Based on the impact of the stress perturbation effect created by simultaneous propagation of multiple fractures in the process of simultaneous hydraulic fracturing, a thorough research on the mechanism and adaptation ...Based on the impact of the stress perturbation effect created by simultaneous propagation of multiple fractures in the process of simultaneous hydraulic fracturing, a thorough research on the mechanism and adaptation of simultaneous fracturing of double horizontal wells in ultra-low permeability sandstone reservoirs was conducted by taking two adjacent horizontal wells(well Yangping-1 and well Yangping-2 located in Longdong area of China Changqing Oilfield) as field test wells. And simultaneous fracturing optimal design of two adjacent horizontal wells was finished and employed in field test. Micro-seismic monitoring analysis of fracture propagation during the stimulation treatment shows that hydraulic fractures present a pattern of complicated network expansion, and the well test data after fracturing show that the daily production of well Yangping-1 and well Yangping-2 reach105.8 t/d and 87.6 t/d, which are approximately 9.4 times and 7.8 times the daily production of a fractured vertical well in the same area, respectively. Field test reflects that simultaneous hydraulic fracturing of two adjacent horizontal wells can enlarge the expansion area of hydraulic fractures to obtain a lager drainage area and realize the full stimulation of ultra-low permeability sandstone reservoirs in China Changqing oilfield. Therefore, simultaneous fracturing of two adjacent horizontal wells provides a good opportunity in stimulation techniques for the efficient development of ultra-low permeability reservoirs in China Changqing oilfield,and it has great popularization value and can provide a new avenue for the application of stimulation techniques in ultra-low permeability reservoirs in China.展开更多
Although open leg fractures are very common in orthopedics and traumatology, bilateral open leg fractures are extremely rare and are usually associated with an increased risk of complications. We report a case of a si...Although open leg fractures are very common in orthopedics and traumatology, bilateral open leg fractures are extremely rare and are usually associated with an increased risk of complications. We report a case of a simultaneous, asymmetrical, comminuted and bilateral open fracture of the tibia and fibula by a firearm that occurred during an escape attempt in a 29-year-old prisoner. The pre-operative radiological assessment found an open fracture of both legs of the ballistic type;multiple traumatic gunshot wounds with a narrow entry hole and a wide exit hole. Early surgical intervention of intravenous antibiotics, tetanus prophylaxis and open fracture irrigation and debridement was performed within the 6 hour rule. The treatment consisted of a posterior splint followed by trimming andosteosynthesis using a FESSA external fixator from the military health service. A second operation was not needed. Evolution was favorable with ambulation starting from the 45th day. Simultaneous and bilateral tibia-fibula fractures by a firearm are exceptional, therefore, the treatment was surgical with the pre-operative and post-operative protocols well managed.展开更多
A simultaneous experimental and numerical study of shear fracture of concrete-like materials is carried out using Brazilian disc specimens with initial double edge cracks and fourpoint bending beam specimens with doub...A simultaneous experimental and numerical study of shear fracture of concrete-like materials is carried out using Brazilian disc specimens with initial double edge cracks and fourpoint bending beam specimens with double edge-notches.The interference effects of two cracks/notches are investigated through varied ligament angles and crack lengths.It is shown that shear fracturing paths change remarkably with the initial ligament angles and crack lengths.The cracked specimens are numerically simulated by an indirect boundary element method.A comparison between the numerical results and the experimental ones shows good agreement.展开更多
Simultaneous ipsilateral fractures involving radial head and distal end of radius are uncommon.We present our thoughts on which fracture should be addressed first.A 68-year-old lady sustained an ipsilateral fracture o...Simultaneous ipsilateral fractures involving radial head and distal end of radius are uncommon.We present our thoughts on which fracture should be addressed first.A 68-year-old lady sustained an ipsilateral fracture of the right radial head and distal end of radius following a fall.Clinically her right elbow was posteriorly dislocated and right wrist was deformed.Plain radiographs showed an intraarticular fracture of the distal end of radius and a comminution radial head fracture with a proximally migrated radius.Magnetic resonance imaging(MRI)showed no significant ligament injuries.We addressed her distal radius first with an an atomical lock ing plate followed by her radial head with a radial head replacement.Our rationale to treat the distal end radius:first was to obtain a correct alignment of Lister's tubercle and correct the distal radius height.Lister's tubercle was used to guide for the correct rotation of the radial head prosthesis.Correcting the distal end fracture radial height helped us with length selection of the radial head prosthesis and address the proximally migrated radial shaft and neck.Postoperative radiographs showed an acceptable reduction.The Cooney score was 75 at 3 months postoperatively,which was equivalent to a fair functional outcome.展开更多
