基于能量法的跟管钻进最大深度计算及应用

为解决潜孔锤跟管钻进最大深度难以确定的问题，基于能量法分析冲击功与应变能的转换情况，提出跟管钻进最大深度的假设条件和理论计算方法，并结合现有相关技术规范，通过类比法对跟管钻进的地层侧阻力取值进行完善和补充，然后应用相关实例分析和验证。通过研究和验证取得成果如下： 1）采用材料力学能量法理论，提出较系统、全面的跟管钻进最大深度计算方法； 2）给出单一地层最大深度的计算公式和多个地层的计算步骤； 3）提出套管与地层间动摩阻的取值依据和方法； 4）提出中和点概念，得出双冲击器作用下套管柱受到的应变能作用原理； 5）增大冲击功和增加套管壁厚均有利于提高跟管的最大深度，但影响幅度较小。

Calculation and Application of Maximum Depth of Drilling with Simultaneous Casing Based on Energy Method

The maximum depth of pneumatic DTH drilling with simultaneous casing is difficult to determine. Hence, a theoretical calculation method for the maximum depth of drilling with simultaneous casing is proposed based on the conversion of impact energy and strain energy using the energy method. The formation friction value for drilling is improved and supplemented using an analog method based on relevant technical specifications. Finally, case studies are conducted to analyze and validate the results. The results obtained are as follows: (1) A more systematic and comprehensive calculation method for the maximum depth of drilling with simultaneous casing is proposed by innovatively adopting the theory of energy method. (2) A method for calculating the maximum drilling depth with simultaneous casing in a single formation and a process for calculating the maximum drilling depth in multiple formations are obtained. (3) The basis and method for reducing friction between the casing and formation are proposed. (4) The concept of neutralization point is proposed, and the principle of strain energy acting on the casing string under the action of double impactors is obtained. (5) An increase in the impact energy and the casing thickness can slightly increase the maximum drilling depth with simultaneous casing.