BACKGROUND： With the development of internal fixation materials, simple operation with internal fixation has become a tendency. Ni-Ti shape memory alloy embracing fixator has such advantages as slight injury, easy op...BACKGROUND： With the development of internal fixation materials, simple operation with internal fixation has become a tendency. Ni-Ti shape memory alloy embracing fixator has such advantages as slight injury, easy operation, security, reliable fixation, and better histocompatibility. The present study was to explore curative effect and postoperative results of Ti-Ni shape memory alloy embracing ？ xator in patients with multiple fractured ribs and ？ ail chest.METHODS： The curative effect and long-term follow-up results were observed after internal ？ xation with a shape memory alloy embracing ？ xator in patients with multiple fractured ribs and ？ ail chest from January 2006 to December 2009.RESULTS： All patients were cured with an average hospital stay of 10.31±3.14 days. Post-operative pain was less severe than preoperative pain （P=0.02）.The rate of postoperative complications such as atelectasis, pulmonary infection, etc was 17.65%. There were fewer long-term complications and less in？ uence on daily work and life.CONCLUSIONS： It is practical to perform an operation for fracture of multiple ribs using a Ti-Ni shape memory alloy embracing ？ xator. The ？ xator, which is less traumatic, simple, safe, and reliable, has a good-histocompatibility and fewer postoperative complications.展开更多
Under the policy background and advocacy of carbon capture,utilization,and storage(CCUS),CO_(2)-EOR has become a promising direction in the shale oil reservoir industry.The multi-scale pore structure distribution and ...Under the policy background and advocacy of carbon capture,utilization,and storage(CCUS),CO_(2)-EOR has become a promising direction in the shale oil reservoir industry.The multi-scale pore structure distribution and fracture structure lead to complex multiphase flow,comprehensively considering multiple mechanisms is crucial for development and CO_(2) storage in fractured shale reservoirs.In this paper,a multi-mechanism coupled model is developed by MATLAB.Compared to the traditional Eclipse300 and MATLAB Reservoir Simulation Toolbox(MRST),this model considers the impact of pore structure on fluid phase behavior by the modified Peng—Robinson equation of state(PR-EOS),and the effect simultaneously radiate to Maxwell—Stefan(M—S)diffusion,stress sensitivity,the nano-confinement(NC)effect.Moreover,a modified embedded discrete fracture model(EDFM)is used to model the complex fractures,which optimizes connection types and half-transmissibility calculation approaches between non-neighboring connections(NNCs).The full implicit equation adopts the finite volume method(FVM)and Newton—Raphson iteration for discretization and solution.The model verification with the Eclipse300 and MRST is satisfactory.The results show that the interaction between the mechanisms significantly affects the production performance and storage characteristics.The effect of molecular diffusion may be overestimated in oil-dominated(liquid-dominated)shale reservoirs.The well spacing and injection gas rate are the most crucial factors affecting the production by sensitivity analysis.Moreover,the potential gas invasion risk is mentioned.This model provides a reliable theoretical basis for CO_(2)-EOR and sequestration in shale oil reservoirs.展开更多
Due to the reservoir heterogeneity and the stress shadow effect, multiple hydraulic fractures within one fracturing segment cannot be initiated simultaneously and propagate evenly, which will cause a low effectiveness...Due to the reservoir heterogeneity and the stress shadow effect, multiple hydraulic fractures within one fracturing segment cannot be initiated simultaneously and propagate evenly, which will cause a low effectiveness of reservoir stimulation. Temporary plugging and diverting fracturing(TPDF) is considered to be a potential uniform-stimulation method for creating multiple fractures simultaneously in the oilfield. However, the multi-fracture propagation morphology during TPDF is not clear now. The purpose of this study is to quantitatively investigate the multi-fracture propagation morphology during TPDF through true tri-axial fracturing experiments and CT scanning. Critical parameters such as fracture spacing, number of perforation clusters, the viscosity of fracturing fluid, and the in-situ stress have been investigated. The fracture geometry before and after diversion have been quantitively analyzed based on the two-dimensional CT slices and three-dimensional reconstruction method. The main conclusions are as follows:(1) When injecting the high viscosity fluid or perforating at the location with low in-situ stress, multiple hydraulic fractures would simultaneously propagate. Otherwise, only one hydraulic fracture was created during the initial fracturing stage(IFS) for most tests.(2) The perforation cluster effectiveness(PCE) has increased from 26.62% during the IFS to 88.86% after using diverters.(3) The diverted fracture volume has no apparent correlation with the pressure peak and peak frequency during the diversion fracturing stage(DFS) but is positively correlated with water-work.(4) Four types of plugging behavior in shale could be controlled by adjusting the diverter recipe and diverter injection time, and the plugging behavior includes plugging the natural fracture in the wellbore, plugging the previous hydraulic fractures, plugging the fracture tip and plugging the bedding.展开更多
