Carrying capacity of the casing will reduce after the casing is worn, which seriously affects the subsequent well drilling, well completion, oil extraction and well repair. A lot of researches on calculation of casing...Carrying capacity of the casing will reduce after the casing is worn, which seriously affects the subsequent well drilling, well completion, oil extraction and well repair. A lot of researches on calculation of casing wear collapse strength have been done, but few of them focus on collapsing failure mechanism, and influencing factors and law of collapse strength. So, significant difference between estimated value and actual value of collapse strength comes into being. By theoretical analysis, numerical simulation and actual test, the collapsing failure mechanism of casing wear as well as the influencing factors and laws of collapse strength are investigated, and the investigation results show that collapse of crescent casing wear belongs to 'three hinged' instability. The severely-worn position on the casing is yielded into the plastic zone first then deformed greatly, which causes the plastic instability of the whole structure. The casing wear collapse strength presents changes of exponent, power function and linear trend with the residual casing wall thickness, wear radius and axial load, respectively. When the flexibility is less than 10°/30 m, the borehole bending has less impact on casing collapse strength. Thus, the computation model for the casing wear collapsing strength is established by introducing wear radius coefficient and casing equivalent yield strength, at the same time, the model is tested. The test results show that the relative error for the computation model is less than 5%. The research results provide a basis for design of the casing string strength and evaluation of down-hole safety.展开更多
This paper deals with the production of aluminum alloy (LM-13) reinforced with titanium carbide (TiC) chilled composites subject to different chilling rates to study the effect of chilling on microstructure, mechanica...This paper deals with the production of aluminum alloy (LM-13) reinforced with titanium carbide (TiC) chilled composites subject to different chilling rates to study the effect of chilling on microstructure, mechanical and tribological behavior. Metallic and non-metallic chills (25 mm thick) were used in this investigation. The specimens taken from casting blocks were tested for their microstructure, strength, hardness and wear behavior. It was found in the present investigation that chilling rate and addition of TiC reinforcement (3 to 12 wt% in steps of 3 wt%) have improved both mechanical properties (strength and hardness) and wear resistance of the composite developed. Out of the chills used, copper chill was found to be good in improving mechanical properties because of its high Volumetric Heat Capacity (VHC). It is concluded from the above investigation that type of chill and hence chilling rate, reinforcement content have an effect on mechanical properties wear behavior.展开更多
文摘Carrying capacity of the casing will reduce after the casing is worn, which seriously affects the subsequent well drilling, well completion, oil extraction and well repair. A lot of researches on calculation of casing wear collapse strength have been done, but few of them focus on collapsing failure mechanism, and influencing factors and law of collapse strength. So, significant difference between estimated value and actual value of collapse strength comes into being. By theoretical analysis, numerical simulation and actual test, the collapsing failure mechanism of casing wear as well as the influencing factors and laws of collapse strength are investigated, and the investigation results show that collapse of crescent casing wear belongs to 'three hinged' instability. The severely-worn position on the casing is yielded into the plastic zone first then deformed greatly, which causes the plastic instability of the whole structure. The casing wear collapse strength presents changes of exponent, power function and linear trend with the residual casing wall thickness, wear radius and axial load, respectively. When the flexibility is less than 10°/30 m, the borehole bending has less impact on casing collapse strength. Thus, the computation model for the casing wear collapsing strength is established by introducing wear radius coefficient and casing equivalent yield strength, at the same time, the model is tested. The test results show that the relative error for the computation model is less than 5%. The research results provide a basis for design of the casing string strength and evaluation of down-hole safety.
文摘This paper deals with the production of aluminum alloy (LM-13) reinforced with titanium carbide (TiC) chilled composites subject to different chilling rates to study the effect of chilling on microstructure, mechanical and tribological behavior. Metallic and non-metallic chills (25 mm thick) were used in this investigation. The specimens taken from casting blocks were tested for their microstructure, strength, hardness and wear behavior. It was found in the present investigation that chilling rate and addition of TiC reinforcement (3 to 12 wt% in steps of 3 wt%) have improved both mechanical properties (strength and hardness) and wear resistance of the composite developed. Out of the chills used, copper chill was found to be good in improving mechanical properties because of its high Volumetric Heat Capacity (VHC). It is concluded from the above investigation that type of chill and hence chilling rate, reinforcement content have an effect on mechanical properties wear behavior.
