate control strategy for imported cases in practice.展开更多
Ever since the Bush administration took office, the U. S. national security strategy has given rise to much controversy. Whether the U. S. national security strategy is of unilateralism or multilateralistm is a questi...Ever since the Bush administration took office, the U. S. national security strategy has given rise to much controversy. Whether the U. S. national security strategy is of unilateralism or multilateralistm is a question in dispute. Many people think it is a unilateralist strategy. According to their views, to achieve its own objective, the U. S. administration has rarely considered the interests and feelings of other coun-展开更多
Currently,a new industrial revolution characterized by artificial intelligence,the internet of things,and digitalization is in a critical transition from initiation to allaround expansion.While injecting new dynamism ...Currently,a new industrial revolution characterized by artificial intelligence,the internet of things,and digitalization is in a critical transition from initiation to allaround expansion.While injecting new dynamism into global economic growth,and promoting inclusive development and human welfare,the new industrial revolution will reshape the pattern of international competition,and provide a window period for latemoving countries to compete and catch up with developed nations.Amid the shocks of the new industrial revolution,countries must adhere to the principles of openness,multilateralism and reciprocity to share the dividends of the new industrial revolution and effectively cope with its challenges.Therefore,multilateralism,rather than protectionism and unilateralism,should dominate the mainstream of change in future global governance.The reform of existing multilateral organizations such as the World Trade Organization(WTO)must proceed under the principle of multilateralism.展开更多
THE G20 Osaka Summit in Japan convened on June 28-29 had the world hold its breath. Not only were front-burner issues, such as WTO reform and digitalization of the economy, discussed there, but there was much fanfare ...THE G20 Osaka Summit in Japan convened on June 28-29 had the world hold its breath. Not only were front-burner issues, such as WTO reform and digitalization of the economy, discussed there, but there was much fanfare around the first high-level meeting between China and the United States since the last G20 summit in Buenos Aires late last year. Given the mounting trade tensions between the two countries, the meeting took global center stage.展开更多
Developing global partnerships is an important focus for China’s diplomacy in the new era.1 President Xi Jinping proposed at the Central Conference on Work Relating to Foreign Affairs in November 2014,“We should mak...Developing global partnerships is an important focus for China’s diplomacy in the new era.1 President Xi Jinping proposed at the Central Conference on Work Relating to Foreign Affairs in November 2014,“We should make more friends while abiding by the principle of non-alignment and build a global network of partnerships.”展开更多
For me,the highlights of these recommendations are the financing and the role of Multilateral Development Banks.The recommendations I follow with most interest are the ones that protect and insure against political ri...For me,the highlights of these recommendations are the financing and the role of Multilateral Development Banks.The recommendations I follow with most interest are the ones that protect and insure against political risk and regulatory risk.These展开更多
文摘Both the EU and China remain committed to safeguarding the multilateral trading system,which is in alignment with the bilateral and common interests of the world.
文摘On March 24,the international symposium themed“Strengthen the Role of the United Nations and Promote Multilateralism”was held in Beijing.The event was hosted by the Ministry of Foreign Affairs of China,and supported by China Institute of International Studies(CIIS),the United Nations Association of China.
文摘After the 2008 global financial crisis, the global governance architecture underwent significant changes, accompanied by transformations in political, economic, diplomatic, and social spheres. What we had learnt since the end of World War Ⅱ was unable to make sense of the evolution and direction of this architecture.
文摘In an era marked by rising protectionism and geopolitical tensions,the world faces a stark choice:embrace multilateral cooperation or succumb to unilateral hegemony.The United States’punitive tariff policies have exposed the negative effect of economic coercion and isolation.Meanwhile,China’s commitment to openness,innovation,and shared prosperity offers a contrast,a testament to the enduring vitality of multilateralism and global integration.
文摘Today,the world is undergoing profound changes unseen in a century,and a host of global challenges continue to emerge.The international community urgently requires effective global governance.As Chinese President Xi Jinping has pointed out,multilateralism is the inevitable choice for addressing the world’s difficulties and challenges.1 However,various negative trends in international politics are undermining or impeding the effectiveness of multilateralism and aggravating the global governance deficit.Against this backdrop,it is essential to reassess the importance of multilateralism in global governance,identify the challenges it faces,and explore feasible pathways for collective action to advance global governance.
基金This work received funding support from National Natural Science Foundation of China(12202042),Highend Foreign Expert Introduction Program(G2023105006L)China Postdoctoral Science Foundations(2021M700391)Fundamental Research Funds for the Central Universities(QNXM20220011,FRFTP-22-119A1,FRF-IDRY-22-001)。
文摘Due to high energy density,clean combustion products and abundant resources,natural gas hydrates(NGHs)have been regarded as an important clean energy source with the potential for large-scale development and utilization.However,pilot tests in NGHs show that their production rates are far below commercial needs.Multilateral well technology may lead to a solution to this problem because it can dramatically expand the drainage area of production wells.This paper presents the practical rate transient analysis for multilateral horizontal wells in NGHs.In developing solution to the diffusivity equation of multilateral horizontal wells in NGHs,the superposition principle and reciprocity are applied.We wrote the governing equation in cylindrical coordinates to describe the NGH flow process.We used the moving boundaries and dissociation coefficients to model the solid-to-gas transition process in hydrates.To obtain solutions for flow in hydrate reservoirs,we used Laplace transforms and the Stehfest numerical inversion method.Superposition principle and Gaussian elimination are applied to obtain the desired solution for multilateral horizontal wells.We validated our proposed model with a commercial numerical simulator.By performing sensitivity analyses,effects on production behavior of the number of branches,dissociation coefficient,radius of the region with dissociated hydrate,and dispersion ratio are determined.A synthetic case study is conducted to show the typical production behaviors.
