Although terrorist bombings have tormented the world for a long time, currently they have reached unprecedented levels and become a continuous threat without borders, race or age. Almost all of them are caused by impr...Although terrorist bombings have tormented the world for a long time, currently they have reached unprecedented levels and become a continuous threat without borders, race or age. Almost all of them are caused by improvised explosive devices. The unpredictability of the terrorist bombings, leading to simultaneous generation of a large number of casualties and severe "multidimensional" blast trauma require a constant vigilance and preparedness of every hospital worldwide. Approximately 1.0%-2.6% of all trauma patients and 7% of the combat casualties require a massive blood transfusion. Coagulopathy is presented in 65% of them with mortality exceeding 50%. Damage control resuscitation is a novel approach, developed in the military practice for treatment of this subgroup of trauma patients. The comparison with the conventional approach revealed mortality reduction with 40%-74%, lower frequency of abdominal compartment syndrome(8% vs 16%), sepsis(9% vs 20%), multiorgan failure(16% vs 37%) and a significant reduction of resuscitation volumes, both crystalloids and blood products. Damage control surgery(DCS) and damage control resuscitation(DCR) are promising new approaches, contributing for the mortality reduction among the most severely wounded patients. Despite the lack of consensus about the optimal ratio of the blood products and the possible influence of the survival bias, we think that DCR carries survival benefit and recommend it in trauma patients with exsanguinating bleeding.展开更多
Stress sensitivity and water blocking in fractured carbonate reservoir formations with low permeability were determined as the main potential damage mechanisms during drilling and completion operations in the ancient ...Stress sensitivity and water blocking in fractured carbonate reservoir formations with low permeability were determined as the main potential damage mechanisms during drilling and completion operations in the ancient buried hill Ordovician reservoirs in the Tarim Basin. Geological structure, lithology, porosity, permeability and mineral components all affect the potential for formation damage. The experimental results showed that the permeability loss was 83.8%-98.6% caused by stress sensitivity, and was 27.9%-48.1% caused by water blocking. Based on the experimental results, several main conclusions concerning stress sensitivity can be drawn as follows： the lower the core permeability and the smaller the core fracture width, the higher the stress sensitivity. Also, stress sensitivity results in lag effect for both permeability recovery and fracture closure. Aimed at the mechanisms of formation damage, a modified low-damage mixed metal hydroxide （MMH） drilling fluid system was developed, which was mainly composed of low-fluorescence shale control agent, filtration control agent, lowfluorescence lubricant and surfactant. The results of experimental evaluation and field test showed that the newly-developed drilling fluid and engineering techniques provided could dramatically increase the return permeability （over 85%） of core samples. This drilling fluid had such advantages as good rheological and lubricating properties, high temperature stability, and low filtration rate （API filtration less than 5 ml after aging at 120 ℃ for 4 hours）. Therefore, fractured carbonate formations with low permeability could be protected effectively when drilling with the newly-developed drilling fluid. Meanwhile, field test showed that both penetration rate and bore stability were improved and the soaking time of the drilling fluid with formation was sharply shortened, indicating that the modified MMH drilling fluid could meet the requirements of drilling engineering and geology.展开更多
Selecting bridging agents properly is a critical factor in designing non-damaging or low-damaging drill-in fluids. Historically, Abrams＇ rule has been used for this purpose. However, Abrams＇ rule only addresses the ...Selecting bridging agents properly is a critical factor in designing non-damaging or low-damaging drill-in fluids. Historically, Abrams＇ rule has been used for this purpose. However, Abrams＇ rule only addresses the size of particle required to initiate a bridge. The rule does not give an optimum size nor an ideal packing sequence for minimizing fluid invasion and optimizing sealing. This paper elaborates an ideal packing approach to solving the sealing problem by sealing pores with different sizes, especially those large pores which usually make dominant contribution to permeability and thereby effectively preventing the solids and filtrate of drill-in fluids from invading into formations, compared with the conventionally used techniques. Practical software has been developed to optimize the blending proportion of several bridging agents, so as to achieve ideal packing effectiveness. The method and its use in selecting the best blending proportion of several bridging agents are also discussed in this paper. A carefully designed drill-in fluid by using the ideal packing technique （named the IPT fluid） for offshore drilling operations at the Weizhou Oilfield, Nanhai West Company, CNOOC is presented. The near 100% return permeabilities from the dynamic damage tests using reservoir cores demonstrated the excellent bridging effect provided by this drill-in fluid.展开更多
