1.Institute of Exploration Techniques, CAGS, LangfangHebei065000, China;2.China University of Geosciences (Beijing), Beijing100083, China;3.College of Construction Engineering, Jilin University, ChangchunJilin130026, China
Clc Number:
P634
Fund Project:
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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.