To the Editor:Choledochocele,also known as type III choledochal cysts in the classification by Todani et al.[1],is a congenital abnormality of the biliary system.It is characterized by a cystic dilation of intramural ...To the Editor:Choledochocele,also known as type III choledochal cysts in the classification by Todani et al.[1],is a congenital abnormality of the biliary system.It is characterized by a cystic dilation of intramural segment of the distal common bile duct(CBD)protruding into the descending duodenum.Choledochocele makes up about 0.5%−4%of choledochal cysts[1,2].Compared with other subtypes,the incidence of choledochocele is extremely low and it frequently presents in adults at a relatively older age,with an average age of 51 years[3].The diagnosis and treatment are challenging.Here,we present a case of a young female patient with this rare disease entity,who recovered after effective endoscopic retrograde cholangiopancreatography(ERCP)management.展开更多
As current calculation models for inter-well connectivity in oilfields can only account for vertical wells,an updated model is elaborated here that can predict the future production performance and evaluate the connec...As current calculation models for inter-well connectivity in oilfields can only account for vertical wells,an updated model is elaborated here that can predict the future production performance and evaluate the connectivity of horizontal wells(or horizontal and vertical wells).In this model,the injection-production system of the considered reservoir is simplified and represented with many connected units.Moreover,the horizontal well is modeled with multiple connected wells without considering the pressure loss in the horizontal direction.With this approach,the production performance for both injection and production wells can be obtained by calculating the bottom-hole flowing pressure and oil/water saturation according to the material balance equation and a saturation front-tracking equation.Some effort is also provided to optimize(to fit known historical production performances)the two characteristic problem parameters,namely,the interwell conductivity and connected volume by means of a SPSA gradient-free algorithm.In order to verify the validity of the model,considering a heterogenous reservoir,three conceptual examples are constructed,where the number ratio between injection and production wells are 1/4,4/1 and 4/5,respectively.It is shown that there is a high consistency between simulation results and field data.展开更多
History matching is a critical step in reservoir numerical simulation algorithms.It is typically hindered by difficulties associated with the high-dimensionality of the problem and the gradient calculation approach.He...History matching is a critical step in reservoir numerical simulation algorithms.It is typically hindered by difficulties associated with the high-dimensionality of the problem and the gradient calculation approach.Here,a multi-step solving method is proposed by which,first,a Fast marching method(FMM)is used to calculate the pressure propagation time and determine the single-well sensitive area.Second,a mathematical model for history matching is implemented using a Bayesian framework.Third,an effective decomposition strategy is adopted for parameter dimensionality reduction.Finally,a localization matrix is constructed based on the single-well sensitive area data to modify the gradient of the objective function.This method has been verified through a water drive conceptual example and a real field case.The results have shown that the proposed method can generate more accurate gradient information and predictions compared to the traditional analytical gradient methods and other gradient-free algorithms.展开更多
基金the Natural Science Foundation of Zhejiang Province(LQ21H160025).
文摘To the Editor:Choledochocele,also known as type III choledochal cysts in the classification by Todani et al.[1],is a congenital abnormality of the biliary system.It is characterized by a cystic dilation of intramural segment of the distal common bile duct(CBD)protruding into the descending duodenum.Choledochocele makes up about 0.5%−4%of choledochal cysts[1,2].Compared with other subtypes,the incidence of choledochocele is extremely low and it frequently presents in adults at a relatively older age,with an average age of 51 years[3].The diagnosis and treatment are challenging.Here,we present a case of a young female patient with this rare disease entity,who recovered after effective endoscopic retrograde cholangiopancreatography(ERCP)management.
基金This study was supported by the National Natural Science Foundation of China(52004033,51922007).
文摘As current calculation models for inter-well connectivity in oilfields can only account for vertical wells,an updated model is elaborated here that can predict the future production performance and evaluate the connectivity of horizontal wells(or horizontal and vertical wells).In this model,the injection-production system of the considered reservoir is simplified and represented with many connected units.Moreover,the horizontal well is modeled with multiple connected wells without considering the pressure loss in the horizontal direction.With this approach,the production performance for both injection and production wells can be obtained by calculating the bottom-hole flowing pressure and oil/water saturation according to the material balance equation and a saturation front-tracking equation.Some effort is also provided to optimize(to fit known historical production performances)the two characteristic problem parameters,namely,the interwell conductivity and connected volume by means of a SPSA gradient-free algorithm.In order to verify the validity of the model,considering a heterogenous reservoir,three conceptual examples are constructed,where the number ratio between injection and production wells are 1/4,4/1 and 4/5,respectively.It is shown that there is a high consistency between simulation results and field data.
基金This study was supported by National Natural Science Foundation of China(Nos.52104017,51874044,51922007)Southern Marine Science and Engineering Guangdong Laboratory(Zhanjiang)(No.zjw-2019-04).
文摘History matching is a critical step in reservoir numerical simulation algorithms.It is typically hindered by difficulties associated with the high-dimensionality of the problem and the gradient calculation approach.Here,a multi-step solving method is proposed by which,first,a Fast marching method(FMM)is used to calculate the pressure propagation time and determine the single-well sensitive area.Second,a mathematical model for history matching is implemented using a Bayesian framework.Third,an effective decomposition strategy is adopted for parameter dimensionality reduction.Finally,a localization matrix is constructed based on the single-well sensitive area data to modify the gradient of the objective function.This method has been verified through a water drive conceptual example and a real field case.The results have shown that the proposed method can generate more accurate gradient information and predictions compared to the traditional analytical gradient methods and other gradient-free algorithms.