基金Project(51404204)supported by the National Natural Science Foundation of ChinaProject(20135121120002)supported by Specialized Research Fund for the Doctoral Program of Higher Education of ChinaProject(2014QHZ005)supported by Scientific Research Starting Projecting of SWPU,China
文摘Based on the impact of the stress perturbation effect created by simultaneous propagation of multiple fractures in the process of simultaneous hydraulic fracturing, a thorough research on the mechanism and adaptation of simultaneous fracturing of double horizontal wells in ultra-low permeability sandstone reservoirs was conducted by taking two adjacent horizontal wells(well Yangping-1 and well Yangping-2 located in Longdong area of China Changqing Oilfield) as field test wells. And simultaneous fracturing optimal design of two adjacent horizontal wells was finished and employed in field test. Micro-seismic monitoring analysis of fracture propagation during the stimulation treatment shows that hydraulic fractures present a pattern of complicated network expansion, and the well test data after fracturing show that the daily production of well Yangping-1 and well Yangping-2 reach105.8 t/d and 87.6 t/d, which are approximately 9.4 times and 7.8 times the daily production of a fractured vertical well in the same area, respectively. Field test reflects that simultaneous hydraulic fracturing of two adjacent horizontal wells can enlarge the expansion area of hydraulic fractures to obtain a lager drainage area and realize the full stimulation of ultra-low permeability sandstone reservoirs in China Changqing oilfield. Therefore, simultaneous fracturing of two adjacent horizontal wells provides a good opportunity in stimulation techniques for the efficient development of ultra-low permeability reservoirs in China Changqing oilfield,and it has great popularization value and can provide a new avenue for the application of stimulation techniques in ultra-low permeability reservoirs in China.
文摘Although open leg fractures are very common in orthopedics and traumatology, bilateral open leg fractures are extremely rare and are usually associated with an increased risk of complications. We report a case of a simultaneous, asymmetrical, comminuted and bilateral open fracture of the tibia and fibula by a firearm that occurred during an escape attempt in a 29-year-old prisoner. The pre-operative radiological assessment found an open fracture of both legs of the ballistic type;multiple traumatic gunshot wounds with a narrow entry hole and a wide exit hole. Early surgical intervention of intravenous antibiotics, tetanus prophylaxis and open fracture irrigation and debridement was performed within the 6 hour rule. The treatment consisted of a posterior splint followed by trimming andosteosynthesis using a FESSA external fixator from the military health service. A second operation was not needed. Evolution was favorable with ambulation starting from the 45th day. Simultaneous and bilateral tibia-fibula fractures by a firearm are exceptional, therefore, the treatment was surgical with the pre-operative and post-operative protocols well managed.
基金Project supported by Iran's National Elites Foundation(INEF)Partial supports of center of excellent for structures and earthquake engineering at Sharif University of technology
文摘A simultaneous experimental and numerical study of shear fracture of concrete-like materials is carried out using Brazilian disc specimens with initial double edge cracks and fourpoint bending beam specimens with double edge-notches.The interference effects of two cracks/notches are investigated through varied ligament angles and crack lengths.It is shown that shear fracturing paths change remarkably with the initial ligament angles and crack lengths.The cracked specimens are numerically simulated by an indirect boundary element method.A comparison between the numerical results and the experimental ones shows good agreement.
文摘Simultaneous ipsilateral fractures involving radial head and distal end of radius are uncommon.We present our thoughts on which fracture should be addressed first.A 68-year-old lady sustained an ipsilateral fracture of the right radial head and distal end of radius following a fall.Clinically her right elbow was posteriorly dislocated and right wrist was deformed.Plain radiographs showed an intraarticular fracture of the distal end of radius and a comminution radial head fracture with a proximally migrated radius.Magnetic resonance imaging(MRI)showed no significant ligament injuries.We addressed her distal radius first with an an atomical lock ing plate followed by her radial head with a radial head replacement.Our rationale to treat the distal end radius:first was to obtain a correct alignment of Lister's tubercle and correct the distal radius height.Lister's tubercle was used to guide for the correct rotation of the radial head prosthesis.Correcting the distal end fracture radial height helped us with length selection of the radial head prosthesis and address the proximally migrated radial shaft and neck.Postoperative radiographs showed an acceptable reduction.The Cooney score was 75 at 3 months postoperatively,which was equivalent to a fair functional outcome.
