Hydraulic fracturing and commingle production of multiple layers are extensively adopted in unconventional tight gas reservoirs.Accurate determination of parameters of individual layers in multilayered tight gas reser...Hydraulic fracturing and commingle production of multiple layers are extensively adopted in unconventional tight gas reservoirs.Accurate determination of parameters of individual layers in multilayered tight gas reservoirs is essential for well performance evaluation and development strategy optimization.However,most analytical models for fractured vertical wells in stratified gas reservoirs focus on fully penetrated hydraulic fractures,neglecting the influence of partial penetration of hydraulic fractures.This paper presents a semi-analytical model to investigate the transient pressure behavior of vertically fractured wells in dual porosity multi-layered tight gas reservoirs.The partial penetration of hydraulic fracture,the vertical heterogeneities of layer properties,the differences between hydraulic fracture lengths in each layer and the stress sensitivity are all incorporated in the proposed model.The point-source solution,Laplace transformation,Fourier transformation,Pedrosa's transformation,perturbation technique,and the superposition principle are applied to obtain the analytical solution of transient pressure responses.The proposed model is validated against a commercial software,and the transient pressure behavior of vertically fractured wells in multi-layered tight gas reservoirs are analyzed.Based on the characteristics of the type curves,seven flow regimes can be identified,including wellbore storage,transitional flow period,reservoir linear flow period,vertical pseudo-radial flow in fracture system,inter-porosity flow period,late-time pseudo-radial flow period,and the boundary-dominated flow period.Sensitivity analyses reveal that the penetration ratio of hydraulic fracture has primary influence on early-time transient pressure behavior and production contribution,while the stress sensitivity mainly affects the late-time transient pressure behavior.Gas production at the initial stage is mainly contributed by the high-pressure/high-permeability layer,and gas backflow will occur during initial production stage for obviously unequal initial formation pressures.Finally,two field cases are conducted to illustrate the applicability of the proposed model.The model and corresponding conclusions can provide technical support for performance analysis of tight gas reservoirs.展开更多
To overcome the limitations of structural height imposed by airspace restrictions in the design of maintenance hangar roofs with long spans,a new diagonal truss roof structural system is introduced for the first time....To overcome the limitations of structural height imposed by airspace restrictions in the design of maintenance hangar roofs with long spans,a new diagonal truss roof structural system is introduced for the first time.In the design of China Southern Airlines No.1 Hangar,4 main trusses were arranged diagonally along the depth direction,forming a W-shape truss.3 lineshaped trusses were arranged along the span direction,and double-layer space latticed structure is laid on them.The design optimized the height of the 183 m+222 m super long-span roof to 11.5 m,the maximum dimension the site could provide,so that the building height is within the permitted 40m.The steel consumption of the roof is only 165 kg/m^(2).The installation of diagonal trusses changed the unidirectional load transmission path of the roof and enhanced the spatial load transmission,effectively relieving the burden on the gate-side truss.This design enables the implementation of a maintenance hangar with a 222 m-span and heavy roof within the constraints of low airspace height.展开更多
The formability of aluminum alloy AA7075 at elevated temperature was investigated through experiment. Stress-strain relationship at different temperatures and forming speeds were investigated through tensile testing. ...The formability of aluminum alloy AA7075 at elevated temperature was investigated through experiment. Stress-strain relationship at different temperatures and forming speeds were investigated through tensile testing. Deep drawing and stretch formability were also tested through limiting drawing ratio （LDR） and limiting dome height （LDH） tests. Finally, post forming mechanical property testing was conducted to investigate the effects of exposure to warm forming temperatures on the mechanical properties. Results show that deep drawing and stretch formability of AA7075 can be significantly improved when the blank is heated to 140-220 °C. At temperature over 260 °C, formability and post forming mechanical properties begin to decrease due to the effect of the heating and forming processes on the material＇s temper.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.52174036,52234003)the Sichuan Province Science and Technology Program(Grant No.2024NSFSC0199)the Joint Fund for Innovation and Development of Chongqing Natural Science Foundation(Grant No.2023NSCQ-LZX0184).
文摘Hydraulic fracturing and commingle production of multiple layers are extensively adopted in unconventional tight gas reservoirs.Accurate determination of parameters of individual layers in multilayered tight gas reservoirs is essential for well performance evaluation and development strategy optimization.However,most analytical models for fractured vertical wells in stratified gas reservoirs focus on fully penetrated hydraulic fractures,neglecting the influence of partial penetration of hydraulic fractures.This paper presents a semi-analytical model to investigate the transient pressure behavior of vertically fractured wells in dual porosity multi-layered tight gas reservoirs.The partial penetration of hydraulic fracture,the vertical heterogeneities of layer properties,the differences between hydraulic fracture lengths in each layer and the stress sensitivity are all incorporated in the proposed model.The point-source solution,Laplace transformation,Fourier transformation,Pedrosa's transformation,perturbation technique,and the superposition principle are applied to obtain the analytical solution of transient pressure responses.The proposed model is validated against a commercial software,and the transient pressure behavior of vertically fractured wells in multi-layered tight gas reservoirs are analyzed.Based on the characteristics of the type curves,seven flow regimes can be identified,including wellbore storage,transitional flow period,reservoir linear flow period,vertical pseudo-radial flow in fracture system,inter-porosity flow period,late-time pseudo-radial flow period,and the boundary-dominated flow period.Sensitivity analyses reveal that the penetration ratio of hydraulic fracture has primary influence on early-time transient pressure behavior and production contribution,while the stress sensitivity mainly affects the late-time transient pressure behavior.Gas production at the initial stage is mainly contributed by the high-pressure/high-permeability layer,and gas backflow will occur during initial production stage for obviously unequal initial formation pressures.Finally,two field cases are conducted to illustrate the applicability of the proposed model.The model and corresponding conclusions can provide technical support for performance analysis of tight gas reservoirs.
文摘To overcome the limitations of structural height imposed by airspace restrictions in the design of maintenance hangar roofs with long spans,a new diagonal truss roof structural system is introduced for the first time.In the design of China Southern Airlines No.1 Hangar,4 main trusses were arranged diagonally along the depth direction,forming a W-shape truss.3 lineshaped trusses were arranged along the span direction,and double-layer space latticed structure is laid on them.The design optimized the height of the 183 m+222 m super long-span roof to 11.5 m,the maximum dimension the site could provide,so that the building height is within the permitted 40m.The steel consumption of the roof is only 165 kg/m^(2).The installation of diagonal trusses changed the unidirectional load transmission path of the roof and enhanced the spatial load transmission,effectively relieving the burden on the gate-side truss.This design enables the implementation of a maintenance hangar with a 222 m-span and heavy roof within the constraints of low airspace height.
文摘The formability of aluminum alloy AA7075 at elevated temperature was investigated through experiment. Stress-strain relationship at different temperatures and forming speeds were investigated through tensile testing. Deep drawing and stretch formability were also tested through limiting drawing ratio （LDR） and limiting dome height （LDH） tests. Finally, post forming mechanical property testing was conducted to investigate the effects of exposure to warm forming temperatures on the mechanical properties. Results show that deep drawing and stretch formability of AA7075 can be significantly improved when the blank is heated to 140-220 °C. At temperature over 260 °C, formability and post forming mechanical properties begin to decrease due to the effect of the heating and forming processes on the material＇s temper.