The use of open abdomen(OA) as a technique in the treatment of exsanguinating trauma patients was first described in the mid-19 th century. Since the 1980 s, OA has become a relatively new and increasingly common stra...The use of open abdomen(OA) as a technique in the treatment of exsanguinating trauma patients was first described in the mid-19 th century. Since the 1980 s, OA has become a relatively new and increasingly common strategy to manage massive trauma and abdominal catastrophes. OA has been proven to help reduce the mortality of trauma. Nevertheless, the OA method may be associated with terrible and devastating complications such as enteroatmospheric fistula(EAF). As a result, OA should not be overused, and attention should be given to critical care as well as special management. The temporary abdominal closure(TAC) technique after abbreviated laparotomy was used to improve wound healing and facilitate final fascial closure of OA. Negative pressure therapy(NPT) is the most commonly used TAC method.展开更多
A coupled CFD-DEM method is used to simulate the formation process of fracture plugging zone.A photo-elastic system characterizing mesoscale force chain network developed by our own is used to model the pressure evolu...A coupled CFD-DEM method is used to simulate the formation process of fracture plugging zone.A photo-elastic system characterizing mesoscale force chain network developed by our own is used to model the pressure evolution in fracture plugging zone to reveal the evolution mechanism of the structure of fracture plugging zone.A theoretical basis is provided for improving the lost circulation control effect in fractured reservoirs and novel methods are proposed for selecting loss control materials and designing loss control formula.CFD-DEM simulation results show that bridging probability is the key factor determining the formation of fracture plugging zone and fracture plugging efficiency.Critical and absolute bridging concentrations are proposed as the key indexes for loss control formula design.With the increase of absolute bridging concentration,the governing factor of bridging is changed from material grain size to the combination of material grain size and friction force.Results of photo-elastic experiments show that mesoscale force chain network is the intrinsic factor affecting the evolution of pressure exerting on the fracture plugging zone and determines the macroscopic strength of fracture plugging zone.Performance parameters of loss control material affect the force chain network structure and the ratio of stronger force chain,and further impact the stability and strength of fracture plugging zone.Based on the study results,the loss control formula is optimized and new-type loss control material is designed.Laboratory experiments results show that the fracture plugging efficiency and strength is effectively improved.展开更多
BACKGROUND:Overwhelming hemorrhage or other intra-abdominal complications may be associated with obstetrical or gynecologic(OB/GYN) procedures and may require the surgical training of an Acute Care/Trauma Surgeon.The ...BACKGROUND:Overwhelming hemorrhage or other intra-abdominal complications may be associated with obstetrical or gynecologic(OB/GYN) procedures and may require the surgical training of an Acute Care/Trauma Surgeon.The OB Critical Assessment Team(OBCAT Alert) was developed at our institution to facilitate a multidisciplinary response to complex OB/GYN cases.We sought to review and characterize the Acute Care/Trauma Surgeon's role in these cases.METHODS:We conducted a retrospective review of all emergency consults during an OB/GYN case at our institution from 2008 to 2015.An OBCAT is a hospital based alert system designed to immediately notify OB/GYN,anesthesiology,Acute Care/Trauma,the intensive care unit(ICU),and the blood bank of a potential emergency during an OB/GYN case.RESULTS:There were 7±3 OBCAT alerts/year.Seventeen patients required Acute Care/Trauma surgery intervention for hemorrhage.Thirteen patients required damage control packing during their hospitalization.Blood loss averaged 6.8±5.5 L and patients received a total of 21±14units during deliveries with hemorrhage.There were 17 other surgical interventions not related to hemorrhage;seven of these cases were related to adhesions or intestinal injury.Seven additional cases required evaluation post routine OB/GYN procedure;the most common reason was for severe wound complications.There were three deaths during this study period.CONCLUSION:Emergency OB/GYN cases are associated with high morbidity and may require damage control or other surgical techniques in cases of overwhelming hemorrhage.Acute Care/Trauma Surgeons have a key role in the treatment of these complex cases.展开更多
In order to solve the problem of rib spalling of high coal walls in fully-mechanized（HCWFM）mines,we used the principle of damage mechanics to analyze coal wall rib spalling.The results show that coal wall rib spalli...In order to solve the problem of rib spalling of high coal walls in fully-mechanized（HCWFM）mines,we used the principle of damage mechanics to analyze coal wall rib spalling.The results show that coal wall rib spalling is,to a certain degree,a macro-performance of the development of micro-cracks.We built a mechanical model to simulate the damage to the front of coal walls,carried out theoretical calculations of the damage parameters,analyzed the effect of mining height,original cracks,seam strength,horizontal stress,vertical displacement of the coal walls and other parameters on coal wall rib spalling, which conform well with the results of our field measurements and numerical simulation.The key to control coal wall rib spalling is to control the development of cracks in coal walls.Accelerating the speed of advancing the working face,improving the setting load of support and the horizontal force of the guard board,strengthening coal walls and other technical measures can effectively reduce the degree of damage to the coal walls and control coal wall rib spalling at HCWFM faces.展开更多
