A two-stage method is developed to solve a new class of multi-storage tank multi-source (MTMS) systems. In the first stage, the optimal storage policy of each tank is determined according to the electricity tariff, an...A two-stage method is developed to solve a new class of multi-storage tank multi-source (MTMS) systems. In the first stage, the optimal storage policy of each tank is determined according to the electricity tariff, and the ground-level storage tank is modeled as a node. In the second stage, the genetic algorithm, combined with a repairing scheme, is applied to solve the pump scheduling problem. The objective of the pump scheduling problem is to ensure that the required volume is adequately provided by the pumps while minimizing the operation cost (energy cost and treatment cost). The decision variables are the settings of the pumps and speed ratio of variable-speed pumps at time steps of the total operational time horizon. A mixed coding methodology is developed according to the characteristics of the decision variables. Daily operation cost savings of approximately 11% are obtained by application of the proposed method to a pressure zone of S. Y. water distribution system (WDS), China.展开更多
Hydraulic fracturing(HF)is a commonly used technique to stimulate low permeability formations such as shale plays and tight formations.However,this method of well stimulation has also been used in high permeable uncon...Hydraulic fracturing(HF)is a commonly used technique to stimulate low permeability formations such as shale plays and tight formations.However,this method of well stimulation has also been used in high permeable unconsolidated sandstone formations to bypass near-wellbore formation damage and prevent sand production at some distance apart from the wellbore wall.The treatment is called frac-pack completion,where a short length but wide width fracture is formed by injecting aggressive concentrations of proppant into the fracture plane.This operation is known as tip screen-out(TSO).Detailed design of fluid and proppant,including an optimal pump schedule,is required to achieve satisfactory TSO.In this study,we first assess the lattice-based numerical method's capabilities for simulating hydraulic fracturing propagation in elastoplastic formation.The results will be compared with the same case simulation results using a pseudo 3D(P3D)model and analytical model.Second,we explore the Nolte(1986)design for frac-pack and TSO treatment using lattice-based software and the P3D model.The results showed that both models could simulate the hydraulic fracturing propagation in soft formation and TSO operation,while some differences were observed in generated geometry,the tip screenout time and net pressure profiles.The results are presented.It was noted that fracture propagation regime(viscosity/toughness),nonlocality and nonlinearity had an influence on the different geometries.The advantages of each model will be discussed.展开更多
基金Project supported by the National Science & Technology Pillar Program during the Eleventh Five-year Plan Period (No. 2006BAJ08B03), China
文摘A two-stage method is developed to solve a new class of multi-storage tank multi-source (MTMS) systems. In the first stage, the optimal storage policy of each tank is determined according to the electricity tariff, and the ground-level storage tank is modeled as a node. In the second stage, the genetic algorithm, combined with a repairing scheme, is applied to solve the pump scheduling problem. The objective of the pump scheduling problem is to ensure that the required volume is adequately provided by the pumps while minimizing the operation cost (energy cost and treatment cost). The decision variables are the settings of the pumps and speed ratio of variable-speed pumps at time steps of the total operational time horizon. A mixed coding methodology is developed according to the characteristics of the decision variables. Daily operation cost savings of approximately 11% are obtained by application of the proposed method to a pressure zone of S. Y. water distribution system (WDS), China.
文摘Hydraulic fracturing(HF)is a commonly used technique to stimulate low permeability formations such as shale plays and tight formations.However,this method of well stimulation has also been used in high permeable unconsolidated sandstone formations to bypass near-wellbore formation damage and prevent sand production at some distance apart from the wellbore wall.The treatment is called frac-pack completion,where a short length but wide width fracture is formed by injecting aggressive concentrations of proppant into the fracture plane.This operation is known as tip screen-out(TSO).Detailed design of fluid and proppant,including an optimal pump schedule,is required to achieve satisfactory TSO.In this study,we first assess the lattice-based numerical method's capabilities for simulating hydraulic fracturing propagation in elastoplastic formation.The results will be compared with the same case simulation results using a pseudo 3D(P3D)model and analytical model.Second,we explore the Nolte(1986)design for frac-pack and TSO treatment using lattice-based software and the P3D model.The results showed that both models could simulate the hydraulic fracturing propagation in soft formation and TSO operation,while some differences were observed in generated geometry,the tip screenout time and net pressure profiles.The results are presented.It was noted that fracture propagation regime(viscosity/toughness),nonlocality and nonlinearity had an influence on the different geometries.The advantages of each model will be discussed.
