气体钻井钻柱轴扭耦合动态屈曲数学建模与求解

针对钻柱轴扭耦合动态屈曲的基本问题构造哈密顿体系,在辛几何空间中将临界屈曲载荷和动态屈曲模态归结为辛本征值和本征解问题,从而形成一种辛几何算法.方法较好的解决了钻柱轴扭耦合动态屈曲的复杂边界条件问题.在解决气体钻井钻柱动态屈曲问题的研究中具有良好的应用前景.     

气体钻水平井井径扩大环空流动特征的数值模拟

由于气体钻水平井中岩屑受力状态与直井有很大不同,特另0是遇到井径扩大,更是携岩的关键点。因此,在分析了气体钻水平并岩屑运移特点以及建立环空连续性方程和动能方程的基础上,以实际并为例考虑了不同井径扩大率,数值模拟了其扩径段气固两相的流动状态,包括气固速度、岩屑浓度、压力分布等。研究结果表明：气体在经历扩径段时环空压力有个降落又回升的过程,随着井眼扩径系数的增大,压力下降又回升,所经历的长度会逐渐增长;扩径系数大于一定值时,扩径变径处存在一定区域的零流动区;扩径系数越大,低速区和回流区就越大越长,扩径下部区域越容易堆积岩屑,填充井眼。     

石油钻井物料清单的随机数量模型研究

针对石油钻井物料投资大、物料消耗随机不确定、管理控制难的现状,本文通过构建石油钻井物料清单,提出以石油钻井物料损耗数量为随机变量,按钻井开次分阶段计算方式,分别采用期望值和渴望水平原则方法,构建石油钻井物料清单的随机数量模型。该模型的建立与应用,为石油钻井企业缩短物资供应周期、降低库存成本,实现钻井物料供应的优化管理提供了辅助支持。     

A novel torque analysis method for drilling deep lunar soil by DEM

In order to solve the torque design problem of deep lunar soil sampling using drilling, a novel torque analysis method was presented based on discrete element model (DEM). This method includes three stages: drilling simulation of the bit and stem segment, resultant torque calculation, and predicted curve fitting. First, special drilling models were designed for a bit and stem separately. A high-density equivalent particle group, boundary vibration control, pre-drilling simulation and constant pressure surface control were designed for the bit and stem drilling modelling at different depths to ensure the rationality of the model. An example of the torque synthesis process was given, and the simulation time was analyzed. Finally, the simulation predicted torque curve was plotted and compared with the experimental curve. The experimental and simulation curves show that as the drilling depth increases, the torque increases approximately linearly first and then flattens out gradually after a depth of 1 m. The consistency between the two results indicated that the proposed method was validated. Using this method, engineers can take short time to analyze the torque and design basic parameters of the drill mechanism. The problem of high experimental cost and long simulation time in torque design is solved.     

基于电缆-无线耦合的随钻测井信号传输新方法及其数值模拟研究

信号传输是随钻测井的重要组成部分, 也是随钻测井进一步发展的瓶颈.针对这个问题, 研究了由Novatek^TM提出的基于钻杆内有线传输, 钻杆间电磁耦合传输的随钻信号高速传输方法.首先, 针对钻杆间的电磁耦合结构的对称性, 采用了高效的数值模式匹配法对该耦合结构进行了电磁建模; 然后, 为了优化钻杆间耦合结构的耦合性能, 利用上述的电磁建模方法对该耦合结构进行了仿真分析, 分析了该耦合结构各个参数对耦合性能的影响, 并得出了一些有意义的结论, 该结论能够指导随钻测井信号钻杆间耦合传输的优化设计.另外, 钻杆内传输线利用矩形传输线设计, 设计出了50 Ω 特性阻抗的矩形传输线, 并计算了相关损耗.最后, 通过仿真和实验验证了优化设计的钻杆间耦合传输结构具有非常好的传输性能, 并且仿真和实验结果符合良好. 关键词： 随钻信号传输 数值模式匹配 电磁耦合 矩形传输线     

振动钻削微小孔中钻头寿命与振动参数的二次回归试验研究

本文采用正交组合设计的试验方法，对振动钻削微小孔加工中钻头寿命与轴向振动参数之间的非线性关系进行了二次回归试验，得到了最优回归方程。用回归方程给出的最佳振动参数钻孔，钻头寿命提高了９６．３％     

Laser drilling of thick material using femtosecond pulse with a focus of dual-frequency beam

Laser drilling is one of the basic, most frequently performed, material removal processes. The drilling aspect ratio is theoretically limited by the size and the focal depth of the machining laser spot. The aspect ratio can be improved by using dual focus. In this paper we describe a focus of two different frequencies based on the longitudinal chromatic aberration arisen when polychromatic collimated light is incident on a positive lens element. In the experiments, a Ti:Sapphire laser of 800 nm wavelength and 150 fs pulse duration was used as a source. Two tightly focused laser spots few hundred micrometers apart from each other were formed by focusing a combined collimated laser beam which contains the fundamental optic frequency and the second harmonic optic frequency. The focus of dual-frequency beam was used to drill a 3 mm thick PMMA plate. The drilling aspect ratio of a dual-frequency beam was compared to that of a focus of single frequency beam. Experimental results reveal that dual-frequency beam increases the aspect ratio and improves the drilling quality in terms of profile of the produced features.     

Use of laser drilling in the manufacture of organic inverter circuits

Inverter circuits have been made by connecting two high-quality pentacene field-effect transistors. A uniform and pinhole-free 900 nm thick polyimide gate-insulating layer was formed on a flexible polyimide film with gold gate electrodes and partially removed by using a CO₂ laser drilling machine to make via holes and contact holes. Subsequent evaporation of the gold layer results in good electrical connection with a gold gate layer underneath the gate-insulating layer. By optimization of the settings of the CO₂ laser drilling machine, contact resistance can be reduced to as low as 3 Ω for 180 μm square electrodes. No degradation of the transport properties of the organic transistors was observed after the laser-drilling process. This study demonstrates the feasibility of using the laser drilling process for implementation of organic transistors in integrated circuits on flexible polymer films.