The hole reaming and side cutting characteristics of offset one-cone bit and conventional one- cone bit were investigated on simulated drilling experimental equipment. The borehole diameter was a little larger than th...The hole reaming and side cutting characteristics of offset one-cone bit and conventional one- cone bit were investigated on simulated drilling experimental equipment. The borehole diameter was a little larger than the bit diameter due to side force. However, the reaming effect was not very apparent, whether drilling with an offset or conventional one-cone bit. The side cutting displacement increased gradually with increasing depth of drilling and side force. The side cutting displacement of offset onecone bits was larger than that of conventional ones under the same conditions of weight-on-bit （WOB）, rotary speed, side force and borehole depth.展开更多
As a new joint structure,the impact of initial imperfection to stress of Concave cone-toroid-cylinder combined shell was analyzed. Firstly the location and shape of combined shell's initial imperfection caused by ...As a new joint structure,the impact of initial imperfection to stress of Concave cone-toroid-cylinder combined shell was analyzed. Firstly the location and shape of combined shell's initial imperfection caused by welding was studied. Secondly dominated stress was chosen after comparing varioustypical stress. Then it was analyzed that the influence of imperfection to dominated stress via changing the shape of frame's deflection and shell's concave-convex. At last the strengthening case for combined shell with imperfection was pointed out. The conclusions are:(1) Stress of frame 9 is more sensitive to initial imperfection than circumferential stress of toroidmidsurface,which is a new concern;(2) To strength the frames in the sides of toroid not only can decrease the stress of frame,but also can reduce the circumference stress of toroid's midsurface.展开更多
The purpose of this paper is to study the effect of presence of fluid within and around a poroelastic circular cylindrical shell of infinite extent on axially symmetric vibrations. The frequency equation each for a pe...The purpose of this paper is to study the effect of presence of fluid within and around a poroelastic circular cylindrical shell of infinite extent on axially symmetric vibrations. The frequency equation each for a pervious and an impervious surface is obtained employing Biot’s theory. Radial vibrations and axially symmetric shear vibrations are uncoupled when the wavenumber is vanished. The propagation of axially symmetric shear vibrations is independent of presence of fluid within and around the poroelastic cylindrical shell while the radial vibrations are affected by the presence of fluid. The frequencies of radial vibrations and axially symmetric shear vibrations are the cut-off frequencies for the coupled motion of axially symmetric vibrations. The non-dimensional phase velocity as a function of ratio of thickness to wavelength is computed and presented graphically for two different types of poroelastic materials for thin poroelastic shell, thick poroelastic shell and poroelastic solid cylinder.展开更多
文摘The hole reaming and side cutting characteristics of offset one-cone bit and conventional one- cone bit were investigated on simulated drilling experimental equipment. The borehole diameter was a little larger than the bit diameter due to side force. However, the reaming effect was not very apparent, whether drilling with an offset or conventional one-cone bit. The side cutting displacement increased gradually with increasing depth of drilling and side force. The side cutting displacement of offset onecone bits was larger than that of conventional ones under the same conditions of weight-on-bit （WOB）, rotary speed, side force and borehole depth.
文摘As a new joint structure,the impact of initial imperfection to stress of Concave cone-toroid-cylinder combined shell was analyzed. Firstly the location and shape of combined shell's initial imperfection caused by welding was studied. Secondly dominated stress was chosen after comparing varioustypical stress. Then it was analyzed that the influence of imperfection to dominated stress via changing the shape of frame's deflection and shell's concave-convex. At last the strengthening case for combined shell with imperfection was pointed out. The conclusions are:(1) Stress of frame 9 is more sensitive to initial imperfection than circumferential stress of toroidmidsurface,which is a new concern;(2) To strength the frames in the sides of toroid not only can decrease the stress of frame,but also can reduce the circumference stress of toroid's midsurface.
文摘The purpose of this paper is to study the effect of presence of fluid within and around a poroelastic circular cylindrical shell of infinite extent on axially symmetric vibrations. The frequency equation each for a pervious and an impervious surface is obtained employing Biot’s theory. Radial vibrations and axially symmetric shear vibrations are uncoupled when the wavenumber is vanished. The propagation of axially symmetric shear vibrations is independent of presence of fluid within and around the poroelastic cylindrical shell while the radial vibrations are affected by the presence of fluid. The frequencies of radial vibrations and axially symmetric shear vibrations are the cut-off frequencies for the coupled motion of axially symmetric vibrations. The non-dimensional phase velocity as a function of ratio of thickness to wavelength is computed and presented graphically for two different types of poroelastic materials for thin poroelastic shell, thick poroelastic shell and poroelastic solid cylinder.