基金Project(12521044) supported by Scientific and Technological Research Program of Heilongjiang Provincial Education Department,China
文摘In order to accurately predict the productivity of herringbone multilateral well,a new productivity prediction model was founded.And based on this model,orthogonal test and multiple factor variance analysis were applied to study optimization design of herringbone multilateral well.According to the characteristics of herringbone multilateral well,by using pressure superposition and mirror image reflection theory,the coupled model of herringbone multilateral well was developed on the basis of a three-dimensional pseudo-pressure distribution model for horizontal wells.The model was formulated in consideration of friction loss,acceleration loss of the wellbore and mixed loss at the confluence of main wellbore and branched one.After mathematical simulation on productivity of the herringbone multilateral well with the coupled model,the effects of well configuration on productivity were analyzed.The results show that lateral number is the most important factor,length of main wellbore and length of branched wellbore are the secondary ones,angle between main and branched one has the least influence.
文摘Multilateral wells promise cost savings to oil and fields as they have the potential to reduce overall drilling distances and minimize the number of slots required for the surface facility managing the well.However,drilling a multilateral well does not always increase the flow rate when compared to two single-horizontal wells due to competition in production inside the mother-bore.Here,a holistic approach is proposed to find the optimum balance between single and multilateral wells in an offshore oil development.In so doing,the integrated approach finds the highest Net Present Value(NPV)configuration of the field considering drilling,subsurface,production and financial analysis.The model employs stochastic perturbation and Markov Chain Monte-Carlo methods to solve the global maximising-NPV problem.In addition,a combination of Mixed-Integer Linear Programming(MILP),an improved Dijkstra algorithm and a Levenberg-Marquardt optimiser is proposed to solve the rate allocation problem.With the outcome from this analysis,the model suggests the optimum development including number of multilateral and single horizontal wells that would result in the highest NPV.The results demonstrate the potential for modelling to find the optimal use of petroleum facilities and to assist with planning and decision making.
文摘Wellbore failure can occur at different stages of operations. For example, wellbore collapse might happen during drilling and/or during production. The drilling process results in the removal of an already stressed rock material. If the induced stresses near the wellbore exceed the strength of rock, wellbore failure occurs. The production process also changes the effective stresses around the wellbore. Such changes in stresses can be significant for high drawdown pressures and can trigger wellbore failure. In this paper, the Mohr–Coulomb failure criterion with a hyperbolic hardening is used. The model parameters are identified from triaxial compression tests. The numerical simulations of laboratory tests showed that the model can reproduce the mechanical behaviour of sandstone. In addition, the simulations of multilateral junction stability experiments showed that the model was able to reproduce yielding and failure at the multilateral junction for different levels of applied stresses. Finally, a numerical example examining multilateral junction stability in an open borehole during drilling and production is presented. The results illustrate the development of a localized failure zone proximate to the area where two wellbore tracks join, particularly on the side with a sharp approaching angle, which would significantly increase the risk of wellbore collapse at the junction.
基金National Natural Science Foundation of China(Grant Nos.41704116,11901234,11926104)Jilin Provincial Excellent Youth Talents Foundation(Grant No.20180520093JH)+1 种基金Scientific Research Project of Education Department of Jilin Province(Grant No.JJKH20200933KJ)Scientific Research Project of Shanghai Science and Technology Commission(Grant No.19511132000)。
文摘While the spread of COVID-19 in China is under control,the pandemic is developing rapidly around the world.Due to the normal migration of population,China is facing the high risk from imported cases.The potential specific medicine and vaccine are still in the process of clinical trials.Currently,controlling the impact of imported cases is the key to prevent new outbreak of COVID-19 in China.In this paper,we propose two impulsive systems to describe the impact of multilateral imported cases of COVID-19.Based on the published data,we simulate and analyze the epidemic trends under different control strategies.In particular,we compare four different scenarios and show the corresponding medical burden.The results can be useful in designing appropriate control strategy for imported cases in practice.
文摘Ever since the Bush administration took office, the U. S. national security strategy has given rise to much controversy. Whether the U. S. national security strategy is of unilateralism or multilateralistm is a question in dispute. Many people think it is a unilateralist strategy. According to their views, to achieve its own objective, the U. S. administration has rarely considered the interests and feelings of other coun-
文摘Currently,a new industrial revolution characterized by artificial intelligence,the internet of things,and digitalization is in a critical transition from initiation to allaround expansion.While injecting new dynamism into global economic growth,and promoting inclusive development and human welfare,the new industrial revolution will reshape the pattern of international competition,and provide a window period for latemoving countries to compete and catch up with developed nations.Amid the shocks of the new industrial revolution,countries must adhere to the principles of openness,multilateralism and reciprocity to share the dividends of the new industrial revolution and effectively cope with its challenges.Therefore,multilateralism,rather than protectionism and unilateralism,should dominate the mainstream of change in future global governance.The reform of existing multilateral organizations such as the World Trade Organization(WTO)must proceed under the principle of multilateralism.
文摘THE G20 Osaka Summit in Japan convened on June 28-29 had the world hold its breath. Not only were front-burner issues, such as WTO reform and digitalization of the economy, discussed there, but there was much fanfare around the first high-level meeting between China and the United States since the last G20 summit in Buenos Aires late last year. Given the mounting trade tensions between the two countries, the meeting took global center stage.
文摘Developing global partnerships is an important focus for China’s diplomacy in the new era.1 President Xi Jinping proposed at the Central Conference on Work Relating to Foreign Affairs in November 2014,“We should make more friends while abiding by the principle of non-alignment and build a global network of partnerships.”
文摘For me,the highlights of these recommendations are the financing and the role of Multilateral Development Banks.The recommendations I follow with most interest are the ones that protect and insure against political risk and regulatory risk.These