Temporary plugging and diverting fracturing(TPDF),involving inner-fracture temporary plugging(IFTP)and inner-stage temporary plugging(ISTP),has been proposed as a widely applied technique in China,for promoting the un...Temporary plugging and diverting fracturing(TPDF),involving inner-fracture temporary plugging(IFTP)and inner-stage temporary plugging(ISTP),has been proposed as a widely applied technique in China,for promoting the uniform initiation and propagation of multi-clustered hydraulic fractures(HFs)in a horizontal well of the shale oil/gas reservoirs.However,how the key plugging parameters controlling the multi-fracture growth and the pumping pressure response during TPDF in shale with dense bedding planes(BPs)and natural fractures(NFs)is still unclear,which limits the optimization of TPDF scheme.In this paper,a series of TPDF simulation experiments within a stage of multi-cluster in a horizontal well were carried out on outcrops of Longmaxi Formation shale using a large-scale true tri-axial fracturing simulation system,combined with the acoustic emission(AE)monitor and computed tomography(CT)scanning techniques.Each experiment was divided into three stages,including the conventional fracturing(CF),IFTP and ISTP.Multi-fracture initiation and propagation behavior,and the dominant controlling parameters were examined,containing the particle sizes,concentration of temporary plugging agent(TPA),and cluster number.The results showed that the number of transverse HFs(THFs)and the overall complexity of fracture morphology increase with the increase in TPA concentration and perforation cluster number.Obviously,the required concentration of TPA is positively correlated with the cluster number.Higher peak values and continuous fluctuations of pumping pressure during TPDF may indicate the creation of diversion fractures.The creation of standard THFs during CF is favorable to the creation of diversion fractures during TPDF.Moreover,the activation of BPs nearby the wellbore during CF is unfavorable to the subsequent pressure buildup during TPDF,resulting in poor plugging and diverting effect.Notably,under the strike-slip fault stress regime,the diversion of THFs is not likely during IFTP,which is similar as the results of ISTP to initiate mainly the un-initiated or under-propagated perforation clusters.Three typical pressure curve types during TPDF can be summarized to briefly identify the hydraulic fracture diversion effects,including good(multiple branches or/and THFs can be newly created),fair(HF initiation along the slightly opened BPs and then activating the NFs),and bad(HF initiation along the largely opened BPs and then connecting with the NFs).展开更多
文摘BACKGROUND： With the development of internal fixation materials, simple operation with internal fixation has become a tendency. Ni-Ti shape memory alloy embracing fixator has such advantages as slight injury, easy operation, security, reliable fixation, and better histocompatibility. The present study was to explore curative effect and postoperative results of Ti-Ni shape memory alloy embracing ？ xator in patients with multiple fractured ribs and ？ ail chest.METHODS： The curative effect and long-term follow-up results were observed after internal ？ xation with a shape memory alloy embracing ？ xator in patients with multiple fractured ribs and ？ ail chest from January 2006 to December 2009.RESULTS： All patients were cured with an average hospital stay of 10.31±3.14 days. Post-operative pain was less severe than preoperative pain （P=0.02）.The rate of postoperative complications such as atelectasis, pulmonary infection, etc was 17.65%. There were fewer long-term complications and less in？ uence on daily work and life.CONCLUSIONS： It is practical to perform an operation for fracture of multiple ribs using a Ti-Ni shape memory alloy embracing ？ xator. The ？ xator, which is less traumatic, simple, safe, and reliable, has a good-histocompatibility and fewer postoperative complications.
基金supported by the National Natural Science Foundation of China(No.52174038 and No.52004307)China Petroleum Science and Technology Project-Major Project-Research on Tight Oil-Shale Oil Reservoir Engineering Methods and Key Technologies in Ordos Basin(No.ZLZX2020-02-04)Science Foundation of China University of Petroleum,Beijing(No.2462018YJRC015)。
文摘Under the policy background and advocacy of carbon capture,utilization,and storage(CCUS),CO_(2)-EOR has become a promising direction in the shale oil reservoir industry.The multi-scale pore structure distribution and fracture structure lead to complex multiphase flow,comprehensively considering multiple mechanisms is crucial for development and CO_(2) storage in fractured shale reservoirs.In this paper,a multi-mechanism coupled model is developed by MATLAB.Compared to the traditional Eclipse300 and MATLAB Reservoir Simulation Toolbox(MRST),this model considers the impact of pore structure on fluid phase behavior by the modified Peng—Robinson equation of state(PR-EOS),and the effect simultaneously radiate to Maxwell—Stefan(M—S)diffusion,stress sensitivity,the nano-confinement(NC)effect.Moreover,a modified embedded discrete fracture model(EDFM)is used to model the complex fractures,which optimizes connection types and half-transmissibility calculation approaches between non-neighboring connections(NNCs).The full implicit equation adopts the finite volume method(FVM)and Newton—Raphson iteration for discretization and solution.The model verification with the Eclipse300 and MRST is satisfactory.The results show that the interaction between the mechanisms significantly affects the production performance and storage characteristics.The effect of molecular diffusion may be overestimated in oil-dominated(liquid-dominated)shale reservoirs.The well spacing and injection gas rate are the most crucial factors affecting the production by sensitivity analysis.Moreover,the potential gas invasion risk is mentioned.This model provides a reliable theoretical basis for CO_(2)-EOR and sequestration in shale oil reservoirs.
