Recently attention has been drawn to the frequently observed fifth power of the golden mean in many disciplines of science and technology. Whereas in a forthcoming contribution the focus will be directed towards <i...Recently attention has been drawn to the frequently observed fifth power of the golden mean in many disciplines of science and technology. Whereas in a forthcoming contribution the focus will be directed towards <i>Fibonacci</i> number-based helical structures of living as well as inorganic matter, in this short letter the geometry of the Great Pyramid of the ancient Egyptians was investigated once more. The surprising main result is that the ratio of the in-sphere volume of the pyramid and the pyramid volume itself is given by π⋅<i>φ</i><sup>5</sup>, where <i>φ</i> = 0.618033987<span style="white-space:nowrap;">⋅<span style="white-space:nowrap;">⋅</span><span style="white-space:nowrap;">⋅</span></span> is nature’s most important number, the golden mean. In this way not only phase transitions from microscopic to cosmic scale are connected with <i>φ</i><sup>5</sup>, also ingenious ancient builders have intuitively guessed its magic before.展开更多
Formation water invasion is the most troublesome problem associated with air drilling. However, it is not economical to apply mist drilling when only a small amount of water flows into wellbore from formation during a...Formation water invasion is the most troublesome problem associated with air drilling. However, it is not economical to apply mist drilling when only a small amount of water flows into wellbore from formation during air drilling. Formation water could be circulated out of the wellbore through increasing the gas injection rate. In this paper, the Angel model was modified by introducing Nikurade friction factor for the flow in coarse open holes and translating formation water rate into equivalent penetration rate. Thus the distribution of annular pressure and the relationship between minimum air injection rate and formation water rate were obtained. Real data verification indicated that the modified model is more accurate than the Angel model and can provide useful information for air drilling.展开更多
文摘Recently attention has been drawn to the frequently observed fifth power of the golden mean in many disciplines of science and technology. Whereas in a forthcoming contribution the focus will be directed towards <i>Fibonacci</i> number-based helical structures of living as well as inorganic matter, in this short letter the geometry of the Great Pyramid of the ancient Egyptians was investigated once more. The surprising main result is that the ratio of the in-sphere volume of the pyramid and the pyramid volume itself is given by π⋅<i>φ</i><sup>5</sup>, where <i>φ</i> = 0.618033987<span style="white-space:nowrap;">⋅<span style="white-space:nowrap;">⋅</span><span style="white-space:nowrap;">⋅</span></span> is nature’s most important number, the golden mean. In this way not only phase transitions from microscopic to cosmic scale are connected with <i>φ</i><sup>5</sup>, also ingenious ancient builders have intuitively guessed its magic before.
文摘Formation water invasion is the most troublesome problem associated with air drilling. However, it is not economical to apply mist drilling when only a small amount of water flows into wellbore from formation during air drilling. Formation water could be circulated out of the wellbore through increasing the gas injection rate. In this paper, the Angel model was modified by introducing Nikurade friction factor for the flow in coarse open holes and translating formation water rate into equivalent penetration rate. Thus the distribution of annular pressure and the relationship between minimum air injection rate and formation water rate were obtained. Real data verification indicated that the modified model is more accurate than the Angel model and can provide useful information for air drilling.