文摘Although terrorist bombings have tormented the world for a long time, currently they have reached unprecedented levels and become a continuous threat without borders, race or age. Almost all of them are caused by improvised explosive devices. The unpredictability of the terrorist bombings, leading to simultaneous generation of a large number of casualties and severe "multidimensional" blast trauma require a constant vigilance and preparedness of every hospital worldwide. Approximately 1.0%-2.6% of all trauma patients and 7% of the combat casualties require a massive blood transfusion. Coagulopathy is presented in 65% of them with mortality exceeding 50%. Damage control resuscitation is a novel approach, developed in the military practice for treatment of this subgroup of trauma patients. The comparison with the conventional approach revealed mortality reduction with 40%-74%, lower frequency of abdominal compartment syndrome(8% vs 16%), sepsis(9% vs 20%), multiorgan failure(16% vs 37%) and a significant reduction of resuscitation volumes, both crystalloids and blood products. Damage control surgery(DCS) and damage control resuscitation(DCR) are promising new approaches, contributing for the mortality reduction among the most severely wounded patients. Despite the lack of consensus about the optimal ratio of the blood products and the possible influence of the survival bias, we think that DCR carries survival benefit and recommend it in trauma patients with exsanguinating bleeding.
基金the National Natural Science Foundation of China(No.50574061)
文摘Stress sensitivity and water blocking in fractured carbonate reservoir formations with low permeability were determined as the main potential damage mechanisms during drilling and completion operations in the ancient buried hill Ordovician reservoirs in the Tarim Basin. Geological structure, lithology, porosity, permeability and mineral components all affect the potential for formation damage. The experimental results showed that the permeability loss was 83.8%-98.6% caused by stress sensitivity, and was 27.9%-48.1% caused by water blocking. Based on the experimental results, several main conclusions concerning stress sensitivity can be drawn as follows： the lower the core permeability and the smaller the core fracture width, the higher the stress sensitivity. Also, stress sensitivity results in lag effect for both permeability recovery and fracture closure. Aimed at the mechanisms of formation damage, a modified low-damage mixed metal hydroxide （MMH） drilling fluid system was developed, which was mainly composed of low-fluorescence shale control agent, filtration control agent, lowfluorescence lubricant and surfactant. The results of experimental evaluation and field test showed that the newly-developed drilling fluid and engineering techniques provided could dramatically increase the return permeability （over 85%） of core samples. This drilling fluid had such advantages as good rheological and lubricating properties, high temperature stability, and low filtration rate （API filtration less than 5 ml after aging at 120 ℃ for 4 hours）. Therefore, fractured carbonate formations with low permeability could be protected effectively when drilling with the newly-developed drilling fluid. Meanwhile, field test showed that both penetration rate and bore stability were improved and the soaking time of the drilling fluid with formation was sharply shortened, indicating that the modified MMH drilling fluid could meet the requirements of drilling engineering and geology.
基金supported by the National Natural Science Foundation(Project No.50574061)the Changjiang Scholars and Innovative Research Team(No.IRT0411),Ministry of Education
文摘Selecting bridging agents properly is a critical factor in designing non-damaging or low-damaging drill-in fluids. Historically, Abrams＇ rule has been used for this purpose. However, Abrams＇ rule only addresses the size of particle required to initiate a bridge. The rule does not give an optimum size nor an ideal packing sequence for minimizing fluid invasion and optimizing sealing. This paper elaborates an ideal packing approach to solving the sealing problem by sealing pores with different sizes, especially those large pores which usually make dominant contribution to permeability and thereby effectively preventing the solids and filtrate of drill-in fluids from invading into formations, compared with the conventionally used techniques. Practical software has been developed to optimize the blending proportion of several bridging agents, so as to achieve ideal packing effectiveness. The method and its use in selecting the best blending proportion of several bridging agents are also discussed in this paper. A carefully designed drill-in fluid by using the ideal packing technique （named the IPT fluid） for offshore drilling operations at the Weizhou Oilfield, Nanhai West Company, CNOOC is presented. The near 100% return permeabilities from the dynamic damage tests using reservoir cores demonstrated the excellent bridging effect provided by this drill-in fluid.
