定向钻进连续取心钻具设计及取心参数仿真分析

Design of drilling tool and simulation analysis of parameters for continuous coring in directional drilling

摘要:

在战略性矿产资源勘探取样过程中，传统的垂直孔面临着单孔投资高、获取地质信息有限等难题，无法满足高效增储勘探的需求。为此，基于绳索取心和定向钻井技术，设计了一种定向钻进连续取心钻具，能够高效精准的获取地下三维空间的地质岩心。针对该技术在硬岩中钻进效率低、钻具易折断、岩心难以连续获取等技术难点，采用仿真模拟的方法分别研究了钻压、转速、造斜率对定向取心钻进的影响。仿真分析结果表明，钻压、转速与钻进速度、造斜率和弯接头应力成正比，当钻压>30 kN、转速>230 r/min时即可满足6°/30 m的造斜需求。综合考虑钻具使用寿命，优选钻压为25~30 kN，转速为230~300 r/min。随着造斜率增大，岩心与岩心管之间的接触应力也随之变大，但最终的接触应力会保持在稳定范围内。当造斜率为9°/30 m时，最大的接触应力为514.7 MPa，均小于岩心管材质的屈服强度。上述仿真模拟为定向钻进连续取心钻具的钻进参数与造斜能力协调优化提供理论支撑。

Abstract:

In the process of strategic mineral resources exploration and sampling， the traditional vertical hole faces some difficulties， such as high investment in a single hole and limited access to geological information， which cannot meet the needs of high efficient exploration. Therefore， a directional continuous coring technique is proposed based on wireline coring and directional drilling technology， which can efficiently and accurately obtain geological cores in underground three-dimensional space. To solve the technical difficulties of low drilling efficiency in hard rock， easily break of drilling tools and difficulty in continuous core acquisition， the effects of weight on bit （WOB）， rotation speed and deviation rate on directional coring were studied by simulation. The results show that the WOB and rotation speed are proportional to the drilling speed ，deviation rate and bend-joint stress. When the WOB is more than 30kN and the rotation speed is more than 230r/min， the deviation rate of 6°/30m can be satisfied. Based on the comprehensive consideration of drilling tool life， the preferred WOB is 25~30kN and the preferred rotation speed is 230~300r/min. The contact stress between the core and core tube becomes larger with the increase of the deviation rate， but the final contact stress will be kept within the stable range. The maximum contact stress was 514.7MPa when the deviation rate is 9°/30m， which is less than the yield strength of coring tube. The study provides theoretical support for the coordinated optimization about drilling parameters and deviation capacity of directional continuous core drilling tools.