基金the National Natural Science Foundation of China fund (Project number: 52174045 and No. 52104011)Research Foundation of China University of Petroleum-Beijing at Karamay (No. XQZX20210001)PetroChina Innovation Foundation (2020D50070207)。
文摘Due to the reservoir heterogeneity and the stress shadow effect, multiple hydraulic fractures within one fracturing segment cannot be initiated simultaneously and propagate evenly, which will cause a low effectiveness of reservoir stimulation. Temporary plugging and diverting fracturing(TPDF) is considered to be a potential uniform-stimulation method for creating multiple fractures simultaneously in the oilfield. However, the multi-fracture propagation morphology during TPDF is not clear now. The purpose of this study is to quantitatively investigate the multi-fracture propagation morphology during TPDF through true tri-axial fracturing experiments and CT scanning. Critical parameters such as fracture spacing, number of perforation clusters, the viscosity of fracturing fluid, and the in-situ stress have been investigated. The fracture geometry before and after diversion have been quantitively analyzed based on the two-dimensional CT slices and three-dimensional reconstruction method. The main conclusions are as follows:(1) When injecting the high viscosity fluid or perforating at the location with low in-situ stress, multiple hydraulic fractures would simultaneously propagate. Otherwise, only one hydraulic fracture was created during the initial fracturing stage(IFS) for most tests.(2) The perforation cluster effectiveness(PCE) has increased from 26.62% during the IFS to 88.86% after using diverters.(3) The diverted fracture volume has no apparent correlation with the pressure peak and peak frequency during the diversion fracturing stage(DFS) but is positively correlated with water-work.(4) Four types of plugging behavior in shale could be controlled by adjusting the diverter recipe and diverter injection time, and the plugging behavior includes plugging the natural fracture in the wellbore, plugging the previous hydraulic fractures, plugging the fracture tip and plugging the bedding.
基金supported by the National Natural Science Foundation of China(Grant No.51974332)。
文摘Temporary plugging and diverting fracturing(TPDF),involving inner-fracture temporary plugging(IFTP)and inner-stage temporary plugging(ISTP),has been proposed as a widely applied technique in China,for promoting the uniform initiation and propagation of multi-clustered hydraulic fractures(HFs)in a horizontal well of the shale oil/gas reservoirs.However,how the key plugging parameters controlling the multi-fracture growth and the pumping pressure response during TPDF in shale with dense bedding planes(BPs)and natural fractures(NFs)is still unclear,which limits the optimization of TPDF scheme.In this paper,a series of TPDF simulation experiments within a stage of multi-cluster in a horizontal well were carried out on outcrops of Longmaxi Formation shale using a large-scale true tri-axial fracturing simulation system,combined with the acoustic emission(AE)monitor and computed tomography(CT)scanning techniques.Each experiment was divided into three stages,including the conventional fracturing(CF),IFTP and ISTP.Multi-fracture initiation and propagation behavior,and the dominant controlling parameters were examined,containing the particle sizes,concentration of temporary plugging agent(TPA),and cluster number.The results showed that the number of transverse HFs(THFs)and the overall complexity of fracture morphology increase with the increase in TPA concentration and perforation cluster number.Obviously,the required concentration of TPA is positively correlated with the cluster number.Higher peak values and continuous fluctuations of pumping pressure during TPDF may indicate the creation of diversion fractures.The creation of standard THFs during CF is favorable to the creation of diversion fractures during TPDF.Moreover,the activation of BPs nearby the wellbore during CF is unfavorable to the subsequent pressure buildup during TPDF,resulting in poor plugging and diverting effect.Notably,under the strike-slip fault stress regime,the diversion of THFs is not likely during IFTP,which is similar as the results of ISTP to initiate mainly the un-initiated or under-propagated perforation clusters.Three typical pressure curve types during TPDF can be summarized to briefly identify the hydraulic fracture diversion effects,including good(multiple branches or/and THFs can be newly created),fair(HF initiation along the slightly opened BPs and then activating the NFs),and bad(HF initiation along the largely opened BPs and then connecting with the NFs).