文摘The use of open abdomen(OA) as a technique in the treatment of exsanguinating trauma patients was first described in the mid-19 th century. Since the 1980 s, OA has become a relatively new and increasingly common strategy to manage massive trauma and abdominal catastrophes. OA has been proven to help reduce the mortality of trauma. Nevertheless, the OA method may be associated with terrible and devastating complications such as enteroatmospheric fistula(EAF). As a result, OA should not be overused, and attention should be given to critical care as well as special management. The temporary abdominal closure(TAC) technique after abbreviated laparotomy was used to improve wound healing and facilitate final fascial closure of OA. Negative pressure therapy(NPT) is the most commonly used TAC method.
基金Supported by the National Natural Science Foundation of China(51604236)Open Fund of the State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation(PLN201913)+1 种基金Science and Technology Planning Project of the Sichuan Province,China(2018JY0436)Sichuan Youth Science and Technology Innovation Research Team Project for Unconventional Oil and Gas Reservoir Protection(2016TD0016)。
文摘A coupled CFD-DEM method is used to simulate the formation process of fracture plugging zone.A photo-elastic system characterizing mesoscale force chain network developed by our own is used to model the pressure evolution in fracture plugging zone to reveal the evolution mechanism of the structure of fracture plugging zone.A theoretical basis is provided for improving the lost circulation control effect in fractured reservoirs and novel methods are proposed for selecting loss control materials and designing loss control formula.CFD-DEM simulation results show that bridging probability is the key factor determining the formation of fracture plugging zone and fracture plugging efficiency.Critical and absolute bridging concentrations are proposed as the key indexes for loss control formula design.With the increase of absolute bridging concentration,the governing factor of bridging is changed from material grain size to the combination of material grain size and friction force.Results of photo-elastic experiments show that mesoscale force chain network is the intrinsic factor affecting the evolution of pressure exerting on the fracture plugging zone and determines the macroscopic strength of fracture plugging zone.Performance parameters of loss control material affect the force chain network structure and the ratio of stronger force chain,and further impact the stability and strength of fracture plugging zone.Based on the study results,the loss control formula is optimized and new-type loss control material is designed.Laboratory experiments results show that the fracture plugging efficiency and strength is effectively improved.
文摘BACKGROUND:Overwhelming hemorrhage or other intra-abdominal complications may be associated with obstetrical or gynecologic(OB/GYN) procedures and may require the surgical training of an Acute Care/Trauma Surgeon.The OB Critical Assessment Team(OBCAT Alert) was developed at our institution to facilitate a multidisciplinary response to complex OB/GYN cases.We sought to review and characterize the Acute Care/Trauma Surgeon's role in these cases.METHODS:We conducted a retrospective review of all emergency consults during an OB/GYN case at our institution from 2008 to 2015.An OBCAT is a hospital based alert system designed to immediately notify OB/GYN,anesthesiology,Acute Care/Trauma,the intensive care unit(ICU),and the blood bank of a potential emergency during an OB/GYN case.RESULTS:There were 7±3 OBCAT alerts/year.Seventeen patients required Acute Care/Trauma surgery intervention for hemorrhage.Thirteen patients required damage control packing during their hospitalization.Blood loss averaged 6.8±5.5 L and patients received a total of 21±14units during deliveries with hemorrhage.There were 17 other surgical interventions not related to hemorrhage;seven of these cases were related to adhesions or intestinal injury.Seven additional cases required evaluation post routine OB/GYN procedure;the most common reason was for severe wound complications.There were three deaths during this study period.CONCLUSION:Emergency OB/GYN cases are associated with high morbidity and may require damage control or other surgical techniques in cases of overwhelming hemorrhage.Acute Care/Trauma Surgeons have a key role in the treatment of these complex cases.
基金provided by the Independent Research Fund(No.SKLCRSM09X02)the Open Research Fund of the State Key Laboratory of Coal Resources and Safety Mining (No.08KF12)the Qinglan Project of Jiangsu Province and the Graduate Students Innovation Fund of Colleges and Universities in Jiangsu(No.CX09B_120Z)
文摘In order to solve the problem of rib spalling of high coal walls in fully-mechanized（HCWFM）mines,we used the principle of damage mechanics to analyze coal wall rib spalling.The results show that coal wall rib spalling is,to a certain degree,a macro-performance of the development of micro-cracks.We built a mechanical model to simulate the damage to the front of coal walls,carried out theoretical calculations of the damage parameters,analyzed the effect of mining height,original cracks,seam strength,horizontal stress,vertical displacement of the coal walls and other parameters on coal wall rib spalling, which conform well with the results of our field measurements and numerical simulation.The key to control coal wall rib spalling is to control the development of cracks in coal walls.Accelerating the speed of advancing the working face,improving the setting load of support and the horizontal force of the guard board,strengthening coal walls and other technical measures can effectively reduce the degree of damage to the coal walls and control coal wall rib spalling at HCWFM faces.
